Older BMW CANBUS Charger - funny issue

[andysdad]

I have the older (grey) CANBUS charger (71607688864). Has worked fine for years on my K1300GT via the Hella socket near the gear lever.

I have just used the Accessory Socket by the headstock to wire-in a relay to a cigarette lighter socket, to power my satnav, using pins 1 and 3. All works fine.

The charger won't have it! I get the Red error light on the charger.

What happens - turn bike on, then off, wait c.60 seconds. I hear the relay drop-out when the Accessory socket shuts-down, then the charger shows "Error".

If I disconnect the plug (that feeds the relay switch) from the accessory socket, all is well.

I know the simple solution is to connect the charger to the battery, but I like the existing set-up.

Any ideas?

 

[landmarkjohn]

Whenever something comes up on these older chargers I post the instructions below. They took me a bit of digging to find. I had bought a used charger and was having trouble getting it to work on my 2008 GS. Bods usually come along and say that's not how it works on my XWZ model so your experience may differ. Anyway I think it is worth a try:

ATTENTION!!!! You must first turn the key on to the bike, then you plug the charger into the accessory socket, then you plug the charger into the wall for power, then you turn the key off.
Failure to do it this way will result in the charger not charging the battery and overheating.

 

[andysdad]

LMJ thanks for that - but it has worked fine for years.

Without the charger connected, power-down works fine - satnav remains live for c.60 seconds then goes off when the Acc Socket powers-down.

I can get the charger to work fine if I unplug the Accessory plug; which negates the whole point of having a switched-live feed.

BTW - if anyone can find a PDF of the factory instructions please send it to me. The only link I could find is dead (I think this model was sold until c.2010!). I have a text copy without pictures.

 

[andysdad]

I think I have solved this - someone on Eurokclub's forum suggested the relay might be the problem.

It is the relay - if I directly power the satnav off the factory acc plug (bypass the relay), it switches off and the charger starts up OK (there seems to be a "but" - see below!).

I put the relay in because the satnav is via a cigarette socket, so something else might get connected that draws more than the Acc Socket provides.

Perhaps the relay coil remains as a load even when the acc socket has turned-off. Anyway, the over-clever charger goes "Error" then.


* - if I leave the satnav in the cradle, after c.75 seconds from shut-down, the charger goes into "Error" again. BUT if I remove the satnav from the cradle before then, all is well.

The power to the satnav switches off c.45 seconds after shut-down, but after a few seconds the power light on the satnav lead starts to flash for about 30 seconds - I think this is the Charger signalling the Canbus. If a load is present at the end of this (if the satnav is in the cradle), it errors. But if there is no load (satnav out of cradle), it charges OK.

 

[knutk]

The described issue is caused by the relay installed.
The thing is, the AUX-port share the input to the ZFE with the hidden GPS-socket.

The CANbus compatible charger sends an 'open the port' signal by adding +12V to it's pin prior to checking voltage and polarity, which is the norm for the none-CAN-bus compatible chargers.

ZFE opens the port, but this will also power the installed relay. This drain from the GPS-socket is registered by the ZFE as a faulty drain, as it has no knowledge of such a drain, hence ZFE close the AUX port again.

I had the exact same setup on my bike, and I resolved it by unpluging the relay when it was time for the winter storage and connecting the charger.

 

[timeandtide]

There are some very clever people on here!