6 volt battery question

drpepper1885

drpepper1885

Member
Last weekend, I replaced my non-starter 1917 engine with a rebuilt 1922 starter engine. The enginer starts up fine using a 12 volt battery, but won't turn over at all with a 6 volt battery. The Interstate 6 volt battery has 640/800 and the 12 volt 725/890 cranking amps. Both batteries are fairly new. I am rewiring the truck to have the same features as a 1922 with the instrument panel, etc. and converting the coil box over. I looked online and saw that one of the parts houses sells the Optima 6 volt red top with 800/1000 CCA.

Since I am rewiring to a stock 1922 setup, can I use one of the optima 6 volt batteries? Do you have to modify the electrical system to use this battery?

Thanks again for your input.
 
Are you sure your present 6 volt battery is charged? If so the Optima battery will not help - the problem may be a connection in a cable or where the cable post is soldered to the field coils. The bad connection may pass enough amperage at 12 volts to work but at 6 volts it needs to carry a lot more to do much.

You will not need to modify anything to use a higher cca battery.
 
I would have the starter checked to make sure is is a 6 volt starter, as it will function on 12 volts either way. Someone may have changed the field coils.

As for the Optima Red Top battery, do some homework on that battery, there are a lot of unhappy people with them. I have been told that they are no longer manufactured in the USA.
 
Red Tops are great when they work. Unfortunately most of them don't. All in all a pretty terrible product that never provided what they promised. I have a very young totally dead one here if anyone wants to come get it. Is your battery hitched up to negative ground?
 
The only thing I have hooked up to the starter at this point is the battery. Cable runs from 6V starter to switch and switch to positive terminal on battery. I have ground the battery using jumper cables to the high volume oil line.

The 12V starts her up first try every time. I checked the charge on the 6V and she was a little bit weak, so I charged the battery up again and tried to use it to start the car again....nothing. Sounds like a dead battery, but I know that it isn't. Put the 12V back on and she started right up.

The motor itself is a very fresh rebuild. It is a bit tight still. Could it be that I need to run it in some more to loosen things up? Would that make any difference?
 
Use a voltmeter and make sure your 6 volt battery is putting out 7 volts or so without load. You don't need a fancy battery; I use the cheap farm and fleet batteries and have good results. If they read 6 volts or so, the starter's gonna drag that down to 3 or 4. I used to have to hand crank mine when it got that low.

Get real heavy cables (the farm store sells those for Ford tractors) and tight connections.
 
They started fine on 6 volts when new and fora good many years afterward. If yours will not start on 6 volts there is a problem. Find and fix the problem, don't just try to cover it up.
 
Dr P, the 6 volt large cables would probably fix the problem (both hot side and ground), but a meter would give a lot of answers. I would measure two things.
1. measure battery while attempting to start. Should stay near 5 volts from post to post.
2. Measure between starter post and engine block. This should come up to near 5 volts while starting.
 
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