Battery chargers all have different charging technologies that allow them to recharge batteriesSimple chargers work by connecting a DC power source to the batteryThese are cheap and inexpensive chargers in that they take longer to recharge batteries to prevent overheatingBatteries left in these devices for extended periods of time will be weakened as a result of over-chargingA constant voltage or a constant current is what these chargers supply to the AA and AAA rechargeable batteries.

The two-way micro chip communication senses the battery level while charging is in progressIt then processes this information between the battery and the battery charger to achieve optimal charging levelsThis communication between the two devices allows for the optimal charge to be achieved in the time allotted.

The most popular method for charging Nicad batteries is using a negative delta V (NDV) cut-off charge system because it offers a rapid response timeThis NDV system alerts the charger when the battery is full charged by dropping the voltage outputThe voltage drop is a response from polarization or oxygen build up inside the battery cellIf a fully charged battery is being recharged, then the terminal voltage will quickly rise, followed by a sudden drop off point, triggering the ready to use stateThis lasts for a few minutes and the battery cells remain cool at all timesIt is recommended to have a charger that responds to a very small voltage decrease, over those that require a larger decrease.

Smart AA and AAA battery chargers are technologically advancedThe charger responds to the charging instructions from the batteryThese chargers use smart batteries that can remember and store information about its specific charging characteristicsThe charger picks up on these requirements and adjusts the charging voltage, current, temperature, and other characteristics to the batteries needsThese chargers are great and easy to use.

Battery chargers can even turn themselves off after a charge has been completedThese are called automatic battery chargers and they utilize an end of charge voltage point to stop the charger or to switch to a trickle chargeThe trickle charger is the slowest battery chargerWith a trickle charger you can indefinitely leave the battery charging without ever overcharging itThis is because the battery is being charges at the self-discharge rate, the slowest rate possibleThe charger is not suitable for Lithium and NiMH batteries, which subject to overheatingSome battery chargers switch to trickle charge when the battery has been fully chargedThis prevents the battery from overcharging and is a good function to look for in a chargerThe trickle charge is advantageous in that in cold climates they can keep the battery warm.

If you have SLA batteries then it is recommended to use a charger that has a taper currentThis will charge the battery at an unregulated constant voltageAs the cell voltage increases, the current diminishesWith the taper current you run the risk of overcharging your batteryConstant observation of the battery is required to avoid overcharging.