Is DC to DC Charger Needed to Prevent Trailer Battery from Draining Truck Battery
Updated 09/08/2026 | Published 08/31/2026
Question:
We have 600 watts of solar, a 300 ah battery and a Victron 100/50 controller. Our tow vehicle is a 2025 Toyota Tundra Hybrid. Do we need a DC-DC converter to keep either battery from being drained by the other? I’ve heard horror stories….
asked by: L N
Expert Reply:
Hey L, yes it is recommended to go with a DC to DC charger with your setup like the part # 331-BCDC1225D that you referenced. This will allow the tow vehicle to contribute to charging in a meaningful way and also will keep the batteries isolated so that one battery does not drain the other. What kind of batteries do you have?
Product Page this Question was Asked From
Redarc In-Vehicle BCDC Battery Charger - Dual Input - DC to DC - 12V/24V - 25 Amp
- Battery Charger
- Battery Charger
- RV/Camper
- Trailer
- 12V
- 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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Lisa N.
9/7/2026
We have a Renogy 300 ah lithium in the camper and the truck has a standard lead acid. As I understand it the Tundra wiring and battery will not effectively charge the camper batteries because the wires are too small so th charge getting through is small. I have no worries about the camper battery. Our rooftop solar is sufficient to do that while on the road. Will the current run the other way from the trailer’s lithium through the 7pin to the alternator? I understand the 2025 Tundra has a smart alternator. Where is this device installed ? On the truck or on the camper?