Charging while towing

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   No I was saying use the inverter to supply AC to the 10 amp NOCO GENIUS10 that requires 150 watts so you could use a 300 watt inverter.  Noco puts out 10 amps of charge to battery and rolls back to 3 when charged.  So I would clip it to the trailer battery and plug it into the inverter hooked up to the  vehicle 12 volt.  Not sure the 85% efficiency would apply.  My thought is between the alternator and the charger that would keep the charge up.  The refrig doesn't run constantly does it?  I could be wrong I am just thinking outside the box.

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pedwards2932 Members Profile Send Private Message Find Members Posts Add to Buddy List Senior Member Joined: 21 Sep 2020 Online Status: Offline Posts: 333	Topic: Charging while towing Posted: 25 Oct 2020 at 10:45am
	No I was saying use the inverter to supply AC to the 10 amp NOCO GENIUS10 that requires 150 watts so you could use a 300 watt inverter. Noco puts out 10 amps of charge to battery and rolls back to 3 when charged. So I would clip it to the trailer battery and plug it into the inverter hooked up to the vehicle 12 volt. Not sure the 85% efficiency would apply. My thought is between the alternator and the charger that would keep the charge up. The refrig doesn't run constantly does it? I could be wrong I am just thinking outside the box.

offgrid Members Profile Send Private Message Find Members Posts Add to Buddy List Senior Member Joined: 23 Jul 2018 Online Status: Offline Posts: 5290	Posted: 25 Oct 2020 at 10:14am
	Not sure I understand, are proposing to install a 300watt inverter in the Escape, then run an ac line to the trailer, and connect it to the existing WFCO charger? Or to a separate charger maybe? Some other configuration? You would be fighting basic physics the whole way, because each of those devices is only about 80-85% efficient. So that's an overall efficiency of about 60-70%. The rest is lost to heat. And you would need to run a new set of conductors for the ac circuit anyway. IIRC, the fridge takes about 11-12 A on DC, so you would need to supply the inverter with 12/0.6 = 20A or so to make up for the losses. That will just put more load on your TV charging circuit. Like everything in the real world, TANF (there ain't no free lunch) applies. IIRC, the fridge in DC mode consumes about 11-12A. So, while its unfortunate that they ran 12 awg wire, it has adequate ampacity for the application. You will lose about 1 volt to wire resistance. So you're right that you won't be able to maintain full charge on your trailer battery. I suppose you could add a dc/dc boost converter on the 12V line, that would be better than an inverter plus battery charger. Or, How about just running the fridge on propane?
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pedwards2932 Members Profile Send Private Message Find Members Posts Add to Buddy List Senior Member Joined: 21 Sep 2020 Online Status: Offline Posts: 333	Posted: 25 Oct 2020 at 9:25am
	The LifePo's are a bit expensive for my budget. The TV will only charge based on the starter battery so it doesn't charge much more than 80%. The Ford Escape is very difficult to run wiring and I just had it wired for the trailer and they used 12 gauge so I would have to pay to get them to run larger wire. The DC to DC wiring would require large wire as well. I like to run my refrig on 12 volt while towing which adds about a 6 amp draw so on a long haul the battery would be down pretty good if I do a pull off stop with no hook up. Just thought this would be a cheap way to boost the charging circuit.

StephenH Members Profile Send Private Message Find Members Posts Add to Buddy List podders Helping podders - pHp Joined: 29 Nov 2015 Location: Wake Forest, NC Online Status: Offline Posts: 6417	Posted: 25 Oct 2020 at 9:07am
	I'm unsure of your question. I ran wires to run a DC to DC charger for an LiFePO4 battery. If you are only running Pb-Acid, you may not need to do anything if your tow vehicle already has sufficient wiring to charge it. If your tow vehicle's wiring for charging is at least 10 AWG, you should be okay. Otherwise, run the wire. Running an inverter and then a charger would add significant efficiency losses. Since your TV should be able to charge the battery, why add these in? Now if it is for a DC to DC charger because you installed an LiFePO4 battery, it is a different matter. The TV won't charge it properly and you need to run the charger. See my mods for what I did.
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pedwards2932 Members Profile Send Private Message Find Members Posts Add to Buddy List Senior Member Joined: 21 Sep 2020 Online Status: Offline Posts: 333	Posted: 25 Oct 2020 at 8:20am
	Not sure if this would work but I was thinking of a way to avoid trying to run really large wiring from vehicle battery to TT. You can get 300 watt inverters fairly cheap that will run off a cigerette lighter outlet. The NOCO GENIUS10 puts out 10 amps and requires 150 watts. Seems like this may be enough to keep the battery charged while towing. I know you can get dc to dc chargers but they require you run really large wires. What do you think?