Is a Diode Required on the 12 Volt Pin for Charging a Trailer Battery

Question

Question:

I use my auto hauler for more than just cars. Therefore, I am installing a solar charging system with a deep cycle battery to use 12v for lights and and other small accessories when the trailer is disconnected from the tow vehicle. The black wire from the 7-way plug supplies power when connected to the tow vehicle. Im thinking I would need a diode in the black wire lead between the tow vehicle and the solar battery. Will the Roadmaster Single Park Light Diode work in this case? Any guidance would be great. Thanks

asked by: Jon

1

Helpful Expert Reply:

You do not need to have a diode between the two 12 volt batteries on your trailer and tow vehicle but it is not a bad idea either. The Roadmaster Single Park Light Diode part # RM-690 will work perfectly for this. The factory 12 volt pin on most 7-way trailer connector is keyed so if yours is not or you do not have a factory 7-way then I do recommend using the diode.

expert reply by: Conner L

1

Answer 1

If all you want is to prevent the 12 volt power supply of your trailer battery wiring from backfeeding onto your vehicle wiring or vice versa what you need is a one-way diode like part #RM-690. This only allows current to flow in one direction so…

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Answer 2

A diode is designed to stop the reverse flow of current in an electrical circuit. Therefore yes, a diode will prevent backfeed to your vehicle from the trailer's battery. The part you referenced part #RM-790 has a dual in, single out function…

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Answer 3

The diode #RM-690 can handle up to 120 volts at 24 amps so it should work just fine for your needs provided nothing else exceeds 120 volts at 24 amps. Regarding your picture, most battery chargers or batteries on vehicles say not to ground the…

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Answer 4

While unlikely, it is certainly possible that the trailer battery could backfeed to your vehicle's battery when hooked up under the scenario you described. To make sure this doesn't happen all you need to do is add a single diode like the…

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Answer 5

If you want the loading lights on the trailer to function with both the switch and batteries as well as off of the reverse light circuit from a 7-Way trailer connector you can certainly make that happen. But instead of the reverse light circuit wired…

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Answer 6

The diode part #RM-690 that you referenced would be perfect for what you are looking to do. It will allow current to go from the one battery to other but not in the other direction. Basically you just need to install it between the two batteries with…

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Answer 7

The charging circuit on a vehicle 7-way style connector, the one that would deliver a maintenance charge to the trailer battery while you tow, is completely separate from the 4-wire brake controller wiring. This trailer charging circuit is usually…

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Answer 8

Yes, you will want to use a single function diode, like part #RM-690. You will need to wire it in between the breakaway battery and the trailer battery to stop the backfeeding from the battery to the breakaway system.

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Answer 9

Typically people will let the breakaway battery run the breakaway system and then would use the accessory battery to power the interior lights etc. This tends to work the best since your breakaway battery needs to always be charged and interior…

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Answer 10

What you would need to do is use diodes on each charge wire so that the amperage can charge each battery but the batteries wouldn't try to charge each other when not connected to a tow vehicle. For that you would need to Y the charge wire that…

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Answer 11

The difference between the Class II and Class III hitches has to do with their Gross Trailer Weight (GTW), their Tongue Weight (TW), and their Hitch Receiver Size. Class II trailer hitch receivers have a 1-1/4 inch receiver and can be rated up to…

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Answer 12

A 4-Way trailer connector has the basic lighting functions only; running lights, left turn signal and brake lights, right turn signal and brake lights, and ground. A 7-Way has these functions and a 12 volt circuit, a circuit for electric trailer…

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Is a Diode Required on the 12 Volt Pin for Charging a Trailer Battery

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