Charging While Driving…
What is the best way to charge the lithium batteries in my RV trailer while on the road?
Hey Mike,
What do you think would be the best way to charge the lithium batteries in my RV trailer while on the road? I think I may need to install a specific converter to charge them while driving, as from what I understand, my current one is not optimal for lithium batteries. Let me know what you think. Thanks. —Joe
Hey Joe,
You’ll want something like a RedArc BCDC1225D DC-DC charger that will boost your alternator voltage high enough to fully charge your Lithium batteries, while limiting the charging current to protect your alternator.
You’ll also need to run a heavy wire (8-gauge or heavier to reduce voltage drop) and 50-amp Anderson connectors between your truck and trailer to handle the large charging currents.
Isn’t the 7-way plug enough?
Not for fully recharging Lithium RV batteries while driving. That’s because the 7-way trailer plug typically only supplies around 5-amps of maintenance current for a breakaway brake battery, which would take up to 20 hours of driving time to fully recharge a single 100 Ah Lithium RV battery, assuming no current draw from any RV appliances.
However, a 25-amp DC-DC charger could fully recharge a 100 amp-hr Lithium trailer battery in about 4 hours of driving time.
Lets play safe out there… Mike
Real world experience here. Mike's solution is good and used by folks I know to have higher charge rates. But I use a Victron DC/DC 12/12-9 converter ($63) that charges at 9 amps through the 7-pin connector. No need to rewire or use separate charging wire to the trailer. I checked to make sure my tow vehicle (4Runner) had 12 ga wire with 10 amp fuse from the factory. I routinely charge at 9 amps while driving (monitored via bluetooth), which I can combine with solar while driving, topping off the batteries nicely. This setup definitely won't fully charge depleted batteries, but has been adequate for us for years to avoid using the generator.
If you are willing to charge with only 20A, Renogy makes a DC to DC Charger for just over $100.
https://a.co/d/6I0zXMu