ORIGINAL: bkdavy

A123 (and other lithium chemistries) do not charge at a constant rate. Instead, the chargers ramp up slowly until they hit either the predetermined charge rate, or the maximum voltage (which for A123 and LiFe is 3.6 volts per cell). They then reduce charging rate holding the voltage constant. Once the charging rate fall below a preset value (normally on the order of a couple milliamps), they are done. This process may happen quickly or slowly, depending on your charger and your battery condition. Further, these batteries are not shipped fully discharged. They have nominal charge to prevent reversing the cell polarity over time.

Not necessarily true, depends on the electonics in the charger. If there is no current limiting, currents can be higher than what is safe and; if the voltage is not limited, they will NOT cut off when the battery approaches full charge.


Its not a good idea to use a Pb setting for A123 cells, as these charge settings don't cut off at the maximum voltage, and you'll risk excess gassing from your cells at best, shortening cell life, or possibly causing a battery fire.

Again, not entirely true, a properly designed Pb charger for 6 volts has a maximum voltage out of 6.7 +- 0.1 volts so will not overcharge a 2 cell A123 (in fact will not quite fully charge it). You can also charge a 4 cell A123 on a good 12 volt Pb charger as it will limit the voltage to approximately 13.7 volts so that is the maximum voltage it will charge the cells to.

Brad