On 08/07/2017 01:53 AM, Matthew Quitter via EV wrote:
Thanks guys... but if the charger is turning off at a fixed voltage how do I get more power into the pack?
The voltage rapidly rises as the cells near full charge. Just as it rapidly drops as they near empty. The cells are supposed to survive up to 4.2v but they are essentially fully charged at ~3.5v. So, your charger can be set to turn off at #cells x ~3.5 v. Individual cells may vary. It is best to use a BMS to turn off charging when any cell gets up above 3.5v. AND turn off demand whenever a cell goes down to ~2.5v. In the mid SOC range, cells should be 3.2-3.4 v. You CAN tell when a pack is near full charge by voltage. You CAN tell when a pack is near empty by voltage. In the mid range, voltage is almost useless. As we noted. An amp-hour counter is needed to keep track of SOC. However, IMHO, an amp-hour counter is a poor way to determine when to terminate charging.
We are talking LFP cells here. You really should educate yourself on the topic before you ruin your pack. It sounds like you may have a pack set up by someone that believed in "bottom balancing".
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