Mitko, with (personally estimated and in concordance with the CPF test) maybe slightly above 22mΩ of internal resistance, the Liito isn't the best in this regard.
However, capacity matters also. A lower IR helps with power delivery, but if the available capacity is a lesser one, the steeper discharge curve slope means the lower IR and lower capacity cell will end up delivering lesser power at some point and beyond.
This means that, even if certain quality 18650s like the VTC5 have slightly lower IR than a LiitoKala 26650-50A(B), soon they're stomped by the massive capacity and cooling performance advantage of these bigger cells.
Can anyone find cycle life specs for these cells… I agree that these cells are cheap, but I am thinking about using them in e-bike (14s2p) and to do this I have to do a lot of soldering, which would be too much work if they only lasted like 150 cycles (to 80%). Most of the time I will charge them to 4,1V (with 1,4A per cell) and discharge to 3,2V… I now use lipo Multistar 10Ah cells, which have low IR - no voltage sag (at a little over 1C discharge ) and are light, but cycle life is not that great and I notice they dont like cold (below 0 celsius). Would these Liitokala 26650 be any better in cold weather? I would only drain max 7A per cell (on average below 5A). Or is it better to buy well known NCR18650B and use them in 14s3p config (so around 4A current per cell)?
Well we dont know how will they perform on a long temr base
My personal ones i charged like 10 times so far, they work great
Cold weather could be an issue, Liions dont like temps below 10deg c
Last winter i went hunting one morning, the temps here could be quite moderate cold ones, that partucular morning they were like - 20 and i lost 4 Samsung 25rs
lost 4 25r?
i have a versapak kit in my trunk that went to 0f and the packs did fine in the drill driving a ton of drywall screws after an overnight cold soak.
never seen low temps kill cells only cut their performance till they warmed up.
these are green 25r and lg he4.
both did equally well.
using them at a high rate warms them a bit.
Mine came today.after careful calibration of the dick smith esr and a test that gave 20 mohms this is the lowest yet.they are getting better.
edit.
after full charge i repeated.
now if i press very hard on the pointy probes i can get to .01 blinking to .02
so 19 or 18 mohms
UDO, you mean you are “absolutely” sure your e-bike limits itself for max 14A amp draw (≈700W of power)? I reeally doubt it.
A 14S3P pack of NCR18650Bs, though slightly lighter, would be a baad idea, imho. 3P NCR18650Bs aren't high drain cells and, comparatively, would barely deliver slightly more current at the same output voltage than a single LiitoKala 26650-50A/B.
For a vehicle, no matter what, it is advisable to use sufficiently high drain/power cell packs. Either that, or its throttle response/slope performance will suck, not to mention battery life would also crumble.
It is also possible to build hybrid battery packs. If, for example, you were to like the idea of having a battery pack combining slightly less weight and capacity but preserve/enhance top power output, you could then assemble, for example, a 14SαP pack, for α = sum of a top notch high drain 18650 plus our 26650.
Cheers ^:)
Originally posted on Fri, 12/30/2016 - 04:10; typo fixup.
absolutely.test equipment is a triton hobby charger.
i still have 2 and will test them over the holiday weekend.
the other 4 from the order are in box mods and doing great.
Are you at all interested in modding my Utorch UT02 (Manker U21)? I would certainly pay for materials. Maybe work a trade of some kind? Maybe a new in package Lumintop TD16? Or something else.
update.
i discovered high resistance in my test rig.banana plugs to my holder were losing their tension.
charged the cells again and started another discharge.holding 4.13v @ 1a at start.
was 3.96v.
so these are likely better than we thought.
stay tuned…
