Dual Battery Setup

tsuper92

supra addict
Apr 7, 2005
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just bridge them together.postive to postive,negative to negative.thats how it's done in my dodge pick-up from the factory.i also have a secondary battery wired in my work van that power's an inverter,which is done the same way.
i've never done it in the sup though.
 

GrimJack

Administrator
Dec 31, 1969
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tsuper92;1299268 said:
just bridge them together.postive to postive,negative to negative.thats how it's done in my dodge pick-up from the factory.i also have a secondary battery wired in my work van that power's an inverter,which is done the same way.
i've never done it in the sup though.
That's great for a truck where you want lots of power to everything all the time, but not so great for a car where you want one to be 'disposable' and the other to be there to start and run the car when you need it.

I've done a lot of these setups back when I worked in the car stereo world. You just need a battery isolator... this allows one battery to completely discharge without affecting the one you use to start the car.

They are used a lot in boating applications as well. Pretty simple to wire up, too.
 

suprra_girl

7M POWAH! ;)
Mar 30, 2005
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Unfortunately the drains I have are something I can't avoid :(

I was going to run a Projecta electronic Isolator and an ns40 battery.

But upon thinking about it, I have a battery with RC of 135 an ns40 is going to be far less.
My main battery will run flat in about 3 days or so with a drain of 0.10.
If I move the 0.07 drain to the ns40 its going to run that flat also so it would then be pointless... I wonder if I just move say the 1 drain of 0.04 to that battery. I would then only have a 0.06 drain on the starting battery and it should last about a week, although the most I don't drive it is usually about 3 days.

I think just moving the one drain is an idea.
 

87tomanymods

87tomanymods
Oct 25, 2008
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what about one of those solar chargers

SolarCharger_135_2.jpg
 

suprra_girl

7M POWAH! ;)
Mar 30, 2005
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I already looked at a solar panel, preferred permanent but there are window restrictions and the panel would not be able to provide necessary voltage. If the sun goes behind a cloud the charge drops right out, so I gave up on that idea.

Prosport Peak & Warn Gauge x 2 at 0.02 each
Turbo timer with other memory functions 0.03
RTR (Light retractor) 0.01
Radio 0.02
 

suprra_girl

7M POWAH! ;)
Mar 30, 2005
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No alarm, and draw change doesn't alter... its the same all the time.

The only thing I can think of is when running the car then switching off something is staying stuck on?
I don't know how I can measure that, to read with multimeter I need to disconnect batt and then that would nullify the test lol
 

tekdeus

Pronounced Tek-DAY-us
Jan 23, 2006
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I had similar symptoms with an optima yellow top battery that turned out to be faulty. It would charge fine, start fine when charged, and pass a battery load test, but if it sat for 2-3 days it would lose a huge amount of charge(even when disconnected) and be very weak. Probably internal current leaks. I posted this a while ago and about a dozen guys chimed in to say they also had problems with their Optima batteries (and that they suck!)
 

GrimJack

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Suzie, these things are actually pretty easy to diagnose.

Just put an ampmeter on it, unplug all the fuses / relays, then plug them back in one at a time and keep an eye on the meter. When it starts showing anything significant, you've found your culprit. I've seen this caused by everything from faulty stereo equipment to a fried alternator, and just about everything in between.
 

T701jz

3M ENGINEER - R.&.D
Jul 23, 2005
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^^^:bigthumb: But I would pull the fuses one at a time and see where the biggest current being dramatically reduce where most likely the potential short will be at.