Wire, Circuit Breaker, and Charger for Connecting Charge Wire for Trailer 7-Way

Question:

Hi, I recently purchased a second hand 06foot Lexus rx400h, with factory tow package. Ive read that the tow package up the towing capacity from 2000# to 3500#. We are going to be towing an 2010 Escape 15, which should be about 2000#-2500#. The tow package included tranny cooler, receiver hitch, and prewired flat 4 pin at the receiver. I want to a combo flat 4/ round 7 pin connector. I see Hopkins make such a connector that has a 4 pin connector on the back, so I can plug in the current 4 pin, without having to cut the factory 4 pin off. So that would leave four wires still left to connect. White to a ground point. Light blue to a brake controller. Black to a fuse and then to the battery. And last, purple ? to reverse light. My questions are: -On this Lexus, can I safely use a saddle tap to connect the Purple to the reverse light line, or is it Can Bus, which could trigger a code in the CPU? -the battery is smaller than usual because its a hybrid. I think Ive read that the alternator might be smaller output too. Is this a concern for running the trailer brakes and the black power line to the trailer, from the battery? If so, what are the fixes? I intend to also use a solar panel while camping stationary, but would still need to charge the trailer with the Lexus while towing. -I know youve said it a million times, but what should the wire gage and resetting fuse be, for the Black power line and the Blue trailer brake line? Im really hoping the Lexus will make a great tow vehicle. Weve been towing a 13foot litfoot Bigfoot with a 05foot Honda CRV, which was fine, but at the top of the CRV towing capacity. So far, the Lexus IS a major upgrade in every way, over the CRV. Thanks, Kevin

asked by: Kevin D

Helpful Expert Reply:

When installing a 4-way to 7-way adapter like the part # 37185 you only have to connect the extra wires of the adapter where needed. Not everyone needs the 12 volt circuit active so some leave that off. You'd want to use 10 gauge wire like part # 10-1-1 (sold by foot) through a breaker like part # 9510 to the positive battery terminal for this.

Even fewer people need the reverse light circuit active since that's not used very often. A quick splice like the # 804C ran to the reverse light circuit of the tow vehicle would be all you'd need.

For the brake output and the 12 volt accessory you'd want to use 10 gauge wire like part # 10-1-1.

Since you plan to charge the battery with also a solar panel you'd also want the Redarc In-Vehicle BCDC Battery Charger # 331-BCDC1225D which is designed for balancing the charging between a vehicle alternator and a soloar panel.