Dual Battery Question (1 Viewer)

Joined
Nov 16, 2004
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Los Angeles, CA
 
 
 
Have an Interstate Battery currently. Can I add ANY battery I like to the second tray? I would love a marine optima but no cash so I am thinking of going with a napa. I hear that it's better to have a deep cycle bat for the 2nd. What are your recommendations?

Eventually dual optimas, but that's a long time from now.

Thanks in advance.

Sam
 
Joined
Jul 7, 2004
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Location
EVERGREEN, CO, USA
PK;

Actually, u can throw any battery in there and it probably will work.

What I would do is check out the battery u have. How old is it? Have a battery test done to determine its condition. If it is marginal, u might replace same and buy one more for the dual battery system. You really would like to have two batteries of same size, manufacture, but they don't need to be optima or high tech dry cell.

If ur original battery is fairly new, say 1 year old, just buy a similar battery for the time being for the dual set up. Standard batteries that are over 4 years old are on the way out and can fail at any time, usually when its 20 degrees F and u need to get somewhere.

...
 

flintknapper

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May 22, 2004
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Deep East Texas
 
 
 
Do you plan to install an isolator? The only real concern with dissimilar batteries (whether by ratings, or condition) is that batteries will always try to equalize.
The weaker battery will draw from the stronger one.
This may not present any problems for you if both batts. are in good shape and close to the same rating.

For my puposes...I use identical batteries and isolate.
 
Joined
Jun 16, 2003
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1,802
Battery manufacturers, and virtually all pros who deal with battery banks (large boats, residential solar / battery / electric, etc) recommend when utilizing batteries in parallel, that the batteries should be the same type, size, and age. This recommendation is made to help ensure the maximum lifespan of both (all) batteries.

It is not a question of "will it work", it is a matter of how long it will work, before battery replacement. The objective is to avoid premature battery failure.

All of the combiners I have seen result in both batteries being electrically in parallel when the second battery is being charged, which is most of the time the engine is running.
 
Joined
May 8, 2004
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958
 
 
 
I'm running a POWER-GATE isolator with two batteries: one is an Interstate as my "main" and a yellow top deep cycle as my "auxiliary." Both batteries are charged from the stock alternator, with the battery of lower charge drawing more current than the battery of greater charge. This will continue until both batteries reach a state of equalibrium, however that state of equalibrium will only occur for a few seconds. The loads of the auxiliary battery cannot deplete the main battery by virtue of the POWER-GATE. You can use dissimilar batteries in a scenario like this, however it's advised NOT to use dissimilar battery when batteries are run in parallel.
 
Joined
Nov 16, 2004
Messages
2,731
Location
Los Angeles, CA
 
 
 
Thank you so much for the help thus far. Just to answer a few of the questions that have been asked. The battery I currently have is about 3 years old if memory serves me right (i will be checking the recipt later) it has a 5 year warrenty.

Mobi: I"m liking the way your setup is sound and will probably head in that direction with my rig.

I am looking to have an Isolator wired into the setup with my 2nd fuse box and switches to control the batteries located inside the cabin.

Thanks guys, keep it coming.

Sam
 

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