Breaksafe - Power supply ??

[Drover]

That other thread on Breaksafe power supply problems mozzed me .............................. Checking out the charging regime on my breaksafe and why it wasn't, lead me to find this thingy which I think is a bridge rectifier, which has a hot 12v supply direct from batteries as I can only isolate it by pulling the main battery fuse and the other wire (purple, yes purple original wiring doesn't follow the plan) when connected to the hot wire (Red) the Breaksafe charger works, so the questions
1. Why is a bridge rectifier fitted ?????

2. Is it stuffed and how do I check it, the 3 other terminals none are live when red connected..............

Supplying power from tug to the purple wire in the harness at the 7 pin powers the breaksafe charger which I discovered ages ago but never followed up on the why, it charged it up as we drove around and batttery always charged until the other day I noticed it was showing dead, nothing in van wiring surprises me now since they rarely follow the installation manual.....battery is all good now after a bench charge....charging from van batteries isn't a problem as its always on charge from the solar panels a more reliable source than the tug.....was actually going to look into it, in the fullness of time but seems it may have always been so but must have failed before I bought the rig and stupid me followed the instructions but once I got it to charge from tug didn't follow it anymore....

Pic of the 4 pin thingy.......................

 

[Drover]

So Mr Google seems to have confirmed my confusion as to why its there ..................... or its not what I think it is.

I have sneaky suspicion it was supposed to be a auto reset fuse .................. and it would have never worked from new in its current state.... .....

 

[mikerezny]

It is indeed a bridge rectifier rated at 35A. I cannot think of any reason why it would be anywhere near a single 12V supply.
They are easy to check. Set your multimeter to diode test and you should see a diode (reading in one polarity, O/C in the other) across adjacent terminals.

I suspect it was wired so the tug charged the breakaway battery, but the breakaway battery could not discharge back into the car which would not be good when you start the car. i.e, just using one of the diodes of the bridge.
Same reason there is a diode in the AUX input for the Setec ST series devices.

If you are connecting it directly to your tug battery you really need a diode AND an auto reset fuse.

cheers
Mike

 

[Drover]

I think its stuffed but will check again tomorrow, It has a hot wire from van battery but the Breaksafe has its own trickle charger and must have diodes incorporated into it to stop any back flow as you can only test the voltage direct onto battery not from terminals or supply line ............. I think I might just chuck the rectifier and replace with a 10 amp resetable fuse as the inbuilt charger is only supposed to be running at 4 amp max and the cable is more than 30 amp, I will disconnect the tug charge as charge from van solar/battery more better..................

Thanks Mike for confirming my Road Side mechanic suspicions.................. I forgot there's a 30 amp fuse in the housing anyway.............. It's not even a Jayco either, is there a school for van builders ?????????

 

[mikerezny]

I think its stuffed but will check again tomorrow,

Although they are rated for 35A, they have to be mounted on a substantial heatsink. Assuming 1V across each diode (0.7V plus resistance losses), then the device will be generating 35W across each diode, giving a total of 140W that has to be cooled.

cheers
Mike

 

[mikerezny]

I don't have a break away unit. But I do recall there may be some quite onerous conditions on how they have to be wired. For instance, real-time monitoring of the break safe battery voltage in NSW. Might be worth checking up to make sure it is wired up correctly to avoid any dramas with insurance and inspections etc.

cheers
Mike

 

[Drover]

QLD, no requirement a battery voltage monitor in tug isn't really a biggy anyway, the main thing is when the plug is pulled they must supply power to the brakes for 15 Mins, the rest is bumpf, mind the plug needs to be pulled before the draw bar digs in and everything turns turtle something overlooked in the regs.

 

[mikerezny]

Found these and thought them worth posting:

http://www.withoutahitch.com.au/caravan/legal-requirements-caravan-breakaway-systems-australia/

https://teambmpro.com/caravan-breakaway-systems/

cheers
Mike

 

[Drover]

Well the charging system on mine is in fine form, I can charge it via the solar/van batteries or travelling by the tug. Never did work out why it ran down on the last trip, I can only assume the connection in the 7 pin failed, I only checked the thing at the start of the trip, if I was really concerned I could put a little volt meter next to it......

Still haven't figured out the need for a bridge rectifier, reckon it was a stuff up.

 

[icetechaus]

The bridge rectifier is often used instead of a diode, mainly because you can use a standard spade connector (no soldering) and they have a hole in the body to bolt it to the chassis.

 

[Drover]

Yep understand that but the in built charger has diodes fitted.................it must never have been checked as the wires were on the wrong terminals.