Upgraded to Lithium and lost my breakway function

[GaryandEllen]

I have a 2020 E21 and I have upgraded to Lithium and a Orion-TR Smart 12/12-10A DC-DC charger. Both of these are under the rear bench seat. Recently I was looking into a breaking issue and realized my emergency breakaway feature was not working. After looking at voltages in the front wire breakout box I realized that after upgrading to lithium I no longer have any battery power coming into the breakout box. I've been trying to figure out how to run a new wire from my batteries to the front breakout box but I may have another solution. I found out that a yellow backup light wire seems to be run from the breakout box to the back under to bench seats. Since I do not have any backup lights I'm thinking of repurposing this wire to bring battery power into the breakout box. Do you think this smaller wire would be large enough to support the emergency breakaway function?
Thanks, Gary

[Centex]

Originally Posted by GaryandEllen

... I've been trying to figure out how to run a new wire from my batteries to the front breakout box but I may have another solution. I found out that a yellow backup light wire seems to be run from the breakout box to the back under to bench seats. Since I do not have any backup lights I'm thinking of repurposing this wire to bring battery power into the breakout box. Do you think this smaller wire would be large enough to support the emergency breakaway function?

Dexter FAQ says that the brake magnets draw 3A each. With no controller attenuation during breakaway, that's at battery voltage, nominally 12VDC.

Circuit Wizard - Blue Sea Systems, or another wire-sizing calculator of your choice, can be used to determine the appropriate wire gauge for that (4 brakes x 3A = 12A) load in consideration of the total length of the circuit (sum of the distance from the batteries to the breakout box, thence to the breakaway switch, thence back to the brakes plus the ground-path distance from the brakes to the battery).

So, for example, assuming 12VDC nominal @ 12A x 25ft (?) total circuit length, a 10AWG wire is appropriate according to the Blue Sea calculator.

I've no idea of the actual distances on an E19 nor the gauge of the mentioned yellow wire?

Just for your consideration, Have Fun!

[Viajante]

Gary and Ellen,

Unless you removed the wire that runs from the breakaway switch to the 7th pin of the junction box you should not have to run a new wire from the battery to the junction box. You need 12v power to the input side of the breakaway switch.

I think if you traced the breakaway switch input wire you would find where you disconnected it from the old battery setup. The input wire needs to go to the battery or another source of 12 power that isn't affected by the battery disconnect switch. That input wire should still be there and would be the proper size.

I think the wire from the breakaway switch to the 7th pin is still there. I think you need to follow the input wire from the breakaway switch back toward its source.

[GaryandEllen]

Originally Posted by Viajante

Gary and Ellen,

Unless you removed the wire that runs from the breakaway switch to the 7th pin of the junction box you should not have to run a new wire from the battery to the junction box. You need 12v power to the input side of the breakaway switch.

I think if you traced the breakaway switch input wire you would find where you disconnected it from the old battery setup. The input wire needs to go to the battery or another source of 12 power that isn't affected by the battery disconnect switch. That input wire should still be there and would be the proper size.

Note: The 7th pin of the junction box should have two input wires, the blue one from the trailer harness and another from the breakaway switch. The 7th pin has one output wire to the brakes. Do not run another 12v wire to the 7th pin. Whenever it is hot the brakes will slam on.

I think the wire from the breakaway switch to the 7th pin is still there. I think you need to follow the input wire from the breakaway switch back toward its source.

I agree with you about Pin 7. Currently I have the breakaway switch connected to Pin 2 and Pin 7. I'm looking at using Pin 3 for the battery power input. I would disconnect the yellow input from the Tow Vehicle, move the breakaway switch from Pin 2 to Pin 3, and connect the yellow wire I found under the bench seat to the battery. I still need to figure out if the wire size can handle the load.

[GaryandEllen]

Originally Posted by Centex

Dexter FAQ says that the brake magnets draw 3A each. With no controller attenuation during breakaway, that's at battery voltage, nominally 12VDC.

Circuit Wizard - Blue Sea Systems, or another wire-sizing calculator of your choice, can be used to determine the appropriate wire gauge for that (4 brakes x 3A = 12A) load in consideration of the total length of the circuit (sum of the distance from the batteries to the breakout box, thence to the breakaway switch, thence back to the brakes plus the ground-path distance from the brakes to the battery).

So, for example, assuming 12VDC nominal @ 12A x 25ft (?) total circuit length, a 10AWG wire is appropriate according to the Blue Sea calculator.

I've no idea of the actual distances on an E19 nor the gauge of the mentioned yellow wire?

Just for your consideration, Have Fun!

All good info Centex. I recently got new brakes and I was told I would get new magnets as part of the brake setup. I'll have to contact the brake company to see what their brake magnets draw. I'm interested in if getting new magnets is normal. I'll see what they say

[Viajante]

https://www.escapeforum.org/forums/a...8&d=1612491984

Gary, attached is a wiring diagram from tdf-texas. According to this the answer to your question is 10ga wire feeding the breakaway switch. I don’t know what size the yellow wire in your trailer is.

[7Gentex]

A bit of a different view, but.........Appears there should be a feed from the DC-DC charger output to the emergency brake circuit.......


Sorry, I lost the authors info.................

[rubicon327]

Originally Posted by 7Gentex

A bit of a different view, but.........Appears there should be a feed from the DC-DC charger output to the emergency brake circuit.......
Sorry, I lost the authors info.................

That drawing is from ETI and the brake wiring is shown wrong. The way it shows it there would be no voltage to the brakes until the breakaway is pulled. A breakaway switch is wired in parallel with the normal brake circuit. I corrected this diagram in another thread but can’t seem to find it.

Edit: I found it. This should help the OP.
https://www.escapeforum.org/forums/f...tml#post418153

[GaryandEllen]

Originally Posted by Viajante

https://www.escapeforum.org/forums/a...8&d=1612491984

Gary, attached is a wiring diagram from tdf-texas. According to this the answer to your question is 10ga wire feeding the breakaway switch. I don’t know what size the yellow wire in your trailer is.

Viajante thanks for the help. I see I need to run a 10awg and not use the yellow wire I found available.

[GaryandEllen]

Originally Posted by rubicon327

That drawing is from ETI and the brake wiring is shown wrong. The way it shows it there would be no voltage to the brakes until the breakaway is pulled. A breakaway switch is wired in parallel with the normal brake circuit. I corrected this diagram in another thread but can’t seem to find it.

Edit: I found it. This should help the OP.
https://www.escapeforum.org/forums/f...tml#post418153

rubicon327 The link was very helpful. I wish I could have found it on my own. I now understand I need to run a 10awg wire.