Charging Travel Trailer Lithium batteries question

[RidingHighNCO]

I have a 21 F-150 XLT w.3.5L turbo and planning to purchase a travel trailer and I’m trying to decide to go with AGM or Lithium batteries in the trailer. The trailer is setup to use either but my question is will there be any issues with the truck charging the lithium batteries while driving. Documentation show that my truck has a 240A alternator.

Is anyone out there doing this? Thanks in advance

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[CND Supercrew]

Are you dry camping?

 

[HammaMan]

Not even a question, LFP all the way - they'll last the life of the TT and then some. You need a proper charging module to up the voltage and limit current regardless of the batt chemistry due to wire length. Look for a 20 amp charger to handle this.

 

[Stormpeakco]

I have a 21 F-150 XLT w.3.5L turbo and planning to purchase a travel trailer and I’m trying to decide to go with AGM or Lithium batteries in the trailer. The trailer is setup to use either but my question is will there be any issues with the truck charging the lithium batteries while driving. Documentation show that my truck has a 240A alternator.

Is anyone out there doing this? Thanks in advance

Believe you will enjoy this top tier set up and the tutorial for the Victron Orion DC-DC charger for 12V power from your alternator for beaucoup delivered amps to your battery bank (video below).



(fyi-This coming May, we're having Tom, Jake and Ely of MYT Solar in La Pine, OR install a full Victron components system-400 Ah-24V Li bank, 3000W Multiplus inverter, Rich 1500W on the roof of our "generator-less" 26' TT, Rich 400W on the ground coupled w/ our (coming) '25 KR power boost Hybrid/P.P.O.) Dave

 

[HammaMan]

(fyi-This coming May, we're having Tom, Jake and Ely of MYT Solar in La Pine, OR install a full Victron components system-400 Ah-24V Li bank, 3000W Multiplus inverter, Rich 1500W on the roof of our "generator-less" 26' TT, Rich 400W on the ground coupled w/ our (coming) '25 KR power boost Hybrid/P.P.O.) Dave

PB makes things much easier for delivering high amounts of offboard power. MAKE SURE they know the PB is GFI and that whatever it's connecting up to has to be able to support it. People have run into issues with some of victron's products due to this. There's another thread where the solution using a 48v system ended up using a ~4400kW 240v to 48v battery charger.

 

[Tall Tail]

You may want to look at a charge controller.

 

[Davexxxx]

I have 600ah of LiFePO4 in the camper and made no modifications to either vehicle, re the 7 pin.

I tested it at various states of charge and the most I saw it draw from the truck was 8A. I believe that circuit is protected by a 10A fuse?

I considered it a non issue and ~6K towing miles, hasn't given an indication that it was a bad decision.

However, on a non PB, I'd go with a DC to DC charger.

 

[Davexxxx]

PB makes things much easier for delivering high amounts of offboard power. MAKE SURE they know the PB is GFI and that whatever it's connecting up to has to be able to support it. People have run into issues with some of victron's products due to this. There's another thread where the solution using a 48v system ended up using a ~4400kW 240v to 48v battery charger.

I used all Victron gear. The Multi Plus 3K has a sensor re GFI and automatically switches for it.

Instant, or close enough to be interruption free. Seamless.

 

[tsigwing]

My solution was solar on the camper. You can adjust the charge controller for Lifepo. I have a lead acid battery in my camper still (waiting for it to puke) but can run my fridge on DC no problem rolling down the road.

 

[Calson]

Lithium batteries require a very different charge profile than lead acid ones. This includes a much higher charge voltage level. A DC to DC charger it the best way to do that with the tow vehicle providing the current. At a campsite it is a different matter as you do not want to be running the truck engine to keep the batteries charged.

Best overall solution is to have solar panels with a special charge controller that has a lithium charge setting. The panels will charge the batteries as you drive down the highway and at the campsite and even while parked along the route.

 

[DHBPhoto]

I have 600ah of LiFePO4 in the camper and made no modifications to either vehicle, re the 7 pin.

I tested it at various states of charge and the most I saw it draw from the truck was 8A. I believe that circuit is protected by a 10A fuse?

I considered it a non issue and ~6K towing miles, hasn't given an indication that it was a bad decision.

However, on a non PB, I'd go with a DC to DC charger.

I have the 2.4kw onboard gen t on my 21 EB. Why not just run shore power off the truck while driving? Won’t that charge the batteries fine?

 

[HammaMan]

I have the 2.4kw onboard gen t on my 21 EB. Why not just run shore power off the truck while driving? Won’t that charge the batteries fine?

Yes, if you can current limit shore power that's the easiest way to charge w/ a PB. Some systems it isn't easier to current limit. If the TT is expecting to be able to access a 30a shore power it may be an issue so it really depends on the configuration.

 

[Davexxxx]

I have the 2.4kw onboard gen t on my 21 EB. Why not just run shore power off the truck while driving? Won’t that charge the batteries fine?

Yes and some have done that but depending on where shore power enters the trailer (on mine, toward the rear) you're talking about running a minimum of a 20 amp grade cord (or relocating the shore power port) that distance and then fashioning some sort of acceptable way to plug it in and have all that survive towing / wind / water / bumps etc.

If your trailer is stock, I'm guessing the on board converter would be ok with 20A vs. 30 but I'd have to adjust my charger down to say, 18A, from 28A, to avoid tripping the circuit. Easily done on the app but it'd have to be done.

It just isn't something I spent any time thinking about, since I have the 7.2, in the PB and solar on the roof of the camper.

I did need to assure that the alternator would be OK, using the 7 pin power connection in a stock configuration, on a Lithium powered trailer and what crude testing I did, backed by 6K miles, shows that it is.

That doesn't mean it would be OK on all other vehicles. Apparently, motorhomes and boats, must have a special isolator / regulator, or a sperate DC to DC charger, else risk burning up the alternator.

 

[Buyer2021]

MAKE SURE they know the PB is GFI and that whatever it's connecting up to has to be able to support it.

I used all Victron gear. The Multi Plus 3K has a sensor re GFI and automatically switches for it.

For the purposes of this discussion do y'all mean to refer to the fact that the PB is "Bonded Neutral"? "GFI" (ground fault interruption / protection) should have no bearing on any connected load.

I tested it at various states of charge and the most I saw it draw from the truck was 8A.

Were those tests with your trailer's solar system also connected / contributing charge to your battery bank?

 

[Davexxxx]

For the purposes of this discussion do y'all mean to refer to the fact that the PB is "Bonded Neutral"? "GFI" (ground fault interruption) should have no bearing on any connected load.

Correct. Possibly both but a for sure yes, on the bonding.

Hammerman says some have had issues with that. The Victron Multiplus 3K, does not.

Were those tests with your trailer's solar system also connected / contributing charge to your battery bank?

I'd have to look at my notes from the time. Can't say for sure but if I hadn't turned off the solar, it would have only been 200W max at the time. I do recall it was at least a mostly sunny day and warm, since I used the camper's aircon, to get varied depths of discharge in a single day.

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