Battery amphers ? How much I need?
 

Hello All,

My '96 airhead (R80 GS Basic) which has a 1 liter engine seems will need a new battery soon.

For 1 liter angine it says 12 V and 16 amphers suits best. But I see some people use 24 and also 30 amphers batteries?

Which one suits best?

Any experiences ? !

Cheers,

Samy

Hi Samy,

Most important question: Does it fit....
Second question: What do you need when the engine is off...

I am not a expert, but I think that the battery is normaly only used for starting and electronica during RPM less then 1000 RPM.
When your are driving (more then 1000 RPM) the altenator/dynamo is providing enough electricity for all electronica and is recharging the battery.

Perhaps I am wrong, so everybody feel free to correct.

I'm no expert but I have found the following through experience.

Boxer engines can require a large amount of power to turn over at times especially when it is very cold.
Another feature of the Boxers is that with standard charging components, they do not generate much charge at low revs.
I would recommend changing the standard regulator to what is referred to as the "Police Spec" regulator. Motorworks - BMW Motorcycle Spares - home part number ELA44410.
They higher amperage battery you can afford would be a wise choice, as when it is fully charged will cope better with short stop/start journeys without you worrying about whether it will start or not.

This website is a very good source of info, check out the forum.

Odyssey PC680
 

While the Odyssey only has 17 Amp Hours listed it is extremely powerful for starting with 680 cranking amps for 5 seconds. My bike never started better.

When it died in Ankara I ended up buying a Panasonic battery that was OK but was dead by the time we got to South Africa. In Johannesburg I got a standard BMW battery which was OK but for a cold start you can't beat the Odyssey. And it does get cold in Cappadocia! As a bonus the PC680 is about half the size of the BMW battery so you have space for tools or other extras.

If all you need is two starts a day, and you have a minimum of at least 20min at above 3000rpm in each direction, and you have access to a charger at home so that you could boost the battery over night (0.5-0.7A).
Then a standard acid 19Ah is ok -:)

But if you have several stops, lugging in traffic jam (with compulsatory low-beam on),... then I would strongly, very strongly recommend Banner 53030 30Ah.
However,... Odyssey PC-680 is really a knock-out battery! It superceeds my wildest expectations! This is my "test": left my R100RT 1981 standing out-doors at winter. No charger on. Termps were hitting down to -15'C and staying below 0 for the better part of the time. 8-10 weeks. Then came a friend by, who is currently living abroad. We just had to start my "new" bike - my friend is a bike-mechanic. The R100 started at once, just as I touched the starter button! To leave an acid battery, no matter size, without any supplementary charging for two weeks will result in a 50/50 chance the the engine will even tick over! 8-10W at sub-zero... mean burst battery (frosen solid) - not a chance in ... that there would be any power at all left in an acid batter in such circumbstances. (Yes - I have tested that too).
Guess what my next battery will be -;)

If I recall correctly, the space in the frame for a battery on the newer /7 GS is larger, so much lager that the smallest car-battery should fit. That would be a 45Ah.
This means that you should be able to install odysseys next size battery...
Odyssey PC925 L

Sure - that is overkill, but when you ride in low-temp climate, traffic jam, stops-an'-goes, it will not seems as an overkill; you'll need all the power you can get.

On my bikes there is always a rectifying diod between the regulator and the two blue wires connecting to it. => 0.6V up and better charging at lower revs.
Then,... my bikes tends to undergo some kind of metamorphosis anyway... 20A alternator transforms to 55A-90A pulley driven... I never have problem getting enough electricity -;)
However, even a car AC will need the rectifying diod at low temps!

My advice is get as strong battery as the budget allows you.
Odysseys are well spent money, but if the budget only allows for an acid battery - get the largest you can fit inside the frame; or get two small and parallell connect them (see e.g. VW campers).

Unless you are driving in cold climates you gain nothing fitting a bigger battery then standard.
Bigger batteries adds load for your charging-system and you need longer driving-time to get them charged.
It’s far better to use a 90% charged 19 Ah battery then a 60% charged 38 Ah battery.

If your bike have problems with starting on a healthy 19 Ah battery and the temperature is above -10°c it’s not related to the battery. (-15° with thin syntetic oil).
The Valeo-starter is much better for cold-starts then the Bosch-starter. The Nippondenso even better.


You should never wire batteries in parallel. The worst battery will discharge the healthiest one. The healthiest will then be less healthy after a while.

The new BMW-battery (Excide 19Ah) for your bike is a sealed unit and I would prefer it before the Odyssey. I have used it for three years now.

Interesting points AliBaba!

Can't say I have experience with small vs large battery. So I will accept your point - and hope I may have a chance to test it someday.
What I have tested is the difference between 24Ah, 28Ah and 30Ah - with Bosch 55A alternator... and even the mere 2Ah difference is noticable at low temps,... I have also tested 13.7V (stock) which will hardly charge a battery at all up to 15.5V (which is not recomendable at summer...) which will fill a battery in a jiffy (and then cook it...).

