Problems with BMW Battery charger

[waterloo700]

Thought I'd share my experience with the latest BMW battery charger - the black one which can handle Lead-Acid and Lithium batteries.

First one failed after two days - couldn't read charge state correctly nor measure any increase in charge so it kept pushing full amps charge into an already fully charged battery.

Second one works fine except...

I have a direct connection to the battery plus the Canbus plug up front (the bike is a 1250 GSA). The direct connection works fine but I've found that the Canbus is not always "woken up" whatever the handbook says.

The charger goes into an energy saving mode when the battery is fully charged (screen off and an intermittent yellow light). It also does this if it can't detect a battery (Canbus in sleep mode). You can't tell which is which until you try to start the bike and realise the battery is flat.

As I said - just my experience but I thought worth sharing to see if this has happened to anyone else.

 

[steve hughes]

Not a 1250 but on my 650 twin when charging through the accessory port the procedure to hold the canbus on was like a dance.
Plug in charger
Switch on ignition
Switch on charger
Switch off Ignition
Walk away

My understanding was then the canbus remained awake for 5/10 mins.

Direct wire to the battery as in your first option would be a sure winner everytime.

Steve

 

[landmarkjohn]

FWIW the following is the procedure I found after struggling to get the grey BMW charger working through the aux socket on my 2008 GS. Other folks have had differing results with the same charger on different bikes.


"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."

 

[OldSteve]

I use an Optimate but I just plug it in to the DIN socket and turn it on and it works fine without switching the ignition on/off. The only thing I do find is that after a long period it sometimes shows a battery fault condition which I am assuming is because the Canbus has not reactivated when the Optimate carries out a routine status check. Optimate off/on clears this.

 

[Popell]

I use an Optimate but I just plug it in to the DIN socket and turn it on and it works fine without switching the ignition on/off. The only thing I do find is that after a long period it sometimes shows a battery fault condition which I am assuming is because the Canbus has not reactivated when the Optimate carries out a routine status check. Optimate off/on clears this.

Don’t have one connected via socket but my understanding was that the socket is controlled by the canbus and if it doesn’t sense a drain/connection , it allows it to go to sleep. Can’t understand how switching the Optimate on and off can trigger an isolated socket.
Pretty clever if it does!

 

[knutk]

The External AUX socket is controlled by the ZFE (Central Vehicle Computer).

When a regular plug is connected to the AUX port, nothing will happen before ignition is turned on.
However, if this plug emits +12V to the socket (which is what the CAN-bus charger do), the ZFE will sense this, and it opens up the port and will remain open for the duration of the charge cycle.
But, in order to prevent draining the battery and quality check the ability for correct charging, there is a built in protection check.

The external AUX port and the internal AUX plug (used by some of us for extras) are both handled by the same input in ZFE (at least it has been on all my bikes).
So.. whenever ZFE sense a voltage from AUX port for opening up, ZFE performs a check for any type of drain not known to the ZFE (i.e a relay or whatever we connect to the internal socket).
If this is the case, this extra drain will cause the sensing from the charger to be screwed up, as the charger no longer handles the battery charging current only, and it will not be able to tell where the current is lead, making it impossible to analyze the battery. Hence, ZFE shuts down the port again.

Thus, even if the charging will work fine on a none-modified bike, using a dedicated charging cable connected directly to the battery makes life less complicated. In my world, my dealer ALWAYS connects a Optimate compatible cable to all new bikes.