CAN-bus Charging

[dba]

I tried searching for answers on the forum but to no avail.

 

I recently purchased a used ’07 RT. While going over some details with the salesman, he told me I can’t use a battery tender in the same way I did on my 1150 RT; i.e. by just plugging the battery tender into the accessory port. He said the ports on the 1200 RT are Can Bus ports and I’d need a different battery tender.

 

Any opinions as to whether I should just add a pigtail connection to the battery and keep it under the seat and connect that way? Or should I invest in a BMW Can-bus Charger.

 

Thanks

 

[Guest Kakugo]

As per my BMW dealer: "You can use gator clamps straight at the battery terminals".

 

That's how they charge bikes they have in the shop and what I have been doing since buying the bike in 2009.

[dirtrider]

I tried searching for answers on the forum but to no avail.

 

I recently purchased a used ’07 RT. While going over some details with the salesman, he told me I can’t use a battery tender in the same way I did on my 1150 RT; i.e. by just plugging the battery tender into the accessory port. He said the ports on the 1200 RT are Can Bus ports and I’d need a different battery tender.

 

Any opinions as to whether I should just add a pigtail connection to the battery and keep it under the seat and connect that way? Or should I invest in a BMW Can-bus Charger.

 

Afternoon David

 

You salesman is partially correct-- you can't charge through the factory power sockets (unless they are modified)--OR you use a special battery charger.

 

The reason he gave is incorrect as the power sockets have nothing to do with your CanBus, the power sockets are computer controlled but have no direct link to the CanBus.

 

As mentioned above, you CAN charge directly to the battery (SAE plug or similar) but you have to be sure that your charger is not a desulfation type charger as you need to be sure that the charging voltage never exceeds 15 volts.

[The Rocketman]

I have been using the CTEK (56-864) Multi US 4.3 chargers on my 3 BMWs (including my '09RT) with Odyssey PC-680 batteries. It is a desulphation charger with charging voltages of 14.4 / 14.7 / 15.8 V depending on the setting you choose. The "snowflake" setting recommended by CTEK, Odyssey & BMW tops out at 14.7 which is the setting I use 24/7. The 15.8 setting I believe is only to revive a totally dead battery (or as they say: Recondition of deep discharged batteries", which I would only use with the battery removed from the bike. Otherwise, I connect with an SAE pigtail right off the battery terminals, and have not had any issues thus far. Previously used the Deltran Battery Tender Plus, but ran into an issue a few months ago with a new PC-680 not holding a charge and went with the recommendation of the above and so far, so good.

[dba]

Thank you all. Still confused as DR writes to make sure the charger is not a desulfation type and Rocketman uses a desulphation type.

 

Rocketman, how do you connect your charger?

[DJ_Fission]

Any opinions as to whether I should just add a pigtail connection to the battery and keep it under the seat and connect that way? Or should I invest in a BMW Can-bus Charger.

 

If you have a standard battery, that would be an easy way to do it. This is what I do. Actually, I have a pigtail connected to the battery that terminates in an SAE connector. I then have that plugged into an SAE extension that runs up to my handlebars, which I use to power my phone charger when I have that on the bike. But it's also handy for plugging into the Battery Tender...no hassle with taking off the seat or bending over at all.

[The Rocketman]

I too have an SAE plug hanging off the side of my bike. Its wired directly to the battery terminals with an in-line fuse, by-passing the CanBus and the accessory ports. Battery charger came with a few connection options, but IIRC I had to splice in an SAE terminal, as it did not come with it. 5 minute job; just get the polarity right!

 

Look at page 5 of this CTEK charging chart. It shows a quick desulphation at the beginning, various charge rates during the process, and only a steady desulphation to revive/recondition a dead battery (only on that setting , which I do not use). As they say YMMV, but so far, so good here on 3 BMWs.

 

Link:

http://www.ctek.com/Archive/ProductManualPdf/MXS%205.0_EN.pdf

[dirtrider]

Thank you all. Still confused as DR writes to make sure the charger is not a desulfation type and Rocketman uses a desulphation type.

 

Afternoon dba

 

The only reason I say don't use a desulfation charger is you NEVER EVER want to exceed 15 volts DC into a BMW 1200RT battery when that battery is hooked up to the vehicle's electrical system. If you disconnect the battery from the bike then you can have at it with all the voltage you want (might hurt the battery but won't hurt the bike's electrical system)

 

So if you have a battery charger that can't exceed 15v (no desulfation cycle) then you can cause no harm.

 

On the other hand if you have a desulfation charger that CAN exceed 15 volts then you better not have any kids or grandkids that like to push buttons.

 

[Stan Walker]

you NEVER EVER want to exceed 15 volts DC into a BMW 1200RT battery when that battery is hooked up to the vehicle's electrical system.

 

I find it hard to believe that BMW's R bike electronics will self destruct at 15 volts, that awfully close to what the alternator puts out. My shiny new F800GT for example thinks that 14.4 - 14.5 volts is an OK output (measured at the battery) while cruising down the highway.

 

We need someone to hook up their CAN bus R bike to a lab supply and turn up the voltage until something smokes.....

 

Any volunteers?

 

Stan

[dirtrider]

Evening Stan

 

You will have to take that up with BMW as that is what BMW says in both the owners manual & a service bulletin.

 

 

[dba]

Thank you all. Got it all squared away.

[racer7]

I have an ancient charger meant for maintenance free batteries of the 70s (Ca in the plates) that will go north of 15V and have used it many times to bring deeply discharged Odysseys back to life. Not hooked it to the bike but have to admit I'm a skeptic about any practical charger voltage frying the bike electronics on a key off off bike.

Some sort of simple over voltage protection is pretty normal on most modern circuit designs.

As most know, Oddysey folks publish their list of recommended stuff (which does not include any of what I actually use...)

[rahbert]

Is the BMW gel battery charger a 'special charger'? Seems to work fine on my 09 RTP through the accessory port...

[dirtrider]

Is the BMW gel battery charger a 'special charger'? Seems to work fine on my 09 RTP through the accessory port...

 

Morning rahbert

 

It depends on what BMW charger but most of the BMW (gel battery) chargers have limited (slightly lower) voltage output.

 

Your 09 should have come from the factory with an Excide Gel battery so that isn't an issue.

 

The BMW (Gel era) charger is probably a little low on the voltage output to (fully) charge an AGM battery but it will work, just won't fully charge the battery, & extended long-term usage could shorten AGM battery life.

[rahbert]

Yes I have the stock pair of batteries. GS-911 reports that voltage was low and since it takes ~24 hours to fully charge

I'm guessing that a new battery (or pair thereof) will soon be needed. Since this is an RT-P with dual batteries I was wondering if there is any load balancing occurring between them?

Or is the second battery used only with police equipment which is no longer present?

[dirtrider]

Yes I have the stock pair of batteries. GS-911 reports that voltage was low and since it takes ~24 hours to fully charge

I'm guessing that a new battery (or pair thereof) will soon be needed. Since this is an RT-P with dual batteries I was wondering if there is any load balancing occurring between them?

Or is the second battery used only with police equipment which is no longer present?

 

Afternoon Robert

 

No load balancing or battery equalization needed as one battery is for starting & basic bike system operation & the other battery is for police accessories or other added accessories on that battery.

 

The battery's are isolated from each other & only charge from the same alternator after engine start/run.