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Another issue was the battery pack seemed to cut out while attempting to close the relays too early. This could be an indication that the cells in series do not posses equal amounts of charge. LSD (Low Self Discharge) cells hold charge better, many have very little capacity but the Powerex Precharged D supplies 10,000mAh per cell. Link: Unfortunately, due to NiMH’s high discharge rate, this is not controllable without active balancing but it can be managed.
For our purposes, it’s important to note that active balancing is not really beneficial as it leads to a higher quiescent current. This is the amount of current consumed by a circuit when it is not performing any work. To maximize battery life, quiescent current consumption should be as low as possible.
Because the pack will have all the cells in series, they carry the same current during charging. One way to address this issue is to provide a full charge (charge to capacity) to the batteries even if it means overcharging some cells and dissipating the extra energy as heat.
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