I just got in some unprotected button top Sanyo NCR18650GA’s from a very reputable source. However upon charging them on the VP2 I have noticed that none of them will charge past 4.12-14 volts. They appear to relax and stay around 4.08-4.10-12 once off the charger for a while, so i’m not sure if these cells have been sitting in a warehouse for a while or am I just expecting too much from them? I charged up a set of LG MJ1’s on the same charger not 15 minutes after these Sanyo’s and they easily topped off at the 4.2 mark and stayed around the 4.18 level once rested.
Any ideas or am I just expecting too much of these cells?
That’s strange. Mine charge to 4.20V on VP4, and 4.24V with WP6II. I would try again, and if you’re unsuccessful, I’d contact supplier. Sanyo GA is my number one choice
The voltage to which a cell is charged is determined more by the charger than the cell. That being said, I think if a cell has a high IR the charger can terminate charging before the cell is “full”. The MJ1 and the GA cell should have similar IRs, so I don’t know what is causing your issue. Possibly the button top is not attached well to the cell electrode or not making good contact with your charger, or something in the actual cell is causing it.
I almost think its because the cells have been sitting in storage for so long. Before I popped them on the charger they were in the low 3.1-3.2 range which makes me wonder. I attempted to charge one set at .5 amp and another at 1 amp to see if there would be a notable difference, but there was not.
I would also suggest trying again after you have used the cells some. How many cells did you get and how many times have you charged them? I don’t really know the details, but I suppose long storage times could somehow increase the IR near full charge.
GA’s are fairly new cells compared to say a NCR18650B. So how long could they have been stored in the first place? Secondly, 3.1V is not exactly a disaster low value or not? How about a full discharge/recharge to see what voltage it terminates at?
I received 4 of these cells Friday afternoon, checked their current voltage and stuck them on the charger. Do you think running them down and recharging a time or two make wake them up a bit?
Potentially. Try it and maybe we’ll all learn something.
When Li ion cells charge, Li ions move from the LiCoO (or some similar oxide material) cathode into the graphite anode. I’m imagining when in storage for a long time, there might be some relaxation in the electrodes which makes it more difficult for the Li ions to move in and out of them, increasing the IR.
If the cells were 3.1V when you bought them then there’s something wrong… resting voltage of 3.1V is nearly zero capacity left, much like when you discharge a cell down to 2.5V but a couple minutes later it goes back to ~3V. It is more damaging to store an empty cell than a full one.
A couple cycles should help but if you feel they get hot towards the end of the charge at 1A rate then consider throwing them away.
Throwing them away?? I just got them Friday, the vendor will be taking them back before I eat the costs of bad cells. I’m currently awaiting word from the actual seller, so I will see what they say.
I have the same cells except they are flat tops (4 of them) as well as the same (2) Xtar VP2 chargers, and they charge to 4.19 volts reliably. Something’s up with yours.
I’m going to beat on them a bit and see if I can wake them up before really perusing the issue too far. I’m still on the fence and cannot decide about getting another VP2 or a VP4….
And yet it might be the charger. I’ve got a Nitecore 4 bay charger that likes to quit when charging cell nearly drained at the 4.14 volt level. Only on high capacity 18650’s and 26650’s. All other cells and cells only half discharged it usually takes them to 4.22 volts. Personally I think the charger gets a little warm and under charges.
The cell/s that will not charge beyond 4.12 to 4.14 but rests at that voltage overnight should be tested through a ‘discharge test’ to know its real health.
I have very new cells that exhibited that ‘anomaly’ (I thought) only to show still about the same discharge capacity to my other cells that charge and rests at 4.18v, regardless I used my iCharger, Pila, Opus, Xtar.
Do a discharge test and see what they come up with capacity wise. I have 8 of these cells and they rest at 4.19 is the vendor trust worthy? It could be possible you got fake batteries. Possibly rewrapped ncr18650b old stock if its not the charger. With a button top you wouldn’t have the normal sanyo raised flat top. Even good vendors get fakes from time to time the distributer usually gets duped. Like earlier this year imr and lion had a batch of fake hg2. Its what the seller does to fix it. They sent out replacement batteries NCR b are dirt cheap and with a button top added on would hide the normal features. And capacity would be the same in a discharge test unless you can test around 5 amps then the line curve would be a lot different. But 1-2 amp discharge would be the same. So pretty much the perfect fake to swap in
Also, I was able to get the 4 completely drained to a safe level and charged back up to 4.2 and resting at 4.19-4.18. I also weighed them for kicks and they come out to about 48.2g a piece and the MJ1 that happened to be sitting near by came in a a 47.6g. I’m going to assume these are legitimate cells for now.
