Electric Brake Controller - Follow up to ThreadID: 138922

Submitted: Monday, Jun 15, 2020 at 11:25

ThreadID: 140152 Views:11186 Replies:3 FollowUps:10

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Member - J&A&KK

I meant to post this sometime ago.

Back in August 19 I posted that I was having problems with the Redarc Tow Pro going into idle mode. Many of you responded with ideas on a fix.

NickB gets the gong for his suggestion. The Prado start battery was replaced and the problem has disappeared.

I always believed that the van hydraulic brakes were powered by the van batteries and just actuated by the Redarc. When the van is disconnected from the tug you can still activate the van brakes by pressing a button on the drawbar. This is in fact the van handbrake. This is what led me to my belief.

However recently I ran the lithium’s in my van dead flat by leaving on an internal light for a very long time. The batteries were so flat the battery condition meter wouldn’t even turn on. So I had to tow the van about 10kms to have the lithium’s fixed. I expected to have no brakes on the van. That wasn’t the case as the Redarc and the van brakes all worked normally. So power was coming from the tug battery.

So have learnt something new from advice by NickB in conjunction with my own blunder.

Cheers John

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Reply By: RMD - Monday, Jun 15, 2020 at 13:31

Monday, Jun 15, 2020 at 13:31

Hello John
I am a bit confused by what you have said. Initially were you unsure or just didn't know the Prado was supplying the braking power for the hydraulic unit? Did you ever switch off the batteries in the Van to check if Prado powered the brakes as a test and not simply assume the van supplied power? ie, diagnosis.
Didn't the Tow Pro become functional when the Prado alternator was making proper voltage? if that was the fault. Did the Prado crank slow on startup? if not there can't have been a lesser voltage affecting the Tow Pro, I wouldn't imagine. The battery voltage during cranking has to have been sufficient for the ECU to generate sufficient power stepup pulses to drive the injectors so it started.
During the battery replacement, are you sure there wasn't a sus electrical connection to the Tow Pro and during the battery job the slight fault of lower voltage to TP, previously undetected, was restored/rectified and now appears as if it was a battery fault. Not saying a battery can't affect electricals but if it started ok then it is hard to see it as the cause, and saying it is may not really be the case.
The controller is in the vehicle isn't it?
The actuator is in the van supplied with a heavy brake wire to run a hydraulic generated pressure similar to EBS systems it seems. Which you activate with the drawbar button in emergencies which runs off the van batteries at that time. If not, where is the power coming from? Gotta love electricals.
So the controller in vehicle signals and the actuator in van actuates, that is the way I see it.

AnswerID: 632162

Follow Up By: Member - J&A&KK - Monday, Jun 15, 2020 at 19:16

Monday, Jun 15, 2020 at 19:16

Hi RMD

Some of what you ask is covered in the original thread. To answer a few of your questions.

I just assumed the van batteries supplied the power to the hydraulic brake unit and the Redarc supplied the actuation signal to the brake unit. Now proven incorrect.

Prior to replacing the tug battery I checked and cleaned every connection except for connections between the van trailer plug and the brake unit and the connections at the Redarc itself. All resistances across all these connections were measured. Hence I can only conclude the new battery fixed the problem.

Cheers John

FollowupID: 908651

Reply By: HKB Electronics - Monday, Jun 15, 2020 at 13:52

Monday, Jun 15, 2020 at 13:52

Had a look at Alko site, they show the actuator along with a breakaway system, if the van has a break away system then there most likely is a seperate battery in the van somewhere to power it?

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AnswerID: 632163

Follow Up By: Frank P (NSW) - Monday, Jun 15, 2020 at 14:04

Monday, Jun 15, 2020 at 14:04

G'day Leigh,

The actuator is a Carlisle Hydrastar from USA. Unless Alko are agents for the Carlisle Hydrastar the actuator is not an Alko brand. A search on the Alko.com.au website for Carlisle and Hydrastar returned nil results.

