A buddy of mine has a Ford 8n tractor and was having problems with starting. I recomended either doing a tune-up and correcting the starting problems or converting to 12volt. He came up with the idea of leaving everything 6v, but use a 8volt battery. it worked fine for a while, but now the 8volt battery is dead and needs charging. any idea on how to charge a 8 volt battery. the only chargers I have are either 6,12, or 24 vdc. Any help would be appreciated so I can get him back going.

Go back to 6V with a high CCA battery, 2/00 cables, bolt the chassis return connection direct to the starter body.
Eliminate any high resisitance connections/switches in the ignition circuit so the coil recieves full battery voltage.
Make certain the coil polarity matches the battery chassis connection. Odds are somebody has it backwards and is weaking the spark.

Charge it at 12 volts but only for a short time.
Walt

Charge on 6 volt side works great.Do this every now and then. Just like you would a 6 volt battery.

8 volt battery at best is a band-aid fix for problems that it has. 6 volt or 12 volt is the only way to go. Funny how people think an 8volt battery is a magic fix but its just another problem on top of what is wrong
Hobby farm

DO NOT CHARGE IT WITH A 12 VOLT. It will boil and maybe blow. You can charge with a 12 volt if you reduce it with some kind of resistor. A light bulb works well. You can get it partialy charged with a 6 volt charger, but that is the big trouble with 8 volts. They are at best just a stop gap thing. Tighten up the spring on the voltage regulator works--then you tend to blow the light bulbs. BTDT.

Hello benji smith.
You can use your 12v charger. Take the 6v and the 8v batteries and put them in series.
Then use your 12v charger to charge them both. If the charger can charge at least 14 to 15 Volts it will bring the 8 volts battery up probably enough to start the engine.
Guido.

did the regulator get adjusted so the charging system puts out more than 8 volts? if not the 6 volt generator will not keep the eight volt battery charged.On a car the 12 volt battery usually gets charged with around 13.9 volts or so. Bill M.

No he just put the 8v battery in and left the charging system 6v. Im gonna let him know the best thing is for him to let me get the tractor running correctly and just continue using the 6v battery. thanks for all the help guys!!

8 volt batteries work OK when generators had cutout relays instead of regulators. In that case, the output voltage of the generator was limited by the battery, not by the generator. The generator wouldn't charge an 8 volt battery as fast, but it would charge it. With a voltage regulator, the output voltage of the generator is limited by the regulator, and it'll never fully charge an 8 volt battery.

It is possible to adjust a 6 volt regulator to properly charge an 8 volt battery, but you need to know what you're doing and have some basic electrical test equipment to succeed.

As others have noted, the best bet is a properly set up 6 volt system. One of the biggest problems is people using battery cables that are too small. Six volt starters draw twice the current of an equivalent sized 12 volt starter, and the battery cables need to be correspondingly bigger. 2/0 is a good size if you can find them, or buy some welding cable & lugs and make your own. The typical #4 or #6 cables sold in auto parts houses are way too small.

In general, using an 8 volt battery is a patch for a problem that should never have existed in the first place.

Keith

PS...it is possible to charge an 8 volt battery from a 12 volt charger by using a series resistance to limit the charge current. A 12 volt tail light bulb is a good place to start for a reasonable sized charger. Just be really careful to watch the state of charge of the battery. As the battery approaches full charge and the current decreases, the voltage drop across the resistor also decreases, resulting in progressively higher voltage applied to the battery. You'll eventually destroy the battery by boiling it dry if you let it continue charging.