Deep cycle batteries - please help me fix!
 

Hi folks

I'm currently on a trans-Africa expedition. At the moment I've got 3 x 110 Amp/hour batteries in my truck, and after a year on the road, they're getting a little tired (ie: after many quite severe discharges they are not holding charge too well, or at least I get that impression - perhaps I'm just using too much charge and need to just increase the total Amp/hours capacity in my truck.) I'm in Nairobi in Kenya at the moment, and can get some new leisure batteries here.

My questions are thus:

1. If I buy some new batteries is it ok to connect them in parallel with the old batteries to eke out what life is left in the old batteries, or will the old batteries damage the new batteries, and therefore should I replace the old batteries in their entirety?

2. Is there a way to tell how much life is left in the old batteries? Will a battery outlet be able to tell me this? At what point should I consider replacing the old batteries?

3. If it's ok to add the new batteries in parallel with the old batteries, should I get new batteries with the same Amp/hour rating as my old batteries, or is it ok to mix and match Amp/hour ratings?

Many thanks in advance for your help!

Regards
Steve

(details on our journey if you're interested: www.overafrica.org)

Hi Steve-long time no speak (as it were!).

To answer your questions:
a) Don't wire the old and the new in together. The new will simply discharge into the old and knacker the new ones too. Bin the old and fit new ones. 300 amp/hr should be more than sufficient for what I remember of your set up. My truck has 270 and will run a compressor fridge full time even here in the UK-though not in the winter. Personally I wouldn't bother going to the extra expence of leisure batteries per se and would just use ordinary ones. The difference is that the plates on leisure batteries are thicker and will cope better with being over discharged and over charged. Provided you look after them a standard battery will do fine. I would suggest that you ensure that the new batteries are fully and properly charged before you fit them as a solar system may not be able to do this by itself

b) There may be. Some shops have a meter which is touched across the two terminals to see what the battery discharge rate is (causes a big spark) and this will tell you whether the battery is OK or not. But if the set up isn't holding its charge then at least one of the batteries is knackered and is pulling in charge from the others. This is because there will be a potential difference between them: i.e. one will be at a lower voltage than the other(s) My advice would be to replace the lot as for example if you replace 1 or even 2 because they're wired in parallel the new one will always be better than the old one(s) and the problem will persist, at least to some extent.

c) you can mix ampere hour ratings safely. As above, the key is the voltage.

Must have a look at your blog. The last time I looked you were in Angola!

Have fun

All the best Q

My system
 

Hi Q

Thanks for your response! Me thinks it must be 1 or more dead batteries. I'm sure, looking at the configuration of my system, it should be more than sufficient.

Here is a breakdown of the system, if that will help shed light on any issues.

Power producing

• 3 x 110Ah batteries
• 2 x 120W solar panels, producing only when sunny (which in Africa is almost all the time) +/-7A produced at midday, +/- 4A produced at 9AM and 5PM. Solar panels are controlled using a Steca PR10 30 charge regulator
• Truck alternator, producing 10A when truck is running (I have a 10A 24/12V converter connected to the truck alternator)
• Mains charging, producing only when at campsites providing electrical hookup

Power consuming

• National Luna freezer - 12V - 2.5Amps average running current. 1.53 - 2.6 amp/hour average power draw (I'd say on average it runs for 1 hour in every 2 hours, during the day)
• Sound system - 400W amplifier (100W x 4 channels), used +/-3 hours per day, when truck is not running
• Laptop computer - 12V 4.6A charger, used +/-3 hours per day
• Surflo pump - can draw 7A, but it only runs intermittently (ie: when a tap is opened – we don't use it for the shower a lot)
• LED lights - minimal consumption, only on for +/-4 hours per day

What do you think?

Thanks again
Steve
www.overafrica.org

It's really best to use identical batteries in parallel, because if you mix types then as soon as some power is drawn from the two different batteries, they won't be identical voltage and one will discharge into the other. You can use somewhat different batteries in series, i.e. in constructing a 24V system.
You will have difficulty finding deep cycle batteries in Angola, but it will be easier in Namibia and RSA.

Charlie

PS (10/15/09): Your solar panels produce only 7A max @ 12V? 120W panels should produce 7A EACH or 14A total; unless hooked in series for 24V (actually 35V regulated down to 28.8). My two 123W panels produce max 12-14A at >60 deg. N in the high summer of July. You may have one bad panel, check with a meter.

True Charlie but that's only really an issue if you use batteries of really different capacities e.g a 70 A/hr and a 170A/hr. I have used a decent 170 Varta and a 110 slightly dodgy Moroccan battery for 2 years now without problem.

Blimey Steve that's one hell of a sound system! Are you broadcasting to Africa? Seriously, I haven't done the calculations but your set up is much like mine so you shouldn't have a problem but that amplifier is going to use a massive amount of energy. I don't know if 400W is the consumption-it surely can't be but if it is-at 12V DC that would draw over 33 amps and really flatten any battery in next to no time. Over 3 hours (if 400W is the consumption) it would use 1200 watts whereas your fridge drawing 2.5 amps and on 12 hours out of 24 would only use 30Watts in a whole day. Can I suggest you try a day or 2 without the sounds (man!) and see what happens.

It's a good sound system! :)
I've managed to find the specs for the amp online, and it says the current drain, at the rated output, is 24A. That's still pretty power hungry isn't it?

Yep Steve. That may well be your problem. See how the batteries stand up after a few days off the music.

Steve
I asked a friend of mine who's up to speed with 'things electrical' for advice.
It seems like the battery/ies that start your truck are designed to deliver high amperage quickly but do not like going under about half their charge. They should not be deep cycle batteries.

