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GeocamperAS 03-18-2019 07:36 PM

TV charging trailer battery
On a different thread someone said they mounted a portable solar panel to their vehicle luggage rack to charge the trailer battery when driving because “their TV did not charge the trailer battery”.

I’m confused.

Someone with more knowledge (not guessing because I am only guessing) PLEASE chime in.

So my understanding:

It all has to do with how many amps/hr the TV puts out vs how many amps/hr the trailer is asking for.

1. If I am running nothing in my trailer, the trailer battery should charge fine. Because nothing is using any of the TV output.
2. If I am running very little in my trailer, as in the refrigerator on LP so just the circuit board is using current, the trailer battery should charge slower. Because the circuit board is using some but less than the TV output.
3. If I am running the refrigerator on the 12v heater, the battery may not charge. If the 12v heater is drawing more amperage/hr than the TV can put out.

GMFL 03-18-2019 08:00 PM

What you state is correct. As long as the amp output of your TV’s charging system is greater than the total amp demand of “BOTH” your TV and trailer your batteries will charge.

My GMC 2500 Has duel alternators (1) 150 amp and (1) 220 amp which helps meet power demands and provide charging opportunity

ROBERT CROSS 03-18-2019 08:08 PM

Our Burb has a single 200a alternator, it's charge rate is determined by the SOC of the TV battery, it will re-charge the AS batteries, but it takes a good long drive/time.
It 'maintains' pretty well while towing with fridge on LP.


OTRA15 03-18-2019 08:10 PM


ghaynes755 03-18-2019 09:12 PM

If you are going to charge from the tow vehicle and plan to use the power pin on the 7 pin tow connector you will be disappointed. Wire size is usually small and you will get 5-7amps through that connection. Which will be a bit of help but as previously stated may not help on short couple of hour trips.

mykytiukr 03-19-2019 10:40 AM

Ok, my ‘65 has a 30 amp fuse between the TV hot wire and the battery. So, anything above a 30 amp draw may blow that fuse. I say “may” because the AS battery is sharing some of that load. Not sure what circuit protection your ‘74 has but that is what is going limit it. If the circuit is complete(no blown fuse or popped circuit breaker)the AS battery will stay as fully charged as the TV’s!

Motor On!!!!

GeocamperAS 03-20-2019 08:53 AM

Thanks for all the above info. That helps.
I have never had an issue with my ‘74 because it has the original refrigerator, furnace, air conditioner etc. no circuit boards. So no battery usage while driving.
My ‘78 has not made it’s maiden voyage yet with all new everything. Circuit boards all over the place.
While driving I plan to run the refrigerator on LP so the circuit board will use a little. Assuming with everything else turned off nothing else will use battery. However going on the concept of a home television, when turned off but still plugged in it still, although very little, uses power I’m not sure what circuit boards in the AS still use power even when you think it’s turned off.
BTW maiden voyage this summer. Alaska here we come.

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