6 volt /8 volt tractors

What"s the story on 8 volt batteries in old farm tractors? Are these systems really 8 volts systems, or just 6 volts systems using 8 volts for a little boost?

Thanks

6 volt systems using 8 for a boost...

In all theory you could put a 12 volt battery in your tractor and just not ride the starter very long or it will get hot.

it will also only charge at 6 volts, but it could work...

6 volt systems using 8 for a boost...

In all theory you could put a 12 volt battery in your tractor and just not ride the starter very long or it will get hot.

it will also only charge at 6 volts, but it could work...

6 volt systems using 8 for a boost...

In all theory you could put a 12 volt battery in your tractor and just not ride the starter very long or it will get hot.

it will also only charge at 6 volts, but it could work...

Did you catch that?

If you want 8 volt, do it right. If you want 12 volt, do it right. Do it wrong, it will haunt you forever. Stick a 12 in a 6v system, it will at least burn regulator, may be coil, points, ballast resistor, bulbs. 8 a little better but same applies. 8 will never charge properly. Batt will be half dead all the time. Follow ad vice on this site and do it right.

To use an 8 volt battery, you need to set your voltage regulator to charge 8 to 9 volts. Otherwise, you'll just be charging an 8 volt battery to 6 volts with no gain.

I bought a 4000 Ford - it has an 8 volt battery in it. Sounds to me like someone put an 8 volt in a 6 volt system. It's good for a long time but eventually the battery goes dead. I was out past dark one night and running the lights killed the battery within an hour. Sound like maybe the charging system is damaged.

Thanks everyone.

You can put a 8v battery in and change nothing and it will keep charged up well.

If you have a third brush generator you can adjust the charge voltage to 9.2 and it will work well. The only drawback would be decrease lamp life, which doesn"t seem to be much as I have been running mine for about 11 years and haven"t changed a lamp yet.

Your 6v generator/regulator will charge a 6v battery higher than 6v, say 6.7 volts. You can and we do use 8v batteries to save that extra charge and it works fine.
Remember that when you're speaking of the old argument of 6v vs 12v, the problem is not with the old 6v systems, the problem is that a LOT of folks try to use automotive or 12v CABLES with 6v systems. To get the maximum starting from the 6v system, you need a larger diameter cable to pass the current than what you can generally get from an auto parts store.
12v systems have more voltage and require less current which means they use smaller diameter cables. 6v means less voltage and more current so require larger diameter cables.

The typical charging voltage for a "6-Volt" tractor battery is 7.2 to 7.4 Volts.

To properly charge an "8-Volt" tractor battery, you'd need about 9.6 to 9.9 Volts.

Charging an 8 volt battery with less than 9 volts will ruin the battery as it will never get above the proper voltage in the battery. It is never correct to use anything but the proper generator with the battery size.
Charging an 8 volt battery with a 6 volt generator will only give you a dead battery as it will never reach the proper voltage to be fully charged.
Walt

The idea of using an 8 volt battery came about when generators still had cutout relays instead of actual voltage regulators. A generator with a cutout relay will charge an 8 volt battery, just a little slower than it would a 6 volt battery, because all the cutout relay does is disconnect the generator when its not running to keep the battery from discharging. With a cutout relay, the generator puts out whatever the battery will take, with a regulator the output voltage of the generator is limited to what the voltage regulator is set for.

Using 8 volts on a 6 volt system that's otherwise in good shape will in fact give you a little extra starting boost, however, it will also eat light bulbs. Using an 8 volt battery to try to compensate for a 6 volt system in poor condition will just lead to additional problems.

Battery cables are the biggest problem with a 6 volt system - just look at all the questions on this site. People assume that a 12 volt cable will work on a 6 volt system, but that's not true. 6 volt starters draw at least twice the current than an equivalent 12 volt starter, which requires cables also capable of carrying twice the current. Voltage is immaterial when it comes to battery cable selection.

I've currently got two tractors & two vehicles with 6 volt systems, all of which will start just fine on 6 volts as long as I use the proper size cable & keep the terminals clean.

A 8 volt battery is a poor work-around for some other problem.

Keith

KEB1. Correct on all accounts.

I use 8 Volt batteries in my tractors, because I'm too cheap to BUY 6 Volt. I check out the JUNK battery pile, if I find a 12 volt that has 4 good cells together on one end or the other, I drain and flush 2 dead cells from one end, CAREFULLY remove the 2 cells, clamp a cable onto the connector bar, and install it as needed. Yeah, I could remove 3, for a 6 volt, but I choose to use 8 Volt. Only a few minutes time invested, no money, and fast starts.

I bought a 8N that hadn't ran in about a year. It had a 8 volt battery in it. I charged it with a 6 volt charger and got it running (barely as two plug wires were crossed). After getting it running right it charges at a little over 9 volts. Starts fine and I think it would start ok on 6 volts but I'm leaving it as is for now. The VR must have been tweaked but it was done right. David.....