So far these batteries have been quite good, giving around 5 days of full day wear on a pair of Oticon Deltas. I made the mistake on the second morning of discarding one of the batteries after the unit did not activate, thinking that the battery was a dud after just one day, but it seems that they do take a short while to get up to speed before the unit will activate - you just have to be a little bit patient.
When I remove the batteries to place the units in the de-humidifier (it is very humid where I live at the moment), it can sometimes take a couple of minutes before the batteries start working once I've placed them back in the units (which I find a bit strange).
If it was not for the delay in powering up, I probably would have given it 5 stars, especially considering the price. My comparison is with the Oticon and Siemens batteries that has immediate power and last up to 6 days.