For slower discharging batteries i.e deep cycle ( for fridges etc) these are designed to give less sudden amperage but for longer and don't mind being totally discharged.- and they are more expensive too-

You do not mention how your system is set up but it seems you may be using 3 of the same deep cycle ones and there is probably your problem.
And as for your hifi..... that's very power munching
Sounds like you may need new batteries and of the correct type.

For slower discharging batteries i.e deep cycle ( for fridges etc) these are designed to give less sudden amperage but for longer and don't mind being totally discharged.- and they are more expensive too-

As I understand it you shouldn't be discharging your deep cycle batteries fully if you want them to last. I'm no expert but from what I've read discharging to 2/3 or max 1/2 regularly will ensure a good lifetime for your deep cycles, any more than that and they'll suffer.

There's a piece here with some good info.

Bertrand, I have 2 12V truck starter batteries connected in series to provide 24V for starting the truck, and indeed they are designed to provide a high current for a short period of time. Then I have 3 12V leisure batteries (aka deep-cycle batteries) connected in parallel to provide 330 amp hours for the campervan side of things (ie: fridge, lights, pump, music etc). Deep cycle batteries, as you mentioned, are designed to provide a low current drain over a long period of time, which is what the campervan side of things will do. This is how the system is designed, and indeed should be designed.

As for deep-cycle batteries being happy with being completely discharged, this is incorrect. You will severely shorten your batteries lifetime if you completely discharge them. An example comparison of discharge depth versus life in cycles (a cycle being one charge/discharge cycle) for one type of deep-cycle battery is: 30% ~ 800, 50% ~ 400, 80% ~ 250, 100% ~ 100.

As for the amp, I've been doing some thinking on that: It would be interesting to know what current drain the amp causes in practice, coz we hardly ever listen to the music at full blast. I'd guess a far lower current drain, proportional to the percentage of max output we listen at?

My reasoning is this: I completed the entirety of the west coast of Africa (which is not at all set up for tourism, so there was practically never a chance to hook up to mains) with the 3 batteries I currently have. At one point, in Congo-Brazzaville, we got stuck for 2 weeks fighting with the Angolan embassy to get visas for Cabinda. During those 2 weeks we sat virtually all day every day in the truck, waiting for word from the Angolans, and the South African embassy who took up the fight for us (to no avail, but that's a long story... if you're interested, read here: OverAfrica - Congo-Brazzaville - the exodus)

Anyway, as you can imagine, we spent a lot of time listening to music while we twiddled our thumbs (probably in the order of 5 or 6 hours a day I'd guess.) There was a fair amount of rain around, being at the equator and just before the onset of the rainy season, so the solar panels weren't producing a huge amount of charge. At no point did our battery charge die. The solar panels were capable of keeping up with the current drain.

With that in mind, I'd say that perhaps the way we use the sound system is ok, and it's one or more batteries that have died. It would also probably be worthwhile getting a higher-current rated 24/12V converter for the truck's alternator, but not hugely necessary.

Any thoughts?

Thanks
Steve
OverAfrica - overland, over Africa

Steve- super website- enjoyed reading it- thank you

From what you say above I'm scratching my head here....all I can think of is that it's perhaps just time to replace your batteries with new ones - if so I would personally chose the same type, brand etc and replace them all together.
Other option as you say is going the higher-current rated 24/12V converter for the truck's alternator.
The minimalist in me also says to lose the hifi..... and go the Ipod and 'inMotion' IM9 route!:innocent:
It has a mains powered transformer but can run off 'C' batteries or better still on universal adapter so no need for mains- unit only needs 17 volts and 2.3Amps- way (too) loud, awesome sound !

Try and get in touch with Quintin who has a somewhat large truck! he might be able to go into details of how he has sorted his out.

I've been speaking to Collyn who wrote the Motorhome Electrics book (which I ingeniously left behind when we started the trip!)

His advice for checking the state of the individual batteries is this:
Fully charge the 3 batteries. Isolate and measure their individual voltage levels. After 30 mins re-measure their individual voltage levels. If there is a significant drop in voltage in one of the batteries (+0.2V) this is most likely the culprit. Now connect a load that draws about 1`0% of the battery Ah capacity (if 100 Ah use about 10 amps) to each battery in turn, and measure the voltage with the load connected after at least 2 hours. Batteries should really be within about 0.2V - if any battery has a voltage 0.5V lower than the others, that is the one that is stuffed.

I'm planning on doing this today... I'll report back with the results! Here's hoping I actually get results that make sense! :)

Hi all. Be intrigued to see what you discovered about the batteries Steve and I agree, in the absence of a 'proper' tester that is the way to go to find out how healthy each of your batteries is. The only problem with that method is that it assumes there is one perfectly healthy battery!

That said, your amp is really hammering your electrics. The fact that you're not turning the volume up is irrelevant because turning up the volume merely increases the pre-amp output voltage, i.e. the voltage that goes into your main amp. It won't affect the amount of power your amp is consuming. In other words no matter how low the volume is the amp will still be consuming 24 amps. I assume you have a standard stereo unit (radio/CD/MP3) plugged into a separate amp. I suspect that the reason you didn't have a problem down the West side is because the batteries were in good condition and (just) capable of satisfying your needs. As soon as they got a bit tired the load proved too much, exaccerbating the tired condition of the batteries.

I would be interested to know what voltage your batteries reach after a standard charge and without any load. Broadly anything over 12.7 volts would be regarded as fully charged. Similarly what is the voltage after say 2 hrs of 'the sounds'? Anything under 12 volts would be substancially discharged. I have seen a table somewhere which lists voltage with remaining battery capacity. Perhaps someone else can post it?

