Secondary battery thoughts... Dual 6V AGM batteries in series?

anthrax323 · Jun 20, 2011

Hey all,

I've been pouring over how to incorporate a second battery into my XJ without having to install a cowl induction intake and pay big money for a secondary battery box (though the latter I could probably build out of some 10 gauge steel pretty easily), and it hit me. These Optima Red Top 6V batteries are apparently pretty popular among street rod builders because of how easily they can be concealed within a smaller vehicle:

http://shop.optimabatteries.com/pro...g+Battery/part_number=6V/1737.0.1.1.0.0.0.0.0

Additionally, the overall power output/capacity of two of these 6V batteries in series is marginally greater than that of the directly-comparable 12V Red Top (of similar specs)...

Regardless, it seems as though I could find space in the engine bay to mount two 6V batteries relatively easily, or could even go so far as to mount them inside the vehicle (under the back seat) for use as a cranking battery.

Anyone have any thoughts on the matter? What kind of voltage drops would I need to worry about running a 6' or longer battery cable?

O-Gauge Steamer · Jun 20, 2011

Volkswagen used two 6V batteries wired in series in the original Bug when they went to 12V. I use a pair of Optima 6V batteries in my 1948 CJ-2a as the lights and ignition are 12V and the gauges and period accessories are 6V. I tap at the dual battery connection for the 6V source. With a 12V generator on the engine the entire system works just dandy. It starts in the cold, the lights are bright, the Trico 6V electric vacuum pump (helps with the wipers you know...) works a charm.

Here is a link to help you decide on the wire size needed.

http://www.powerstream.com/Wire_Size.htm

There is also a voltage drop calculator there to help out. Hope this helps. Use welding cable as it is more flexible and is easier to route around all of the obstacles.

Just my .02...

Markos · Jun 20, 2011

anthrax323 said:
Hey all,

I've been pouring over how to incorporate a second battery into my XJ without having to install a cowl induction intake and pay big money for a secondary battery box (though the latter I could probably build out of some 10 gauge steel pretty easily), and it hit me. These Optima Red Top 6V batteries are apparently pretty popular among street rod builders because of how easily they can be concealed within a smaller vehicle:

http://shop.optimabatteries.com/pro...g+Battery/part_number=6V/1737.0.1.1.0.0.0.0.0

Additionally, the overall power output/capacity of two of these 6V batteries in series is marginally greater than that of the directly-comparable 12V Red Top (of similar specs)...

Regardless, it seems as though I could find space in the engine bay to mount two 6V batteries relatively easily, or could even go so far as to mount them inside the vehicle (under the back seat) for use as a cranking battery.

Anyone have any thoughts on the matter? What kind of voltage drops would I need to worry about running a 6' or longer battery cable?

If it were me, I'd go with two 6v deep cell batteries to handle the items that have extra draw. Continue to use a good starting battery in the stock location. Golf cart batteries work well, and are typically used for electric cars. If you keep them under the hood, you don't need AGM batteries.

anthrax323 · Jun 20, 2011

Markos said:
If it were me, I'd go with two 6v deep cell batteries to handle the items that have extra draw. Continue to use a good starting battery in the stock location. Golf cart batteries work well, and are typically used for electric cars. If you keep them under the hood, you don't need AGM batteries.

Yeah, I thought the same thing, but I've already got a D34/78 Optima Yellow Top in the factory position, so now I'm looking at cranking batteries to complement it. Optima's only 6V option is a Red Top as well (only reason I'm looking at theirs is due to the abundance of bottom-clamp billet battery trays available for them).

EMSJEEP · Jun 21, 2011

What are you running that you need a second battery? I used an isolator and 2ga. welding cable and put it in the cargo bay under ratchet straps. (Actually I have 2 Optima Blue Tops in parallel.)

Secondary battery thoughts... Dual 6V AGM batteries in series?

anthrax323

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O-Gauge Steamer

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Markos

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anthrax323

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EMSJEEP

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