Ford 641 Overcharging

WildcatFord

New User
Just replaced the VR on a Ford 641 with 6 V positive ground.
Previous VR was suspected faulty (no charge warning light on
constantly when tractor was running, but extinguished when
BAT and ARM terminals jumpered at fast idle). When opened,
the previous VR was stuck closed on the side between ARM
and FLD terminals.

Tractor is now charging, but voltage reads between 7.2 (slow
idle) and 8.4 V (~1500 rpm) across battery terminals when
running. This appears to be high compared to recommended
value of ~7.4 V. Is this a problem?
 
Is your battery currently discharged? Perhaps leave battery on for a few hours, and try running tractor again. I would bet your problem goes away. How is the condition of your battery? If in doubt, have it tested. Good luck!
 
Battery shows 6.3 V across terminals when tractor is off. I suppose it could be discharged some despite good voltage reading, since it was not charging for a while.

When you say to leave battery on for a few hours and then try running tractor, are you suggesting charging the battery?
 
Is this a "breadwinner"/hard working/pulling down 8-12 hour shifts tractor or a "toy"/hobby tractor?

How accurate is your voltmeter?

Is there any sign of battery "gassing"/wetness on top/boiling/heating?
 
Almost all batteries without a completely dead or shorted cell will show the proper voltage when there is no load, regardless of the ability to hold a charge. Put some sort of small load on the battery while the tractor is not running, like a test light, and measure the voltage. If it doesn't stay above 5.9 then it either needs to be charged or cannot hold a charge. Easiest thing to do is pull the battery and take it to any auto parts store, as they will do a proper load test for free and tell you if the battery is good or not so you're not guessing.
 
That charging voltage is high; but you only have a 12 amp generator; my 861 did the same for about 15 minutes then cut back to 6.6 or so.
 
It?s a hobby tractor.

Voltmeter is pretty new. I don?t have a reason to doubt it, but it is digital.

No indication of outgassing as of yet.
 
(quoted from post at 20:05:28 10/15/18) That charging voltage is high; but you only have a 12 amp generator; my 861 did the same for about 15 minutes then cut back to 6.6 or so.
0
 
(quoted from post at 05:52:26 10/15/18) Almost all batteries without a completely dead or shorted cell will show the proper voltage when there is no load, regardless of the ability to hold a charge. Put some sort of small load on the battery while the tractor is not running, like a test light, and measure the voltage. If it doesn't stay above 5.9 then it either needs to be charged or cannot hold a charge. Easiest thing to do is pull the battery and take it to any auto parts store, as they will do a proper load test for free and tell you if the battery is good or not so you're not guessing.

Following up on this, I got a load tester and confirmed the battery was weak. Yesterday, I was able to run the tractor for a while, and the charging voltage had gone down considerably. I'm pretty sure the battery was simply run down from not being charged for a while due to the faulty VR.
 

We sell tractor parts! We have the parts you need to repair your tractor - the right parts. Our low prices and years of research make us your best choice when you need parts. Shop Online Today.

Back
Top