Is It Okay to Charge A Lithium Battery on a Trailer While Towing
Updated 05/09/2026 | Published 05/06/2026
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Question:
If you tow vehicle charges the trailer battery when you drive. Are there any issues with essentially having a connection between your vehicles lead acid battery and a lithium battery on your trailer?
asked by: Darrin N
Expert Reply:
Hey, Darrin.
If everything is set up properly, you won’t have any issues charging the battery on your trailer while towing. It’s a bit hard to fully answer your question without knowing your full setup.
Typically, there will be a circuit breaker inline on the power wire that runs from your vehicle’s battery to the 7-way to prevent any sort of backfeed. On the trailer side, you would also need something like the Redarc Trailer Battery Charger # RED36TR. Without this, you won’t be able to properly charge your battery while driving.
Would you be able to tell me a little more about your setup and what you have installed on your trailer?
Product Page this Question was Asked From
Redarc In-Vehicle BCDC Trailer Battery Charger - Dual Input - DC to DC - 12V - 12 Amp / Solar 40 Amp
- Battery Charger
- Battery Charger
- RV/Camper
- Trailer
- 12V
- 24V
- Charges and Maintains
- AGM
- Calcium
- Gel
- Lead Acid
- Lithium
- Solar Panels to Auxiliary Battery
- Vehicle Battery to Auxiliary Battery
- Smart Charge
- Trickle Charge
- Redarc
more information >
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on Battery Charger
Norman
5/9/2026
We have a 2019 F150 diesel. My understanding is that 1) The "hot" port on the 7 way plug does NOT have voltage UNTIL the engine is running and the transmission is in drive; 2) Once the truck battery is fully charged the "smart" alternator cuts way back on voltage and thus the voltage at the 7 way plug is way to low to charge the house battery.... The Redarc device in some way overcomes this issue (I'm still not sure if it takes the lower voltage and converts it to a higher charging voltage or if it convinces the alternator to put out a higher voltage - I suspect the first option is correct.).... I was pleasantly surprised that the Redarc also acts as a solar converter so I was able to remove my "cheap" one that I was using (although if you want to know what your panels are putting out you will need a separate current meter) which automatically "decides" if its best to charge your house battery from solar or the tow vehicle. Yes, as I recall it does have a lithium charging setting.... In summary the device does more than I expected when I ordered it.