BMW R1200RT/R1250RT Forum

Tony Fyson wrote:Any ideas why the battery should not be capable of turning over the engine?

What does the voltage drop to under load when cranking to start the engine.

How to monitor battery voltage during start 2013 BMW R1200GS - YouTube

Hi David


Cold cranking voltage is from 8.9 volts, rising to 9.3 volts after a couple of starts.
Does this mean that my battery is getting a bit tired?

Tony Fyson wrote:Does this mean that my battery is getting a bit tired.

I would say yes, time for a new battery.

OK - thanks
There are several threads on replacement batteries.  Can you recommend a suitable replacement?

Tony Fyson wrote:Can you recommend a suitable replacement.

Most recently, Casbar bought one of these, AGM12-16 EXIDE MOTORCYCLE BATTERY 12V 16AH 170A 4920 | AGM Batteries | Batteries & Power Electronics | Battery Group

It would be good if he can provide some feedback.

See this thread for further details, BMW R1200RT / R1250RT forum - The BMW R1200RT/R1250RT forum

Bit of feedback on the 12/16 Battery I bought. It is fine, haven't had any issues with starting. Like I posted previously, the Exide 12/16 is exactly the same battery as BMW supply as OEM on the 1250RT. BMW do quote a different CCA, but they measure at a higher temp than Exide do, so the 170 Exide quote is the same as BMW. This is the same battery, Exide do not make a special battery for anyone. The thing i also like are the posts, which are fixed. The posts on the Yusa are screwed in, and on another bike where we have that battery, if you tighten the cables onto the terminal it can move and loosen, which is not great where the battery is located on the LC RTs. Anyway in summary, all good and very happy with my purchase. Especially happy with the £55 I paid as opposed to the £135 quote from Mr BMW for the same battery

Casbar wrote:Bit of feedback.

Thank you.

Hi David and Casbar
Thanks for all your help regarding the battery on my RT1250.


However, this does not explain why my bike would not start after a 50 mile journey along the M5, and the engine would not turn over after I stopped to drop of a PCR sample in a collection box.  After a wait of two hours (recovery did not turn up) I tried to start the bike and it instantly burst into life.


I have read somewhere about some sort of decompression device, that enables the engine to turn over.  Could this be malfunctioning?


The no load battery voltage is 12.89 volts, and 12.4 volts with the ignition on.


Thanks again.

Hi Tony, the no load and engine running voltages look just fine. The under load cranking voltage looks suspect.

If the battery is removed from the bike, fully charged, left to stand for awhile then load tested with a bench tester, that would verify if the battery is good or not.

As for the decompression device, when were the valve clearances/timing last checked.

[size=2px]Hi Tony[/size]
I personally wouldn't bother with valves settings etc on a 2019 bike with only 11000Km (6800ish miles)


More than likely its the battery, BMW had a batch where the internal cell connections fail when warm.  Leaving the bike for a while they can restart once cooled down.
You could bench test it with a 'drop tester' but make sure it hasn't just been removed from a charger, the gases can sometimes ignite when the drop tester sparks on connection.


Getting the battery out and back in on a 1250 can be a nightmare so I would have a new battery ready to just put in.

My battery voltage shows 14.2 with the engine running and at least 11.2 with the engine stopped  (2021 1250rt). I have fitted the terminals with nord locking washers. The battery on my bike comes out on the right hand side. When putting it in it is easy to get a small turn on the inboard terminal because of lateral movement of the battery and the rigidity of the wire. If the inboard terminal is then loose, the battery will not charge properly and starting problems occur even if the bike has run a good distance. Since fitting the nord lock washers I have had no further problems.Best Wishes,
Pete

redcomet wrote:I have fitted the terminals with nord locking washers.

Did these replace the original #3 spring washers.

redcomet wrote:At least 11.2 with the engine stopped.

11.2V is quite low.

David
Tony


Your story and mine, are identical.........mine is at the dealer now for its 18,000 mile service and initial reaction by service  rep .... "it probably needs a new battery.  These bikes have so much electronics tied to them, don't expect a battery to last beyond 2-3 years."  Yes, mine is a 2019 R1250RT, 18,000 miles, shows load and no load voltage of a consistent 14.1 v, all BMW service performed (including valve clearance),starts right up, ride it 15 minutes, won't start back up., wait 5-15 minutes, starts up, with or without auxilliary lights, high beam, Nav5, Satellite radio, etc. all "on" at start up.  I souunds more like a starter problem to me, but we shall see.  Not my first "electrical" problem.....my 2016 RT had a low beam headlight issue where bulbs would burn out after 3 months, and after weeks of investigation by dealer and BMW engineering support, they determined I had a major electrical issue, hence why I'm on a 2019 replacement RT.  If the new battery doesn't solve the problem, despite my love of the RT's,  I will search for another bike, and likely not a RT or a BMW.  I had a 2015 GS1200, worked flawlessly (never had a battery replaced) and should have never sold it! 


Hope your new battery solved your "problem starting issue."
Donna

Just to jump on this thread as my bike, a 2016 1200 with 39000 miles with a full BMW SH is also intermittently not starting when hot. It will almost turn over but then all power goes which resets all settings. After a few seconds it then fires up with no issues so I was thinking that maybe the battery is starting to fail. I think it’s the original battery but have yet to check. Any ideas anyone?