I bought, separately, what looks like the identical battery and the identical charger.

The battery was probably a counterfeit. It worked - once I bent the contacts back where they should have been. But it had about half the capacity of the Nokia BP-4L. I complained to the seller, and he refunded my money. I bought this battery instead; it is more expensive, advertised at 1200 mAh, and seems to be fine.

The charger works fine, with two caveats. The battery does get a bit warm when it's near full charge. I posted a question about that and got the advice that it wasn't a problem, FWIW. The other issue is that while it's charging, LEDs inside the charger put on a multicolored light show through those two translucent side panels. Haven't decided whether that's a bug or a feature, but I'm carrying masking tape on my trip just in case.