How do you charge an 8 volt battery???

Sun Jun 20, 2010 9:51 pm

My 'new' Super A-1 has an 8 volt battery in it. It has gotten weak and won't start the tractor. Do I need to charge it on the 6 volt setting or 12 volt? My charger is an old "buzz box," suitable for electrolysis work---no electronic goodies in it.

tia
Al

Re: How do you charge an 8 volt battery???

Sun Jun 20, 2010 10:20 pm

Al,
Using a standard 12 volt car charger, the charger will charge a lead-acid battery to 13.8 volts, or 2.3volts per cell. For an 8 volt battery this is 9.2 volts for a fully charged 8 volt battery. To use a 12 volt charger, connect a 4.5 ohm 10 watt resistor in series with the charger to the battery. This will limit the current when fully charged to about 1 amp since as the battery charges, the voltage will rise and approach 9.2 at the battery and 13.8 at the charger. The resister will drop 4.6 volts and the charger will be supplying 1 A when fully charged. When fully charged, the resister will be dissipating 4.6 watts, which is pretty toasty so be careful not to touch it. If the battery is deeply discharged, the resister will be dissipating a lot more. If deeply discharged, you may need to use a resistor with a higher wattage rating. A 10 watt resistor will safely charge a battery that is down to about 6-7 volts.
Gerry

Re: How do you charge an 8 volt battery???

Sun Jun 20, 2010 11:03 pm

Interesting question.

Try this first. Put the battery on your charger, 6 volt setting. After about an hour on the charger check the voltage across the battery terminals with the charger working. Guessing - you will see about 7.8 - 7.9 volts, maybe a little more. This should be sufficient to charge the battery to around 80 plus percent.

Reason I'm suggesting the 6 volt setting is that I purchased a battery charger with digital readings. The display giving voltage readings showing in the upper 15 volts and sometimes in the 16 volt range when charging a 12 volt battery.

Why not jump start the tractor and let the tractor charge up the battery?

Re: How do you charge an 8 volt battery???

Mon Jun 21, 2010 7:54 am

Eugene wrote:Interesting question.

Try this first. Put the battery on your charger, 6 volt setting. After about an hour on the charger check the voltage across the battery terminals with the charger working. Guessing - you will see about 7.8 - 7.9 volts, maybe a little more. This should be sufficient to charge the battery to around 80 plus percent.

Reason I'm suggesting the 6 volt setting is that I purchased a battery charger with digital readings. The display giving voltage readings showing in the upper 15 volts and sometimes in the 16 volt range when charging a 12 volt battery.

Why not jump start the tractor and let the tractor charge up the battery?


Thanks fellows for your input. The charging system is not working. The rubber strips that insulate the voltage regulator box from its mounting hardware have both dry rotted in two. I think I may need a new regulator.... I am tempted to just go ahead and buy a 6 v battery but that is only one item on a long list of necessary things to get it like it ought to be. I was thinking I could charge it on the 6 volt setting but wasn't 100% sure.

thanks,
Al

Re: How do you charge an 8 volt battery???

Mon Jun 21, 2010 8:06 am

There is a reason the 8 volt battery was installed in the tractor. Probably the starter is beginning to drag.

My thought.

It would cost about the same to convert to a 12 volt single wire alternator as to buy another voltage regulator. Maybe cheaper to convert.

I would disassemble the starter and repair. May only take new bushings and brushes - not expensive.

Re: How do you charge an 8 volt battery???

Mon Jun 21, 2010 3:37 pm

Eugene wrote:There is a reason the 8 volt battery was installed in the tractor. Probably the starter is beginning to drag.

My thought.

It would cost about the same to convert to a 12 volt single wire alternator as to buy another voltage regulator. Maybe cheaper to convert.

.


Sacrilege!!

Just kidding......I don't really like 12 volt conversions, but if this was on a Cub, or an H or M, where the generator or alternator is hidden, this one would indeed be a good candidate for a conversion. Since it's a Super A-1, the generator is right there for the world to see. Plus, there were only around 1600-1700 Super A-1s (19xx of them if you count Super AV-1's and Super AI-1's) made. Not something I want to do a bunch of modifications to. My plans for this one aren't exactly for it to be a trailer queen, but close to it.

Wouldn't an 8 volt battery require a heavier cable, much like a 6 volt? This one has little bitty, suitable for 12 volt, cables on it. I might just go ahead and get some decent 2/0 battery cables made and go ahead and put a 6 volt battery in it.

Thanks again everybody for the feedback!

Al

Re: How do you charge an 8 volt battery???

Mon Jun 21, 2010 4:16 pm

Al, it was being charged by the 6 volt gen. so just charge it with the 6 volt setting on the charger.
A lot of the old farmers put 8 volt batteries in 6 volt systems. This was done because of bad grounds, bad starters etc. Chances are if you put good cables on it the 6 volt battery will start it fine. One good thing starters and generators are much Ezer to find for the SAs. Than for cubs . Watch out though the starter for a reg A will not work on a SA. But are the same on the SA 100 130 and early 140s.

Boss

Re: How do you charge an 8 volt battery???

Mon Jun 21, 2010 7:11 pm

Super A wrote:The rubber strips that insulate the voltage regulator box from its mounting hardware have both dry rotted in two. I think I may need a new regulator....
Hi Al - it seems like replacing those would be one of the first things to do. I'd be looking around for an old inner tube to make a replacement.
Here's a question: if it starts with a jump from a good battery, can't the output of the charging system be measured with a volt meter while it's running to eliminate that as causing the problem? When troubleshooting this, it would be good to know that the system is able to keep the battery charged.
Super A wrote:Wouldn't an 8 volt battery require a heavier cable, much like a 6 volt? This one has little bitty, suitable for 12 volt, cables on it. I might just go ahead and get some decent 2/0 battery cables made and go ahead and put a 6 volt battery in it.
I was told years ago that with a 6 volt system, the battery cables should be "as big as Groucho Marx's cigar". TM's website has 6v cable that's #2 gauge copper wire, so if it's smaller than that you might think about replacing them. Their 12v wires are #4 gauge.
Corrosion on the wires near the terminals is also pretty common. It might be worthwhile to cut a little of the insulation back if you can't see what the wiring looks like at those terminals.