Is it bad to mix match batteries?

[dan5505 10+ year member]

Im thinking about adding a second battery. Does the battery under the hood have to match the second battery? Obviously they have to be the same voltage. Would it be bad to mix match brands or cold cranking amp ratings?

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[lostdaytomorrow 10+ year member]

Don't mix non deep cycle and acid batteries.

Do all Deep cycle if you're going to do one.

 

[dan5505 10+ year member]

whats the harm in adding a second acid battery

 

[dan5505 10+ year member]

i know that a deep cycle can be repeatedly drained without harm, but i don't plan on draining either of the batteries.

 

[atsaubrey 10+ year member]

Preferably you want the same size, brand of battery. It is also recommended to purchase them at the same time from the same place to limit any differences in them. No two batteries will be exactly the same but you purchasing them this way makes them a s similar as possible. who knows how true it is but considering if the resting voltage is different whatsoever they will continue back forth to equalize each other. who knows maybe I am full of shit, but I try to do this just in case //content.invisioncic.com/y282845/emoticons/wink.gif.608e3ea05f1a9f98611af0861652f8fb.gif

 

[Brian Owens 10+ year member]

Preferably you want the same size, brand of battery. It is also recommended to purchase them at the same time from the same place to limit any differences in them. No two batteries will be exactly the same but you purchasing them this way makes them a s similar as possible. who knows how true it is but considering if the resting voltage is different whatsoever they will continue back forth to equalize each other. who knows maybe I am full of shit, but I try to do this just in case //content.invisioncic.com/y282845/emoticons/wink.gif.608e3ea05f1a9f98611af0861652f8fb.gif

That is what battery manufacturers recommend. when I orderd my optimas (direct from optima), the tech guy was not happy when I planned on running different batteries under the hood than in the rear. I made the arguement that they would not be charging the same anyway, since the 2 under the hood are 3 ft from the alt, and the 7 in the rear are 20 ft away - voltage drop would definitely be different. He still insisted I needed the same batteries front and rear.

Brian

 

[dan5505 10+ year member]

That is what battery manufacturers recommend. when I orderd my optimas (direct from optima), the tech guy was not happy when I planned on running different batteries under the hood than in the rear. I made the arguement that they would not be charging the same anyway, since the 2 under the hood are 3 ft from the alt, and the 7 in the rear are 20 ft away - voltage drop would definitely be different. He still insisted I needed the same batteries front and rear.
Brian

I didn't think about the voltage drop being different. It would be ~10 ft away from the alternator running through 1/0.

Can anyone tell me why it is bad to run a second acid (starting) battery? If there is no problem, i may go look for a cheap wallmart one.

 

[Brian Owens 10+ year member]

Nothing wrong with it. Deep cycle just takes the abuse of being discharged if you use the system a lot without the car running. . .

 

[snoopdan 5,000+ posts]

I ran combinations of deep cycle and lead/acid for years with no issue, and have plenty of great scores to back it up. Just keep maintenence on the lead/acids by keepn em full of water and not boiling them and you'll be peachy.

 

[dan5505 10+ year member]

ok, cool. Ill probably just go with another leadacid. Anything special as far as wiring a second battery? Can i just put them in series?

 

[azimuth 5,000+ posts]

ok, cool. Ill probably just go with another leadacid. Anything special as far as wiring a second battery? Can i just put them in series?

parallel.

 

[bonesninja 5,000+ posts]

i use a Die Hard up front and a Optima in back with no issues at all ....i just wired the positive up front to the positive in back and grounded both to frame rail. Then just ran the amps both power and ground to the rear batt

 

[Rawr-DQ 10+ year member]

I have 1 1400 kinetik under the hood, and 2 optima d34a, 1 d34t in the trunk. So far after about a year, no issues. I have 1 positive and 1 negative 0 gauge wire between the two and 2 250 amp fuses within 2 feet between each battery bank on the positive wire.

I also run the system with the engine on, and never off. 200amp alt under the hood.

 

[dan5505 10+ year member]

parallel.

ok, thanks. The only reason i asked was because my physics professor said that running batteries in parallel was pointless because they drain each other.

 

[azimuth 5,000+ posts]

ok, thanks. The only reason i asked was because my physics professor said that running batteries in parallel was pointless because they drain each other.

running them in series i believe doubles the voltage. get an isolator if that will be a problem.