Wasabi Power Battery (2-Pack) and Dual USB Charger for Olympus BLN-1, BCN-1 and Olympus OM-D E-M1, E-M5, Pen E-P5

Q: Why can't you use the Olympus charger to recharge these batteries?

not 100% sure but I think the Oly charger has more connections that it uses to verify an original Oly battery. This charger will charge Wasabi and Oly batteries

Q: Does this battery work for the em1 mkii?

No. The om-d em1 mk ii uses a BLH battery.

Q: Can it charge only one battery? Or do I have to put in two all the time?

You can charge only one battery in either one of the slots.

Q: The red light goes off after just a few minutes, without turning green. The battery does not seem to be fully charged. Is this normal?

I've never had that happen with mine. I think it's supposed to stay red until it's charged, then it turns green. At no point does the light actually go off