9v rechargeable battery

[BrianG]

The wall "charger" is likely just a transformer and recitifier. The charge rate is determined by the battery hooked to it and the charge level. Since the output resistance is pretty high (judging by how far the output v drops as the current increases. As such, the actual charge rate varies. But, for a rough estimate, use the 30mA figure. So, 280mAh at 30mA would take over 9 hours. Really though, I would terminate the charge when the battery temp gets over 100*F...