I'm not quite clear about you leisure side charging set up. Are you charging the leisure batteries (LBs) direct off the alternator simply using a voltage dropper and without regulating the alternator output? If so you could well be over-charging the LBs which might explain why they failed-if they have. I may be confused because I seem to recall you had a Sterling Battery-2-Battery charger. These are dead good because they vary the charge according to the state of charge of the LBs. Anyway, that's a side issue.....

Be interested in your results Steve

Q

Good point Q. I'll be sad to see my amp go, but for the sake of keeping the system in good health, it's gotta go. :( I've only got an iPod, no car radio or anything, so it's directly connected to the amp, I guess I'll just have to replace it with a lower power one.

For the testing side of things, here are my results:

I managed to get a hydrometer to test specific gravity. All I know about reading the results is that if it's in the "green section" (1.24), then the cell's ok, if not, then that's bad! :)

What I did is this:

Charged the batteries overnight, disconnected and measured the voltages.

Battery 1 had 12.81V
Battery 2 had 12.71V
Battery 3 had 12.73V

Specific gravity results:
Battery 1 (12.81V after charging)
Cell 1: 1.245
Cell 2: 1.24
Cell 3: 1.23
Cell 4: 1.245
Cell 5: 1.245
Cell 6: 1.25

Battery 2 (12.71V after charging)
Cell 1: 1.245
Cell 2: 1.24
Cell 3: 1.24
Cell 4: 1.245
Cell 5: 1.235
Cell 6: 1.245

Battery 3 (12.73V after charging)
Cell 1: 1.255
Cell 2: 1.25
Cell 3: 1.25
Cell 4: 1.255
Cell 5: 1.25
Cell 6: 1.255

Not sure what all this means, but I see batteries 1 and 2 both have a cell that is below 1.24.

Then I connected a handheld spotlight (not sure of the power rating, but since it's the same load for each battery I guess it should show if 1 battery is buggered over the others) for an hour to each battery in turn, and measured the voltage afterwards (with the load connected).

Battery 1 reads 12.25V (so a 0.56V drop)
Battery 2 reads 12.2V (so a 0.51V drop)
Battery 3 reads 12.2V (so a 0.53V drop)

I really don't know what these results mean... Battery 3 I thought would fare better, after the specific gravity check, but it's got pretty much the same voltage drop as the others.

Probably best to just change all 3, costly, but better than having them all die on me when I'm in the middle of the boondocks somewhere?!

As for the alternator charging side of things, I have a 15A switch-mode 24/12V converter. (Previously I said I had a 10A converter, but I made a mistake, it's actually 15A - which is still a bit low perhaps?) Not sure of the make, it has "AVDCDC15" written on it, Google reveals this is made by a company called "Amber Valley" but I can't find anything relevant online.

Any ideas at all?

Thanks for all the help
Steve

Your converter is from "K Po" I think.
K-PO - CB-Radios and Accessories -

http://www.everthammink.nl/images/00016556.JPG

Right Steve, at least 2 of your batteries are past it; caused almost certainly by being over-discharged which has caused suphation of the plate surfaces. The third isn't brilliant either. After a full charge the specific gravity should have been at least 1.26 across all cells. Ideally you should have left the batteries at least a couple of hours before testing the SG and for that reason I rather discount the post-charge voltage readings as they are too high for these SG readings. See this table. I should explain that the higher the voltage, the higher the SG should be.

State of ChargeSpecific GravityVoltage

12V 100% 1.265 12.7
75% 1.225 12.4
50% 1.190 12.2
25% 1.155 12.0
Discharged 1.120 11.9


I would be interested to to know what the SGs were after your lamp experiment. Bet they would be at best 1.2. If so basically this would mean that after drawing the current of the work lamp for 1 hour the batteries were at 50% capacity. A 100 Amp/hr battery ought theoretically to be able to provide 100 amps for 1 hr, 50 amps for 2 hrs etc. I don't know what bulb is in your work lamp but if its a 55 Watt H3 bulb, that would draw 4.58 amps. You will see from this that the batteries simply aren't doing the biz. The voltage ought to be more than 12.2. The bottom line is that its time to get some new ones.....

A word about your charging system. If this is a simple voltage dropper fed off your alternator rather than a proper charger i.e. a device that varies the rate of charge (i.e. the amps) according to the battery's needs then there is a risk that the batteries could be over charged. Putting 15 amps constantly into a fully charged battery will just damage it. I don't want to alarm you unnecessarily as it may be that what you're using is rather more sophisticated than that. Why don't you ask on the SBMCC forum? Someone there might be able to help.

As far as the sounds go, why don't you simply buy a car radio with an auxilliary input for your I-Pod? This will use far less power and be perfectly loud enough.

All the best Steve and tell us how you get on.

Q
I can't get the table to format properly so its best to look here Battery Tutorial | BatteryStuff.com

Hi Q

Thanks for all the info. Comprehensive as always!

After fully charging, I left the batteries standing for about 6 hours then did the voltage and SG checks, connected the loads, and did the post-load voltage check. I didn't do an SG check after the load though, which as you say, would have probably yielded more interesting results. I went to a solar place here in Nairobi yesterday and found 3 100Ah batteries for +/- US$800, or 2 200Ah batteries for +/- US$1000. Pretty expensive, so in the interim I've left my 3 110Ah batteries with them to be properly tested. They seemed pretty confident they could test them properly, so I'll find out what they say on Monday or Tuesday.

As for the car radio route, my setup is a bit more complicated unfortunately. We have a single amp, with 2 sets of speakers connected to the same 2 channel output. 1 set is in the cab, the other in the box. I then have a 2-way switch which switches between cab or box. I have an input for the iPod in the cab and box, and just move the iPod between the 2. However, that said, I think I may have found someone here in Nairobi who wants to swap my high-power amp for a lower power one. I didn't think it would be tricky to find someone, coz I reckon it's a pretty sweet deal for whoever gets the bigger amp!

