Unfortunately, it seems this deal for NCRB’s is over -> This coupon has expired :~
Oh…. any similar deals for these?
NCR18650A over at DX, for $12.50/pair, not a bad deal imo…
These look like the same
Can anybody confirm if they are protected?
They are protected.
Thank you, Sirius9!!! I’m ordering them!
Will the specific PCB that is used have a dramatic affect on the performance at higher current draw?
I notice that this particular battery that HKJ tested performs significantly worse than the stock NCR18650B. I have NCR18650Bs that use Seiki PCBs and they look different from the ones HKJ tested here. I wonder if my NCR18650B would perform closer to the stock NCR18650B at 5A.
The PCB controls two parts:
1) The control IC
2) The switch transistors.
The control IC has a threshold for maximum current, this depends on the actual IC model, but can be 0.1 volt (It has nothing to do with Japanese/Chinese IC). This threshold defines the maximum voltage drop, just before the over current protection trips. I.e. with a 0.1 volt IC, the output voltage will be 0.1 volt lower than a unprotected battery, just before over current trips.
The switch transistors is used to disconnect the cell, but does also define the over current limit, i.e. when there is "threshold" voltage across the transistors, the over current will trip. A high current transistor or many transistors in parallel will give a higher current before the over current trips. This will also mean a lower voltage drop at lower currents. This means that a battery with higher over current value will have better performance, than one with lower over current protection, if the same IC is used.
What is the current preferred vendor in getting these and shipped internationally?
When you are inside EU I would check these:
I got my order of LiitoKala protected NCR18650B from this seller:
Since these are my first and only protected 18650s, how do I know that they are indeed protected — they look like protected batteries, as per the description from this thread by HKJ: How to see if a battery is protected - they are much longer than ordinary 18650s.
How do I check that the protection will work (aside from shorting them, which I don’t want to try doing at the moment)?
I’d like to ask also what does “protection” really do? — does it protect from draining to too low voltage? from overcharging to too high voltage? from drawing too much current?
If draining to too low voltage, what might the the low voltage threshold — is it 2.50v? How about high voltage threshold — is it over 4.20v — will charging to 4.21v trigger the ‘protection’ or maybe over 4.25v?
I’ve tried draining the battery down to 2.50v momentarily (@ 1A drain rate), but I didn’t notice anything happen (no shutdown, after the load was removed, voltage recovered quickly).
Protection chips check for over charger, over discharge and over current.
In many of my battery test I trip the over current protection.
I did run some test on the over discharge protection here: Discharge protection test
Do you know if the over current protection also works for charging, or is it discharge only?
It also work for over charging, you can see it on some 4.35V protected batteries I have tested, they usual use 4.2V protection chips and cannot be charger to 4.35V due to that.
A small piece of information:
Four of those batteries, fully charged to 4,2V and stored for ~28 months in 20-27 (mostly 22-23), sometimes shortly ~30 Celsius (68-80, mostly 72-74 sometimes ~86F) had IR increased by ~30 mOhms (one 50) .
Discharge test of those batteries to 2,8V:
Shortly after purchase: ~3100-3200@3A + 60-100@1A
Now: 2750-3000@3A + 150-300@1A; 50 mOhms one had 2550 + 400
IR: charger measured ~90-100 on purchase, 120-130 (one cell 150), ten measurements, average of 3 lowest.What is the real IR-cant say exactly, due to my limited hardware
FreeMagenta, that is likely consecuence of storing the batteries at maximum voltage. See BU-808: How to Prolong Lithium-based Batteries.
I take that information very seriously, even to the point of avoiding using my cells above 14/15th of their maximum voltage. Pays off (in a device like a smartphone, a lot).
Thanks for the link to that experiment. So it seems, common undervoltage protection are set to 2.50v, 2.40v, and 2.30v.
I hadn’t dare drain the protected NCR18650B I got below 2.50v yet; I think it doesn’t trip at 2.50v, but possibly lower.
Will I permanently damage the protected NCR18650B if I attempt to drain it to 2.00v? (I’ll use EBD-USB+ and 18650 battery holder and try to drain at 1A, or should I drain at a lower current for testing at which voltage the protection kicks in?)
d_t_a, if your cell is protected I really doubt the protection circuit will let you go down just a bit below 2.5V, if at all. Related: How far can LiIon be discharged?
Despite whatever is said by HKJ there, a cell's chemistry doesn't immediately changes upon deep discharge. I've had a couple of deep discharges at 2V or less without apparent damage, but of course I don't leave cells to sleep in such state, they are recharged without delay.
I knew. However, I did it for the test (how much will the batteries degrade if stored on max voltage?…) . Also, for having fully charged batteries in case of emergency. Since I am using mostly 1S lights, the potential differences in degradation won’t matter much.