Replacing the Battery in my BMW R1150RT
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: http://www.vonwentzel.net/Battery/index.html. 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.
- 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.
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.
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:
- Remove left side fairing
- Remove air cleaner cover
- Unbolt and remove air snorkel
- Slide battery out and disconnect terminals
- Slide new battery in and re-connect terminals
- Turn ignition on and rotate throttle twice to full open. (This is to reset Motronic 2.4 calibration.)
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): http://xs-adventure.com/r1150rt-service-manual.pdf