Bests & Worsts Reviews from Amazon

The AmazonBasics Ni-MH AA & AAA Battery Charger with USB Port is a reasonably good product. It offers several features I like: 1. It is a 'Smart' charger. That means it actually monitors the battery voltage profile during charging, and stops when a negative delta-voltage is detected. In contrast, a 'Dumb' charger blindly charges your battery for certain number of hours. This results in over-charging which is bad for battery lifespan 2. The charging current is 600mA (actually pulsed from 0 to 1.5A at 40% duty cycle) for AA, 350mA for AAA. To recharge a set of 2000mAh AA cells such as the AmazonBasics AA Pre-Charged Batteries takes just around 3.5 hours, less if the batteries were not completely exhausted. This is a good compromise between 'shorter charge time' and 'longer battery lifespan'. 3. It has an USB output port, which can be used to power or recharge other USB devices. However, there is one major drawback with this AmazonBasics charger: it can only charge in pairs. That is, you cannot recharge just a single cell, and you cannot group one AA with one AAA cell in a pair. This is very inconvenient if you have appliances that require odd number of cells. Now you are left with one cell that you cannot recharge. If you try to charge one exhausted cell together with one partially-charged cell, the charger will not stop until both cells are full. But by then, the second cell will become toasty hot due to over-charging at 600mA. Charging in pairs is also bad for battery lifespan in the long run. This is because even if you start with same brand of recharge batteries, there is always some difference in their capacities. When you charge two unequal cells in a pair, the one with lower capacity ends up being over-charged, which further reduces its capacity over time. So your overall battery capacity will deteriorate much faster. Some other minor issues you should know about this AmazonBasics charger: 1. It cannot recharge batteries and also power its USB port at the same time. As soon as you plug an USB device into the USB port, battery charging is terminated. 2. The USB port power is only available when the charger is plugged in to 100-240V AC. It cannot be powered using rechargeable batteries in the charger. 3. The output current of USB port is rated at just 500mA. This is inadequate for many power-hungry USB devices, such as cell phones and tablets. Note that in actual testing I’m able to draw 0.8A from the port, but I cannot tell if this will cause thermal damage in the long run. [Bottom Line] If all your appliances use even number of rechargeable cells only, then this charger is still worth considering. Otherwise, pick the Panasonic K-KJ17MCA4BA package instead. For the same price as this AmazonBasics charger alone, you get an individual-cell charger (BQ-CC17), plus four eneloop AA batteries. If you need a better battery charger with an USB port, consider the Duracell Mobile Charger CEF23DX4N package. The charger handles each cell individually, can operate from 12V car battery, and its USB port can be powered by internal 4x AA rechargeable batteries.