So to summarize:
To use extra Battery Kits with NI Battery 1.0 :
Delete the text: volume="1.000000" with a text editor in all .kit you wish to load. It only have to be done once:
<?xml version="1.0"?>
<BatteryPatch name="10 STUDIO KIT SMALL" volume="1.000000" version="3.3">
Should be:
<?xml version="1.0"?>
<BatteryPatch name="10 STUDIO KIT SMALL" version="3.3">
And if an error loading a "bad" kit appear, it will reappear even with good ones, until Battery be closed and reopened.
Deleting the "Battery Session" file can help a bit, as in others NI standalone Apps.