Before assuming you have a bum battery, check these possibilities:
- Make sure you're using the proper adapter. Briefly, you want a 500 mA, 12v model (sometimes marked KXA-11). (There's also more information about compatible adapters.)
When measured with a volt meter, this type of adapter will indicate 16 to 18 volts when not connected to anything. If the adapter being used only measures 12 to 14 volts unloaded, it is not adequate.
- Make sure you're charging the board with the board turned off. In normal mode, the yellow charge light should come on.
- Try giving it a Zap charge. Every hour or so, monitor the pack by holding the Handy Board in your hand. When the pack is fully charged, it will get noticably warm—that's the time to take it off Zap charge. Zap charge should take about 3 to 4 hours; don't leave it on charge beyond that!
- It is also possible to experience power-related problems if the power adapter is rated for too much current. Users have reported trouble with adapters rated at 1000 milliamps; what happens is that the adapter is unable to provide enough voltage because it is more concerned with delivering enough amperage.
If you've checked all of these things and your battery still is lasting only a few minutes, then you probably do need to replace the nicads.