As for the charger, I think I've just got a basic converter that shoves the 15A into the batteries when I'm driving. Perhaps that's not good for the batteries, although that leads me to wonder about what happens with a car's charging system. When the alternator is running it's generating quite a large amount of amps (my truck's alternator generates 24V/55A, most 12V alternators generate in the order of 100A). What happens to the vehicle's batteries when that huge amount of current is pouring into the batteries while driving? Surely they too would be damaged?

Cheers
Steve

I always thought that the state of charge of the battery will determine how many amps it is being charged by. As the state goes goes up, so does it's voltage and the alternator and battery eventually come to a state of balance when it is fully charged.

Your normal truck batteries are charged from the alternator and you've no problems with these? But your leisure batteries are charged from the alternator via the 24/12V converter.
If they are being overcharged is it this that is the problem?

I can't say I really know for sure what I'm talking about and I may be asking more questions than giving answers, hopefully I'll be corrected by someone more knowledgeable. But I suppose an ammeter connected in line between the converter and the batteries will tell you if the amperage is dropping as the batteries become more charged.

Steve at that price you'd be daft to get some new batteries when basically all you're using them for is to power your amp. The batteries ought to be more than capable of powering the rest of your load (LED lights, fridge etc). I suggest you sort out the stereo etc and save your money. It's most unlikely that one or more of the batteries are going to die completely in the near future (they're not that bad) so what I would do is monitor the LB voltage and make sure that you don't completely discharge them.

Don't forget that you don't need to use leisure batteries. Sure they have thicker, stronger plates designed for slow long-term discharge (it's all explained in that link I posted in my last message) but a battery is a battery and a standard 'starter' battery will do all you need. Sure they're capable of providing instant high current but I've been using them on my truck for 3 years now without any problem. The one thing you mustn't do with them is discharge them fully as the plates will sulpate up more readily. The guy who runs my local truck electics place uses standard i.e. non-leisure batteries in his caravan as well.

I really don't know much about alternators etc but I'm just a bit queasy (spelling?) about a system where you've effectively got 5 batteries all being charged by the one source with the only regulation being, if you pardon the pun, the regulator. The Sterling system separates the starting and the leisure side and controls the amount of charge going into the latter depending on it's needs. With your system there's no such separation. Surely someone here with more knowledge than me can comment?

Q

Theres a lot of info on here too:-

Motorhome Forums, Motorhome Discussion, Motorhome Chat - Forums

I have a Sterling system. It charges the leisure batteries at as fast a rate as is safe by raising the voltage a bit till the leisure batteries get near fully charged. It protects the chassis batteries by letting them take the full alternator output for the first 2 min after starting and also refusing to charge the leisure batteries till starting battery voltage >13.2V. Their BB241230 takes power out of a 24V alternator system and reduces it to 12V (actually ~14V of course) and puts out a max 50A output (25A input @ 24 or actually 28V).
I'm sure Sterling's site or Mr Sterling himself can tell you how you have been damaging your leisure batteries by simply charging them with a convertor. One obvious thing is the voltage drop in the convertor. Another obvious thing that I previously mentioned is if your solar panels are in parallel (to charge 12V) their current output is too low for their size you being near the equator, one may be defective. You should be getting 7A EACH.
Sterling Power Products: Battery to Battery Chargers

Charlie

Q, I had my doubts about whether the power consumption would be a static 24A, regardless of the amplification level.

I would imagine that the output voltage level is directly proportional to the power consumption, and since the output voltage level is proportional to the input voltage level and the gain settings, I would say keeping both of these low would reduce the power consumption.

As previously mentioned, I took my batteries in to be tested. Driving back to the campsite, my alternator via the 24/12V converter was powering my 12V system. I was listening to my music, and realised that the 15A converter was capable of powering my 24A amp, and this along with running an electric coolerbox we have in the front which draws about 5A (Campingaz Powerbox 24l) and powering the GPS (minimal current I admit!)

This got me thinking... I've just done some tests with an ammeter between the battery and the amp, and checked the current. Dependant on the music (and therefore the input voltage) the current bounces around, but at the levels we listen to it's generally in the order of 5A, peaking at 7A.

Perhaps it's just the batteries, which have been used continuously for +365 days, that are getting tired now?

I'll report back once I've checked my panels and have the test results for my batteries.

Cheers
Steve

Hi folks

So as I said, I gave my batteries to a solar & battery place in town. They've just called to say that after 3 days of charging (each being charged separately), the batteries still won't get fully charged. What does that mean? Are they just buggered? Do I need to get some replacements?

Thanks
Steve

Steve we've lived in our truck for the last 12 months and the batteries are fine. We don't have a huge stereo, and have never discharged them below around half, but are totally fine. We initially had a 24v proper sized microwave though, with 6.5m of cable connecting it (!) but soon took that out!

Charlie do you have sealed batteries? I was thinking of the Sterling thing myself but thought I'd read you ideally wanted unsealed batteries so they could be topped up? Sterling being so good at acheiving 100% charging and occasional desulphating the battery is mildly boiled? Very good reviews though and would certainly help Steve if you could get one!?!

I have AGM batteries which is probably the best for my application because they are buried beneath a sub-floor, so not easy to get at for top-up if they were open cell. The Sterling charger does have a setting for AGM.

