Need to confirm tow vehicle alternator is safe from lithium battery upgrade

[treeofliberty]

I've done some online searching and reading, and believe that we are safe, but I would appreciate some feedback form the collective wisdom on this forum.

We have a solar and inverter setup in our fifth wheel and I recently replaced the aging lead acid battery bank with 2x400ah lifepo4 batteries. What my online research has led me to believe is that the tiny wiring in the 7-pin connector between the tow vehicle (2013 F350 diesel) and the RV will keep the draw from the batteries from overheating the alternator. Am I delusional? Are there other unintended consequences I need to mitigate?

Thanks for any feedback and/or advice.

Tim

 

[Tomthumb62]

I've done some online searching and reading, and believe that we are safe, but I would appreciate some feedback form the collective wisdom on this forum.

We have a solar and inverter setup in our fifth wheel and I recently replaced the aging lead acid battery bank with 2x400ah lifepo4 batteries. What my online research has led me to believe is that the tiny wiring in the 7-pin connector between the tow vehicle (2013 F350 diesel) and the RV will keep the draw from the batteries from overheating the alternator. Am I delusional? Are there other unintended consequences I need to mitigate?

Thanks for any feedback and/or advice.

Tim

Fwiw, I’m in a similar situation and have researched this a bit as well.

From my understanding, it’s not a good idea to try to charge a lithium bank from the 7pin. Lithium can draw a lot of amps and the wiring in the 7pin is too small to support this and could overheat. Use a DC-DC charger instead like the ones Renogy or Victron sell as this will control the current and give your batteries a proper and safe charge.

The problem is that if your system is 12v and your batteries are a long ways from your tow vehicle alternator, you’re going to need some pretty thick cables to avoid much voltage drop. Depending upon the size of your DC-DC charger. For a 800Ah bank, you’re going to want as large a DC-DC charger as your alternator can support. For example if your 800Ah battery bank is down to 50%, it will take 10 hours of driving with a 40A DC-DC charger to bring it back up to 100%, assuming no loads on the system and assuming you have no solar panels (or it’s cloudy) to supplement.

What I decided was it was cheaper and easier to not add a DC-DC charger and simply add more solar panels to the roof. Now our loads and battery are completely charged everyday by solar power alone. But our loads are low (mostly running a fridge) and our battery bank is only 200Ah. Powered by 400W panels and a 30A MPPT. But this only works this well in good sun, too many cloudy days and we gotta plug in the shore power charger.