I was using my XP4 to charge some 18500s (6 of them) tonight, using the 1.0 amp setting, and they all came off the charger at between 4.16 - 4.17 volts.
Is that ok? It seems a little low…
Does the XP4 have problems terminating Li-ion too soon also?
4.16 to 4.17 is ok, it will depend on the age of the battery and the charge current, using a lower charge current will get you a slightly higher voltage (Because the termination current is less).
I will not recommend it, but if you need the maximal capacity a 0.25A charge is best (The termination current is about the same on 0.5A and 1A, i.e. you do not really get anything extra at 0.5A).
The 18650's in the thermal image, were these protected cells or unprotected cells? Protected cells have naturally a higher thermal resistance at the plus pole because of the altered and longer thermal path (and at the minus pole because of the added PCB).
Unprotected 18650's get considerably hotter in the XP4 than protected 18650's.
Any ideas on whether charging to 4.2V (while charging) with 1A, then switching to 0.5A till 4.2V and then 0.25A to finish could cause any problems? I was thinking about this because for some reason an old cell in my VP1 got hot, and I was thinking having a lower maximum current at the end would be a bit safer.
For the 18500s I mentioned earlier, not sure if this is good or bad, but I’ve put them in my Jetbeam i4 pro afterwards, and let that finish them off, and ended up at about 4.21V - 4.22V.
I am quoting them verbatim from the email I sent to them. I guess it means that they will discuss it in their weekly meetings and will find a way to fix it in the next revision. That was about 2 weeks ago, they have not sent any updates on the progress.