2023 r1250rs intermittent fail to start?

[Chris216]

Your battery tender wiring may not be up to the amp draw of trying to start the bike with a jump pak. I'd be cautious about that.
Chris

[Duckbubbles]

Here’s a new question. Should one use the battery tender connection to use a jump starter rather than clamping directly to the battery (in the unlikely I even need to), or is that wire harness to frail to take the current of an auxiliary battery? 
Jay

Probably safer to use the battery connections.  The tender connection is intended for use with a charger that limits the amperage going to the battery.  Just be sure you have a tool to get the side cover off to access the battery.

Frank

[Lee]

I appreciate the input from you all. So I bought a small “jump start” battery to throw in my pannier just in case, until I replace the battery as an insurance policy. Here’s a new question. Should one use the battery tender connection to use a jump starter rather than clamping directly to the battery (in the unlikely I even need to), or is that wire harness to frail to take the current of an auxiliary battery? Don’t want to find the hard way. If in doubt, I can just jumpstart the old fashioned way if it ever becomes necessary. Just curious anyone has tried that. Thanks
Jay

Go straight to the battery. You only have to remove the one screw to remove the battery cover.
Don't forget there's a remote positive post under the red plastic cap so the positive and negative of the battery is easy to get at.

If you happened to buy a Micro Start jump pack they sell a harness that can be connected to the jump pack but that's really for bikes that don't have easy access to the battery.

Somehow I missed the other replies

[Lee]

 Just be sure you have a tool to get the side cover off to access the battery.

Frank

Do you remember what size torx is under the seat?

[Lee]

 Just be sure you have a tool to get the side cover off to access the battery.

Frank

Do you remember what size torx is under the seat?

T25 and T40. T25 is the one for body panel screws.

   

[Becksy]

That’s happened to me a couple of times, starts and then immediately cuts out, but then starts again fine. My bike even cut out mid ride this year whilst changing gear, was luckily on a downhill straight, and it fired up again whilst on the move. We don’t have winter fuel but have wondered if it could be due to using standard fuel rather than super.

No engine fault or Limp Mode when this happened?k

No, neither. Just cut out.

[mspratz]

The Asheville NC BMW dealer recently replaced the battery in my 2024 R1250RS under warranty. On the way back from a trip to Santa Fe NM I stopped for gas and then the bike would not start, there was not enough juice in the battery to turn the engine over. The gas station had some jumper cables for $12 and another customer offered his SUV to jump it. It started first go and after that I made sure to turn off the ignition, not just the kill switch, so the lights etc. were not draining the battery. I managed to get home without further incident.
The dealer tested the battery and found a bad cell. When I arrived at the dealer I found a friend with a recent model S1000XR with exactly the same issue.
The new battery is so far doing fine.
I wonder if BMW had a bad batch of batteries?

[Grumpy Goat]

The Asheville NC BMW dealer recently replaced the battery in my 2024 R1250RS under warranty.
...
The dealer tested the battery and found a bad cell. When I arrived at the dealer I found a friend with a recent model S1000XR with exactly the same issue.

Sure sounds like it. Sounds like your battery may have been just about a year old if the bike is a 2024 MY, so that suggests a fault from the outset. Do you remember the brand? 

The 2016s came out with re-badged Exide batteries. After that original battery died, I replaced it with a Yuasa which just died after 5+ years. Based on the fact that I had my bike maybe 9 years now, that Exide may have lasted 4 years. Both were within the expected range.

[Toruk]

My 2023 RS has 17 months of driving with almost 11k miles. I have not had any start issues! If I am not riding for more than 5 days my RS is on a battery tender using the lead the Dealer installed directly from the battery.

[Jcrouch]

As an update I did have a new battery installed, which has bigger cold cranking amps than the oem battery. I haven’t had an opportunity to check it out, but I’m optimistic it will solve my problem. Interesting factoid, my mechanic had a boxer engine open on the stand for service. He showed me a compression release valve that automatically actuates to aid in startup cranking. This is not known to be a problem in our engines, but I though it kind of interesting, because that would explain a condition wherein the motor would not want to turn over at one point, and then suddenly crank like no problem. Just food for thought.
I’ll post results of the new battery when I know more.
Jay

[Grumpy Goat]

I’m very interested in this compression release valve …

[Boxflyer]

The compression relief feature has been on the BMW Boxers since they were first introduced, and they are a very simple mechanical device that is not prone to failure.
Here's a small discussion and display of the operation.
https://youtu.be/PQeNcD0gGOw?feature=shared&t=1044

[Grumpy Goat]

The compression relief feature has been on the BMW Boxers since they were first introduced, and they are a very simple mechanical device that is not prone to failure.
Here's a small discussion and display of the operation.
https://youtu.be/PQeNcD0gGOw?feature=shared&t=1044
...

Thanks for that Boxflyer. Simple and ingenious, and I guess by reducing compression in this way the engine is easier to turn over and start, possibly using less voltage from a weaker battery.

[92232]

T25 and T40. T25 is the one for body panel screws.

BMW no longer supplies the T40 with the tool kit under the seat.  That is the way it was with my 2024 RS.  So I bought one through the parts counter.
Also, the RED frames were not available on the 2024 RS.  

Bill

[Lee]

BMW no longer supplies the T40 with the tool kit under the seat.  That is the way it was with my 2024 RS. 

Bill

So the torx wrench under the seat only has a T25 end?