Replacing the Battery in my BMW R1150RT

Winter 2008/2009

My 2004 BMW R1150RT was exhibiting signs that the original OEM battery was about to fail. It was starting to crank a little slow and needed extra time on the battery tender. Five years is outside the service lifetime for this battery, so I decided to replace it before it failed while I was out on a trip somewhere.

I looked around for a replacement motorcycle battery. This was less straightforward than I anticipated. Replacing the battery in my car is simple. Take the old battery out. Take it down to the neighborhood auto parts store and buy a replacement battery. With my BMW motorcycle, not so simple.

Step 1. Find a replacement battery

As with all things BMW, I assumed that the OEM BMW branded part would be more expensive than equivalent commodity brands. A short look around confirmed that this was true for batteries (see prices below). What I did not realize was that there are several different types of batteries to choose from. You can choose between traditional lead-acid, Absorbed Glass Mat (AGM), and gel type batteries. Further complicating the situation is that many people use the terms gel and AGM interchangeably, although they are not the same thing.

After some searching around, I found the following web page that explained the three technologies and differences between them: My BMW comes with an OEM gel battery. After reading the information on this website, I decided to replace it with an AGM battery.

I priced the following options:

BMW OEM gel from local dealer $175.00
BMW lead-acid from local dealer $140.00
Odyssey PC680 AGM $135-$145+shipping
Westco AGM $99.0 incl shipping

BMW OEM Exide gel battery
This battery was just too expensive. I would have felt ridiculous paying $175 for a battery. I also decided, after reading about AGM vs gel, that I wanted an AGM battery.

BMW lead-acid battery
Also ridiculously over-priced. It was just a normal lead-acid battery from one of the main battery manufacturers (Exide?), but they put a BMW sticker on it. I also did not want a traditional lead-acid battery.

Odyssey PC680 battery
There was a lot of talk about the Odyssey PC680 battery on various motorcycle forums. It seemed to be a very popular replacement battery. I decided against it for the following reasons

  • Seemed like overkill. The advertising information talks about "military grade tank batteries" and massive cranking power. For my application, I did not see a need for either of these.
  • Military Grade

    Only Hawker Odyssey batteries are based on the same battery technology offered by Hawker to the military for aircraft and tank batteries. Odyssey batteries are of military grade and have endured rigorous tests that demonstrate their overall ruggedness and exceptional tolerance of mechanical abuse.

  • Form-factor not a drop in replacement. The PC680 has screw in terminals. The OEM battery has post terminals. To get the PC680 to work, you must use an adapter or bend the cable-end adapters like this. I also read that the size is also slightly different than the BMW battery and you need a spacer to make the battery strap fit properly.
  • Not compatible with my BMW battery tender. In some situations (e.g. charge drops too low on battery), the BMW gel battery tender does not generate enough current to adequately charge this battery.

Westco AGM
This is the battery I selected. Performance seemed adequate and the price, although high by car battery standards, was cheaper than the alternatives. The form factor was supposed to be identical to the BMW OEM battery, though I found out later this was not true (see below).

Step 2. Replace the battery

This procedure was not as bad as I anticipated. There were a few wrinkles, but no major problems.

The simple battery replacement procedure:

  1. Remove left side fairing
  2. Remove air cleaner cover
  3. Unbolt and remove air snorkel
  4. Slide battery out and disconnect terminals
  5. Slide new battery in and re-connect terminals
  6. Turn ignition on and rotate throttle twice to full open. (This is to reset Motronic 2.4 calibration.)

This is what you see when you remove the left side fairing. Note that the battery is blocked by the snorkel to the air cleaner.
R1150RT-left-side-panel removed

This is what it looks like when you remove the air cleaner cover and then unbolt and slide the snorkel out. I took advantage of this opportunity to replace the air cleaner as well.

Side by side comparison of Westco to BMW OEM battery. I thought I read the specs to be identical size, but the BMW batter was 7mm taller than the WestCo. To account for this, I put a few pieces of shim under the rubber strap during reassembly. Also, the BMW battery has a plastic cover over the positive terminal. I don't think it was necessary, but I put some electrical tape over the positive terminal and adapter during installation of the new battery just to be safe.

