We want to take the best care of Cocoon, our Casita travel trailer that we will pick up soon. This includes keeping the house battery fully charged and maintained while traveling. This article is about the first step, adding a DC power connection to the back of our tow vehicle to charge the battery.
The power in a vehicle’s trailer connector often isn’t enough to charge a trailer battery effectively while driving. This is especially true when a refrigerator is running on DC power on the road. In extreme cases, the battery can be drained during towing, leading to extra discharge cycles and premature battery failure.
The connector will mate to a matching power cable on the front of the trailer. It will power a DC-to-DC charger in the Casita that maintains the battery’s charge and powers the refrigerator.
Boon-Docking
A side benefit is that it can charge the battery when our vehicle is idling. This will be useful when we are boon-docking since we won’t have solar panels initially. The charger we plan to use also has a solar charge controller for when we do.
Lithium Battery
At some point, we will convert our Castia to a lithium battery, and the charger will work with it. We won’t need to buy a new lithium-compatible converter-charger to replace the stock lead-acid-only converter. Instead, I will disconnect the stock converter from the breaker panel, and it will power the charger when we are on shore power.
Engine Bay
I ran the cable when installing the skid plates under Campbell, Our Toyota Land Cruiser, a few months ago.
So it was just a matter of connecting the forward end to a circuit-breaker and the starting battery I upgraded last year. Then adding a connector at the rear.
Wiring
The cable is 1-AWG, and it is rated to carry 150 amps with a 10% voltage drop over 50 feet. The charger will use 50 amps at the most. No doubt we will find a use for the extra capacity.
When the engine runs, the alternator generates around 14 volts, so the lowest voltage the charger will see is about 13.5 volts under full load. That is well within the charger’s specified input voltage.
Please check back.
I plan to write an article describing the trailer-side of the project.
Materials
Parts
Wiring
- TEMCo WC0237-25 ft 1-AWG RED
- TEMCO 10-Pack Cable Ends 1-AWG 3/8″ hole ( only 1 needed)
- TEMCO 10-Pack Cable Ends 1-AWG 1/4″ hole ( only 3 needed)
Other
- Fasteners to mount the circuit-breaker
- Heat-shrink tubing to seal the cable ends
- Star washer for added conductivity under the rear negative lug.