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TheEngine

Automotive
Dec 26, 2006
1
Hello. First time poster and learning about deep cycle 12v systems. Here is my idea and set up, if anyone can spot an issue or concern. Thanks.

Use: power about 90w of 12v accessories in a vehicle for a period of 18 to 24 hours.

Temp controled vehicle cabin range 60f to 85f

2 - 220ah 8D 12v batteries same age model and brand wired in parallel using 1 gauge wire at 12" length.

Xantrex truecharge 40+ charger
Xantrex temp sensor
Xantrex Battery Monitor

Blue Sea model 7039 50A switched disconnect breakers (one each located close to the positive terminal on the battery bank)

AMP? Size negative bus common bar (could use input on which to get, or if needed at all.

I would like input on what I shoud put after the + and - from the battery bank to the accessories. I was thinking a typical fuse box with 15 amp fuses and a common bus for both + and - wire runs with each accessory on its own fuse.

I plan on discharging the batteries to about 80% before a recharge (hopefully).

Does anyone have experience running about the same wattage over 18 to 24 hours in varied temp conditions? I was wondering if Im under estimating my required Amp hours.
Thanks.
 
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Sounds like you are on the right track.

You'll definitely want to use an automotive fuse block, not regular cylindrical fuses.

You never really want to draw those batteries down below 60%. Sorry! If you do their life will be severely shortened. If weight is a large factor in the picture or maybe you can not place another battery somewhere, then you may just have to trade off short battery life for your system.

Battery life example:
Discharge to 60%, may provide you with 1000 cycles. Discharge to 20% may give you 100 cycles. If you're only going to use around 20 cycles in a year, you may be fine with the short battery life.

Keith Cress
Flamin Systems, Inc.-
 
90W/12V = 7.5A

7.5A x 24Hrs = 180AHrs

220AHrs/battery x 2 batteries = 440AHrs

(440AHr - 180AHrs)/440AHrs = 59% (Time to recharge!)

So essentially for every 'day' you run your system you should recharge it.


Keith Cress
Flamin Systems, Inc.-
 
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