Problem with GS 125 battery draining over time.

tvr321 · Nitrous Nuisance Joined: 20 Sep 2009 Karma :

Hi, I have a problem with my GS 125's battery draining over time.

It's not the battery, the battery holds it's charge fine. (Tested)

If I charge the battery right up with a charger, it is usable for about a week. After which the headlight starts to dim and then dies completely whilst I'm going along. All electrics fail to work once battery becomes drained.

If I switch the lights off for a minute or two whilst riding, and then switch them on again, they'll last for around 10 sec, before dying completely again, so the bike does charge the battery, just very slowly.

The lights will not work if the battery is not charged -> Won't run off the alternator.

At first I thought there was a wire earthing somewhere, but I have been all over the wireloom (It's very basic) and found nothing.

Since the lights will not run off the alternator, it leads me to think that perhaps it is not producing sufficient power to charge the battery, but I am no expert so input would be appreciated.

Thanks.

temeluchus · World Chat Champion Joined: 01 Oct 2008 Karma :

fully charge the battery. Read the voltage with a meter and it should show 12.5 volts approx fully charged.

Start the bike, and rev it up a bit. Should reach 14.5 volts if the system is charging. If it stays at 12.5 and starts to drop, you either have a wiring fault, dodgy regulator/rectifier or a knackered alternator.

heres a handy guide

https://www.electrosport.com/technical-resources/library/diagnosis/pdf/fault-finding-diagram.pdf
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Kal · World Chat Champion Joined: 02 Jan 2007 Karma :

tvr321 · Nitrous Nuisance Joined: 20 Sep 2009 Karma :

Thanks, that link is very helpful.

Another question that is not quite related to the original topic but still concerns the GS 125.

I don't think that the dim/full beam etc system has ever worked properly on my GS. I'd like to know how it should work so I can fix it.

I need GS 125 owners here. I think it involves the key, does it not?
My bike will not start on the key's third notch, however, the light does come on (dipped). If I have the key on the second notch, the bike will start, and with the light switch off, the lights will be off. If I flick the light switch, full beam comes on. So basically, I can't switch between dip and high beam. Not really a problem since full beam isn't all that powerful, but still, I'd like it to work properly.

So how does it work on properly functional GS's?