Charlie

Steve what a saga! I'm not sure what they mean about them being not fully charged but guess they mean that each battery is still taking a considerable amount of current. Quite what is "considerable" in the context of your batteries, who knows but if after 3 days they still aren't at full capacity putting it at its best, they've seen better days. But, and it is a big but, it rather depends on how they're charging them. If they're simply using a basic charger by now the acid should be bubbling happily away and if it isn't that suggests the plates are heavily sulphated. That said, your Specific Gravity figures don't suggest this to be the case. If they're using a smart charger (which does what a Sterling B2B charger does and which unlike an alternator system is capable of charging a battery to 100% capacity) it rather depends upon what current the batteries are still taking. 100% capacity using a smart charger is when the voltage is simply being maintained at a given voltage- this is called the float stage; it's sort of like achieving battery Nirvana. At this stage the charger will be putting out extremely modest charge. But without knowing how they're doing it I cant say more.

I have realized one thing about your system (touched on above) which is you'll never ever charge your batteries to 100% capacity using an alternator system even with your voltage dropper. With start batteries this isn't a problemo because all they ever have to do is churn over the engine. Once the engine's started all the electrics are driven off the alternator which in turn tops up the start batteries. And in your case the LBs too. The advantage of the Sterling system, as described by Charlie, is it that though fed 24 Volts off the alternator, it charges the LBs quite separately from the alternator and being a smart chager (i.e. the charge rate and time is all computer controlled depending on the receiving batterys state of charge) will achieve far higher charging capacity than an alternator ever will.

I appreciate this is all a bit theoretical Steve and what you want is some practical advice! Well your system has worked well so far and your batteries got you all the way down the west side and coped with a musical hammering waiting to get into Angola. Since then and assuming your solar system is functioning properly (worth checking as Charlie said) and if you're right that the music is so low current then your problem is down to the battery(s) being knackered. Simple. The question then isn't an electrical one, it's an economic/pleasure/comfort one. Put simply, is it worth you spending $800 (when it would cost half that in the UK) being as certain as you can be that the system will work as well up the east side? I know you can get obsessed about these things-I got uptight when the chip on my Sterling charger died in Mauri and I was totally reliant on my solar alone which cut off when I was driving. But it all worked out though I occasionally had to turn off the fridge! Don't forget even if they all die totally you can get all the power you need simply by running the truck engine. If you ask what I'd do, I'd keep my old batteries (assuming the solar and battery place hasn't done for them!) and buy 1 new one just in case. But it's your decision..........

All the best

Q

PS Are you eventually heading back to the UK? If so a beer beckons.
PPS How are the (tubed) tyres?

Steca charge controller
 

Hi folks

I bit the bullet and bought some new batteries - E-Solar AGM batteries. My old batteries are indeed past it, and heading into the wilds north of Kenya I think it pertinent to have an electrical system I can rely on.

Now, something interesting (perhaps!) As previously mentioned, I have a 24/12V 15A converter which converts my 24V alternator output into 12V for charging my batteries. Similarly I have a 220/12V converter which converts a 220V mains hookup into 12V/15A for charging my batteries. Neither of these are "smart" chargers - they don't vary the voltage or current according to the batteries state.

Now I also have a Steca PR2020 solar charge regulator, which IS a "smart" charger. (From their website: The auto-adaptive state of charge algorithm results in optimal battery maintenance and control over the module output) I was wondering if you know if it's possible to connect the outputs from my other charging systems (alternator and mains hookup) to the solar input of my solar charge regulator to take advantage of the smart charging?

Many thanks for all your help, it is much appreciated!

Best regards
Steve

Looking at the Data Sheet I don't see any obvious reason why you shouldn't connect up the output from the dropper to the input of the regulator though I've never actually heard of anyone doing it that way. The input current of the regulator can be up to 20 amps and the voltage anything less than 47 volts. I wouldn't connect up the mains hook-up (suitably rectified and dropped to 12V) with the solar regulator input though as you won't know how good the 220/12V comverter/charger is at producing pure DC. Anyway all you need the hook up to do is provide basic charging and powering your fridge/lights etc when you're parked up. The solar and vehicle chargers (if you do decide to feed the dropper via the regulator) can do the smart stuff.

Q

Steca error code 100?
 

That's what I would think, but of course you never want to take the plunge without knowing for sure my solar regulator isn't going to end up a smoking mess!

I've got other issues now - after checking my solar panels, they are indeed only producing 7amps. Turns out I was defrauded and sold 2 x 60W panels, instead of 2 x 120W panels. Grrrrr, what a pain. That is no small part of the reason why my batteries were stuffed! Anyway, what can you do. I'll try fight the guy when I get back, but it was bought of German ebay in July 2008, and his account has been suspended, and any attempts to contact him has proved fruitless so far.

Anyway, that aside, I've now reconnected my panels to my Steca regulator and they're not producing any current at all. I've done an auto-test on the regulator, and it spits out error code 100 (with the 1 flashing). I've done some searching online but can't find what this means. Anyone had this error before and know what it means?

What a saga!! :funmeterno:

Thanks again for all the help
Cheers
Steve

Suggest you re-connect the regulator Steve. If you don't have the blurb, this is what it says:

Connect the individual components to the symbols provided.
Observe the following connection sequence during commissioning:
1. Connect the battery to the charge regulator - plus and minus
2. Connect the photovoltaic module to the charge regulator - plus and minus
3. Connect the consumer to the charge regulator - plus and minus
The reverse order applies when deinstalling!
Please observe that the automatic adjustment to 12V / 24V systems does not function
properly, if this sequence order is not followed. An improper sequence order
can damage the battery!

This would suggest that the installation sequence is important. If this doesn't fix it, suggest you e-mail the company. The contact is via this page.
STECA E-mail the Solar Electronics division

Good luck

Q

WOW this went on for a while LOL. Glad the family on here are helping you out Steve.

