Well today i pulled my first set of batteries form a Fujitsu Siemens laptop batterypack BTP-C1K8 , 11.1v 4400 mAh
It came from a older defect lapop, probably main board defect. (wouldn’t turn on anymore)
it contains 6 cells, Sanyo UR18650FJ, they are 2200mAh
The sanyo labeling is very difficult to see at first, the clearly printed info on the cells lead to nothing
All 6 read around 3.8v after separating.
Kept 4 out of 6, 2 of them were dented on the side and bottom, although the plastic housing was not damaged.
Put them in the nitecore d4 and let them charge
After a while and some checking up on them every 15 minutes for the first hour or so it seems all okay, and i let them run a while.
But… after 4 hours (and some occasional check on them) they got around the 4 volt mark, they started getting warmer,
at the 4.10 - 4.15 volts they got very very uncomfortable to touch!
Think this is not good ? i should recycle them and not use them ?
A charger can get very hot when charging 4 batteries at the same time. Did you charge 4 other batteries at the same time without batteries getting warm? I would try charging just one to see if it also gets hot.
Generally I dont feel comfortable with li-ion batts that has a increase in temp while charging, as a rule of thumb 100F (or body temp) is where I set the line. Also you can test the internal resistance of the batteries manually to see if they are any good. Secondly if the batteries have been un-used for so long they might need a couple of charge-discharge cycles to get them up to speed, but I wouldnt count on that one.
The charger is new to me, had only one other single cell on hand (the one in my light) and charged it after i charged the four red hotties…
This cell (an eagletac 2600 mah) didnt even become warm.
I juiced it up to 4.18volts, then had to pull it out, it was time to leave work and go home for dinner ….
Tomorrow i’ll run one of the sanyo cells a while in my light, enough to get it arround 3.80 again, and ill charge it again after that (single cell) lets see if it gets hot again.
I ran down 2 of the pulled batteries to around 3.8 volts in arround 20 minutes of use on high(after a 90sec turbo) in my convoy s2.(T5-5B1, 8x7135) (from what i measured when building this light, high is up around 1A on the tail.)
Then charged them in the Nitecore i4, 1 at a time, and i let it charge until the charge was stopped by the charger.
It beefed up my first to 4.16, and the second to 4.12 (measured after a minute of the charger)
There is a difference tough when charging one, in stead of 4, when charging one it uses 750mAh, when charging 4 it uses 375mAh
And most important :
No heat signs on these first 2 charges when charging them one at a time, they where colder than when they came out the convoy. 8)
Currently i’m running down the other 2 and will charge them one by one too, to check if there might be a problem with one of these.
i’ll do an other rundown of the cells and try to charge 2 at the same time on monday. (2x750) to get the full potential of the charger with 2 cells in stead of 4
Nitecore channels are bonded, 750mA max between ports 1/3 and 2/4, individually you get the full 750mA, put two in the bonded group, you now get 375mA (divides the current between the slots)
It goes little further than that bond by group, when using slot one and 2 you have 2x750mAh, use any other extra slot, you have 375mAh on each.(tested that)
Sadly, because when it correctly would spilt its 2x 750, it could do one at 750 and 2 at 375 (ie when charging one 18650 and 2 Nimahs)
[edit]
Charge finished …
All 4 charged well when charged as a single cell, no heat. On monday i’ll charge 2 at 750, lets see what that brings.
If I had to guess I would say that it’ll heat up as much as with 4 cells when charging two cells at 750mA. The total power delivered by the charger is the same… So it should heat up the same. Maybe just a little bit cooler because more airflow where the cells are missing.
No problems charging 2x 18650, tried both sets, slot 1&2 and 3&4
AND i tried all 4 again!
No sign of heat this time !
They were not as cold as when charging a single cell, but nothing i worried about.
(they felt very comfortable to hold, maybe like body temperature)
They all had 5 cycles now (ran them down around 3.8 every time) since i pulled them from the battery pack.
i suppose sinner was right, they had been laying around a while, and needed to get back on track.
