Amperage of Brake Magnets and Size of Wire Used To Connect 7-Way Trailer Plug To Electric Brakes

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Question:

How much much amperage does each electric brake magnet require? I am trying to figure out what size wire to run from the trailer plug to the electric brakes. Thanks

asked by: Tom H

0

Expert Reply:

On each individual electric brake magnet the amperage draw would be 3.0 to 3.2 max amps at 12 to 13 volts on 7-inch brake magnets and 3.2 to 4.0 max amps at 12 to 13 volts on 10 and 12-inch brake magnets.

The max amperage draw for the brake magnets on a single axle trailer (2 brakes) would be 6.3 to 6.8 max amps on a 7-inch brake system and 7.5 to 8.2 max amps on 10 and 12-inch brake system. The amps will be higher if using a tandem axle or triple axle trailer.

I am including a link to a FAQ page on Electric Trailer Brake Magnets that will show you how to test them and list the numbers I mentioned above.

On a 7-Way connector the suggested minimum wire gauge for the White (ground) wire, the Red or Black (power) wire, and the Blue (brake power) wire is 12 gauge. The minimum wire gauge for the remaining Green (right turn/brake) wire, the Yellow (left turn/brake) wire, the Brown (tail lights) wire, and the Purple (reverse light) wire is 16 gauge.

expert reply by: Jeff D

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Jody P.

7/10/2020

I just put a brake controller on my Mercedes suv and curious how much current the controls require. Do I need an amplifier/booster or will this drive a two axel brake system?

Reply

Chris R.

7/14/2020

You shouldn't need any kind of amplifier for the brake controller - the controller itself should be getting power directly from the vehicle's battery. Are you having any issues with it?

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Akshay S.

12/4/2020

@ChrisR Hi, We are developing a semitrailer where brake controller is installed on trailer and getting power from drive unit battery.when detached we need to track trailer so we also place one auxiliary battery in trailer so, that it can power when detached. Can u please suggest how much current will be taken by controller for 12V. Supply. Thank you,

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Jon G.

12/4/2020

@AkshayS What size brakes are you dealing with on your semi-trailer? It's my understanding that semi-trailers use air brakes so you'll need to make sure you have some kind of conversion if this is the case. Jeff D addresses 10" and 12" brake assemblies above so if you have something else then that power draw can be different. Just to give you a reference point, the Hopkins Engager Breakaway Battery Kit # 20400 is used for up to 2 axle trailers with electric brakes.

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Answer 1

Maximum amperage draw for 4 Brakes that are 10 or 12 inch diameter is 15.0 to 16.3 amps at 12 to 13 volts. The 14 gauge wire may be sufficient but for maximum braking effectiveness at full load capacity. I would opt to run 10 gauge wire. Larger…

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Answer 2

That's a very good question, we tend to be extra cautious and say to use 10 gauge wire because that would be more than enough. When you get into longer trailers that will end up using a lot of wire the heavier gauge wire becomes more…

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Answer 3

The battery you use for a break away system needs to be able to power the trailer brakes on full for 15 minutes. A 12 volt battery rated for 5 amp hours is normally used, unless you have 3 axles each with brakes, then you would benefit more from a…

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Answer 4

The reason that 10 Gauge #10-1-1 or 12 Gauge #12-1-1 wire is recommended for 10" brake assemblies, like part #AKEBRK-35-SA, is because they pull more power than the lights on your trailer. I believe the green wire you are referring to…

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Answer 5

There are a few things you can check to make sure the brakes are adjusted correctly, but it sounds like there may be a short in the system. I would start by checking the trailer wiring connector on the truck and trailer for corrosion. If there is…

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Answer 6

Traditionally, trailer manufacturers did not use electric brakes on boat trailers because the brake magnet wiring and trailer wiring did not always have the best insulation or water protection. These days, more and more manufacturers are using…

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Answer 7

Hydraulic brakes are better suited for boat trailers for the simple fact that wires and water do not like to cooperate with each other, but the etrailer.com Self Adjusting Electric Trailer Brakes, #AKEBRK-35L-SA, can be used on a boat trailer…

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Answer 8

Based on your image it looks like you only need a Replacement Handle Assembly #PLR158-100-SS welded onto the cam lock that you already have. If the entire assembly needs replaced the Cam-Action Lockable Door Latch w/ Split Bushings for Large Enclosed…

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Answer 9

To answer your first question, there isn't a traditional "adapter" to allow the 7 way on your trailer to plug into a 4 way connector on your vehicle- at least not in the manner that you're thinking of. For that reason you would…

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Answer 10

The wires on the Dexter Nev-R-Adjust Electric Trailer Brake Assembly #K23-478-00 are 12 gauge wires. We recommend using 10 Gauge Wire #10-1-1 from the trailer 7-Way connector to the brakes though to help ensure enough power gets to them.

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Answer 11

That will depend on the amount of brake axles your trailer has. . The 20 amp breaker like #9506P is for 1 and 2 axle brakes, and the 30 amp like part #38630 is for 3 and 4 axle brakes

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Answer 12

Yes, that all sounds correct. The computer systems on the newer trucks require a constant draw to provide power to the vehicle's 7-Way connector. To work around this you will need the 7-Way Vehicle Power Adapter item #FR87PR. This plugs directly…

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Amperage of Brake Magnets and Size of Wire Used To Connect 7-Way Trailer Plug To Electric Brakes

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