We left England 3 years ago with an 100Ahc geltec, Engle, 40w panel and a electronic split charger.

We now have 210 Ahc in 2 Gel btys 1 engle 40 ltr fridge, 1 engle 21ltr set up as a frezer, morningstar 30A controler, 2 90w sunpower solarpanels, 40w Kyrocera panel through a 7A controler, victron 350w pure sine wave, waterpump, lights and now a Cetec xs25000 charger. all monitored by a Victron BVM 602.

We are finally satisfied the btys only get down to 85% capacity over night so are getting looked after and we try to plug the cetec in once a week to look after the btys.

The final thing we will fit is a Bty to Bty charger in place of the split charger Cetec will be releasing one soon had our hands on the protatype but it looks good and will be cost effective, basicly unafecting the starter bty but doing the same as their smart chargers when the engine is running.

The BVM 602 can also be conected to a PC to download the last 40 days of usage in to an excel doc to help monitor bty state and usage.

Forgot to mention I was alwayd told look after your earths. lots of them and take them off clean with sand paper the put back. If earthing is not good then you will draw more current to push it through, did mine and noticed the drop couldnt belive it the fridges used .5A less dosent seem much but in the long run.

But now you have power enjoy the ride mate

No answer
 

Thanks Q. I've got the manual, and have been connecting/disconnecting as specified.

I emailed Steca through their website Wednesday last week, but they haven't responded yet. It's a bit frustrating, stuck here with no idea what's wrong and no response.

I've had a look inside to see if there is an obvious culprit. One of the MOSFETs has some discolouration on the back, so I'm thinking perhaps that's blown. That's the only thing I can see that could be the problem. Code on the MOSFET is IRFZ48N. From what I can see online it's rated at 55V / 64A... I really don't think I've put anything close to this into the regulator, so if it is blown, I have no idea how it happened.

I've taken 2 of the MOSFETs off. Tested the one with discolouration, and the drain is conducting all the time... blown. Tested the other to make sure, and it's working as expected. How on earth did I blow that MOSFET?

Now just gotta find a new MOSFET somewhere here. Naturally, 3 days ago I left Nairobi! Aaaargh! I do have a glimmer of hope - spoke to a guy who has a solar company here in Nakuru and he reckons he has MOSFETs - we'll see about that tomorrow. Wish me luck!!

I hope Steca isn't reading this forum - don't think they'll honour my warranty when I'm busy desoldering their circuit board!

Blimey Steve talk about being born under a bad sign!

I assume the MOSFETs are used as simple swiching devices. If the worst comes to the worst you'll have to wire in a switch to stop the system back-discharging to the panels at night and basically dump the Steca unit. As your panels are so small perhaps this isn't quite the disaster it might be (careful monitoring of the battery voltage will be needed though) and in the end, as an alternative you might have to abandon using the solar side altogether.

Good luck!

Q

Q, as they say - when it rains, it pours! :stormy: Boohoo!

I'm really loathe not to have the panels - the current they produce is enough to keep the freezer running indefinitely, plus some. (Freezer takes about 2Ah, Panels produce between 4A and 7A during the day.) Without them, and the fact we're heading out into the boondocks in the near future, well - don't want to have to sit and run the truck all the time just to keep the LBs charged up.

Anyway, I had an idea, and it's looking like it may work.

The Steca has 3 connectors: for the panels, batteries and load. The way mine is wired up I don't use the load - all the consumers are connected directly to the battery bank, so I just have the batteries and panels connected to the solar regulator.

The regulator allows you to turn on and off the load at will - ergo, there must be a similar transistor that is used for the load. I had a look at the circuit board and found a transistor where the drain was connected to the load's negative connector. I swapped that transistor with the blown one on the module input, and voila, it's working! Well... sort of. Since the transistor now on the load is blown, its drain is always transmitting, so I can't turn off the load. Nothing is connected, but I'm not happy with the electronics thinking it's off, yet it's actually on. Tomorrow morning I'm going to experiment with taking the blown transistor out of the system, and thereby disallowing the load function of the regulator altogether.

I'll let you know how I get along. I really hope I can get this thing going again, coz as previously mentioned, I want to try connecting the alternator's 24/12V converter to the regulator. I haven't tried that yet, coz the regulator blew (here's hoping I don't get the regulator working, then connect the alternator and blow it up!)

I've got a 2-way 24V relay which I'll have the ingnition switch between the panels when the truck is off, and the alternator when the truck is on. I'm worried about having both the panels and the alternator transmitting into the regulator at the same time. Shouldn't cause a current overload, but the voltages will be different (panels are about 16V, alternator will be at about 13V) - I don't know if that will have an affect - am thinking the higher voltage panels will prevent the current from flowing out of the alternator and into the regulator... can anyone confirm if this is correct, or if not, what would happen?

Cheers
Steve

www.overafrica.org
www.overlandcamperforsale.com

Steve (this is beginning to get like a 2-way conversation!) I use exactly the same relay-controlled set up in G4. When the ignition is switched on the Sterling B2B is livened up charging the LBs and the solar side isolated and when the ignition is off the solar side does the charging and the Sterling is off. I would have thought this is the way to go because aside from anything else, if you wire up the dropper output directly into the input of the Steca regulator, you're going to discharge the truck batteries through the panels unless the dropper is itself swithed by an ignition-controlled relay. See what I mean?

V clever of you to cannibalize the transistor though. V impressed!

Good luck!

Hi again Q. Yes indeed it is almost a 2 way conversation! :)

The dropper is actually already wired up to a relay switched by the ignition. It's a simple (and therefore not very good) solution - truck batteries connected via a relay to the dropper, which is connected to the leisure batteries. Obviously without the relay the truck batteries would permanently power up the dropper and soon go dead if we don't keep the alternator running.

