2 six volts run longer?

[Snowking]

can i hook up two six volt batteries up in a series to make 12 volts? will it last longer than 1 12 volt? they do it to motorhomes why not a trolling motor?

[Surface Tension]

It would if they made a six volt deep cycle battery. Starting batteries are made for just that. Plus draining them down is bad for them. Deep cycle's are the oppisite. Low draw over a long time.

[musky hunter]

You don't state the application. If it's for a trolling motor, no combination of starter batteries will work better that one good trolling battery. The deep cycles produce relatively low current at 12 volts for a long period of time. Starting batteries do the opposite, high current for short periods of time. I'd recommend buying a quality battery that is designed for you're intended use, you'll be much happier in the long run.

[Guest]

This is really interesting.

In order to combine voltage, the power sources have to be hooked up in a series arrangement. The guys are right. Regular starting batteries would not work for a couple reasons. If you did hook them up in parallel, it would generate 6 volts, but for a considerably longer time period. You will not be able to hook them up in parallel, because in a parallel formation the voltage is not added. If you hooked up the two 6 volts in parallel, you would have a 12 volt batery series that would last nearly half as long as one 12 volt. It never crossed mind that it would be possible to run 2 12 volt deep cycles in parallel and receive twice the running time if not more. Is there anyone out there who operates their trolling equipment in this fashion? Matt

[This message has been edited by Bigguns3 (edited 03-27-2002).]

[Guest]

Maybe I am wrong, but I thought it was the other way around. Hooking them up in series doubles the volts, parrallel doubles the amps. At least that is the way I remember our old JD 3020 tractor. It was 24 volt, 2 batteries hooked up in series. The other tractors were 12 volts were hooked up in parrallel.

[perchpro]

I have used 2 six volt batteries for my fl-8 and it seemed to last a bit longer than my dad's twelve volt. It took more charges too.

[hydro]

Ok, here’s the way it works guys.

1. Batteries wired in series algebraically adds the voltage.
2. Batteries wired in parallel algebraically adds the amperage output capacity.
3. Starting or deep cycle has nothing to do with it. That’s another discussion.

What this means to you is that if you want a load to run at a given voltage and amp draw for a longer time, you wire multiple batteries of the correct voltage in parallel. If you do not have batteries of the correct voltage available, say for a 24V system, you wire multiple batteries in series.

The reason that you see 24V trolling motor systems is that there is less power lost in the system wiring through IR losses. This enables the use of smaller wires and more compact motors for a given power output. In general a 24V system is considerably more efficient than a 12V system of the same power output.

It all goes back to Ohm’s law where Volts=Amps/Ohms and Watts=Volts X Amps.

Finally to answer Snowking’s questions, (A) yes you can wire two six volt batteries in series to power a 12 volt device and ( no, they will only last about half as long as a single 12 volt battery with the same amperage output rating.