8 volt battery in 6 volt system?

I had someone ask me if they were to put an 8 volt battery in their 6 volt tractor, would a resistor be needed for the 6 volt coil? His tractor is a Farmall M and it has a 6 volt alternator on it, not a generator. Thoughts on this?

I put an 8 volt in my old Massey....had to adjust the regulator slightly so the generator would fully charge the battery. Worked fine for a few years, but I went back to a large 6 volt battery at replacement time. Factory specs seemed to work best.

Ben

THe thoughts are, replace the battery cables,rebuild the starter and by a 6 V battery. THe 6v is not the problem,the other things are the problem and will still be there after the 8v is installed.

dont put a band aid on a problem, fix it. 8 volt is not needed.

He's not really having any problems, just replaceing an old battery. It does have like new 2/0 cables. He said there was a $10 difference between a 6V or 8V battery and was wondering if it's worth it to get the 8V. My opinion was get a good quality 6V with a high cranking amp rating.

You'll have to adjust the voltage regulator upwards to charge the 8 volt battery. I don't think you'd have to change anything in the ignition.

Best thing I ever did was get dad the 6v battery in his Ford the previous owner had an 8v in. All of his issues were solved with that and getting rid of his points.

Get a group 2 six volt battery. Has a lot more capacity than a group 1!

On the 1960's and 1970's many N ford owners put 8 volt batteries in those. I've hauled many many of them to the scrap that had 8 volt batteries in them.

Used to run some 8V batteries,better than 6V but neither is close to being as good as a 12V with an alternator.

I agree with your advice

If it works dont fix it then.

(quoted from post at 18:07:12 07/12/23) He's not really having any problems, just replaceing an old battery. It does have like new 2/0 cables. He said there was a $10 difference between a 6V or 8V battery and was wondering if it's worth it to get the 8V. My opinion was get a good quality 6V with a high cranking amp rating.

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The answer to getting an 8V battery is no. Use the $10 for a couple of slices of gas station pizza and a lottery ticket.

There is no such thing as a "good quality 6V" battery anymore, though. That's why I convert to 12V. An alternator and a good 12V battery costs less than a junk 6V that you have to replace every other year.

The 2N Ford ran a 8 volt for years with no adjustments and no problems, The resistor on those tractors cut the 6 volt down to slightly over 4 volts and would not have enough power to start. Ended up getting rid of that resistor that Farmall and John Deere did not have in there6 volt distributor that they say if you put 6 volts to the Ford points you will burn them up. After getting rid of that resistor that was making the tractor stop at bad times and putting a 6 volt battery in place as 8 volt was not avaiable no problems. The 1950 International truck would hardly start as not enough power to points putting an 8 volt battery in with no other change used for years. All the problems they say you will have with the 8 volt battery we never had. I have had more problems with electronic ignation than we ever had with points. Dad and I both had cars with the electronic we had to carry a new modual in car to change many times on the road as it would just stop the car from running. If I could go back to points it would get rid of the electronic ignition problems I am having in my daily driver. That electronic system left my late wife stoped dead with the car in middle of traffic in left lane of 4 lane road in town. Several men following when it shut down pushed the car out of the road. I hate electronics and would never by a trtactor converted. But no do nothing to put a 8 volt in instead of a 6 volt. I am going by experiance.

I would not worry about the coil needing resister. However you might need to find an 8 volt regulator for you 6 volt alternator. You can trick the alternator to make more volts via remote sense wire but I don't think you would gain 2 volts.

Thousands of people solved hard starting issues with an 8 volt battery. 99% of the time the 8 volt was dropped into the 6 volt spot with nothing else being done. Most of that went away when alternators become cheap and people with issues just switched to 12 volt systems with minimal cost. I did a quick search on Amazon and the cheapest 8 volt battery I saw was $250. It would pay to buy a 12 volt and switch it over.

Too look at it one way.. voltage is pressure, and current is flow. An 8 volt battery if charged correctly, will have 33.3% more pressure than a 6 volt battery. And would pull 33.3 % more current assuming your cables are still 6 volt (2/0) cables. SO... by simply making a small adjustment to the voltage regulator, you can.... spin the engine over faster.. meaning that it will develop more compression on a cold crank.. and, it will have enough voltage to have a hotter spark. SO... the engine should... start quicker, with less cranking time. IF your six volt tractor is perfectly tuned and in perfect condition, you will probably see no difference. If your six volt tractor has been down the field many times, you probably will see a difference, mainly on starting times.

Problems with this.
most folks replace bad battery cables with small 12 volt cables that only have to carry smaller cranking currents. But with a six volt starter, you must have the very large cables still in place, even with a 12 volt system.

second, they dont adjust the voltage reg up to correctly address the 8 volt battery(9.46 volts), so your not really gaining anything as the battery is under charged, and could actually be worse in this undercharged condition than a six volt that is charged correctly(7.1 volts).

What are your thoughts?

(quoted from post at 08:27:40 07/13/23) The 2N Ford ran a 8 volt for years with no adjustments and no problems, The resistor on those tractors cut the 6 volt down to slightly over 4 volts and would not have enough power to start. Ended up getting rid of that resistor that Farmall and John Deere did not have in there6 volt distributor that they say if you put 6 volts to the Ford points you will burn them up. After getting rid of that resistor that was making the tractor stop at bad times and putting a 6 volt battery in place as 8 volt was not avaiable no problems. The 1950 International truck would hardly start as not enough power to points putting an 8 volt battery in with no other change used for years. All the problems they say you will have with the 8 volt battery we never had. I have had more problems with electronic ignation than we ever had with points. Dad and I both had cars with the electronic we had to carry a new modual in car to change many times on the road as it would just stop the car from running. If I could go back to points it would get rid of the electronic ignition problems I am having in my daily driver. That electronic system left my late wife stoped dead with the car in middle of traffic in left lane of 4 lane road in town. Several men following when it shut down pushed the car out of the road. I hate electronics and would never by a trtactor converted. But no do nothing to put a 8 volt in instead of a 6 volt. I am going by experiance.

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o regulator to adjust on a 2N.

seems lately most all batterys are becoming new junk. but he the
prices sure went up. quality died out n warrety is very short too

I was going to go the 8 volts route on an SC and DC CASE. After research on YT and a local tractor salvage parts store owner who had several people there who had been there for years, said no on the 8 volt system. Too many changes to be made with little improvement. Said one needs amps, not volts. These Guys talked from experience.
Yes, it is hard to find a good 6 volt battery. I converted both tractors to 1/0 cables. From battery to starter button, and button to starter. Also put in cut -out switches, so there is no drain, as these antiques tend to set a lot. That way they are OFF! Also when displayed at county fair, they are off. Some kids gets on there and pulls the ignition switch ondead battery!
I was having starting problems for a long time with both tractors. Replaced coils, wires,plugs, rotors, distributor capswent through it all. Then had starters checked and rebuilt if needed. Then had carbs cleaned and rebuilt. Not much change in starting! Actually worse on one of them.
The problem was the starter buttons! These are momentary switches. Replaced them, now both start good.
I tore those old switched apart. Simple spring loaded contacts inside. Burnt!
That was the problem in the first place.
Keep fresh fuel in them. Add a quart of that super fuel they use in small engines, 4 cycle,also add fuel stabilizer( StarTron) , and keep trickle chargers on the 6 volts. Not sure if the super fuel helps, but actually I had best luck on 6 volt batteries from local farm supply store and also from a Wal mart battery.
Hope this sheds new light and good luck.
By the way, should one still use lead additive in these old tractors? Its hard to find. Maybe if one was farming with them, maybe not just for show and parade.