Now I'm going to have a 2nd 2-way relay that will take the output of the dropper and the output of the panels and switch between them for the input into the solar regulator (no power to the relay switch, the panels are connected to the regulator - when the relay switch is powered up (ignition) then the dropper is connected to the regulator)

Why do you bother to turn off the solar side when the truck is running, if each has its own "smart" charging sytem? I'm thinking the answer is going to be something like what I was alluding to in my previous post, but if you could elaborate I'd appreciate that.

Cheers
Steve

Sure Steve. Basically I wanted to keep the two systems separate and simple. I did reckon that mixing the inputs (which inevitably would be at a potential difference-i.e. different voltages) would be likely to 'confuse' both the Sterling unit and the Solar regulator.. So I have exactly the system that you're proposing-ignition off: solar on etc.

Q

What happens when you plug in mains?

Hi guys,

Just so its not a 2 way conversation i have a few questions regarding my own set up. I dont want to hijack your thread as it has been incredibly informative and has raised questions about my own set up that i am having a few problems with..

I have just built an MAN camper. The truck is 24v and i have used an IBS 24v split charger to charge 24v LBs (2 x 12v65amh exide gel) that uses a relay and has battery monitors.(showing the starter bat and LBs seperatly ) Also charging the LBs is an 85w solar panel with 24v regulator.
From the 24v system there is an engal fridge, an erberspacher heater and a 24v-240v inverter.
There is then a 24v-12v dropper and the interior lighting and cig lighter for computer from the 12v side.

I thought i would have enough juice to use the fridge and a light in the evenings and the computer , but the LBs seem to drain very quickly.

Should the dropper and the inverter be on switches so that they are only on when in use ?
Also the solar is on all the time, the IBS allowing it to charge the Starter batteries when the LBs are full, only they are never getting full?

Even after driving 5 hours they dont seem to get fullycharged, and if the led shws they are as soon as you use a light it drops.

Am concerned the batteies are not good as when i first set it up i didnt charge them up fully and then used them for a while with just the solar as i wasnt driving any where..

I am in germany trying to get it sorted before heading south, i have bought a ctek 24v charger to try and get them in shape, but need to know if i should alter the set up, and maybe get another set of 24v batteries to increase the AHrs( The problem with this set up is that its based on 24v so i will have to get another 2 batteries)

Anyway, help appreciated and hope you get yours fixed steve, your a brave man de soldering regulators!

Cheers

Stan

I'll try do a brain dump here that may be a help. I'll probably ramble for a lot of it, so try bear with me! :)

After all the help I've been receiving on this and other forums, I found this excellent overview of using multiple charging systems. I would highly recommend reading it: Multiple Charging Sources to the Same Battery Bank - Cruisers & Sailing Forums

Using just the alternator's 24V output to charge your LBs will only charge them to about 50% of capacity. The alternator generally works for starter batteries because all they have to do is deliver a high current to turn over the starter motor before the alternator takes over. Leisure batteries are used differently (slow discharge over time), and as such we're more concerned over the state of charge of the batteries. Really you need a smart charging system which alters the current and voltage output according to the state of the batteries it is charging. My solar regulator does this, does yours? (what is the make / model?)

As you will see from reading this thread, and from the above link, it would probably be pertinent to use a relay to switch between your panels and your alternator, depending on a signal from your ignition. To be honest it's probably worth finding a good 'smart' charger that can be driven off your alternator, and then use a 2-way relay to switch it on when driving, and the panels on when not. That way you'll get your batteries charged up properly when driving.

Certainly I would put a switch into the 24V input line to your inverter, alowing you to remove it from the system when not needed.

Another thing to look at is the power usage of your system, as this will determine how large your batteries should be.
What power rating is your inverter? Now you can work out the amps the inverter is using (P = IV, so I = P/V where V = 24V) Remember that an inverter is quite inefficient, generating a fair amount of heat when converting to AC. If you use a very high power inverter, when you're consuming only a low amount power, you'll be wasting a lot of battery power needed. The inverter won't always consume the full power it can produce (ie: if a 300W inverter is on but the AC is not being used, it won't be consuming 300W of power), however, a higher power inverter will use more power producing AC than a lower power inverter will - so try match the inverter to your needs.
How many amps does your Engel use? (will be in the technical docs supplied with it)
How many amps does your Eberspacher use?

Basically, what you want to do is work out how many amp/hours each thing uses - how many amps, and for how many hours - that will give you an indication of total amp hours you use per day.

Now, in an ideal world, you don't want to discharge your batteries more than 1/3rd - so if you're using, for eg, 16amps and you want to use them for 2 hours a day - then that's 32Ah you're consuming - you want to have 100Ah of battery life to be able to supply this, and over the course of the day you want to put back 32A into the batteries.

In ideal sun conditions your panels will produce 3.5A. Let's say you average half that over a day, of say 8 hours. That's 28Ah you're putting back into the batteries - which means that every day you're actually taking 4Ah out of the batteries you're not replacing (consuming 32Ah, producing 28Ah) - that means you can sit parked up, relying on only your solar panels, for a maximum of 8 days before you want to think about charging your batteries from another source (100Ah battery, you want to discharge it to a maximum of 1/3rd (ie: 33Ah), you're taking out 4Ah a day, so 33/4 = 8 days)

Steve you've got it absolutely right in that last post. Sorry for silence but the world of work........

