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Discussion Starter #1
Hi guys,

My 03 955 needed a new battery a few weeks ago, wouldn't hold enough charge overnight to start the bike. Fitted a new battery, carefully trickle charged before fitting, and now it's gone the same way!
Checked out charging voltage and seems a bit on the high side and the reverse of what I was expecting. At idle I'm getting 14.7v, dropping to 13.8v as I raise the revs over 2K.
I would have expected the opposite figures, 13.8v at idle and rising as the revs build up.
I suspect the regulator is goosed and overcharging the battery, anyone seen this before?

Graeme.
 

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It doesn't sound like overcharging, but I'd definitely suspect the regulator / rectifier.
 

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The passive field charging system on your bike is acting normally. It differs from a proper automotive charging system (found on the previous generation fuelies) in that voltage regulation is by sinking current through a zener diode in the regulator. The voltage you measure with a common DVM is RMS (root mean square) whereas the regulated voltage is peak.
OK maybe that was the long way around, but I'd suggest you clean and tighten grounds at the battery and regulator.
 

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But presumably Sherekhan is using the meter across the battery therefore RMS doesn't come into it?

Ah, the faint smell of gently cooking Zener diodes......
 

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Discussion Starter #5
Yep, Ian's right. Normal multimeter across the battery terminals. Sorry, but it's not got nothing to do with cleaning/tightening terminals, etc, the batteries won't hold a charge overnight after being charged on the bench, not in the bike. Any battery that I fit to the bike is fine until I do a run over 50 miles, then it's toast. I've got the local bike shop sourcing a new regulator for me. It's not undercharging, it's overcharging, warping and sulphing up the plates.

Thanks for the interest and replies though.

Graeme.
 
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Hello,

I had the same trouble as Sherikan and changed the rectifier.
Then I still have the same value : from 14.6v at idle decreasing to 13v at 200rpm.

Today I am waiting for a G75 generator from Electrex.

Has anybody tried this part?

Regards
 

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Discussion Starter #8
Hi Tiger69,

I changed out my regulator/rectifier and together with another new battery all seams well. Yes I'm still getting similar voltage levels as well but only when first started, as the battery recovers from starting the bike it gradually fades down to about 14.2-14.4 volts at idle. I've also done a couple of trips and the battery seems fine, it hasn't fried like previous occasions and has plenty of power spinning the engine over the following morning. With the old rectifier and a new battery it wouldn't even crank over the following morning after a run, the battery being totally fried.

Hope this helps.

Graeme.
 
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Well

That seems even better than mine

I'll change the generator anyway during my next 60M km inspection.

I've forgotten to tell you the plastic part of the 3 wires were fried at the rectifier connector side and I wonder if I'm not going to build a new harness between the generator connector located LHS near upper engine mounting and the rectifier connector

To be continued...

Bye
 
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