Ford 641 battery/electrical question

ToledoTractorBoy · May 6, 2019

Question on the ramifications of connecting battery cables to the wrong battery terminals.

Purchased a 1958 Ford 641 last fall. Previous owner had installed new battery (6V) prior to sale; sticker indicating date of installation was visible. Didn't give it much more thought until this weekend when battery was dead. Initially thought maybe light switch, ignition, etc. had been left on. Charged battery overnight but still nothing. Started troubleshooting and discovered somebody at some point had installed battery incorrectly. Along the line over the past 60 years my tractor ended up with two RED battery cables. Somebody hooked one of those red cables to the positive terminal. The problem is that cable is the ground.

Without a doubt I need a new battery; this one won't hold a charge. My question is are there electrical components that may have compromised by the fact the cables were reversed?

The tractor started and ran with the cables reversed. I haven't operated it a lot yet because of the winter we had but enough to go through a couple tanks of gas. Am I going to be fortunate enough to get by with just a new battery or am I going to have other problems as well?

Thanks -

Shaneard · May 6, 2019

You may have to polarize the generator after the new battery is installed but other than that it shouldn't have hurt anything.

ToledoTractorBoy · May 6, 2019

Thanks! How would one go about polarizing a generator? Haven't had to do that before...

Ford850 · May 6, 2019

When I first bought my 850, the battery was connected properly but needed constant charging. I replaced the battery and had the same issue. Then I realized the dash gauge was showing a negative charge while running, so the generator was not charging. With the help of Soundguy (member here) I polarized the voltage regulator or generator (sorry I forget the details but it involved the regulator) and it instantly started charging properly. It's worked great since then!

Shaneard · May 6, 2019

Typically you would Polarize like this:

After all leads are connected:
Disconnect the "Field" wire from the Regulator.
Momentarily touch the "Field" wire to the "BAT" Terminal on the Regulator
Reattach "Field" wire & start engine
Check Voltage & Charging

DO NOT POLARIZE IT WITH ENGINE RUNNING!!!!

ToledoTractorBoy · May 6, 2019

Thank you, appreciate the help!

ToledoTractorBoy · May 6, 2019

Want to add a couple comments to my original post in the event it may be helpful to others. I learned I was wrong; the battery cables were NOT connected in error - they were correct all along. I learned my tractor has a "POSITIVE GROUND". The young tech at the battery shop first tipped me off that might be the case. I followed up by confirming with an old-time, experienced, farm boy turned mechanic who knows these machines inside and out and has worked on my particular tractor. He added that, in fact, a positive ground is fairly common in many older machines with six-volt systems.

RickB · May 6, 2019

Not only common, very nearly universal. There are also many 12 volt positive ground systems that were engineered before 1960 or so. Those systems exist, but 12v negative ground systems coexisted in the same timeframe.

ovrszd · May 6, 2019

As I read down I was prepared to discuss the positive ground situation. No need.

My Dad bought a 1959 641 new. I was always around the old Ford tractors growing up. All positive ground. When Dad bought a new 1974 4000 he had to adjust himself in regards to hooking up batteries.