Too much battery draw?

[WebCrush]

While I'm on the road hauling my trailer, I'd like to keep the fridge running to prevent items from going bad, etc. I guestimate the unit pulls about 800watts running, 2000 surge.



I just snagged a high efficiency Coleman power inverter 2000/4000 which I was gonna power the trailer off of while traveling. The trailer has a marine deep cycle battery which also gets charged by the truck while hitched up.



Since the truck already has two batteries, I would like to assume the charging system is pretty beefy.



Sooo--the question is:



1. Will I be ok running with this setup?

2. Will I be draining the batteries?

3. If so, how long before I'm down to the reserves needed to start the truck if I shut it down?



Thanx.

 

[Big White Beast]

Just guessing here.......

But ohm's law for power is P=E X I so 136 amp alternator at aprroximately 13. 5 volts would be 1863 watts. Other than the grid heaters there isn't that much normal draw when the truck is running. (Depending on what your aftermarket stuff is) Now this would be optimal. I would assume a 25% loss to be on the safe side plus anything the truck is drawing. The rest could be feasibly used for other things.



I did find some useful info for you though while searching for our alternator rating. One of the threads said something about the deep cycle batteries used on the trailers and that the 13. 5 volts out of the alternator was insufficient. It required over 14 volts to adequately charge. Here is a link to that thread.



https://www.turbodieselregister.com...&threadid=63562&highlight=alternator+and+amps



Garrett

 

[EricBu12]

I know it is a little late on the fridge you have but I have the ARB chest fridge/freezer. It is able to run on either 12 vlt or 110 and when on 12 vlt, it runs on like 3-5 amps and it cycles so when it gets cold, it shuts off. ran it for 2 days on a reg. deep cycle without killing the batt... ...



Get it here.

I use it on the road while truck driving, I use Everyday Continuously. Non Stop. Never has a problem



http://www.off-road.com/rock/arb/freezer_fridge/

 

[WebCrush]

Thanx for the fridge tip, but I'm talking about a 12 cubic foot fridge i have, not a lil cooler/chiller.

 

[HC]

One problem you're likely to experience is that you're wanting to pass 60 to 70 amps of power back towards the refrigerator, if your 800 watt figure is correct. Your regular wiring harness will have wires too small to pass that much current on a continuous basis, and you'll get a significant voltage drop between alternator and load due to their distance apart unless you run monster wires. This in turn will probably lead to drawing down your trailer batteries even if your alternator is putting out good voltage. So, my answers to your original questions would be:



1. Will I be ok running with this setup?

Not really. Unless you're willing to route the "monster wires" to the trailer, OR, mount the inverter near the main truck batteries and then run AC back to the trailer (a bit dangerous? maybe... )

2. Will I be draining the batteries?

You will drain the trailer batteries, but not the truck batteries. (Again, I'm assuming you're planning to put the inverter in or near the trailer, and run only DC back to the trailer. )

3. If so, how long before I'm down to the reserves needed to start the truck if I shut it down?

As long as the truck is not connected to the trailer electrically when shut down, you will not ever drain the truck batteries or have trouble starting the truck. But your trailer's marine batteries will likely need to be charged at night from a power source.