g2 dead battery

[peabody1945]

Hi all;
I'm a new member and have a problem with my brother inlaw's 1990 Yamaha g2 gas cart. He just bought this cart and the battery went dead the first day. I need some troubleshooting advice on the charging circuit. First of all, when I ooked at it, the wiring was a mess. Looks like the previous owner had a short circuit. Lots of melted plastic and chared wires. He put it back together and left a few wire unhooked. Didn't even use connectors or solder, jusaty twisted the wires together and taped them with plastic non electrical tape. I downloaded the wiring diagram and put it back according to the print. Now I want to do some tests and the charging circuit. I'd like to check the output of the starter generator and the voltage regulator. What voltage should I have between the green and red/white wire from the generator? What wire from the voltage regulator should have the supply for the battery and what should the voltage be? I have years of troubleshooting experience and have a good DVM, so all I really need is the voltages.
thanks,
MIke

[Michael Eddie]

Hi peabody1945!

The VR should be reading 14.0-14.5 volts at WOT. Green wire from the starter/generator to battery negative, and the red wire to battery positive.

Most often these charging problems happen when there is a loose or missing connection.

[peabody1945]

g2 dead battery

Matti,
thanks for the reply. Sorry it took so long to get back, been kinda busy last few days. I only have 12.8 volts at WOT which is same as battery voltage with key turned off. So I don't think it's charging at all. I checked the voltage at the output of the generator with leads unhooked from the rest of circuit. I had 0 volts DC and only 2.9 volts Ac.(WOT) I'm not sure if this means anything since this is my first time fooling around with this type of starter generator. I have experience with small engines(Garden tractors) with the alternator under the flywheel and normally get about 30 to 35 Volts AC with the leads unhooked. My suspision is the starter generator was toasted by the previous owner when he had his short . Do you know of anyone who repairs these things or a good source for a replacement? Is there a way to test the voltage regulator without having a generator input(diode check for example)? Are there any other checks I can make on this thing. I have replace all of the burnt wires and it is wired as per the print I downloader from this forum and even had someone else check my work so I'm pretty confident it isn't a disconnected or misconnected wire.

thanks for your help!
MIke

[Michael Eddie]

If you are getting around the 12 or 13 range, you are half way up the hill. You now know that it is either a bad voltage regulator, battery or starter generator, however it could not just be the unit but the connections leading to them. Make sure they are all tight and clean, take off the connections on the starter generator and clean them. Check out the battery, make sure it is in good condition and watered.

[peabody1945]

g2 dead battery

Matti,
When I rewired this cart I cleaned and tightened all connections. When I checked voltage at the generator output, it was less than 3 volts AC and zero volts DC. The coil reads open(megohm scale) . I'm suspecting the ac coil is bad. Where is a good source for parts. Also I want to check out the VR are there any troubleshooting tips for these. The 12.8 volts is the battery voltage and actually goes down to 12.4 when running. It's going to be a few days before I can get back to it. I plan on removing the SG and take a look inside. If I get lucky I'll find a broken wire that is repairable or will be able to buy the coil instead of the entire SG.
Mike

[peabody1945]

g2 dead battery

Matti
I forgot to add in my previous post that I swapped the original battery with a nearly new fully charged battery from a car. I am confident that I don't have a battery issue. I slow charged the original battery and checke water levels and it holds a charge and passes a load test.
Mike