Except that they specifically say to NOT use them with rechargeable calls.
Possibly to prevent users from draining the rechargeables too much, because that would destroy them.
Well, that depends on the chemistry of the cell... Some don't like repeated deep discharge (like lead acid, of course), but for NiCd, for example, you're SUPPOSED to store them in as deeply discharged of a state as possible (or fully discharged, then stored shorted) to prolong the cell life.
For long term storage of spacecraft NiCd battery packs, NASA reccomends:
1. Discharge at C/2 constant current rate to first cell at 1.0 Volts
2. Drain each cell with a 1 ohm resistor to less than 0.03V
3. Short each cell with a bar
4. Place batteries in a sealed bag with dessicant (stops condensation)
5. Store in cold temperature (about 0 deg C)
Edit: Note that for battery packs, you must discharge each cell individually!!!
Trying to fully dicharge multiple cells in series will end up reverse-charging the cells that get low first with the "magic pixie juice" from the rest of the cells and destroy the first ones!!!As I've said several times before, if the product had been designed as a converter which boosted the typical 1.2v from a rechargeable to 1.5v, it could be a useful product in more instances. They could even have the converter attempt to mimic the output voltage curve somewhat so that battery gauges would still work, at least somewhat... but NO, it is supposedly to be used only with primary cells.
They simply would have to design a version with a cut-off voltage for rechargeable cells.
Well, obviously.... and that would be a far more useful product for all those circumstances where the various rechargable cell chemistries don't work well in products designed for primary cells...
But that isn't what they're peddling!