Will the generator kill my battery ?

The battery in my MF 202 (very similar to 35) seems to take and hold a charge well when out of the tractor but when I leave it sit for a day or two it is drained to the point where it won't even roll it over.
I have checked and replaced a lot of the wiring and everything runs off the key switch. The only thing that has a direct connection to the battery is the generator. It seems to charge just fine so I'm wondering if it is presenting a load on the battery when the tractor is turned off. Is there anything in the generator or regulator that might cause this? I guess it might also be that my battery is just shot too.

I have not yet done a current draw test but I will.

"The only thing that has a direct connection to the battery is the generator."

Actually, it DOESN'T have a "direct connection" to the battery. The voltage regulator is between the generator and the battery, specifically is "cutout relay".

If the cutout isn't opening at shutdown the battery will drain rather rapidly back into the gnerator, overheating, and possibly damaging it.

If you have a SLOW drain that takes overnight or longer, it's probably NOT the VR/cutout.

Have to agree with Bob. My AC D19 had the same issue. Contacts in the VR were stuck together.

Ah, that makes sense. I will check out the regulator.

Thanks guys.

The "current draw" test you mentioned should help locate the cause of discharge. The battery is connected to the BAT terminal on a Voltage Regulator and theres no other connection from the battery direct to the genny whereby the genny is draining your battery as you ask. Inside the VR is a Cutout Relay between the VR"s BAT and GEN/ARM which is supposed to open when shes off (so battery dont discharge via genny).

HOWEVER as Bob noted if the Cutout Relay portion of the VR is sticking closed, then there is a low resistance very high curent discharge path (to drain battery) to discharge the battery via the stuck cutout relay and the genny via its ARM post.

If you were to loosen or remove the genny belt if the cutout relay is indeed stuck THE GENNY WILL SPIN. Its supposed (if not sticking closed) to open when you shut the tractor down but close once the genny is charging so it can get to and charge the battery via the closed cutout relay inside the VR.

Also if the cutout relay is stuck, when you shut down there would be a high discharge reading on the ammeter and the genny will get HOTTTTTTT and again the genny would spin if the belt were loosened !!!!!!!!!! if that happens upon shut down and the ammeter reads a heavy discharge see if it stops if you remove the wire off the BAT terminal?? If so then the cutout relay is sticking.

HOWEVER IF THATS NOT THE PROBLEM (such will discharge the battery and heat up the genny very rapidly) then theres perhaps a higher resistance lower current draw slowwwwwwwww dischage thats running the battery down UNLESS THE BATTERY ITSELF IS BAD?????????

John T

There is no ammeter although I should probably install one instead of the voltmeter as the ammeter would be much more useful.
I have a background in electronics so I should be able to nail it down pretty quickly but I have never worked with a generator type system before.
If the regulator checks out ok I'll check for any other current draw and failing that it's gotta be the battery.

Sounds like a bad cell in the battery if it won't hold a charge very long. Swap it out with one from a vehicle and see if you have the same problem. Anymore, I pull the ground cable when I leave mine set. Probably need to buy a little charger from HF to keep it up otherwise the constant discharge will ruin the battery anyway.

I have a few small solar panels that seem to do a good job of keeping it topped up so if I don't find anything else I may just do that 'till the battery dies all together.
I was also considering just getting a disconnect switch and then if the battery is still dying then I know it's the battery.

On my 560 Diesel I have 2 12V batteries and it starts real good, I do have the largest batteries that fit the box and the highest cca i could get. This engine has approx 200 hours on a complete rebuild.

Buy an 89 cent hydrometer and test the battery.

If you are still having the same problem after checking regulator,try taking off a battery cable and use a test light From cable to post if it lights there is a drain. see if light switch may be on and wire may have fell off causing power loss.
some have a single rear work light with separate switch on housing .