Sefepoder#1 charge log

[last updated: 2025-05-05]
battery - home page
Charging LiFePO4 batteries
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• First Sefepoder, 15Ahr LiFePO4
  2025-05-04
  • Initially, as best I recall, battery was at 13.08v.
  • With Hammetek bench supply alternatively in constant current, then constant voltage modes
  • First doing 4.5A as recommended, after ½ hr or so, removed charge, let battery rest/stabilize for maybe 20 min, battery reads 13.25v.
    Back on charge 0:30. Now 13.35v after 0:10 rest.
    Charged 0:20. Voltage 13.38 after 0:13.
    Charged 1:00. Something weird at the end of the charge period:
    The power supply shut down for a few seconds, then restarted, then did it again after a few seconds.
    I shut it down, it was at the end of my intended charge period anyway. Voltage still only 13.38 after 0:15.
  • Waited awhile, then started charging at 1.0A.
    Worked a couple of minutes, then shut down again
  • Repeated at 0.5A, same result.
  • Lowered voltage to 14.2, reduced current successively down to 0.2A, but ultimately same behavior.
  • After 0:20 rest, battery voltage: 13.72V
    after another 0:10 (12:05) - 13.67V (5 mV/min)
    after another 0:10 (12:15) - 13.61V (6 mV/min)
    after another 0:25 (12:40) - 13.52V (3.6 mV/min)
    after another 1:50 (14:30) - 13.36V (1.5 mV/min)
    after another 2:10 (16:40) - 13.32V (0.3 mV/min)
    after another 1:40 (18:20) - 13.31V (0.1 mV/min)
    We'll call this stabilized, after 6:25 hrs, at 13.31V.
  • Another charge cycle started about 18:30 at 0.2A.
    Voltage at start of charge: 13.36V.
    Found it shut off at 19:35. Restarted. Reduced charge current to 0.1A.
    Shut off again at 20:05, battery at 14.25.
    After 1:10 (21:15) - 13.69 (8 mV/min) -
    another 0:20 (21:35) - 13.61 (4 mV/min)
    After 08:25 (06:00 next day) - 13.30, virtually unchanged from previous charge cycle.
    Seems that's all this battery is going to give me.

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