8 volt batt.

kp

kp

Senior Member
Thinking on installing 8 volt Batt. in my 31 A ,I know its been tossed around before (cant remember what I had for supper last night much less what I have read here in the past on 8 volt batt). but what complications will I run into ? Will it work ok as is ? Do I need to install a resistor ? :confused:
 
Remember, an 8 volt battery needs charging at over 9 volts to maintain its charge. Also, bulbs will be short lived. I don't think the bulbs are available in 8 volt. May be wrong on that.
 
WHY?????

As Russ said, the bulbs will be short lived, and maybe the points and coil also to some extent. A Model A doesn't need to spin fast to start. I just came in from firing up my 28 for the first time in over 5 months. It started on the first or second compression stroke. I haven't used a battery tender nor battery charger on it when it sets all winter, but the battery keeps a good charge. I park it at the first sign of road salt and don't even look at it for the next 5 or 6 months, but the 6 plus years old junk yard 6 volt battery just keeps on doing it's job. I have an electronic voltage regulator inside my powerhouse generator and within 2 minutes of starting it today the amp guage was back to 0 to 1 amp, indicating a fully charged battery.

I'll have to look and see what brand the battery is, because I bought it at a junk yard over 6 years ago and even though it was dead, I charged it up and it's been doing great since then.
 
An 8 volt battery will work,as long as you are using a stock A charging system.The battery is really the voltage regulator in the A.Old bulbs will survive pretty well,the new repro bulbs will pop pretty fast,even of they are marked 6-9 volts.They seem to pop fast on 6 volts.I just don't see any reason to do it.If it doesn't crank right on 6,something is wrong,and the 8 will help to cover it up for a while.Dim lights are not the result of voltage,they are the result of bad reflectors,connections,lenses,etc.Candlepower is candlepower,no matter how many volts are running the bulb.I can see wanting to go to 12 volt if somebody wants to run accessories,but not just to get around a problem that needs to be fixed in the first place.Is there a reason you want to do this? I have run into people that want to go to an 8 volt battery because they remembered their dads doing it in the 50's to keep the car starting.
 
I agree that an 8 volt batt is probably un-necessary for an A and would create some other issues. I do have a '51 flathead V-8 that was really slow cranking and one of the tricks that was suggested to me by the guy that rebuilt my starter years ago was to re-wire it so that it was a 4-volt starter. It did indeed crank better after I installed it, but I have no idea the specifics of how he redid the field coils, etc.
 
I remembered some people changed to 8 volt batt. years ago. it was just a thought ,dont have any problem with it cranking ,just lights seem dim ,probable need to replace all the wiring and make some good grounds,and get my headlight reflectors replated. Maybe I can find some good ones at a swap meet.
 
A 6 volt system doesn't charge an 8 volt battery, so you essentially still have a 6 volt battery, a regulator system can be adjusted to charge more, but I don't know what a cut out generator system will do, correct size cables,clean connections and a well charged battery are the key to good starting.
 
I would'nt change it either, make sure all electrical connections are clean, your grounds super clean. They do sell polished aluminum reflectors that are sealed, supposed to stay shinny for at least 5 years. I know this sounds dumb, but rememder these lights are 80 years old, back then they probably were to bright for most. Don't forget to correctly align the headlights as well, they will always seem dim if not pointing correctly.
 
ABento said:
A 6 volt system doesn't charge an 8 volt battery, so you essentially still have a 6 volt battery, a regulator system can be adjusted to charge more, but I don't know what a cut out generator system will do, correct size cables,clean connections and a well charged battery are the key to good starting.
Click to expand...

With a third brush generator and cutout the battery is the VOLTAGE LIMITER, so the generator will put out the battery voltage up to the generator's maximum output, which is between 30 and 40 volts. That's why bulbs pop as soon as you have a bad connection in the charging circuit, if the lights are turned on. That's also why I only use regulated generators.

I like the term "VOLTAGE LIMITER" better than "VOLTAGE REGULATOR" to describe the battery and charging system as the factory made it. That way there should be less confusion between a stock charging system and a regulated charging system for the Model A.
 
I have wondered myself about the pros and cons of using the 8 volt batterys. We have two Model A's with 8 volt Exide batterys, which were purchased from a local agriculture dealership. One of the A's has a Nurex 6 volt altenator, the other uses the original style powerhouse generator.
The main reason I chose to try the 8 volt battery, was due to the fact most batterys available locally, just don't stand up. Even with using distilled water and the like.

Charging voltage for these 8 volt batterys have been somewhat of a question, for me also. Will the battery in service on the vehicle just act as a variable capacitor, and accept possible voltage spikes from the power house generator to possibly 8-9 volts ? I would assume the altenator system would hold the voltage constant.

If a person was to use a 12 volt charger for bench charging, will damage occur to the battery, or will it just stop at 8 volts, and hold. "I don't like things that go boom"
 
Glenn C. said:
I have wondered myself about the pros and cons of using the 8 volt batterys. We have two Model A's with 8 volt Exide batterys, which were purchased from a local agriculture dealership. One of the A's has a Nurex 6 volt altenator, the other uses the original style powerhouse generator.
The main reason I chose to try the 8 volt battery, was due to the fact most batterys available locally, just don't stand up. Even with using distilled water and the like.

Charging voltage for these 8 volt batterys have been somewhat of a question, for me also. Will the battery in service on the vehicle just act as a variable capacitor, and accept possible voltage spikes from the power house generator to possibly 8-9 volts ? I would assume the altenator system would hold the voltage constant.

If a person was to use a 12 volt charger for bench charging, will damage occur to the battery, or will it just stop at 8 volts, and hold. "I don't like things that go boom"
Click to expand...

You could damage the battery charger and the battery by using a 12 volt charger.

The STOCK powerhouse will charge the 8 volt battery at whatever amps you set the third brush to.

The 6 volt alternator will NOT charge the battery at all. That means the 8 volt battery will NOT be charged to 6 volts and act like a 6 volt battery. It will simply be a dead 8 volt battery.
 
Thanks for all the advise,installed a Car Quest 6 volt batt.,Car Quest batts. are american made.
 
You must log in or register to reply here.
Back
Top