6 NiMH Overview

NiMH battery chemistry is a mature technology and readily available. These type of batteries are lower cost than lithium-based batteries and available in a number of sizes and capacities. Charging options are flexible with fast charge that can be over 1C (1hr or less) or low rate charge (reducing system power supply demand and simpler charger designs). NiMH is capable of high current discharge applications, 2C is common and higher is because the internal impedance is lower.

Discharge at as low as -40 degC is possible with some types of NiMH battery.

Limitations are self-discharge of about 1% a day requires a refresh or topping off charge to bring the cells back up to full charge. This feature is incorporated into a number of chargers.

NiMH has lower cell voltage of 1.2 V and typically requires multiple cells in series. Common configuration is 3 to 4 cell reach voltages similar to Li-Ion single cell.

NiMH cells are non-flammable with fewer shipping restrictions.