I haven't asked before and since I don't have a replacement charger yet - Sabrewolf, have you already sent it to me?
In the meantime I checked how the one I have works in the 90mA version. I broke the connection to the LED when I was resoldering it
😱 but it works otherwise so I measured it:
As you see, when charging at 90mA it finishes the "fast charge" phase at ~4.1V and then switches to charging with a small, diminishing current.
There are two problems here. It took 17 hours to fully charge a battery that was half full when inserted. The charger also didn't stop charging after it reached 4.20V - it kept trickle charging the battery. I waited half an hour and when I disconnected it, the battery was 4.2015V. I don't know if it would continue charging - I didn't want to wait another tens of hours to see it. If it trickle charges infinitely, I think it would take around a hundred hours before a 14500 battery is damaged.
What worries me, is that the measurements in this post and in my previous one for 280mA current (
#233) are perfectly in accordance with the IC specification, although not with what I would expect from an Li-Ion charger.
If you look at the charge profiles in the specification, the IC is expected to stop its "high current" phase at ~3.9V and ~4.1V for 280mA (DC charge) and 90mA (USB charge) respectively:
This is exactly what I and others saw here. The trouble is, that operating this way it takes around 24 hours to fully charge an empty 14500 battery at 90mA and paradoxically much longer, probably around two days, to charge it with 280mA current. For a 18650 it could be a week :shrug: According to the specification, this behavior seems to be perfectly correct so I'm not sure if my charger is really faulty or this is the way it is designed.
Maybe this IC works correctly only for smallest batteries? Sabrewolf, what do you think?
for a 100ma charger. Paypal transaction #1XX66122WF928110B
