Providing a Maintenance Charge to a Trailer Mounted Battery on Trailer Towed by 2010 Acura MDX  

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Expert Reply:

In order to provide a maintenance charge to a trailer mounted battery you would need to have a trailer connector on the vehicle that has a 12 volt circuit. A 4-Way flat, like what is on harness # C56038, only has the basic lighting functions.

But you can add a 7-Way trailer connector and keep the 4-Way in place. You would need adapter # 37185, a 40 amp circuit breaker, # PK54540, and about 25 feet of wire # 10-1-1. Put 25 in the quantity box to get 25 feet.

The 4-Way you have will plug into the 37185. then you will ground the white wire to the vehicle frame on your 2010 Acura MDX. There will be 3 more wires left over. the black one goes to the 12 volt pin on the 7-Way. Using the 10-1-1 wire attach one end to the black wire. Then route the other end to the vehicle battery avoiding areas that can pinch or burn the wire such as exhaust and suspension components.

Once the wire is near the battery you can mount the circuit breaker. The wire you ran will be long enough to reach the circuit breaker with some wire left over that you will need. Attach the end you ran to the AUX post on the circuit breaker. With the left over wire attach one end to the BAT post on the circuit breaker and the other end to the positive battery terminal.

The other wires on the 37185 can be taped up and stowed out of the way.

If the trailer does not have a 7-Way connector you can easily add one using # H20042. Its wires functions are:

White Wire = Ground
Red Wire = Left Turn and Brake
Brown Wire = Right Turn and Brake
Green Wire = Tail Lights
Blue Wire = Brake Power
Black Wire = 12 volt (hot lead, this is what would go to the positive battery terminal on the trailer)
Yellow Wire = Reverse Lights

Any functions the trailer does not need, such as reverse lights or brake power, can be taped up and stowed out of the way.

Please keep in mind that this set up will only maintain the charge that the battery has. It cannot charge up a battery because the vehicle alternator will not be strong enough to push back the required amperage and the wiring on trailer connectors is too small to handle it.

To charge the battery using shore power I recommend CTEK battery charger # CTEK56353. I own one of these chargers and it works beautifully.

expert reply by: Michael H

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