6 volt battery type??

sphooch

sphooch

Senior Member
Hi Guys can anyone tell me the proper cranking amps for the 31 stock engine should be. This will be my 3rd battery to install. I may have been getting the wrong type in the past because it always cranks slowly. it doesn't take long to start its just the way it cranks . the car is always in a heated garage and every thing was restored. the battery i'm using is a NAPA 6 volt. I don't have to replace it i'd just like it to crank better. thanks for looking THE HOOCH
 
3rd battery ??? Better check your starter or your cables. We use a Group 1 in our T's.
 
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You have the correct battery. What you should do is make sure all the battery connections are clean so there is little resistance to electrical flow. Also you need 0 or 00 gauge cables to carry the load. If you have an ohm meter check the resistance of the connections frame to the + battery post and - starter post to - battery post if positive ground.
 
Look at the CCA, cold cranking amps, rating of the battery. Also, as said, look at the size of the cables, connections, the condition of the starter switch, and the condition of the starter motor.

The CCA of a 6 volt starting battery will range from 440 to 800 amps. 600 to 650 is common. But you cannot use the full CCA if there is a problem with the connections, cable, switch, or starter. I think the cranking current on a 6 volt Model A is about 300 amps, but I could be way off.

You should be using 2/0 size cable, the thick stuff.

If the commutator in the starter is dirty it will cause the starter to run slow. 6 volt systems are very susceptible to any resistance. Even restored cars can have problems like dirty commutators, depending on how thorough the person who did the work was.

When the car is parked for more than a couple of days use a battery maintainer.
 
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J Franklin said:
Also you need 0 or 00 gauge cables to carry the load.
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Just as a note 00 gauge is the same as 2/0 AWG as stated in some product listings.

An extra ground will also help if everything else is tight and making good contact. Two possible locations is on the transmission shift tower or one of the starter bolts. Might recommend the starter over the transmission due to its proximity with potential oil contamination.
 
Are you sure it is really cranking slow,or are you comparing it to a modern car?The size or capacity of a 6 volt battery won't make any difference in cranking speed,but only for how long it cranks it.If it really is cranking slow I would be looking elsewhere for the problem.I had a slow crank problem in my 31 coupe,and found it was a failed cutoff switch.It cranked the same speed with the switch in the on or off position.I put a pair of vise grips across the terminals and it spun right over,as fast as an A will ever turn over anyway.
 
Battery cutoff switches are a common cause of slow cranking. Easy test is to disconnect the cable from the battery to the cutoff, touch it to the terminal on the starter switch, and pull the starter rod down with your other hand to turn the starter on. If it cranks faster, you found the problem.
 
If you're not using a voltage regulator, I would use a liquid cell battery. Keep after the cells to be sure they stay full (i.e. same issue in 1930)

If you have a VR, I would use an AGM battery. It should drive and maintain like a modern car.

Joe K
 
It is likely something simple. Are you a member of your local Model-A local chapter club?
 
This slide should guide you.
 

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Joe K said:
If you're not using a voltage regulator, I would use a liquid cell battery. Keep after the cells to be sure they stay full (i.e. same issue in 1930)

If you have a VR, I would use an AGM battery. It should drive and maintain like a modern car.

Joe K
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I my experience I feel the Optima likes the higher charge rate— I have the charge rate at 14 amps with the original generator and the first Optima lasted 16 years— never on maintainer,then I had a 12 volt conversion agm battery from a Mercedes that I converted to 6 volts with a sawsall— that battery was 10 years old when I converted it and the Mercedes had declined to like charging it.(it lasted me 4 years)Now the current Optima is 12 years old and still going strong.
My friend has a voltage regulator and uses a maintainer and his Optima batteries only last 6 years.
On long daylight drives I do turn on the headlights for some of the drive,the 14 amps gives me a positive 1 amp with the halogen headlights on.— and I have never used a maintainer.
The original generator (date coded) has been fine at the 14 amps although I did have to replace a bearing after 50 years.

To the original poster— crank the engine for 30 seconds with the ignition off and feel all the wires and connections for heat — clean those hot connections and replace any rusty lock washer and nuts,take a magnet to the cable terminal ends — some manufacturers used steel terminals that rusted inside and make high resistance connections and of course the wire has to be for the 6 volt system—- twice the gauge of 12volt wire
 
Kurt in NJ said:
I my experience I feel the Optima likes the higher charge rate— I have the charge rate at 14 amps with the original generator and the first Optima lasted 16 years— never on maintainer,then I had a 12 volt conversion agm battery from a Mercedes that I converted to 6 volts with a sawsall— that battery was 10 years old when I converted it and the Mercedes had declined to like charging it.(it lasted me 4 years)Now the current Optima is 12 years old and still going strong.
My friend has a voltage regulator and uses a maintainer and his Optima batteries only last 6 years.
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It's both – AGM batteries like a higher charge rate AND more precise voltage regulation. If your voltage regulator is set to deliver less than 7V, you'll get that short lifecycle problem.
 
You know, LiPo batteries are getting cheaper. They have twice the capacity of lead-acid batteries and half the weight. And last a long time. Shop around.
 
nkaminar said:
You know, LiPo batteries are getting cheaper. They have twice the capacity of lead-acid batteries and half the weight. And last a long time. Shop around.
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Be careful when buying a LiFePO4 battery – make sure you know its CCA capacity. Here's one that costs $100 and puts out 270 CCA. That's enough to start a Model A, but probably not on a cold February morning.

There are very few turn-key options for 6V LiFePO4 high-output batteries at the moment.
 
Good Afternoon...Agree with Milke 1291. A number of us in the desert run Optuma batteries with 800 cold cranking amps...I've had Miss Princess for 21 years and she just is about two years into her third Optima Battery. Princess is driven every week of the year...Ernie in Arizona
 
So I can charge my 6V Optima (red top) with a conventional 10 amp charger set on 6 volts? I was told that this type of battery would suffer a short life when charged like a typical wet cell battery.
 
ursus said:
So I can charge my 6V Optima (red top) with a conventional 10 amp charger set on 6 volts? I was told that this type of battery would suffer a short life when charged like a typical wet cell battery.
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AGM batteries are the same as flooded lead acid except the electrolyte is contained in Absorbent Glass Mat (AGM). Still need venting, usually through a tube to the outside in modern cars. They are also spill proof, so can be shipped as nonhazard material.

Charge as usual.
 
I just looked up Optima's official spec for its red-top batteries. It says if you are charging the battery in a vehicle (via generator/alternator), you can give it 7.5V, with no amperage limit, but only if a regulator is present that will cut the feed if current drops below 1A.

If you're charging it via battery charger (i.e., the battery has run down and you are charging it up on the bench), they recommend 10A at 7.5V as the maximum sustained current over multiple hours.

For a float charge/maintainer, they recommend 1A at 6.9V.
 
Herb Concord Ca said:
Alexiskai, can you explain what a float charger is? And how they work?
Thank you,
Herb
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Sorry, that's just the classic "battery tender." You might know it as trickle charging. Small-amperage chargers that you put a battery on over the winter. Float charging replenishes the charge in the battery continuously, counteracting its self-discharge action.
 
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