Hi I just received 4 Sanyo ncr18650ga cells from Aliexpress - being in the UK and with the restrictions on shipping li lon cells my choice of where to buy was limited - they came well packaged in plastic boxes and individually wrapped then bubble wrapped and boxed again, we’re even marked lithium cells on the package . All good thus far.
My concern is though they maybe fakes or maybe rewrapp Ncr18650 cells ?
They came charged at 3.61 volts, which I believe is about right?
I then put them on my opus 3100 and did a charge test at 1 amp, they charged ok, but on the discharge test they got quite warm and some warmer than others (is that normal for a 10 amp cell ?)
Anyway they are showing on the charger of having between 3170 mah to 3270 mah capacity,which seems quite low to me?
As the last new 3200 Panasonic cells I bought and tested were almost exactly 3200mah when I tested them on the opus at 1amp.
Also looking back through some post on here, Miller bought some of the same Sanyo cells from aliexpress and his showed around 3400 mah on his opus charger screen shot.
HKJ’s test shows about 3250mAh at 1A discharging to 2.8V for the GA. It is hard to say whether there is something wrong with your cells from the info given. If you have a direct drive light, measuring the current with a fully charged cell is a good way to compare the IRs of different cells.
Hi Will34 they are still on the charge cycle, I’m just monitoring then to see of they get hot or anything.
Soon as they are charged I’ll post up some pictures, thanks
Thanks for the reply. So measure the cell by connecting it after its fully charged to something drawing say a constant 1 amp and monitor the voltage and when it gets to say 2.8 volts, I can work out the mah used from the cell from the time taken to reach 2.8 volts.
Is that correct?
Well, you could do that, but I was saying something different in my post.
HKJ’s measurement of the capacity is approximately the same as yours, so there’s no reason to think your cells aren’t genuine based on your measured capacity.
The main difference between the GA and the 18650B cell is the internal resistance, which you can compare with the method I briefly described above if you have both types of cells. In a direct drive flashlight the LED is essentially connected directly to the cell, so the current that flows depends on the IR of the cell.
They seem genuine to me, with the QR code and all. Do keep in mind that these are only rated 3,500mAh but their actual capacity is about 3,350mAh.
At 0.5A discharge rate down to 2.5V with D-reduce of 100mA I got 3,380mAh in my skyrc MC3000. Since you’re discharging them at a higher rate and higher LV cutoff, 3,200mAh sounds about right.
And probably most of the heat comes from the charger itself and not the batteries, the opus has a very inefficient fan.
Ok, thanks, I saw the IR bit, but I didn’t make the connection, I see what you mean now about the different IR between the B and the GA cells.
I’ve used HKJ’S method of testing IR on old laptop pulls before so I’ll try that on the Sanyo’s.
Thanks EasyB
Just a thought, if I put the cells in my olight x7 and use the Turbo S mode - Olight says it needs at least 8 amp cells - would that give me a quick idea if they are B cells or Genuine GA cells.
I’m guessing if they were B cells they would not have enough amps to run the Turbo S for long if at all ?
The NCR18650GAs I got from Illumn tested similarly, so these ones are probably legit or renamed fakes. The Opus chargers also aren’t perfectly accurate when measuring the capacity of cells, and the measurements are a little different between chargers even when testing the same cells.
Thanks for the reply, re assuming to know you got similar readings to me on your opus charger, when you tested your cells purchased from a respected seller
Thanks
Hi it’s Blue, it also has Sanyo 18650GA very very faintly stamped into the heat shrink.
The heatshrink isn’t as translucent as some as my other Sanyo cells? but I’m guessing it’s normal as my other Sanyo’s are quite old
You are 90% good to go.
I agree with you that mAh is on the low side for GA cells.
Do you have any other Panasonic cell that does not have many cycles on it?
Hi thanks for the reply and the link, I have some protected 3200mah Panasonic’s with about 6 cycles on them I’ll try a side by side 0.5 amp discharge on one of then and one of the Sanyo’s and also see how they compare to HKJ’s tests
Thanks
Those are NCR18650BE (hopefully). Protected will have higher internal resistance (it depends on protection and quality of spot welding), so capacity will be a bit lower than bare NCR18650BE.
We should not forget that Opus charger is not very accurate, that is something to think about, too.
Why I am (just a little) suspicious is the fact that BT3100 usually reads higher value than cell real mAh.
I think it will be OK.
