Best way for Dual 6V batteries?

[CarNucopia]

Yes, I'm paranoid. There have been other threads about trying to find a 6V "jumper" battery like people use for their 12V cars. It does not seem like one is available. A nagging fear for me (though maybe not rational) is that I will need a jump and not be able to get one. Since there's room in the battery box for a second Optimal 6V battery, I think I may add one there. I know there are ways to jump from 12V, but the piece of mind I'll get for the extra $115 is worth it to me.

 

So here's my question: am I better off connecting the two batteries in parallel, doubling the amperage or leaving one as a spare that I can use in an emergency? If I use the batteries together, does that overstress the generator?

Edited April 17, 2016 by Buick64C (see edit history)

[Daves1940Buick56S]

If you connect the 2 batts in parallel, you are making available twice the current (theoretically) while halving the internal resistance of the battery combo, meaning less voltage drop under a heavy load. The starter will still draw roughly the same current (although with a lower v drop in the battery it will likely draw a bit more) with roughly the same v drops due to various resistances in the line (wire gauge etc). Bottom line is you will likely see the difference when cranking and maybe your headlights will dim a bit less at idle. If you drive during the winter you will likely see great improvement in starting when cold.

 

As far as the generator, the regulator should have a current limiter to limit you to about 30 amps, so if it's adjusted properly no worries.

 

An ideal solution is a heavy duty switch to wire in the batts either in parallel or each one singly. Probably won't be cheap though at these currents.

 

Cheers, Dave

[Marty Roth]

I just leave my pairs of Optima batteries hard wired with 000 (Triple Aught -or welding cable) - in Parallel.

I've not had any starting problems and this has not had an affect on the generator.

I have lots of reserve cranking Amperage.

Night traffic, coming home from a tour or a cruise, with many stops means that I do not have to rev the engine to keep up the amps , avoiding drainage.

 

I suppose that a switch, preferable remote inside the car, might be an interesting option, but see no major advantage, other than if I left the headlights "ON" accidentally for many hours, there would still be a reserve function. I carry a Jumper Pak (12-Volt) in some cars to help others. This can also be used to power a GPS, charge a cell phone, etc. In a pinch, I could safely hook the Power lead to the starter or solenoid, hit the starter, and temporarily touch the ground lead to a ground surface, spinning the starter momentarily without  causing any serious damage, disconnecting ASAP. 

[CarNucopia]

Thanks for the info. Since my goal is to have a backup, I think I'll stick with the simplicity of having a primary battery and a backup.

[Guest Downtimesfl]

you could always use a battery switch like a boat, charge both and only actively use one for running.