low battery leading to no use of GS911

[TRJeff]

2022 R1250 GS standing voltage at battery 12.8 vdc, turn on bike drops to 12.4 vdc and under bike does start if  done right away. GS 911 will not do anything saying add battery charger.  starting bike voltage drops to 8.8vdc (BMW dealer says no issue all 1250 GS bike the same)  use battery charger and still cannot keep 12.5 or higher with ignition on not started. bike running bike is charging at 14.4  vdc.  battery has been load tested by 2 different shops plus BMW dealer and all have said battery is in very good shape.  Help

[WayneC]

I have not looked at the 2022 R1250GS in detail but I would be looking for a larger capacity battery & would only fit a Lithium battery, they maintain voltage during start far better than any Lead Acid battery, 9V is the normally accepted minimum the minimum in automotive systems

Re diagnosis, for the bikes BMW specify minimum 13.5v & for the cars 14v, below that some diagnosis routines will fail, that is set by the firmware in the ECU's not by the GS911 & I am aware that even on one of the older models I have worked with simply resetting service spanner requires 14v as the reset routine in the ECU fails without 14v

In workshops power supplies, not chargers are used & are critical when programming vehicles due to the test routines done as ECU's are updated, where 14v is not maintained the ECU updating can report failures

[TRJeff]

Would I be able to use a deep cycle battery as a standby power source to keep voltage high enough to do a scan and other GS911 work. would be able to easily remove if a bike start is needed. bike is running fine, but the battery drop bothers me.

[WayneC]

It would depend on the capacity of the deep cycle battery but I doubt it would keep the voltage high enough

[TRJeff]

Thank you for the reply, I may as time permits pull battery and start checking electrical plugs and grounding.

[GS Jim]

Trying to do any GS911 work without a charger is going to be difficult. Even using a trickle charger is probably not going to work well especially if you have engaged cruising lights that cause the low beam to come on along with the side lights without running the engine. Most trickle chargers only put out 800 ma and you may find that is not enough and will need a charger capable of 4 amps.
Last week I had to do a recode (restore) to the RDC (throwing constant erroneous faults on dash) while on the road so I unplugged the headlight to allow enough time to complete the restore before the voltage dropped below 12.5v.