G6200 Battery Voltage

[krivs388]

Hey guys,

Was just curious what you guys are seeing on your G6200 when it comes to battery voltage when running. My G6200 is a 1987 model and has roughly 1800 hours. I noticed the dynamo doesn't really raise the voltage until the RPM's go way up. Most I see when running at full throttle is about 13.6ish. At idle it's below 13 unless it was recently at full throttle and the voltage is gradually coming down.

Reason I ask is since a new battery was put in the tractor right before I bought it 2 years ago and now it's junk. Seeing as the new 51R batteries for the G6200 are stupid expensive, I'd like to avoid having to replace it again in the near future. Not to mention a new OEM dynamo is also over $200 and I don't want to buy that for nothing either, especially if the voltage I'm seeing is normal.


Any thoughts?

Thanks!

 

[Edke6bnl]

Where are you taking your reading and are there any voltage drops on the cables going to the battery ground and positive?

 

[krivs388]

Where are you taking your reading and are there any voltage drops on the cables going to the battery ground and positive?

Readings were taken right at the battery and cables are good. No drop across them. Put a tester on the battery and it failed. With a jump starter on the battery it turns over fast like it should. I'm actually a master electrician and have done everything I can electrically, but I'm going at it blind without knowing the specs of the charging system. If I knew the nominal resistance value for the dynamo, I could rule that portion out at least. I did come across a used known good voltage regulator for dirt cheap. I'll swap that out to see if there's any difference.

I was just a bit worried at seeing that lower voltage at idle. However, I would think 13.6 at full power is plenty.

 

[85Hokie]

Dynamo's are famous for low output at low RPM's .... however 13.6 is a bit low BUT if that is charging the battery I would not be worried.

Dynamos rarely go bad other than bearings - but the voltage regulator is the culprit most of the time.

YOU can check the dynamo - get your meter out, place on AC and find the wires that go to regulator - you will see a voltage come up slowly as the RPMS come up - something above 30 VAC should be seen.

 

[GreensvilleJay]

a 'cheat' is to replace the dynamo pulley with a slightly smaller one. That increases the dynamo RPM to up the output voltage.

 

[krivs388]

Dynamo's are famous for low output at low RPM's .... however 13.6 is a bit low BUT if that is charging the battery I would not be worried.

Dynamos rarely go bad other than bearings - but the voltage regulator is the culprit most of the time.

YOU can check the dynamo - get your meter out, place on AC and find the wires that go to regulator - you will see a voltage come up slowly as the RPMS come up - something above 30 VAC should be seen.

Excellent. That known 30 volts is great info for me to check.

Thanks

 

[krivs388]

Hey guys just wanted to update and close the thread. That used regulator I got on ebay for dirt cheap fixed my issue. The replacement regulator brought my charging voltage up to 14.5v at full throttle, which is more in line with what I thought. Unfortunately the old one was what killed my old battery.

Thanks for the help!