Bests & Worsts Reviews from Amazon

During the past 9 years, I have tested probably every model of eneloop battery chargers available in the US. This latest Panasonic Advanced eneloop Individual Battery 3 Hour Quick Charger (BQ-CC55) is definitely the best. [Individual Charging] The BQ-CC55 handles 1-4 AA or AAA cells independently. This is the only way to ensure each cell is fully charged but without overcharging. In contrast, the old charger MQN06 can only charge in pairs. [Faster Charge Time] The BQ-CC55 is advertised as a ‘3-hour charger’. On the back of the unit it claims output current is 750mAx4 for AA, 275mAx4 for AAA. But my actual observation shows that it is a bit complicated. The unit uses pulsed current for charging: - When charging 1-2 AA cells, the current pulses from 0 to 3A at 46%, for an average of 1400mA - When charging 3-4 AA cells, the current pulses from 0 to 3A at 23%, for an average of 700mA - When charging AAA cells, the current pulsed from 0 to 1.25A at 46%, for an average of 575mA. For example, suppose you are charging some 2000mAh AA cells. The charge time will be around 1.5 hours for 1-2 cells (because 2000mAh / 1400mA = ~1.5h), or 3 hours for 3-4 cells. This is significantly faster than the previous model Panasonic BQ-CC17, which takes around 7 hours since its average charging current is only 300mA. [Battery Status Indicator] The BQ-CC55 has four battery status indicators. Each indicator changes color according to the fullness of each cell: Red = nearly empty Yellow = half full Green = Full Blinking Red = Bad cell. Note that the description says Yellow = 20-80% and Green = 80-100%. This is not entirely accurate based on my observation. The moment an indicator turns Green, charging for that channel stops. That means the cell is already 100% charged and safe to be removed. Once all four channels have finished charging, the unit enters low-power standby mode and all LEDs are turned off. [Power Consumption] I measured the input power of the BQ-CC55, using my EUM-A1 Power Usage Meter: - In standby mode the unit consumes just 0.2W - When charging 1 AA cell: ~4W. This is consistent with an output of ~2.5V at 1.4A. - When charging 2-4 AA cells: ~8W [Bottom Line] The Panasonic BQ-CC55 is a big improvement over previous eneloop chargers, including MQN05 and BQ-CC17. If you don't already have an Advanced charger at home, I definitely recommend getting this unit. [Minor Issues] - Charger makes a faint buzzing sound while charging with pulsed current. - Due to higher current, this charger is more likely to reject batteries with marginally high impedance. Some explanation on impedance check: Many smart chargers (including the Panasonic BQ-CC17, BQ-CC55, Maha MH-C9000, etc) perform an impedance check before the start of charging. This is done by sending a high current pulse briefly through the cell, and measure its voltage drop. This gives an estimate on the internal resistance of the cell. The reasons for doing this are: 1. If the user accidentally put an alkaline cell in the charger, it will be rejected due to its higher resistance. Otherwise if you recharge an ordinary alkaline cell in a NiMH charger, it may leak or rupture. 2. If the cell is the correct NiMH type but suffers from higher resistance, it will also be rejected. Otherwise the cell will generate excess heat when charged at high current. Heat will shorten the cell's lifespan, or even cause the cell to leak or rupture.