USB power module and 41CL update

[burkhard]

I did a 41CL v5 flash update yesterday using my USB-41 for power--worked great!

One more question occurred to me on the topic of using the USB-41 as a power source.
Is the battery pack somehow isolated from the power coming through the USB-41?

I ask because while it would be neat to have a rechargeable pack (or NiMH N-cells) replenished, I would suppose charging conventional alkaline N-cells in situ might incur a risk of leakage.

Thanks!