Charging Issue

[ChasF]

R100GS has been charging at 13.2 volts (at best) for sometime - there is a little voltmeter on the USB charger I have on the handlebar, initially I thought it was a dodgy meter but eventually check it with a multimeter and it is accurate. The battery did eventually go flat as I was riding a lot in slow traffic (Nice and Ste. Maxime, bloody horrendous) with the headlight on. Charging light goes off at the normal revs. I’ve had a quick look and nothing seems amiss, I’ll probe around with a meter later, my theory is that one phase has gone down o the stator or the diode board. Anyone had similar or any idea what the most likely cause is?

 

[casbar]

Had similar on my R100CS, was advised to change the voltage regulator which I did. Charging went up to 14v+. I didn't know a solid state regulator could degrade, but it did.

 

[DrFarkoff]

The battery did eventually go flat as I was riding a lot in slow traffic

If the red charging light was on? Whilst you were doing all this slow speed riding then it wasn't charging at that time

Phase down will usually drop it below 10 v

 

[casbar]

If the red charging light was on? Whilst you were doing all this slow speed riding then it wasn't charging at that time

Phase down will usually drop it below 10 v

When I had the issue, I was trying to determine if my battery could handle the extra led lights and sat nav etc being run. So I measured the charge to the battery whilst the engine was revving over 3k, it was down to around 13v. I then changed the voltage regulator (standard, not high output) and did the same tests, voltage at the battery went up to 14.6 volts. I was about to go down the alternator upgrade route, but decided my system could handle the extra drain of the lights etc

 

[ChasF]

If the red charging light was on? Whilst you were doing all this slow speed riding then it wasn't charging at that time

Phase down will usually drop it below 10 v

The light was out even at ‘tickover’ although tickover was pretty high and erratic in the heat. The last time it failed the charging light was on and had been on for several days and the battery went flat owhen I stalled the bike on a level crossing in Luderitz in Namibia. Getting a new rotor was a bit challenging but it seems it’s still going strong after 30 years.

I haven’t got any electrical extras on the bike so I think a just replace the regulator as a first call and see how that goes.

 

[theoneandonly]

https://gutsibits.co.uk/pr/TheShed/Downloads/BoschChargingSystemFaultFinder.pdf

start at the beginning

yes i know it's for a guzzi but the systems are the same .
....check don't guess.

rotor 3.6 - 4.2 ohms , infinity to earth
check the brush pack for résistance through the brushes ( I've had a few with high resistance ) loosen nuts that hold contacts and retighten .
resistance through brushes AND rotor about 6 ohms
stator earthed
3 yellows on stator to each other 1 ohm. infinity to earth .
regulator , if light works reg is usually ok.
diode board . check all looks good , sniff it . I've recently had diodes break off the board . check earth on cold side of diode board to battery.
if all is good , flash the rotor .
engine running , take a wire from battery+ to d+ , light goes out , count to 5 , remove wire . turn off engine , restart engine light on , goes off when revved .

 

[Steptoe]

(Nice and Ste. Maxime, bloody horrendous)

Is the Trident bar still going in Ste. Maxime on the seafront ? Used to be a meeting place for bikers a couple of nights a week back in the 1980’s..

 

[theoneandonly]

i wonder what happened ? did he get killed by a jealous husband ? or did the wife suffocate him in his sleep ?

 

[ChasF]

Ordered a replacement voltage regulator from Siebenrock who unfortunately use DHL the world’s most useless delivery company. So the new regulator has been circulating around France for a couple of weeks, it finally arrived yesterday but not before I’d taken the carbs off for a bit of a clean up. It’ll probably be a few weeks before I canrun the engine to see if the new regulator solves the problem.

 

[Mad Hatter]

If the new reg doesn't fix the problem I've got a complete spare charging system and you're welcome to borrow any of the parts from it to do some swapnostics