BMW R1200RT/R1250RT Forum

Just purchased the bike. Was thinking about hooking up my Garmin car GPS, the wire for my electric jacket and figured I'd go ahead and add a pigtail to the battery for the Battery Tender. Since this bike has the CanBus I read the scantly worded owners manual. It seemed to elude to the fact that you had to use the overpriced digital CanBus charger or if you went directly to the battery the battery had to be disconnected. This seemed wierd to me. Did I misread or can you hook a pigtail to the battery plug in your conventional battery trickle charger or do you really have to isolate the batter by disconnecting. This is my first encounter with a CanBus bike.

Yes you can attach whatever battery charger you want directly to the battery, no need to isolate the battery.


For years I've had an Optimate 4 DP CanBus charger that I plug into the accessory socket when parked. It charges, conditions and does desulfation and at $67 I don't think it's overpriced (especially on a $24k motorcycle).

Second outlet installed on right side triangle panel, fused, wired direct to battery
Used for optimate charger, heated vest and cyclegear pump, 100% trouble free

My bike came from the dealer with a battery tender cable already attached to the battery and nicely zip-tied to the frame.  They do this for all new bikes as they are installing the battery.  Picked up a decent battery tender at Costco, and it works beautifully.  No reason, IMHO, to buy an expensive BMW or other canbus charger.

timminator wrote: My bike came from the dealer with a battery tender cable already attached to the battery and nicely zip-tied to the frame. They do this for all new bikes as they are installing the battery. Picked up a decent battery tender at Costco, and it works beautifully. No reason, IMHO, to buy an expensive BMW or other canbus charger.

Ditto. Maybe I don't understand the Canbus system but I get confused reading some topics here about charging the battery. I have a $50 battery tender, in which I have used on all my bikes, and it works perfect. Plug it in the to cable that came from the factory and bingo, done.
https://www.amazon.ca/Battery-Tender-02 ... B000CITK8S

Thanks all. Assumed you could just hook to battery but wanted to be careful. It is what you don't know that gets you!!! Didn't realize that Optimate or other after market would work with the port. Thanks!!!

The beauty of the Optimate (at least the one I have) is that it can change mode either to charge the battery directly via a 'pigtail' or to do so via a power socket utilizing the Canbus. Best of both worlds as I can use it to charge more than just my BMW bike.

I went ahead and bought the BMW battery charger, and am delighted with it.  It is indeed a very high quality item.  It works flawlessly, and lets me know exactly what is going on.  It is very convenient to simply plug it into the accessory socket on the right side of the fairing.  I have over 20 grand (US dollars) in my bike, so I figure the cost of the well-engineered BMW battery charger is worth it.  GLTA.

freyguy17 wrote: I went ahead and bought the BMW battery charger, and am delighted with it.  It is indeed a very high quality item.  It works flawlessly, and lets me know exactly what is going on.  It is very convenient to simply plug it into the accessory socket on the right side of the fairing.  I have over 20 grand (US dollars) in my bike, so I figure the cost of the well-engineered BMW battery charger is worth it.  GLTA.

Believe it or not, the BMW charger is not made by BMW its made in China and re-badged. There is nothing wrong with the Optimate, my BMW dealership sells them.

I have an old Optimate 3 charger which I have used with great success on many bike and car batteries for a number of years. I now have a 2014 RT LC and would like to use the same Optimate charger.

Having read this forum I now understand that I can 'pig tail' an accessory lead directly to the battery as I have done in the past. However, I would like to just plug into the BMW provided auxiliary socket on the front panel - seems nice and convenient

Can I purchase this

https://accumate.co.uk/tm95.htm

which seems to have the same small white connector on one end (to attach to my old charger) and also has the appropriate BMW auxiliary port connection on the other.


Would this work do you think?

Many thanks.

Eddiex wrote:Would this work do you think?

Don't think the Optimate 3 will work with the CAN-bus system via an auxiliary socket.

Within the spec. for the 12V DIN Plug Lead, it says, "Ideal for use with OptiMate 4 Dual Program on CAN-bus equipped BMWs."

Looks like you'll have to "pig tail" directly to the battery.

Thanks for the above - looks like I'll purchase an upgrade on my old charger !

David. wrote: "OptiMate 4 Dual Program has a function to connect to batteries of BMW motorcycles which have CANbus (or LINbus) wiring which in practice is most made since 2008. These bikes have 12V DIN sockets which are controlled by the bike’s Battery Management System. The system is designed so as to turn off the socket 15 minutes after the ignition is turned off, ironically in order to protect the battery Voltage, as the socket was initially only envisaged as a power outlet. To use the socket to charge the bike’s battery it is necessary to communicate with the Battery Management System to keep the socket awake – otherwise charging will stop after 15 minutes. When set in the “CANbus” Program, OptiMate 4 can be used to charge these bikes via the socket for as long as you like. NB this only applies to BMW motorcycles. The word “CANbus” refers to the wiring communication network used on a great many vehicles – OptiMate 4’s “CANbus” program is only for BMW Motorcycles."

And this can be the problem with the BMW charger. It charges fine but if like me you don't get to ride as often as you like, once it has done it's job it can then stop keeping it charged. The Optimate keeps the socket awake no matter how long it is plugged in for. And I am talking about a 2016 RT Iconic where after 2 weeks I had to unplug and plug the charger back in and let it get to around 40% before the bike would start. And the downside to there not being enough power is it resets all the menu items to default.

Thats poor, I would have expected the BMW branded charger to be able to be left plugged in and it would do its stuff. Glad I have an Optimate 4, had it a year now with no ill effects.


Although I do leave my bike off the charger for a few weeks to give it a rest and have never had an issue with the bike starting.