400 W TV Inverter to Recharge TM Battery?

[DRanger]

This weekend I arrived at my camping destination with a near dead TM battery on account of powering the fridge on DC while traveling.

I don't have a generator and I managed to conserve power over the weekend.

So I was thinking that I needed to buy a generator to save me from this in the future. I was reviewing all of the many threads on generators throughout the forum when I had a 'duh' moment, maybe ...

My TV has a 400 W power inverter. Can I use it to connect to the TM for the purpose of powering the converter to recharge the battery?

I'm sure an inverter on the TV can be used for this, I just don't know if 400W is enough to do it and if it would do it in reasonable time.

[Bill]

Originally Posted by DRanger

This weekend I arrived at my camping destination with a near dead TM battery on account of powering the fridge on DC while traveling.

Old vaudeville line -
Patient: "Doc, it hurts when I do this."
Doctor: "Don't do that."

In other words, you don't have to run the frig while traveling, unless you are running a really long day in really hot weather. Start with cold food, pack the refrig with ice or ice packs before you leave in the morning, and shut if off while you travel.

My TV has a 400 W power inverter. Can I use it to connect to the TM for the purpose of powering the converter to recharge the battery?

Maybe. Two things to bear in mind. First, you are going to take about 400 W at 12VDC out of the TV battery, convert it to 120 VAC in the inverter, then reconvert it back to 14 VDC in the converter. The combined efficiency of the pair of conversions may be around 70%, but not much more. Your 400 watts will become 300 watts, which is around 20 amps of charge current at 14 VDC. That is certainly enough to do some good, though it will take a while. Second, the inverter will draw around 30-35 amps out of your TV battery, which is enough to do it some harm in an hour or so. This means that for a serious charge, you have to run the TV engine. All good so far.

The big question in my mind is this. If the TM battery is seriously depleted, the converter will want to supply a serious amount of charge current - say 30 amps offhand. It will want somewhat more than 400 watts of input power. How will your inverter react to this demand? Will it overheat and fry? Will it switch itself off? Will it lower its output voltage to something less that 120 VAC?

On paper, you can tweak all these numbers a bit - volts, amps, efficiency, and I'm sure some of us will do that. But the result won't change much. Let us know if it works - it would be valuable to other TM'ers.

Bill

[DRanger]

Yeah I've read all of the various topics and threads covering the fridge issue. I'm still cutting my teeth on this thing and mistakes were made. Will definitely try a different strategy next time.

I was more wondering in the general case and under better/nominal conditions, whether I could treat my truck like a very inefficient and horribly expensive generator and avoid buying an actual generator.

I know the TV needs to be running to use the inverter (read the TV manual) so I am not too worried about the effects on the battery there.

I was mostly unsure about how much power the TM would draw while in a charge cycle and whether the inverter could supply it. The converter/power distribution center manual doesn't really provide much info other than the three operational mode and what fuses there are.

Sounds like it may be in the realm of possibility. I'll add an extension cord to my packing list for the next trip.

[rickst29]

One of these would keep your fridge going on DC, and also have a few amps left to do a bit of battery charging as well. Just two warnings: #1, Don't consider anything larger than the 20A model, because bigger ones will kill the Bargman cable. And #2, it needs to be installed in a place with a bit of free air around it, for ventilation.

https://www.amazon.com/Renogy-Batter...dp/B07Q5VYPCF/