How to Charge a 100 Amp Hour Battery While Towing with a 2018 Toyota Highlander Hybrid

Published 02/17/2019

Question:

What do you recommend for charging the 100 AH auxiliary battery in my trailer? I want to run a dorm refrigerator while I drive and camp without hook ups. Also I’ll need to run a cpap, lights, and phone chargers. I haven’t seen anything about charging the trailer battery from a hybrid 12v battery. Would a dc to dc charger work? If so how would the blue wire be connected since the hybrid starts off the traction battery? Thanks

asked by: Jacque

Helpful Expert Reply:

In order to charge the 100 amp hour auxiliary battery on your trailer while in tow with your 2018 Toyota Highlander Hybrid you will need to use a DC to DC battery charger. The 12 volt pin on your 7-way would not be sufficient to charge the auxiliary battery on your trailer as it is generally only used to charge a very small 5 amp hour breakaway battery.

For a DC to DC battery charger I recommend using the Redarc In-Vehicle BCDC Battery Charger part # 331-BCDC1225D which is largely considered to be on the best on the market. This battery charger will take unused power from the vehicle's battery and then use that to charge the trailer's battery while the vehicle is running. It has a 75-200 amp hour rating and will also allow for solar panels to be used while parked for even more charging power.

If the blue wire you are referring to is the one on the Redarc In-Vehicle BCDC Battery Charger then this will need to be attached to any keyed circuit or one that only gets power while the vehicle is on. The most common for this is the ignition but that should not be an issue on your Highlander as it would still have a keyed ignition circuit whether it is a Hybrid or not.

expert reply by: Conner L