Your point on parallell connected batteries is valid only if you bolt them on as with a permanent connection between them. If you do it as it is done on the VW camper, taxis/cabs, trucks etc - then there are only benefits by having dual batteries. I have jumpstarted my VW Type 4 several times by using the second battery (one installed in my tryck for the U-lift (U-Lift ) ).
It is as it is with everything - done correctly it works, done incorrectly and it causes more headaches -;)

As a rule of thumbs I have learnt that it takes a minimum of 10min at full charging from the alternator to replace the electricity used to start the vehilce. Is that recommendation reasonable, or is it merely a hearsay?

If you have similar batteries with different capacities the biggest battery will always have most crank-power, if both are charged 100%.

The problems with big batteries are:
-Weight
-Price
-They stress your charging system
-They usually need more time to get fully charged

On the other hand driving in cold weather (-10°c and below) or with a highly modified engine you might (or will) reach the limit where a standard 19Ah battery can’t deliver the crank-power you need. It also depends on a lot of other factors like your charging system, oil, compression, how easy the bike starts, type of starter etc.
If you are on the low side with cranking-power you will use a lot of your battery’s capacity to start and it will require a long time recharging

A battery has full capacity at 25°c, at -18°c it’s only 40% left. This means that my 19Ah battery only have 12Ah left. That’s not much when it’s cold…
As a rule of thumb you should have 14.2-14.4V at 25°c and increase the voltage with 0.3V for each 10°c the temperature drops. (-15°c => 15.1-15.3V)

There are a lot of things that can be modified on the airheads-charging systems to get better charging.
My charging system is original (except a Thunderchild diode-board). I haven’t rebuilt it because for my use it works. It’s always easy to start the bike if it’s hotter then -10°c (or -15°c with synthetic oil) and that’s enough for me. The numbers might be a bit better now after I fitted the ND starter.
If you increase the voltage (which is good for your battery) you will also increase load on your generator. But again; different needs requires different solutions.



Hmm, eight years ago I had approximate 8 km (7-15 minutes) to work. In January/February I had to drive some extra kms 1-2 times a week to keep the battery up. The rest of the year it worked flawless.
I guess it works as a rule of thumb on a healthy system operating in normal temperatures.

I replaced my yuasa battery with an odyssey in my XT600E..

The difference is the cranking power and HOW LONG it will crank...

If you're having any types of problem and your bike isn't catching on the first 1-2 cranks, then having a battery which won't flatten in a few minutes is definitely an advantage..

The odyssey has a really deep cycle meaning if can sustain those high amps for a greater period of time..

I have to agree with Alibaba though, running parallel only works if BOTH batteries are in very good condition and using a high amp battery does take longer to charge.

Hello Alibaba,

I ride my bike mostly over 0 C (celcius). It's upgraded to 1000 cc bike. Do you think Odyssey 680 will be much for that or should I go for something like normal 19 AH battery like BMW you mentioned.

I know BMW doesn't make any accesories itself but makes it to produce other companies. May be we can find it cheaper under another brand !

I am a bit confused now...

Regards,

Sami

I don’t know the Odyssey 680 first hand. It’s 17 Ah compared to the standard 19Ah.
Personally I had chosen the standard-battery if the price is more or less the same.
A lot of US-riders are pleased with Odyssey.


The battery is made by Exide technologies, but I can’t find it in their catalogue.

As stated.
I have tested BMW, Banner, Yuasa, and a few more. None does even come close to the power and reliablity of the Odyssey.

The pricetag is just about x2 for PC680 vs standard 24-28Ah; but it is well worth it as I see it.
Remeber, I am used to Banner 30Ah and find those to be far better than any 28-24-19Ah batteries - and the Banner 53030 is out-classed compleatly by the Odyssey...
Remember that the beemer have a tendency to discharge it self... I know for a fact that there are some major problems getting the electricity to stay put in an acid battery on the beemers... and to get them charged by the stock alternator... The Odyssey surpassed my wildest expectations by far - it works where the acid batteries does not.

However, all batteries with the modern technology are said by my friends and aquaintancies to be superior to acid batteries.
SMF techonogy:
Biltema Sverige
Gel technology:
Biltema Sverige

Still a new battery is better than an old worn -;)

The Odyssey!
 

I agree with the Odyssey fans above. I've had an Odyssey in my R65 for a few years now and have never, ever had a problem with it, despite leaving it connected for months without starting it still started the engine first go. It can be charged and stored for months on end, it can be deep discharged regularly (they are used for racing engines with no alternators). It can't freeze, even at -40 C, it is sealed and non-spillable, small but powerful.
I'll never buy a different battery...
Sean