Test/review of Samsung INR21700-40T 4000mAh (Cyan)

With which “charger/discharger/analyzer” did you perform the Lishen LR2170SF cell test capacity measurements? SkyRC MC3000?

Maybe he used a constant current load?

I’m not sure, I have a strange presentiment, let him answer thank you, if I’m right I explain why I asked my question this way and you’ll understand quickly …

Same thing for me :slight_smile:

Xtar Dragon VP4 Plus

Ok thanks for your quick answer, why else did you do this measure of capacity twice on certain cells in particular? And did you change the test slot during the second capacity measurement of these cells? If no, what slot number of XTAR VP4 Dragon did you use? N1, N2, N3 or N4?

I measured those two twice because the numbers seem either too low or too high so I wanted to confirm it. I can’t remember whether I remeasured them on different slots or which slots I used. But I don’t think the slots matter because from my testing, most of my other cells were very consistent.

However, there is a fairly common problem that is revealed with the wear and regular use of XTAR VP4 Dragon (I am at the 3rd replacement of my VP4 Dragon, although I also have a SkyRC MC3000 (which also is subject to this type of problem with wear and time unfortunately, it is not specific to XTAR) and ZKETech EBC-A40L (much more reliable have no problems, but for a device that costs a little more than 180 usd I think it’s normal)), so the recurring concerns are the even-numbered slots, ie the slots 2 and 4 which with the time of use and the wear, end up having a reading wrong measures, which give either too low or too high results, which therefore push us to often re-perform the various tests by bail, but gives again erroneous results too inferior or too high, the only solution being to operate the Charger/Analyzer warranty if it is still running or buying a new one (I know something :cry: …).

I was going through the chart supplied by the OP and noticed a strong correlation between discharge rates and storage capacity. Probably the same thing for recharging lifetimes.

Interesting to me because I have some second hand li-ions that top out somewhere in the 1800mah. I’m in the market for new cells, but can’t make up my mind if I should buy the highest amperage batteries or more higher mah. Then the question, do I care if the lifetime is measured in a few hundred cycles.

Obviously, there I’d too much temptation to max out the light output.

Given history……after much thought and consternation…I will buy the cheapest.

Once again, a thanks to the OP for his great work for testing all these batteries.

I swapped the Cell 4, which was tested at 4,524 in Slot 1 into Slot 4 and it measured 4,520 mah. Slot 4 is where I measured Cell5 at 4,834mah. Therefore this rules out the potential problem you suggested.

You don’t want to generalize too much as far as discharge rates in relation to capacity. You also have to factor in age. Batteries designed many years ago, like 8 or 10, are not comparable to newer batteries. The older cells had less capacity as well as less discharge capability. Like the 2012 Panny B 3400mah with a 5A continous discharge rate and the 2016 Panny GA 3500mah with a 10A continuous discharge rate. Both cells are almost identical in capacity, but the GA is a newer design/chemical mix with much less voltage sag.

As far as charge rates, they can vary a lot. Usually a high drain battery can charge at a higher rate than a high capacity battery, but not always. You really have to look at each batteries datasheet to see what charge rates are recommended/safe.

Keep in mind that 200 cycles (low), if charged once a week, equals 3 years. It’s not like the battery is dead or useless after 3 years though, it just typically has a reduction in capacity of maybe 20%. So I really wouldn’t worry too much about the cycle life. We may have a whole new batch of high capacity, high discharge batteries come out in the next few years that we’re going to want to upgrade to.

I just tested two Vapcell 40T (gold wrapper) and got 4,101mah and 4,156mah, which is an improvement from the older Vapcell 40T (gold wrapper also), which measured 4,038mah. I’m thinking the current batch uses the production 40T, whereas the older batch uses the preproduction 40T.

40T or 50E better for Convoy S21A?

If you mean a stock S21A with “SST-40 6A” driver, the 50E is better suited. With slightly more drain the 40T starts having an edge, and only in high mode. 40T mostly makes sense for a heavily modified flashlights with high current drains.

Thanks! I mean the stock one

You can look at both batteries on HKJ’s comparator and see that at 6 amp the 50E’s advantage starts at around 3.5v. At around 2A or 3A its advantage starts at around 3.7v.

So if you want maximum runtime and regularly run it down well below 3.8v then the 50E has the advantage. It will give longer runtimes. If your like me and only run your cells down to 3.7v-3.8v and then recharge it, you won’t see any advantage to using the 50E. It’s really at the lower voltages that you see the 50E advantage.

JasonWW's points are worth considering too Tendou. In essence it all comes down to how do you intend to use your flashlight, be it in long continuous runs at some mid power level or mostly short bursts on high, and namely how will you manage its battery. I don't recharge often and also don't fully charge my batteries, I focus on cell lifespan versus having cells full or near fully charged at all times. With this in mind the 50E would make more sense for me.

Another thing to consider is how the flashlight driver works. Boost drivers, for example, make use of most of a cell's capacity and energy without tapering down output power and thus it all comes down to selecting the highest capacity cell which meets the torch's current demands without problems.

Fri, 03/27/2020 - 03:48

How many amps can a fw21 X9L take ?
What is that led ? SBT 90.2 ?

What’s the best 21700 for that light ?

These cells just keep getting better and better. As most enthusiasts are already aware, version 3 of the INR21700-40T is in circulation from several resellers and are rated for greater charge cycles than its previous versions. This is one tough cell.

The cheapest genuine cells I could find from a US supplier is at Aloft Hobbies, and Ive purchesed several from them. While their stock photo does not reflect current stock, I just received a qty of 20 that are v3.

Here’s some info on that led.

It’s basically a high amperage 3 volt LED. It can easily take 20 plus amps.

The best battery for that light will depend on how you want to use it. If you only use it a few seconds at a time and you want the absolute highest output (on Turbo), then you want to use a very high drain battery. It will pull the highest amps, but get hot very quick.

If you don’t really care about getting max output (on Turbo) and instead want it to run a little bit longer before getting hot, you can use a much lower drain battery. It will pull lesser amps.

This Samsung 40T is a nice middle ground battery.
The 30T will pull more amps.
The 50E will pull less amps.