Stan, looking at your system Steve has identified the design deficiencies though I could add that your IDS device has the wrong priority: it should charge the starter battery first then turn to the LB. You need a smart chager powered off you charging systen like the Sterling B2B device (honestly I haven't got shares!). There is one that takes 24 volts and charges at the LBs at 24. You must have the inverter off when its not in use as it'll waste loads of power just doing nowt. I imagine the dropper is less than efficient too.

As Steve has shown you almost certainly haven't got nearly enough battery capacity Stan. In the winter you won't be getting a great deal out of your panels yet the demands (save possibly by the fridge) will be higher. Remember the key is to work out your power needs, minimise them as much as possible e.g. use LED lamps etc, and basically as a rule of thumb, have 3 times this battery capacity. Frankly without a smart charger driven off the vehicle charging system and some more capacity you'll be struggling. With a fairly low wattage solar system you're reliant on the vehicle side to charge your LBs-just regard the solar as a adjunct.

Oh and Steve my mains system is totally separate from the leisure side. I have mains lights for example only used when the mains input or generator is doing it's stuff. I do have a mains smart 12V charger but I found that the generator had the habit of killing off mains chargers.

Q

Welcome back Q, you were missed! :)

Re the voltage dropper: These days most people use a switch-mode converter for their voltage dropper which is very efficient, so you don't have to worry too much about the power consumption for that Stan.

To report back on the changes I've made to my system:

I have a 24V 2-way relay, normally closed line connects the solar panels to the solar regulator. The normally open line is switched with the ignition, and connects the output of the 24/12V dropper to the solar regulator instead (so alternator takes precedence when driving)
I also have a 24V 1-way relay which is switched on the ignition - this connects the 24V truck batteries to the dropper - ie: they're only connected and therefore the dropper only runs, when the truck is on.
I then have a 12V 2-way relay - normally closed line connects the output of the previous relay (ie: either solar or alternator (aka: 24/12V dropper)) to the solar regulator. The normally open line is switched by the 12v output of my mains charger, and connects the main's 12V output to the solar regulator (so mains takes precedence when on shore-hookup)
That means mains is always 1st precedence, then alternator, finally solar.

I've made a bit of a stupid mistake, and that is that when the 12v output of the mains charger signals the 12v 2-way relay, and connects the mains 12v output to the solar regulator, even when mains turns off, the solar regulator input continues to energise the 12v switch of the 2-way relay. Tomorrow I'm going to hunt down a diode to put in the output line of the relay, to prevent the solar regulator's charge returning through the closed line of the relay and energising the switch (switch and 12v line input to normally-open are attached together)

I think this will work. Any comments? I'll let you know how it comes along.

So long and thanks for all the fish.
Steve

I don't know if your leisure batteries are AGM such as the Odyssey range but I have just found out that they need to be charged at 14.7volts. 14volts will only charge to 60% and will lead to premature failure of the battery. I had this problem and found that my alternator regulator was only 14volts - I have ordered a 14.7volts one and will see what happens but hopefully i'll be able to charge my new battery properly. I'll let you know.

Thanks to all the contributors to this informative thread btw.

Thanks for the info guys, its been massively helpfull.

Due to costs of redoing the system i will have to stick with it as it is, but i will increase the 24v Battery amphours. ~If i change anything i may add 12v solar totally seperatly and just run the 12v stuff- interior lighting and toilet flush off this. This will reduce the AHrs needed on the 24v side and not require as many batteries.. ?

Can you use the lights etc when a mains (ctek) charger is plugged in? As i dont have 240v so if hooked up to mains it is just to charge batteries. I have unplugged the solar when using this charger.

Thanks

Stan

Inverter Charging
 

I did post this on Motorhome facts previously indirectly linked to earlier, so sorry if this would have worked for Steve but a little late for him now!

But, since the alternator only charges to 2/3rds capacity, and a Sterling is quite pricey, what if an inverter was run directly from the alternator? (How?) A smart mains charger could be plugged into this and would have put a full charge into the LB's, the inefficiency of the inverter being more than made up by the charge then acheivable by the alternator?
I am no sparky, the whole thing seems hocus pocus to me, but can anyone say if this is doable, the only drawback being switching the inverter back for hairdryer use if you wanted to? ;)

Got this response from the manufacturer:

From what I understand, with the DC/DC converter connected straight to the battery it just shoves 15.8V at 15A into the battery, and will either over-charge and damage the battery if we leave it on for a long time (ie: drive for a long time), or if for a short period, will not charge efficiently. To achieve efficient charging of deep-cycle batteries you need to use a smart charging algorithm that alters the current and voltage sent to the battery according to battery state (ie: Steca's PWM charging system)
Yes, if the DC/DC converter is connected directly to the battery, then someone will have to make sure "manually" that the battery is not overcharged.
As you know from my last email I have already connected the DC/DC converter to the Steca regulator, and (luckily) neither were damaged! Can you tell me why they could be damaged? Can you also tell me why the Steca receives 0A from the DC/DC converter when I know the DC/DC converter is capable of producing current?

The Steca charge controllers use a regulation mode which short-circuits regularly the energy source. This is fine for solar modules, but can certainly damage any other energy source. Additionally, the mosfets inside the charge controller can heat up and get damaged irreversably, if the IV characteristic of the solar module is not recognised.

I have a solar system that is working correctly - it is the alternator charging system that I have the problem with. What I need to find is a PWM or MPPT battery-to-battery charger than can take my 24V alternator output and charge my 12V deep-cycle batteries, except this is not easy since I'm in Africa. Hence the reason I'm trying to use the Steca as an ad-hoc battery-to-battery charger. What would happen if I connected my alternator directly to the regulator? (it produces about 26V, and can produce 55A)

This will not work, because again, we can only use solar modules at the input, and secondly, the current is way too high for the PR controllers.