If you are experiencing charger failure, your batteries should be tested for correct voltage. When a charger fails it could be due to the fact that one of the batteries has a shorted cell. Which can put an excessive load on the charger causing it to fail.
The batteries can be tested at one of our service centers. A service center list is available on line at blackanddecker.com or by calling our toll free number 1-800-544-6986.
The batteries can also be tested using a digital multimeter. To test the battery, it should be charged on a good Firestorm three-hour charger (do not use any other charger). The battery only needs to be put on the charger for two minutes (this will not damage the charger if only done for two minutes). After charging for two minutes its nominal voltage should be reached (example: 9.6 volt will read 9.6 volt).
Batteries that do not reach their potential voltage will have a shorted cell. A battery that has a shorted cell should not be used.