R80 keeps blowing bulbs
 

I was out on my R80 this evening and the dipped beam blew, I was about 1/2 mile away from home so I switched to the main beam and the cars would have to live with it. It lasted about 2 seconds. Literally. I pulled over and found that the side light had also gone (I don’t know when in the sequence it had failed) but the rear lights were OK. I carried on as there was little traffic apart a van that I followed. Ahem, sorry officer. The bulb is a standard power of Osram parentage - they have been in for about 20 miles after the last one failed.

So clearly there is an electrical issue. Other symptoms are that the battery doesn’t seem to be holding its charge too well evidenced by a sluggish turn over when starting.

OK, so my assessment is as follows.
1. The battery needs to be replaced (it is a gel battery and about 3 years old but didn’t get used enough for 2 years as it was off the road) - this change is planned anyway
2. The bulbs blew due to high voltage as I think the voltage regulator may have fried as a result of the battery being half dead so would need to be replaced.

Firstly question - do my assessments make sense and / or are there any other things that I should look at?

Second question - as it is a standard alternator and I am intending to replace it at some point for a 400W Endurolast system do I bite the bullet and replace the alternator now (as well as the battery) or just the voltage regulator (assuming it is fried)? I am not fixated on the Endurolast system but I am not after vast amount of power either as I am not planning on running anything with that draws much power but could do with a little more than the standard 280W (having said that is the 600W on sale at Motorworks worth looking at?).

For the record the bike is an R80 Mono from 1986.

Thanks for any advice.

Yes, all you have said could result in a good repair.

On the other hand it may not. The diode board could have a shorted diode. I'd test it.

Once you have replaced things ... check the charging voltage of the system.

And get ready to replace a few more globes - they too will have been stressed by a higher voltage leading to a shorter life. I'd replace the tail/stop light just as a safety matter, most of the other lights will tell you when they fail.

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You do know that you need to disconnect the battery to remove the front engine cover? Not doing so can blow the rectifier.
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Why the replacement of the alternator? Unless your running hi power accessory electricals more power is not needed.

Thanks for that - I will first visually inspect the board to see if there is anything obvious then test the board and check the charging voltage.

Changing the rear bulbs makes sense. I should have thought of that myself.

I knew that I had to disconnect the battery when removing the front engine case - I cant remember where I picked it up from though, quite possibly this good place.

I am gradually fettling the bike ready for a trip in a few years and I will want to charge various items so having some head room on the charging side makes sense to me.

The problem with going 'non standard' is it reduces the chance of finding replacements if you breakdown. The voltage regulator was fitted to many older vehicles ... including trucks and tractors... and old motoguzzies. Should be able to get one at any auto-electrician, or any automotive spare parts place.

I know that but the Endurolast has a good reputation for reliability. Also I won’t be against the clock (maybe against a monthly calendar but not much more) on my trip so I can wait for spares to be shipped out to me - I wasn’t planning on getting rid of the original but leaving it at home. What that would mean is that I would have to get the shed organised for other people, I can find things but no-one else could be expected to easily.

On the plus side it would mean that I would get a chance to explore a specific area better.

Well I have started the testing process but got driven in by the cold - it is about 2C here and as I don’t “need” to get the bike ready in a hurry I retired inside.

I am pretty convinced that a voltage cross the battery of 16V when I rev the engine up to 3,000 rpm is not normal. So the voltage regulator is fried. I suspect that whilst stripping things off to get that changed I might as well replace the diode board as well.

And then comes the crunch decision - the cost of replacing the diode board and the voltage regulator is £112 but the cost of the 400W Enduralast complete kit is £270 though Snowbum seems to like the 600W Emerald Isle system more (I think that is about £420)...... decision, decisions.

An uneventful afternoon spent changing the diode board, voltage regulator ad battery seems to have done the job. Instead of 17V+ at 3,000 rpm it is limited to 14.2V even when running at 4,000rpm. I need new bulbs all round except indicators (they will be changed anyway as a precaution) including the instrument console. The actual changing was a doddle with the exception of the battery that is a little taller and narrower than the previous one so I am going to have to find a better way of strapping it down than it is currently.

Well done Jay! BUT I'd be careful of that battery - make sure the toolbox doesn't interfere or sit on it - that could cause you all kinds of trouble down the road. Stock there is only a tiny bit of clearance.

I'm personally a fan of ANY QUALITY aftermarket electrical bits for those bikes. When new and unmodified they're fine, but 30 or 40 years later not so fine, and adding anything stresses them.

I had an Motorrad Elektik on my R80G/S and it worked great. I hear good things about the Endurolast unit too, dunno about the other.

Be sure to give the wiring harness and all connections a REALLY good going over, cleaning everything to sparkling clean, check the insulation for hardening and potential cracking. Make the grounds perfect!

Good luck, they're wonderful bikes if looked after, and you know their weaknesses and deal with them in advance.

Thanks Grant. I am probably going to drop the tool tray as it currently is as I am after a location for a couple of USB power packs that are out of the way and some associated electronics.

I did a check over the rest of the system and cleaned various components that looked like they needed some love and a better grounding. Considering it is almost certainly the first time they have been touched in 32 years I think that they have stood the test of time pretty well.

Just to be on the safe side yesterday I went out on the bike to make sure that it was behaving properly in terms of electrickery and all seemed well. Bulbs all good after an hour and half of riding, voltage nice and stable, started well when I had pulled over for half an hour or so to grab a coffee and a can of paint and a few odds and ends (SWMBO is insisting on decorating at home). The weather was smiling down on the UK this weekend so all was well.

As the sun is shining again I may have to test the bike again, you never know, I don't want to get caught out by a false sense of security. Honest, dear.

we believe you...

Well, that is a relief. The bike was fine in terms of electrics but she was shaking her head at the start of the ride - slightly low tyre pressure that was soon rectified (pun intended). The weather is about to break so the last ride out for a few weeks.

I also received yesterday some voltage regulators to play with from DX.com to sort out a small (10W) solar panel that puts out 19-20V as standard - now set at 14.2V and it is now sat trickle charging (well it will in the morning) the battery.