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Discussion Starter · #1 ·
Does anyone know if the truck will charge rv batteries while towing or if you have to purchase an after market product?
 

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I always arrive at my destination with my camper batteries fully charged so I've always believed the truck charges the camper in-transit. I'm not positive, but I believe if you leave the camper connected after you reach your destination, the camper will consider your truck batteries as connected in parallel with the camper batteries and start slowly draining them.
 

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Mine did with the factory tow package. Put a voltmeter on the RV battery before connecting the trailer's pigtail. Nominally, that should be about 12.6 volts or so. Then connect the pigtail and start the truck. Measure voltage at the RV battery again. It should build to about 13.6 volts or so. If you don't see any increase, dig deeper.

(Also note: this connection is intended to keep charged batteries topped off until you reach your destination. Athough it will charge, it is NOT intended to be a substitute for a battery charger, although many have that expectation.)
 

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Discussion Starter · #4 ·
Mine did with the factory tow package. Put a voltmeter on the RV battery before connecting the trailer's pigtail. Nominally, that should be about 12.6 volts or so. Then connect the pigtail and start the truck. Measure voltage at the RV battery again. It should build to about 13.6 volts or so. If you don't see any increase, dig deeper.

(Also note: this connection is intended to keep charged batteries topped off until you reach your destination. Athough it will charge, it is NOT intended to be a substitute for a battery charger, although many have that expectation.)
great idea on the volt meter, i'll do so.
 

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It will provide some charge, but it's not going to be much.

I installed a Victron DC-DC charger in our trailer and ran a dedicated 4 AWG +/- charge circuit from the truck battery to the back of the truck with a 175A Anderson plug. We can now charge the LiFePO4 batteries in the trailer at a constant 25A and 14.4V.
 

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Discussion Starter · #6 ·
It will provide some charge, but it's not going to be much.

I installed a Victron DC-DC charger in our trailer and ran a dedicated 4 AWG +/- charge circuit from the truck battery to the back of the truck with a 175A Anderson plug. We can now charge the LiFePO4 batteries in the trailer at a constant 25A and 14.4V.
that sounds like a good idea. what size of charger did you get? looking at them, seem less expensive than the redarc 40 amp one i'm looking at
 

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The Victron and DC/DC converter is the right way to go especially if you want your TV to be a "real" battery charger. Multi-stage charging with the correct stages, battery type selection and even temp compensation (essential for flooded and AGM), n/a for LiFePO4.

Lots of $$$ in that kind of setup when you start including LiFePO4. There are many ways to skin this cat. Between AGM, flooded and LiFePO4 different charging needs, each with their own efficiencies and pitfalls. Don't rush into it unless you know what you are doing.

Also know that LiFePO4s don't charge well under 14.2 volts and prefer 14.4-14.7 depending on mfr, generally speaking. They accept very high rates of charge all the way up to nearly full charge, contrary to the ramp down current of AGM and flooded. If you are seeing 13.6 on your current RV battery hooked up to the TV, that won't charge an LiFePO4 at all. Most are equipped to shut off charging in freezing temps unless equipped with heating pads or a special internal BMS (Battery Management System).

I have two Battle Born 100ah (~$900 each) and use a 45 amp LiFePO4 charger at home or on a generator in camp or 600w solar to charge each separately, because they have to be balanced separately. I also make sure they are topped up before leaving home or camp. Part of the ritual. My TV puts only the 13.6v on them which is nothing more than a float voltage.

Assuming you have flooded, for the time being, a good 3 stage battery charger (unless your RV converter is a true 3 stage), topping up before you leave on a trip on house power, (at least 80% charge on gen in camp for best gen efficiency), the voltmeter, a DC clamp ammeter (shows rate of charge) and a good TV connection will give you peace of mind. The size of the charger won't matter too much for flooded (but I suggest 10-15 amp) because they like slower rates and in the last 20%, charge current ramps down so quickly it's easily within the range of the TV to supply even through the 7 pin. There's more, much more. But if you're serious about battery charging and getting the most out of them, you'll get into it.
 

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The Victron and DC/DC converter is the right way to go especially if you want your TV to be a "real" battery charger. Multi-stage charging with the correct stages, battery type selection and even temp compensation (essential for flooded and AGM), n/a for LiFePO4.

Lots of $$$ in that kind of setup when you start including LiFePO4. There are many ways to skin this cat. Between AGM, flooded and LiFePO4 different charging needs, each with their own efficiencies and pitfalls. Don't rush into it unless you know what you are doing.

Also know that LiFePO4s don't charge well under 14.2 volts and prefer 14.4, generally speaking. They accept very high rates of charge all the way up to nearly full charge, contrary to the ramp down current of AGM and flooded. If you are seeing 13.6 on your current RV battery hooked up to the TV, that won't charge an LiFePO4 at all.

I have two Battle Born 100ah (~$900 each) and use a 45 amp LiFePO4 charger at home or on a generator in camp or 600w solar to charge each separately, because they have to be balanced separately. I also make sure they are topped up before leaving home or camp. Part of the ritual. My TV puts only the 13.6v on them which is nothing more than a float voltage.

Assuming you have flooded, for the time being, a good 3 stage battery charger (unless your RV converter is a true 3 stage), topping up before you leave on a trip on house power, (at least 80% charge on gen in camp for best gen efficiency), the voltmeter, a DC clamp ammeter (shows rate of charge) and a good TV connection will give you peace of mind. The size of the charger won't matter too much for flooded (but I suggest 10-15 amp) because they like slower rates and in the last 20%, charge current ramps down so quickly it's easily within the range of the TV to supply even through the 7 pin. There's more, much more. But if you serious about battery charging and getting the most out of them, you'll get into it.
Yep lots of ways to go.

Between the 200W solar suitcase I built and the DC-DC charger we can leave the inverter generator at home now. I also installed a Progressive PD9160ALV 2-stage converter.







 

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Does anyone know if the truck will charge rv batteries while towing or if you have to purchase an after market product?
I simply ran some 00 gauge wire from the battery to the rv batteries. I used a winch connector to make the connection between the two vehicles. The ground I ran goes to a good frame ground, not the battery ground. When I get to the campground, I pull the winch connector apart and the batteries are full. Been doing this since I got the truck in 2016 and no issues.
 
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I simply ran some 00 gauge wire from the battery to the rv batteries. I used a winch connector to make the connection between the two vehicles. The ground I ran goes to a good frame ground, not the battery ground. When I get to the campground, I pull the winch connector apart and the batteries are full. Been doing this since I got the truck in 2016 and no issues.
That works if you are running LA batteries, not so much if your running LiFePO4’s, especially with the newer smart alternators that vary voltage.

Of course that much 2/0 now would probably be a wash versus a DC charger and 4 or 6 AWG circuit. I’ve seen some people run 8 AWG charge circuit with a DC charger and do fine.
 
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