VCCA Home Forums TECHNICAL - 1945 AND EARLIER 1937-1945 BAtteries in Parallel

For some reason my 1938 chev 4 door has a 12 volt battery installed under the hood and wired into the starter motor with a relay. I have no idea what the battery is supposed to do as it is not wired with positive to ground and added to boost the starter up to 12v to get a more rapid turn over,

The problem is its hooked up so that the positive is to the starter, the negative is to the relay and the others are to the switcj on the dash 0 makes no sense -

NOW - the idea to put 2 x 6 volt batteries in parallel so there is the same V and higher starting power through a similar relay set up = anyone see any problems with that

Not sure what someone was doing....

But... I converted my 1947 Ford 8N Tractor to 12 volts 3 years ago... used a Chevy alternator, 12 volt Walmart battery and had to get a 8N coil special wound for 12 volts... its been bullet proof so far...

I was told to leave the 6 volt starter alone as it can handle 12 volts unless you just crank and crank....

And if it ever fails just have a rebuild shop do it to 12 volts...

Maybe the 6 volt Chevy starters can tolerate 12 volts?????

Did you mean to say negative to ground?


Sounds like it is set up to "complete" the circuit using a switch on the the negative side....not a safe thing to do... Probably did it out of convenience instead of doing it right.


Doing this is not going to give you any more 'cranking speed power', but it will allow you to have more time available to keep on crankin'. Ohm's law is consistent...if you want the starter to crank faster, then increase the voltage at the starter....which is probably what the previous owner did...

p.s. There was a thread about this not too long ago....someone had a relay that isolated a 12V battery from the car's main electrical circuit feeder during normal operation, but put 12 volts on the starter (only) during cranking....don't remember who/when though

I can tell you from experience that the biggest problem with 6 volt systems is that when battery cables are changed out, someone installs 12 volt battery cables which are too small for amperage that the 6 volt system needs to work properly. The other reason someone might do that is the starter has an issue.

A friends restored '36 Chevy pick-up would only start on the first try if he added a little gas to the carb. When he asked me to look at it I noticed right away that both the positive and negative cables were for a 12 volt system. I told him to search for the correct size cables or make new ones from 1/0 cable.

As he had 1/0 cable, he added ends and installed both a positive and a negative cable and has not had a problem starting his truck since.

When I had my 51 L110 binder, I had a series/parallel switch on it to use 2 6V batteries for start only. Hit starter, both batteries kicked in for 12V but when off starter, electrical system went back to 6Volt. Charged both 6Volt batteries when charging. Still have that switch and instructions, but couldn't keep up with batteries. One was always lower than the other and so dragged it down even further. Ended up with 1 12Volt battery and converted truck to all 12 volt and all was well after that.

Some European trucks about 1969 had a series / parrallel switch for 12v normal and 24v on starting which seemed to work well at the time. I havent seen similar for many years now though.
Tony

Some American truck manufacturers also had series parallel switches for 12/24 starting while using 6 volt batteries. Both White Motor co. and Mack Truck used them and probably others well into and perhaps past the 70's. The switches were made both by Delco-Remy and Leece Neville.

FYI, the 2001 Dodge 2500 diesel that I came with two 12v batteries from the factory. I guess the extra umph was needed to turn over the Cummins inline 6.

Cheers, Dean

If a 6 cylinder engine is properly tuned AND a 6 volt electrical system is working properly, with GOOD 6 volt cables, such as 1/0 rating, one does not need to consider a 12 volt system.

My 1/0 cables came from my local Farm implement store here .... Tractor Supply.

Others I know have added an inline 6 volt electric fuel pump, toggle switch operated, to get the float bowl filled rapidly, instead of cranking needlessly.

One of my '51's has the stock 6 volt electrical system, while the "modified" '51 with its 235 has a 12 volt system. The 6 volt starter works just fine, with the 12 volt ...... but long cranking time is not recommended.