Battery Charging parameters and states

[gropi75]

I would like to collect here the requirements/features, how to charge the battery, to have highest capacity and longest lifetime. If we have a good set, than we can implement them.

Good source of information are:

• solacity.com
• diysolarforum.com

Main points for me are:

• avoid battery temperatures above 45°C
• the charger shall turn off the charging and not the BMS
• set charging voltage a bit above 3.5V / cell and maximum charge of 0.5C as long as the cell voltage reaching 3.5V
• reduce charging current above the cell voltage of 3.5V to less than 0.1C (accumulation stage?)
• limit the time in this accumulation stage (e.g. one hour)
• afterwards switch to float mode or turn off charging

Any comments, additions?

[barakuda21]

Good idea, our BMS has actually the purpose of an emergency device and is not a charge controller. Since there are all information in the ESP regarding Batt. state, it can also take over the function of an charge controller. some features which could be considered

• control of max. charge current by: max. possible charging current under certain conditions like temperature of Batt and Charger and SOC estimated daytime or charging time with the goal to be at SOC 100% in the evening to reduce charging current Charging according to CC CV (Standard LiFePo charging modes) Summer winter mode for charging, in order to consider average weather conditions. Summer Mode: constant charging over the whole day. Winter mode: as soon as there is exceeding energy store as much as possible.
• maximize battary lifetime as well as utility of the Batt. Storage. At least on full cycle a day

[barakuda21]

Here some more source of information how to charge, discharge a LiFePo Link Link2 Link3