Thread: 24v to 12V electric brakes?

The problem with a pot or resistor is you have to dissipate heat. Although the voltage drop is small the amps are large.

It's entirely doable but if you don't do it correctly it'll fail and murphy dictates it'll fail at the worst time.

If you can take a feed from one 12V battery that's a much nicer solution. Maybe a switch and a diode to pull in the extra 12V as required...

I've done this before, either one of two ways. The more expensive but correct way is to have a 24 - 12V reducer. These are used to fit 12V radios, run 12V lights, etc. on 24V vehicles. You'll need one with enough capacity to run everything that's connected to it, including your controller and magnets (12 Amps for 4 wheeled brakes at full lock). These reducers can have several cicuits for running all the different lights on the trailer, and the brake light circuit is used to trigger the Brake controller unit (this means running an extra wire from front to rear).
The other way to fit the controller is to tap into the positive terminal of the battery that is connected to Earth/Ground on the truck. Sounds simple enough, but you also require a 12V feed to the brake light trigger for the controller. This is what Tekonsha were refering to with a relay. Some will urgue that's it's not good for the batteries to have one being drained more than the other, but the drain is fairly miniscule and is not constant. If it is a concern, swap the batteries every three to six months so that each one has a turn at being the 'Earth' battery.

Originally Posted by glenn k

Last unit I had just had a lever for manual over ride and a slide to adjust voltage

I'm going to have stab and say it was a Hayman Reece controller? I can't think of any that only has the one adjustment. There is a timer delay adjustment on the H/R, but not many know it's there or use it.
Don't get me started... they should stick to what they do very well, and that's making towbars.

Redarc make a 24v to 12v reducer that is wired ready for the Tekonsha Voyager. Had this on my Hino and it was good.

Bought a GSL electronic Brake controler they make them in 12 and 24V. The 24V has only been out about 8 months sounds much the same as a Tekonsha but made in Australia.
Thanks for the posts everyone.

Originally Posted by glenn k

Bought a GSL electronic Brake controler they make them in 12 and 24V.

Oh dear God no...

The 24V has only been out about 8 months sounds much the same as a Tekonsha but made in Australia.
Thanks for the posts everyone.

I'm sorry to burst your bubble glenn, and the following is not personally directed at you, so I hope you don't take offence.

From what I read on their website, they are definately not the same as Tekonsha. The only similarity is the words "Brake" and "Controller" in their titles, and only one of them actually should be called a Brake Controller. The Tekonsha units are all controlled by an accelerometer, which detects how hard you're braking and varies the output to the trailers brakes accordingly. The other is purely a time based variable voltage output device, is downright dangerous for inexperienced tow drivers, and will void any warranty offered by the Axle manufacturers on their brakes.

I wonder if it could be proven if a fatal accident was caused by one of these timer based "controllers", and if it could, would they be then removed from the market?

Thanks Yonnee I was reading that Tekonsha units are all controlled by an accelerometer I thought the GSL was aswell (as they say new generation of brake controlers utilising microprocesser based technology which is true) but as you say they only mention variable time delay.

Go for the Tekonsha with the Redarc 24v to 12v reducer.

The Redarc brake controllers are pretty good quality, but are old technology.

I picked up a Tekonsha Primus IQ proportional controller on Ebay for $100 delivered before Xmas.

I have installed the 24V GSL unit it works much better than having 12V going straight to the trailer, but it does seem to be on or off and it resets everytime the truck starts up. I have sent an email to the manufacturer to see if this is correct.
While installing it I found a wire tapping one battery used for something else so I used this to make a 12V cigarette lighter for my GPS and there is a solinoid at the rear of the truck that switches 12V when the brake is applied so with 6m of wire I could run a 12V system,Tekonsha or what ever.

Is a Tekonsha that much better?

Originally Posted by glenn k

Is a Tekonsha that much better?

I can't comment personally, as the Tekonsha is the first brake controller I've owned and used.

I purchased a Redarc controller originally at the recommendation of my mechanic mate and his auto elec, but changed my mind the day before I was going to install it and decided I would be better off with a proportional controller.

With the old type controllers the trailer will only brake as hard as the voltage it's been preset at. With a proportional controller the trailers brakes will match the brake force of the tow car.

Check out all the caravan and camper trailer forums and the overwhelming majority of people recommend the Tekonsha. Most of these people have use all types of controllers over the years.

Originally Posted by glenn k

Is a Tekonsha that much better?

When I was running Melbourne Trailer's Repair & Service Centre, the amount of times I had customers come in with what they think is a braking problem with the Caravan, only to find the controller was from the people who should stick to making towbars. So we hooked their Caravan up to our company car with either a Tekonsha or Dexter controller, and they'd asked to have it changed on the spot. Some went to ask for their money back from where they'd bought it from, others just threw it in the bin on the way out.

The biggest issue, is that "Solid State", or "Microprocessor Controlled", or whatever fancy name they give it for "no moving parts" Controllers, have absolutely no way of telling how hard you're braking. They know no difference between a light braking application to gradually slow to an intersection, anticipating a light change, or a moderate aapplication because you missed the light change, or a severe application because a child ran out chasing a ball. You also have no way of adjusting a timer based controller for wet or gravel roads either.

With the right controller, you shouldn't have to change your braking habits to suit the controller.

Thanks Kyle and Yonnee (love that name) for your comments. I can turn the braking up and down with the push of a button and it has a lever for full power so it is much better than a trailer mounted option. I'm getting the truck and trailer registered on Wednesday so I didn't want locking trailer brakes while I was backing over VICROADS pit. So I needed something quick. I will then try it out for a while and see how it goes for real. If I go for a new unit what would you suggest as the best model? The truck has a gross weight of 5.2 net 3.2 and the trailer is 3.2 but it doesn't carry anything as a load. I'm only 200Kg below the maximin towing capacity of the truck.

Maybe look at the Tekonsha Voyager, a manual unit, which IIRC is adjustable both for trailer braking delay and strength.

I picked up the Tekonsha Primus IQ on Ebay for $100 delivered. This is a proportional controller with 3 adjustable boost settings for heavier loads. It does up to 3 axles, but doesn't work on electric/hydraulic brakes. The Tekonsha P3 is around $180, has the same features as the IQ but uses a more comprehensive LCD readout, can do up to 4 axles and electric/hydraulic brakes.

The IQ is fine for my Pajero and 1400kg caravan, but the P3 maybe better suited for your truck.

Should have mentioned trailer only has 1 axel 9.00x17.5 tyres probably 12" brake drums with straight electric brakes. So it may not need a larger unit.