Tow Vehicle Battery Drain

[SimchaSabre]

Seem like I should know this ...but I don't.

We plan on dry camping for one night this weekend and we will likely be using a 12 volt inverter to power TV, fans etc. If I'm plugged in to the tow vehicle, will the camper limit the power drawn from the truck or will it just act like a 2nd battery in parallel and drag it down as well.

I don't plan on excessive use of the inverter, but would like to know if the vehicle battery would be protected from a deep discharge in case of heavier draw, like from prolonged furnace use, etc. (not likey in June, but I am in Michigan) .

[MtnGuy]

Many of the newer vehicles have an isolation circuit on their tow vehicles. If the ignition switch if off, there is no power from the tow vehicle battery. If your Ram has that arrangement, then it will not draw down the truck battery.

If your Ram does not have the isolation circuit, then yes, your tow vehicle battery will act like a parallel battery to the trailer battery.

[Dave_Monica]

Nope! Bring booster cables so some kind soul can boost-start your truck!

It's no different than leaving the headlights on...dead battery.

Dave

Edit: Seeing what mtnguy pointed out, I may be blowing smoke.

[Herk7769]

Originally Posted by SimchaSabre

Seem like I should know this ...but I don't.

We plan on dry camping for one night this weekend and we will likely be using a 12 volt inverter to power TV, fans etc. If I'm plugged in to the tow vehicle, will the camper limit the power drawn from the truck or will it just act like a 2nd battery in parallel and drag it down as well.

I don't plan on excessive use of the inverter, but would like to know if the vehicle battery would be protected from a deep discharge in case of heavier draw, like from prolonged furnace use, etc. (not likey in June, but I am in Michigan) .

Well, I am not sure what you mean about being plugged into the tow vehicle or what size inverter you are talking about.

There was a recent thread (I will try to find it) where the poster wanted to use an inverter to do what you want to do, but use the tow vehicle to provide power while it is running.

Many tow vehicles will not provide power to the Bargman plug with the engine off; but some will. If you have one that will, the draw on the truck battery will kill it much quicker than the camper battery due to the design of the truck starting battery.

Most starting batteries do not even post their "amp hour" numbers since they are designed to give up their charge in minutes (for starting cold engines); not hours.

[Herk7769]

Some good info here:
http://www.forestriverforums.com/for...ock-22659.html

[SimchaSabre]

Herk,
I actually found that boondock thread a few weeks ago. Your comments very helpful. For a while I thought it was taking us down the perpetual motion path trying to charge the battery with the battery.

As far as my request...here is a little more info. The inverter is small-ish (400W/800w peak) that we would only use briefly to power the TV, a fan or simular low draw appliances. but also.. Sometimes in late fall/ early spring we will need the furnace... And sometimes by the morning, the camper battery is quite low.

I just didn't want the camper load to drain the car battery if I left the trailer plugged in.
...but if I can safetly leave it plugged in and if i were to awake in the cold..I could then just hit the truck remote start. (Maybe even from bed if i plan it correctly)

I will measure the 12v out from the truck trailer connection to confirm it is off with the key. And, hopfully that will be the case.

btw we do have a 2kw Honda Generator that we use for more serious boondocking, but don't carry it on all trips. My concerns here are only for trips like the one this weekend where we will be doing one night at a Flying J on the way to Indy.