Pros and Cons about installing a 2nd car battery


New Member
May 25, 2014
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So I'm thinking about installing a 2nd car battery (in the trunk) because
I don't drive long distances daily and my 2-channel car cam seems to stop recording
some days due to low voltage (it has automatic shutdown when it detects the car
battery is getting low to not drain it and leave enough power for startup).

I'm hoping that a 2nd car battery will allow me to run things like car cams and
maybe some LED lights while car is off and parked.

I've never done this before, don't know much about batteries, so it would be helpful
if anyone can mention what some pros and cons about doing this are. I'm only looking
for about a 45 AH battery or so as the 2nd battery.

Not sure if I'm accurate on the pros and cons but here are some that I think may be relevant:
Cons: extra weight (30-40 pounds?), maybe more stress on the alternator?

Pros: having more power to run equipment off of while car is parked and off, so as to not kill the
main battery.


Post Whore
Oct 9, 2009
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Evansville Indiana
I run a dual battery system now as I was building a high power stereo prior to my wreck and wanted to be able to play it with the motor off and still start it. I run a large system battery and a smaller starting battery both by AGM kinetik batteries and they are sepereated by an isolator. The isolator is important to make sure they are both charged and they are separated when the key is off or it will cause the batteries to "fight" each other as the higher voltage battery tries to charge the smaller and basically drains them both. It is important to get both batteries at the same time so they have the same age and charge/discharge characteristics so price is a bad point as even if you have on battery only a couple years old you will need to replace it, and buy the 2nd, isolator and power wire to connect them both. Yes it will weigh more but you should be able to use your cameras and not worry about it not starting.

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