Reassemble, do the Motronic/throttle reset procedure and that's it. My bike is now cranking over much faster and I am ready for the summer riding season.

I few final items:

I have not tried my BMW gel battery tender with this battery yet. I am assuming that it will work fine.

The Clymer manual was not very helpful. It was confusing, incomplete and wrong about a few things. The instructions were incorrect for fairing removal. The battery replacement procedure said to remove the gas tank in order to access the battery. This is not necessary. Finally, it did not have a good picture of the battery and attachment wires. This became important because I forgot which wires went to positive and negative terminals (hint: red or white wire-positive terminal. black wire-negative terminal).

I found the Motronic reset procedure in the BMW R1150RT service manual. I don't remember where I originally downloaded this from, but I have a copy on my website (16.8MB):

battery replacement,,

I can't "thank you" enough for posting your hard earned information,
I looked at the battery underneath the tank and thought "Now what?".
Thanks again for the info. > and shame on those engineers! \Minneapolis

battery replacement

Just got back from my dealer and he wants $289 for a new battery and equally as much to replace it...
I find your description so detailled (with pictures and Motronic reset procedures) that I will try to do it myself.
Thanks a lot

Where did you get your Westco battery and any item # is it good for 19AH

My dealer specified to me that with ABS I needed at least 19AH advised me against Odyssey PC680 with only 16 AH


Battery replacement in R1150RT

Really appreciate your time & effort to put this together - I was going to have a dealer install as I thought getting to the battery would take up way too much time. Thanks to your easy steps/guidance, it turns out I had the battery replaced, bike back together and running in 40 minutes. Awesome!!!
Mr. Z - Ohio

Perfect Information

Thanks for the article with the pointers. All worked perfectly!


Hey Bro...thnak you for your very informative article and service manual download!

battery change

Just wanted to say thank-you for this insightful post on replacing battery for the RT. I just bought a 2002 1150RT and I assume the directions would be the same. Thanks


Thanks for the work you did. It was EXTREMELY helpful. Got it done in about 25 mins.

Power Sonic Battery

Hi, has any had any experience with the Power Sonic battery ?

lead acid batteries

Yes indeed, those lead acid batteries can leave you stranded if you don't keep an eye on them!
I was let down once in British Colombia, and once after a long, hot ride in El Salvador. Riding in crazy San Salvador traffic with no lights, signals or horn, not fun!

I'll certainly be looking for a gel battery now.


car manuals

You can short out this kind of minor issue by taking help of manual if u have otherwise must buy for save your time,In fact, im working at a car-garage, repairing cars and motorcycles all day long. I got all the manuals i needed from! who has all the manuals in stock and has 50 % off at the moment. Check it out - they have the best quality manuals for cheapest price in my opinion. I use it everytime, when im confronted with a problem, where i need some help.

Thank you so much for this.

Can not thank you enough for this work you did. You really helped me out alot.

help with left faring?

I have the left faring almost off except it seems "stuck near the left mirror>>>?
any idea on how to finish removing?
need some help..

left mirror

I have a 2002 R1150RT, to remove the mirrow just pull it straight out 90 deg from the front fork. Mine has three slots it snaps into and two wires for the turn signal. Don't drop it when you pull it out.

There are some tricky

There are some tricky screws. This link has a great pictorial on how to remove the left side fairing.



Thank from Paris !

yes, no need to remove the gas tank...
thank you

Right on the money

Dec 27 2009, This article was a great help and spot on the money in every way. I went with the Westco battery and trickle charger bought direct from Westco online. Yes the battery is still 1/4" short so I had the piece of nylon ready to make the shim for the strap. Thanks a bunch!!

R1150RT battery info

Great info and links. Very helpful. Thanks

r1150rt battery removal

Thanks, you saved my butt. Had no idea how to do this prior to finding your post.

Great Link

Thanks for your insight and that link! Shame I just paid for the same info on Fleabay!

Thanks for this

Thanks for this information...very helpful for my '04RT.