Thoughts on Battery Disconnect-'99 R1100RT

[blackrt]

Hi all,
I'm planning (wanting) to install a battery disconnect switch on my '99 R1100RT. I'm hoping to mount the switch on top of the air box, just behind the battery. While I won't go into the reasons for the disconnect, I plan to use it regularly if it won't adversely affect the bike's performance. My question is if the regular power loss to the bike's "brain" will cause any issues with regards to the fuel injection "parameters". While I don't know much about BMW's fuel injection, I know that many vehicles will perform in "open loop" or "closed loop", depending on the vehicles "memory" and that a disconnected battery requires varying driving conditions to "reacquire" those parameters.
I'd appreciate any input from a technical perspective, or anyone who has installed one and uses it regularly. Suggestions for specific switches would be appreciated as well. Thanks in advance for any helpful input.
Steve

 

[gsaddict]

The motronic will have to relearn its settings after each time the battery is disconnected.
Can take up to 3 tanks to do so.
You will need to twist the throttle to full twice each time as well so the motronic learns the TPS swing.

Roger, jump in here..........

 

[roger 04 rt]

Hi all,
I'm planning (wanting) to install a battery disconnect switch on my '99 R1100RT. I'm hoping to mount the switch on top of the air box, just behind the battery. While I won't go into the reasons for the disconnect, I plan to use it regularly if it won't adversely affect the bike's performance.

My question is if the regular power loss to the bike's "brain" will cause any issues with regards to the fuel injection "parameters". While I don't know much about BMW's fuel injection, I know that many vehicles will perform in "open loop" or "closed loop", depending on the vehicles "memory" and that a disconnected battery requires varying driving conditions to "reacquire" those parameters.

I'd appreciate any input from a technical perspective, or anyone who has installed one and uses it regularly. Suggestions for specific switches would be appreciated as well. Thanks in advance for any helpful input.
Steve

Steve,
It would help if we knew more about your application. (Anti-theft? Hoping to ride more on Open Loop parameters? Saving drain on the battery when you're not using it?) Here's what happens to the bike when you pull the battery.

1. You lose the time set in your clock. You have to reset it.

2. You lose all adaptives for fuel trim (long term and short term). It will take a short while to idle well. If you run fuel with 10% ethanol you will start out with a fairly lean-fueled engine. It will take several tanks of fuel to fully rebuild the adaptives.

3. You lose any throttle-range info that it learns. Not sure about this on the 1100RT. It may effect idle at first.

Other than the above, no consequences I can think of.

On my 1150RT, I just pull fuses 3 and 5 when I'm not going to ride for 3 weeks or more. That brings the drain low enough (<0.5 mA) that the battery can sit a couple months without discharging the PC680 (about 5% discharged).

 

[pauls1150]

I concur that it would lose the throttle range info.

If you're worried about the battery, decent trickle chargers are reasonably cheap (some threads in this Forum compare them). I have absolutely Zero qualms leaving my little made-in-China BMW trickler (tickler?) hooked up for extended periods if I'm not using the bike.

If you're worried about theft, then 1) BMWs aren't typically on the "high-loss" list (though I certainly would not be comfortable leaving my bike alone in some of the neighborhoods around here, or some places I've visited), and 2) decent cables & locks are also reasonably priced.

 

[cjcs]

If the battery is disconnected for a significant length of time the ABS may have to be reset also.

 

[MotorradMike]

Are you guys sure that the adaptive features apply to all versions of the Motronic controller?
I've had the battery disconnected many times and have never noticed anything other than the clock being affected.

 

[pauls1150]

"Pretty" sure...
The default/initial map is close enough that the bike should run fairly decently at startup; coarse corrections begin to happen immediately and continue, and "fine" corrections (sometimes known as "dithering" in the electronics world; not the dictionary definition) just take a bit longer.
The computer has enough in the way of capacitors that its memory won't be lost immediately upon battery disconnect; that's why it takes 5 to 10 minutes after pulling the fuses (or cable) to force a re-learn.
Maybe Roger has a plot of this action, just for illustrative purposes...?

 

[happy wanderer]

Are you guys sure that the adaptive features apply to all versions of the Motronic controller?
I've had the battery disconnected many times and have never noticed anything other than the clock being affected.

You may not have noticed anything but the adaptation features are alive and well in both the Motronic 2.4 and 2.2. I gathered a fair bit of data on my 2000 RT which Roger04RT analyzed and published in his Wideband O2 sensor thread proving beyond any doubt that adaptation takes place in both.

 

[blackrt]

Thanks to all for the prompt input and advice. The disconnect is actually intended for safety reasons-fire protection. I have a background in fire investigation, and a storage area that is currently "under construction" and does NOT have the protection rating that will allow me to sleep well at night...or leave pets in the house, without disconnecting a battery. May sound "paranoid" to some, but I've seen enough vehicle fires occur "for no reason" that it's currently a "must have" for my garage.
It sounds like the consensus is that it would possibly be inconvenient, but NOT be detrimental to the bike in any way, so advice appreciated. If anyone out there IS currently using one though, I'd appreciate suggestions on ampacity,size, etc...Thanks again to all

 

[happy wanderer]

Given your level of concern rather than introduce another possible point of failure by adding a cutoff switch I would simply disconnect the ground cable from the battery. I am not sure about your bike but on my 1100RT it is possible to do this without removing the left side faring. I can do it from the airbox space.

 

[blackrt]

Thanks for the suggestion, but that's what I 've been doing! and is not as easy as a switch for regular use.