More electric trailer brake issues

Submitted: Friday, Feb 15, 2008 at 22:16
ThreadID: 54612 Views:7294 Replies:5 FollowUps:5
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I have spent more time trying to get my trailer brakes working and have come to the conclusion it must be the brake magnets.
I get 10.6V at the magnets yet they still offer hardly any retardation. But if I use the mechanical handbrake, it totally locks the wheels - shows all is OK mechanically. And given there is some retardation from the electric brakes, it shows mechanically things are working inside the drum.

When the magents wear out, I was under the impression that they either worked or didn't, not that they just slowly lose their effectiveness.

The magnets appear to be in good nick and have plenty of thickness left - I don't want to replace them only to find they were not the problem.

So, does anybody know how to tell when the magnets need replacing? Or do you know where else I should be looking for the problem?

Cheers

Captain
Its not what you drive, but how you drive it!
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Reply By: V8 Troopie - Saturday, Feb 16, 2008 at 01:09

Saturday, Feb 16, 2008 at 01:09
Captain, have you got a DC Amp meter? Or a multimeter with a 10A range?
Connect that in *series* with one of the two wires that emerge from the brake drum.
Apply the brake, you should read about 4 Amp with the brake full on.
(I measured that on a single brake drum, using a fully charged battery as a current source.

If you get that the magnet's coil is OK. Insufficient braking can be caused by a layer of thick glazed rust on the surface the magnet glides on.
The mechanism obviously works or your hand brake would not work.

Testing magnets by measuring voltages can be misleading. Magnetic power depends on Ampere/turns. The coil turns are fixed, so with insufficient Amps flowing poor braking results.

You DO need sufficient Volts to push these Amps through the wires. Amps = available Volts divided by the wire (coil & trailer wiring) resistance.
Klaus
AnswerID: 287719

Follow Up By: Member - Captain (WA) - Saturday, Feb 16, 2008 at 23:35

Saturday, Feb 16, 2008 at 23:35
Hi Klaus,

Will follow-up and check with my amp meter - I take it that if OK it will mean the controller is good and the magnets just are not working whereas if the amps are too low, most likely the controller

Thanks

Captain
Its not what you drive, but how you drive it!
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Follow Up By: V8 Troopie - Sunday, Feb 17, 2008 at 00:32

Sunday, Feb 17, 2008 at 00:32
"whereas if the amps are too low, most likely the controller"

or too high resistance in the brake wiring or connections.

find out which wire supplies the electric brake at the trailer plug (unplug it from the car!).
connect a 12V battery between there and trailer earth.
If you now get the current I mentioned above the problem is on the car side (controller, wiring, whatever).
Klaus
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FollowupID: 553158

Reply By: furph - Saturday, Feb 16, 2008 at 08:31

Saturday, Feb 16, 2008 at 08:31
Captain
Had a similar problem with the van we bought last year. Came complete with Tekonsha Voyager controller which I installed and wired up to the instructions with it.
On test, the led glowed green, progressing to red as the control was activated. The magnets "buzzed" at the same time but there was no braking effect whatsoever. removed the drums, magnets surface a bit worn, but considered ok.
Jacked a wheel up and applied 12v. at the plug connection - 100% braking, checked both wheels, the same.
Reconnected and checked controller voltage at brakes - 11.5v. but still no braking effect. Disconnected controller at its plug and applied 12v there - 100% brakes so the juice is getting through.
Took controller to auto elec. for testing. He had a gadget which checked its circuits etc. - result - 100% ok.
So re install, static test, road test, led goes from green to red - still no brakes whatsoever.
Scratch head and considered new magnets?? but not convinced.
Spotted a Voyager controller on ebay, so bit the bullet and bought it. ($100 incl postage) Removed the old controller, plugged in the new one - and voila - brakes work perfectly.
Sorry this has been a bit long winded, but the whole sorting out was much the same. It seems controllers can have a problem, (high internal resistance?) even when they test ok.
furph




AnswerID: 287729

Follow Up By: Member - Graham H (QLD) - Saturday, Feb 16, 2008 at 13:14

Saturday, Feb 16, 2008 at 13:14
You should have bought the Prodigy It gives you a readout of how much power is being applied to the brakes. Also has a boost with it so you can alter the range of when it cuts in like slightly before car etc.
A lot of the older Voyagers had problems and are still being replaced free I believe.
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Follow Up By: Member - Captain (WA) - Saturday, Feb 16, 2008 at 23:38

Saturday, Feb 16, 2008 at 23:38
Will see if I can borrow a controller from my BIL and check it out.

Cheers

Captain
Its not what you drive, but how you drive it!
LC 200 + AOR Quantum

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Reply By: PradOz - Saturday, Feb 16, 2008 at 09:24

Saturday, Feb 16, 2008 at 09:24
try these links for info - i think they may even have a phone number?

champion


more elec brakes
AnswerID: 287740

Follow Up By: Member - Captain (WA) - Saturday, Feb 16, 2008 at 23:37

Saturday, Feb 16, 2008 at 23:37
Thanks for the links, it says that the magnet strength actually gets better as they wear - unti they fail all together!

Cheers

Captain
Its not what you drive, but how you drive it!
LC 200 + AOR Quantum

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Classifieds: AGM battery 120 a.hr (2 available)

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Reply By: MEMBER - Darian (SA) - Saturday, Feb 16, 2008 at 15:43

Saturday, Feb 16, 2008 at 15:43
My "offroad heavy duty" magnets have very two small holes (maybe 1.5mm or so) drilled into the wearing face - they are only about 3mm deep when the magnet is new - they are supposed to be the wear indicators - no holes left, replace them (and they are about $120 each as I recall !
AnswerID: 287791

Reply By: Member - 'Lucy' - Saturday, Feb 16, 2008 at 23:24

Saturday, Feb 16, 2008 at 23:24
Dude!

Have you got it sorted yet - if not , member message me as I now refuse to comment on anything in the forum.

I have CT that had the same issues.
AnswerID: 287858

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