In a Kimberley Karavan, the battery that supplies the manual brake and the breakaway system is the van's house battery. That much I am 100% certain of.

I don't have my vehicle at present. If I did I would hook it up to the van, isolate the van batteries and verify John's findings.

Like John, I always thought that the hydraulic pump - the Hydrastar - was powered by the van's house batteries and controlled by a signal from the brake controller in the tug. John has thrown me a curved ball which will do my head in until I can resolve it for myself!!

John,
Maybe you could post on the KKOG forum. I think your finding will surprise many. It would be great to get it verified bu other KKOG members.

EDIT: I just found this on page 3 of the on-line manual which verifies your finding, John:

"4. The Hydrastar™ actuator is powered from the electrical system on the tow vehicle.
In order for the Hydrastar™ unit to function properly, it must have adequate
electrical power. (See Section C. ELECTRICAL INSTALLATION REQUIREMENTS)"

Cheers

FrankP

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FollowupID: 908644

Follow Up By: RMD - Monday, Jun 15, 2020 at 14:48

Monday, Jun 15, 2020 at 14:48

G'day Frank
I wonder how John's action of pressing the button on a frame initiates braking on the van when it isn't on the vehicle, ie, handbrake as he mentioned. There seems no sense in having the button work only when van attached to the vehicle. If pushing the button then, the vehicle would/should be "Park" and not need the button switch. To me it seems the full story hasn't been revealed yet. Maybe it works from either source of power. Even so, if the Tow Pro is going to sleep it indicates something up front and not in the van system.

FollowupID: 908646

Follow Up By: Frank P (NSW) - Monday, Jun 15, 2020 at 15:19

Monday, Jun 15, 2020 at 15:19

G'day RMD,

Having looked at the manual, I am now convinced that my long-standing impression of how it works was wrong. I never bothered to research it until now.

I can see now that the unit is designed to have two power sources - one from the tow vehicle to operate the service brakes, ie the blue wire - and one from a battery in the trailer for the breakaway system, which also doubles as a park brake. Rather than have a dedicated breakaway battery, Kimberley uses the van's house battery.

I still want to test it though - seeing is believing!

Re the park brake:
The parking brake button on the A-frame is a momentary on switch. It shorts out the breakaway switch, activating the actuator via the house battery. You then turn a valve in the hydraulic outlet from the actuator and this holds pressure in the brakes until the valve is released. It is NOT a true parking brake. Chocks etc must be used. Owners are told of this in the van manual and on handover from the dealer.

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Follow Up By: HKB Electronics - Monday, Jun 15, 2020 at 16:22

Monday, Jun 15, 2020 at 16:22

Document makes it clear, I initially thought it was being suggested the tow pro was power the pump.

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Follow Up By: RMD - Monday, Jun 15, 2020 at 19:15

Monday, Jun 15, 2020 at 19:15

I have a hydraulic pump system from a wrecked Asian vehicle. The size of the connector for the main 12v feed is quite a bit larger than the control/regulating wire which most brake controllers use. I never considered the TowPro had thick wires from front to vehicle rear. Therefore, I was of the opinion there had to be two power sources used. I would not like to rely on the valve and system holding effective brake pressure for very long. I don''t know, but unless there is a one way valve incorporated with that valve, having to hurriedly open the valve so you can effect another button press to stop a couple of tons + moving, scares me a bit. All is good while all is good I suppose.

FollowupID: 908650

Follow Up By: Member - J&A&KK - Monday, Jun 15, 2020 at 19:36

Monday, Jun 15, 2020 at 19:36

Hi Frank

Many thanks for your input and in reading the manual. Funny I never thought to read the manual!

I did the test today. Hooked up the van, disconnected the van batteries and pushed the brakes in the Prado. Redarc light went from blue to red as it should do and the hydraulic brake unit made all the correct noises. Turned the van batteries back on, they have a full isolator switch, and all the same as the test without the van batteries connected.

