Charge light fault

[timpootle]

Here's a weird one.

The fault light has been on on my 'good' Berlingo for a month or so, since a recent brush change and battery water. Not having access to a new-spec evlite or Citroen diagnostic, I have been carefully ignoring it.

Then one very cold night last week my housemate got in the van to return from work, reversed a short distance out of the car park and when selecting 'Drive' the green charging light and red 'stop' light came on. He carried out an electrical reset, but this brought on the red '12v' light (the green charging light disappeared). The AA towed him home on a dolly.

I have removed the aux battery to charge it, and noticed that the positive clamp was cracked. This may have been the original fault, combined with a very cold day(?).

Refitting the (now charged and warm) aux battery, with a mole grip assisting the broken clamp, has not fixed it. I have replaced the 12v harness (canibalising the project car) and tried another 12v battery. Still no good.

I am now in the process of swapping the motor controller, guessing I have fried the DC/DC converter somewhere along the way.

Any suggestions?

[timpootle]

The controller is swapped, the fault light has gone away, and the car moves forward and backwards! Woo-hoo!

The red 12v light is still on, however, so I am reluctant to use the car until I know what is putting it on.

I'm really impressed with the controller design- the swap went without a hitch, and all the pieces just slotted into place.

[timpootle]

until I know what is putting it on.

From the French workshop manual-

Chapter 6 page 108

Indication of a problem charging the auxiliary battery

The 162v/12v converter monitors the battery voltage and communicates its actions to the computer, which controls the lighting of the lamp if the auxillary battery voltage is less than about a 11v, or if a failure of the converter is detected. It is commanded by mise-à-la-masse (Pin 27 on the computer)

12.65 volts measured at the aux battery, with traction fuse in or out.
J'avez une panne du convertisseur, n'est pas?
(No, you're right. I can't speak French)

[ChrisB]

Mmmm does sound like you may have fried the DC-DC in the old controller, think this is one of the main reasons the order of disconnection is fairly critical.

i.e Traction and then 12v Aux

As for why the 12v aux battery light is STILL on is a bit odd though ??

ChrisB

[Grumpy-b]

I had a fried DC To DC controller, and its was not too horendous. The later units post 1998+ seem to have a thin section of the circuit board that basically burns out. I just bridged this and the unit works fine. I do have some photos of this but I dont have a way of putting them on the Forum. I dont use an Image site externally.

Once again a good point to watch is the 12v side of things. Anybody out there able to produce a simple warning circuit that could detect a drop below say 12 v and bring up a warning light. I know the sysstem does give a warning, but not if it does it whilst the power is turned off.

Grumpy-b

[ChrisB]

Trouble is the cos we dont use the 12v for starting and the DC-DC does such a good job of keeping everything running, the poor old 12v aux can become really bad before anything shows up, and even then it only will show up as the pumps and possibley the fan running at odd times.

I suppose if you set up a basic comparitor type circuit or zenner diode type thing that would turn a warning light on at say under 12v, that would surfice, I think from memory, the DC-DC will only kick in while the vehicle is switched off once the battery volts fall below 10.5v which to be honest is way to low and if a LA 12v is down to 10.5v off load its a dead battery !

Of course you could just load test the 12v Aux say every 6mths ????

ChrisB

[timpootle]

Mmmm does sound like you may have fried the DC-DC in the old controller, think this is one of the main reasons the order of disconnection is fairly critical.

i.e Traction and then 12v Aux

As for why the 12v aux battery light is STILL on is a bit odd though ??

Yes, I have been careful to observe the sequence, and so was Stu.

The 'new' controller was an unknown quantity. GrumpyB; can you shed some light on the history of this? Was the DC/DC fried all along, perhaps? That is, have I got TWO DC/DCs to fix?

And another thing: Is it allowed to drive the van with the 12v light on, charging the aux battery off the car overnight, until I can fix it? Or would that be a BAD IDEA?

[Grumpy-b]

The condition of the controller was totally unknown. So I really dont know if and what faults it had.
Check the circuit board on the DC tO DC unit for burns. you mat be lucks as I was and just have to repair the board. The weak point is in the underside and can be seen through the alloy casing.

Grumpy-b

[ChrisB]

And another thing: Is it allowed to drive the van with the 12v light on, charging the aux battery off the car overnight, until I can fix it? Or would that be a BAD IDEA?

Is the 12v Aux still not charging then ??? I got the impression that after the controller change it was but the 12v Aux dash lamp was just still on even though the batt was charging ??

If its not charging then I doubt the 12v Aux batt will last long, the power steering alone can pull 30A
You can kill that side of things by pulling the red link by the pump though, but you still will have stuff like the vac pump, water pumps and lights etc running of course.

Doubt you'd get much more than 1hrs useable power from the battery if that.

ChrisB

[timpootle]

I removed the DC/DC from the spare controller, and spotted MOSFET Q3 had let the magic smoke out. With the help of Antoni Offert (as my de-soldering skills were not up to the job) I swapped a good FET from the toasted board into it's place. We tested the function of the FET while it was off the board, and it seemed to do what it should.

Re-assembling the controller, I turned the key to find....... same fault :-( 12v red light shining.

I have now done all I know how to. Help!? I will email Evan, as he seems to be the guru as far as controller repair goes.

I now have:
One controller from the project car, which will allow it to drive (only tested slowly in the drive) but with the red 12v DC/DC light on, and probably other components on the DC/DC board fried invisibly.

One controller with two completely toasted boards; the DC/DC converter and the '55-way control board' at the near side of the controller.

Any suggestions as to what I can do would be gratefully received. I personally think the controller from the 'good' car is beyond repair, so I will be looking for a replacement (!) for the project car. I think the DC/DC converter is repairable, but I don't have the skill or knowledge to do it.