Charge light on at high rpm off at low

wesmann · Feb 3, 2021

My ym276 charge light has flickered for a month. Now it's on at working speeds all the time but off at low rpms. Too cold to tinker right now so I put a charger on it if I have to. Any suggestions on what to look at first when it gets warm again? I did tighten the belt a bit but no luck.

winston1 · Feb 3, 2021

I would check voltage at battery with tractor running to start with. Then go from there depending on what you find.

bmaverick · Feb 3, 2021

wesmann said:
My ym276 charge light has flickered for a month. Now it's on at working speeds all the time but off at low rpms. Too cold to tinker right now so I put a charger on it if I have to. Any suggestions on what to look at first when it gets warm again? I did tighten the belt a bit but no luck.

Do you have the YM276 Service Manual? See Section 40.10 & 40.11.

If you need the manual, it's FREE with many others at the Yanmar Tractor Owners Group.
main@yanmar-tractor-owners.groups.io | Home

RustyA · Feb 3, 2021

Possible light is on because it's overcharging at higher roms? Turn headlights on and check battery voltage at different roms. If it's over 14.6 volts it's overcharging. Perhaps regulator is stuck on? Is there staining on top of battery or is battery hot after use...sign of overcharging system.

wesmann · Feb 4, 2021

Thanks for the tip on the Yanmar Owners Group. I will check it out.

rScotty · Feb 4, 2021

RustyA said:
Possible light is on because it's overcharging at higher roms? Turn headlights on and check battery voltage at different roms. If it's over 14.6 volts it's overcharging. Perhaps regulator is stuck on? Is there staining on top of battery or is battery hot after use...sign of overcharging system.

Yes, it's always worth thinking about overchanging. Today overcharging is more likely to be a problem with some battery types and voltage-sensitive components. I wouldn't be surprised to find that modern voltage regulators are capable of reporting overcharging as a fault condition.

But on these older ones - there were several different old style regulators - but none of them had the ability to report overcharging back to the operator. The old regulators could reduce the voltage in a couple of different ways, but they did it invisibly.

So the lamp flicker isn't an overcharging message, but that doesn't mean that the regulator hasn't broken down and is allowing overcharging. As you say, that is still worth checking with a voltmeter. Also check for AC vs DC voltage at the battery. These old Yanmars were built back in an era when overcharging was less of a problem. All we had as a chargng target for energy storage were vented lead/acid wet cell batteries mounted out in the open. That type system is less affected by too high of a charging voltage. Or at least not in the same way that the modern gel, AGM, and litium batteries are.
rScotty