Lithium Batteries
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More Turbo
Joined: Aug 2010
Posts: 630
Likes: 30
From: Green Acres, Ca.
Lithium Batteries
I'm getting a new 33' Genesis toy hauler and it comes with two 100ah lithium batteries in it. How will my 2019 F350 handle the charging of these batteries? Is there something that needs to be done for it to work? Thanks.
Fleet Mechanic
Joined: Feb 2021
Posts: 1,409
Likes: 1,172
From: East TN
Short answer - through the 7 pin plug it will charge some. It will not damage the truck or any of the other horror stories you read about LiFePO4 batteries. If you want the truck to really charge them, you need a large cable running from the batteries to the RV. A Victron Orion XS will throw 50 amps into them and protect the truck's electrical system at the same time. https://www.victronenergy.com/dc-dc-...ttery-chargers
Hotshot
Joined: Jul 2013
Posts: 14,302
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putting in an isolating charge controller is a good idea because on a straight wire connection the vehicle's lead acid battery will always discharge the lithium battery . The reason for this is due to the lithium battery having a .8 volt higher state of fully charged voltage than the lead acid.
also keep in mind that unless the lithum is an internally heated battery, it won’t charge when temps are below freezing , typically 25 to 20 degrees.
make sure the lithium battery does not get wet, it could ignite
also lithium has poor short circuit tolerance…a shorted lithium can ignite.
it would also be a good idea to put a solar panel on the roof of the rv to help charge the lithium battery.
also, some recent year super duties will not charge a trailer battery unless the key fob is inside the driver cab area…so for example…if engine is running and you go into a store with the truck locked and key fob in your pocket..the trailer battery will stop charging.
also keep in mind that unless the lithum is an internally heated battery, it won’t charge when temps are below freezing , typically 25 to 20 degrees.
make sure the lithium battery does not get wet, it could ignite
also lithium has poor short circuit tolerance…a shorted lithium can ignite.
it would also be a good idea to put a solar panel on the roof of the rv to help charge the lithium battery.
also, some recent year super duties will not charge a trailer battery unless the key fob is inside the driver cab area…so for example…if engine is running and you go into a store with the truck locked and key fob in your pocket..the trailer battery will stop charging.
Fleet Mechanic
Joined: Aug 2022
Posts: 1,592
Likes: 1,119
you get such a minimal charge from the truck with a regular battery (and it's worse with a lithium due to them having a higher voltage) that personally, I'd simply disconnect the charge wire at the trailer connection and rely on solar unless I was driving long distances frequently... then I'd get a DC to DC charger and set it up properly.
so yeah, what they said.
2 cents,
Dave
so yeah, what they said.
2 cents,
Dave
Trailering
Joined: Jun 2025
Posts: 21
Likes: 2
If I wanted to install a DC-DC charger, where do you make the wiring connection on the truck, taking the BMS into account? Do you go directly to the battery or ?
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Mountain Pass
Joined: Nov 2024
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A DC-DC charger should be installed on the trailer between the 7-pin and the lithium battery. The charger must be configured to limit current to 15amp so it doesn’t blow a fuse on the truck, or you have to install a separate circuit and trailer connection on the truck and trailer to handle higher current.
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Trailering
Joined: Jun 2025
Posts: 21
Likes: 2
A DC-DC charger should be installed on the trailer between the 7-pin and the lithium battery. The charger must be configured to limit current to 15amp so it doesn’t blow a fuse on the truck, or you have to install a separate circuit and trailer connection on the truck and trailer to handle higher current.
Mountain Pass
Joined: Nov 2024
Posts: 188
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Ah, as long as you connect the DC-DC charger negative input to a good ground on the truck, you will be on the right side of the truck BMS. The positive can go directly on the battery terminal or to the main positive buss on the fuse panel. I’d add a suitable fuse, and use a charger with a remote on/off switch and use an upfitter switch to shut off the charger when not trailering or engine is off to prevent additional battery drain (the charger will pull some juice even when its not charging).
Lead Driver
Joined: May 2021
Posts: 5,939
Likes: 3,540
From: Uh oh, CA
I installed a Victron Orion XS in my camper a few months ago. I ran a 4 gauge pure copper stranded welding wire from the positive terminal of my passenger side battery to a 175A Anderson Plug that I mounted to the back of my truck. I ran another 4 gauge wire from the plug to a ground on the frame at the back of a truck.
It’s worked well. I had seen it push 50A however it’s a little harder to watch it while driving down the road. The Bluetooth connection is a little far away for a solid connection but it did seem like it dropped down to about 30A for much of the time. Of course I was also driving cross country so it was on constantly for hours at a time. Combined with the 600 watts of solar on the roof it works well enough that I will turn on my AC well before our stops and still have decent battery available once I arrive.
It’s worked well. I had seen it push 50A however it’s a little harder to watch it while driving down the road. The Bluetooth connection is a little far away for a solid connection but it did seem like it dropped down to about 30A for much of the time. Of course I was also driving cross country so it was on constantly for hours at a time. Combined with the 600 watts of solar on the roof it works well enough that I will turn on my AC well before our stops and still have decent battery available once I arrive.
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