i5 cache battery - anyone replace on the fly?

All,

3:30am Sunday one of the cache batteries in the System i failed. (Never mind that I check them the first of every month, which was last week, and there were no impending warnings, let alone failures. But that's another issue.)

The CE will be here at 1:30pm to replace it. There a _possibility_ it can be done without shutting down the system. The CE (not our usual one) said he will not know for sure until he gets here. STRSST shows this for that battery:

Battery Information

Resource name . . . . . . . . . . . : DC06
Serial number . . . . . . . . . . . : 09-4352085
Actual type-model . . . . . . . . . : 2780-001
Unit ID . . . . . . . . . . . . . . : U0595.001.103875E
Planar ID . . . . . . . . . . . . . : CB1
Card . . . . . . . . . . . . . . . : C08
Battery type . . . . . . . . . . . : Lithium Ion (LiIon)
Battery state . . . . . . . . . . . : Error condition
Power-on time (days) . . . . . . . : 149
Adjusted power-on time (days) . . . : 175
Estimated time to warning (days) . : 0
Estimated time to error (days) . . : 0
Concurrently maintainable
battery pack . . . . . . . . . . .: Yes
Battery pack can be safely replaced : Yes

The other cache battery in our System i does _not_ say it is concurrently maintainable. It's a type/model of 5709-001 NiMH.

My question is this: Has anyone actually replaced one of these on the fly? And it worked?

Thanks.