Dear RMD

There is not a no return valve in the hydraulic brake circuit. Just a 90deg on/off valve. I have left the van with the brakes on in my garage for in excess of 6 months and the brakes are still very much on. I agree that you wouldn’t trust your life with this system, chocks are needed, but after nearly 6 years it has never failed.

I have used the button a number of times whilst rolling the van down my gently sloping driveway. If it failed I would be relying on my neighbours fence across the road to bring this to a stop. So next time I will have a large chock handy.

Cheers John

FollowupID: 908652

Follow Up By: Frank P (NSW) - Monday, Jun 15, 2020 at 20:23

Monday, Jun 15, 2020 at 20:23

Hi John,

After reading the manual and your account, I'm convinced. It makes no difference to what we do, but a correct understanding of how the system works is no doubt of considerable benefit in fault finding!!!!

RMD,
There's no need to be turning the valve on and off if you're manoeuvring the van while disconnected. You just press and release the push button to brake as required, then to park press and hold and turn the valve to set the brakes. I do this every time I park my van on my sloping site at home to allow it to settle onto the chocks in a controlled fashion.

And as I posted earlier, we don't rely on that brake as a permanent parking brake. We rely on chocks or the tow vehicle.

Cheers

FrankP

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Reply By: qldcamper - Tuesday, Jun 16, 2020 at 09:29

Tuesday, Jun 16, 2020 at 09:29

John,
Just do a quick check and make sure the vans breakaway switch is still supplied with the van disconnected from the vehicle and your vans isolation switches turned off, if you turn forget to deisolate the batteries there may be nothing to stop the van if it breaks away.
To be legal the supply to the breakaway switch should be on a dedicated un interuptable circuit, usually through an auto reset cct bkr to a battery that is connected to a charging scource from the tow vehicle. Recently some states also require that some form of indication of that battery being charged be within view of the driver which is a proper pita needing either a wireless device or a dedicated wire run from the van batteries to a display or warning device in the cab.
Most vans used to be set up with a 7AH sealed back up battery seperate from the house batteries being charged through a diode and large resistor connected to the tail lights.
I know this was a crap system with a very large margin for failure, and they did, but it got the vans out the door legally.
I used to do a lot of work for a large van repair shop near maroochydore who were service agents for most of the bigger southern manufactures and got to do a lot of the warranty repairs.

AnswerID: 632169

Follow Up By: Frank P (NSW) - Tuesday, Jun 16, 2020 at 13:51

Tuesday, Jun 16, 2020 at 13:51

"Just do a quick check and make sure the vans breakaway switch is still supplied with the van disconnected from the vehicle and your vans isolation switches turned off, if you turn forget to deisolate the batteries there may be nothing to stop the van if it breaks away."

That's a good point, qldcamper, thanks.

Before I did my lithium conversion I'm pretty sure my van was compliant. Now that I've done the conversion and following your post, I'm pretty sure it is not compliant. The BMS isolator, which on my system can be operated manually for storage, isolates the batteries from everything except the BMS's own parasitic load of a couple of milliamps.

I will have to rejig one wire to the batt +ve.

Re monitoring the breakaway battery, I *think* NSW is the only state with that requirement. Unless they've changed it recently it's very basic. You only need a warning, visual or audible to the driver, if the breakaway battery goes under "operable voltage".

See NSW's Vehicle Inspection Bulletin 6.

Cheers

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Follow Up By: Member - J&A&KK - Wednesday, Jun 17, 2020 at 09:51

Wednesday, Jun 17, 2020 at 09:51

Hi Qldcamper

I agree with FrankP. A very good point. I checked it last night. Breakaway switch still works when the battery isolator is activated.

I had my lithium conversion done by a local (Perth) professional installer. Similar to Franks set up I have a push button switch that isolates the batteries for storage.

Always good to comply with the regulations even when they appear a little daft. I am not sure who would be towing their van with the house batteries isolated. However it is possible in the setup I have.

Cheers John

FollowupID: 908670