A friend was given a flashlight bought in Saudi Arabia with a unique cell inside. The light comes with a charger but I’m just surprised that this Nicad cell is not 1.2v nominal but 2.4v. Has anyone encountered a 2.4v Nicad cell? All the while I thought ALL nicads are 1.2v.
My iCharger tops it out at just over 3.0v.
The size of the cell is 22mm in diameter and 65mm in length.
I guess it’s a stacked battery with 2 cells under the wrapper. Also exists in a 3.6V version.
Stacking is not new. As a kid I knew the 3V carbon-zinc primary battery (2R10) with 2 cells. And everybody knows the famous 4.5V battery. When you *oogle it, you will see many 2.4V versions of Ni-Cd batteries (for sale).
Yep it’s just two 1.2v NiCd cells in series. Suspect you might even be able to feel a ridge or bump where the heat shrink changes from red to black.
I just felt the body and there is no ridge or bump, perhaps packed well in one piece.
I wonder if my Opus can recognize it at that voltage. Gonna try it sometime.
If you look in the Wikipedia List of battery sizes, your measurements almost correlate with the cylindrical “B” cell, which, they say, was commonly made as a 2-cell battery in the UK. It is in section 6.1 Cylindrical single-cell (because the basic battery size was generally a single-cell).
Edit: There is such a thing as 22650 Li-Ion cells. 
I have found the OPUS to be really smart, however at this voltage it may get fooled into thinking it is a Li-Ion. It would be interesting to see what happens. Be careful.
Do not leave the OPUS unattended!
Hello my good friend dchomak!
Actually I tried it in my Opus earlier before doing it my iCharger. The Opus’ display was 2.8v and climbing and was alarmed and stopped the session for at that time I did not notice the 2.4v rating in the cell’s wrapper.
Yes, I will try it my Opus later and see how smart it is by knowing if it can recognize a 2S nicad and terminate at max. of 3.2v (1.6v max for each cell)
My iCharger does recognize it a 2s nicad and terminates accordingly at just below 3.2v. ( I chosed the nicad mode)
Ok, I just finished discharging the cell in the OP with my iCharger and am now charging it in Opus 2.2 using the left-most slot at 2A charging rate.
Since it is a 65mm cell but has lower voltage than a ‘normal’ li-ion, I wonder which of the two features will the Opus recognize and correctly apply to.
Edit 1: So far the Opus has behaved like the iCharger. I chose the 2A charging rate but it did not pump that much amperage in the beginning until the voltage of the cell has risen considerably from the starting voltage of 2.4v. Now at 3.01v, the Opus has gone up the the chosen 2A (2002mA) charging rate.
It will be exciting to observe if the Opus can recognize it as a 2s Nicad and terminate at about 3.2V rather than recognize it as a li-ion and terminate at 4.20v.
Edit 2: For some reason, after some more minutes, the cell heated and the voltage went down (from 3.01v) to 2.87v while the charging rate remained at 2A. My cell took in as high as 3A rate without heating up in my hobby charger. So the charging session is stopped.
sounds like 2 4/5sc nicads.
unlike li-ion these can be charged with a cheap dumb charger.
other than a hobby charger no smart charger will charge these properly.
If my current charging with my Opus will exceed 3.2v, and will keep on rising, then I will terminate the session. Let’s see if the Opus is smart enough.
Edit: Please see edit 2 in post # 8
Negative dV + heat sounds to me like the battery is full. NiCd will barely heat for about 70% of the charge, then heat some until full charge, then put out the full current as heat (as in “I just burned my fingers”).
Previous to these sessions, I have cycled the cell in my iCharger perhaps for 4 complete cycles (which increased the cell’s capacity by about 150mah) and never had this heating and sudden decrease in voltage while charging. Hmmmmm…
+1
4/5SC size = 22.5mm (0.87”) x 33.5mm (1.26”)
i doubt it was designed to detect 2s ni cell packs. the detection of a full 2s ni pack vs a discharged li leaves too much room for error.