I received an answer from nkon. Despite the time being post 5 pm on a Friday!
So it seems like they’re fine. Although Hunter’s post makes me curious as to the measurements and batches, if nothing else…
I’ll order a bunch anyhow!
Hi Imp…
Yes it must be batch variations. Mine Keeppowers are 35.09 to 35.19 in length and 18.27 to 18.29 in width.
Otherwise, exactly the same battery as described.
The Aspire, Vapcell, and this Keeppower are same cell, all made by the same factory. Yongdeli New Energy Battery. Tony, the owner of Aspire E-Cig is part owner in the battery factory. At least he was a year ago.
I have now received my five batteries. They are indeed about 35 mm long.
The measurement of 39 mm corresponds to Keeppowers protected 18350 cells, so the error was probably made by looking at the wrong specs, but has since been corrected.
The cells arrived in retail boxes of two, including a case for two 18350 or 18500. With a bit of cutting they can be made to fit three 18350s though! (And the fifth cell came in another of the same case, even though I ordered several other cases, one of which was used to package the two HG2s I also bought).
Furthermore, the Keeppower case for one 18650, which is apparently made with protected cells in mind, can just about fit two of these cells, with a very thin insulator! With a little bit of cutting it should be possible to fit a somewhat thicker piece of plastic in between, making it a very compact case for the job! 
Thanks for the info. With regards to the insulator thing, no need for it strictly speaking unless you aim to prevent any scuff marks, 
?
Cheers ^:)
No, I’m more after a “spacer”, or something to hold the cells in place, as the case is on the large side and they will rattle and move if there’s only one in there. Yes, “insulator” may have been a bad choice of word, but it was natural in the circumstance.
What's up, fellows? 
Just dropped by to ask how these cells are doing lately, or how are these cells being made right now. I at least hope their performance is up to par.
I am namely asking because after looking at their sale advertisement in the Convoy store, this is what I see in the pictures:
I see a six lobe cell top with round disc atop of it, a clearly different shape than before. Did anyone purchased this cell recently to confirm this?
Also, any comments with regards to this cell's lifespan and self-discharge are appreciated. I may use it to build a custom power tool battery pack.
Thank you and cheers.
I ordered two of Keepower (UH1835P) cells on May 2021 from a different Aliexpress seller. The cells looks different from HKJ’s review and appears to be the same as the one sold on Convoy store.
Both of my cells show very high self-discharge rate. One lost 0.20v from full in 26 days and the other in 20 days. I am not sure if these cells generally show very high self-discharge rate, but I have not yet come by other information that shows otherwise.
However, the cells seem to pump the high current it claims.
Here are my previous discussion on these cells:
Barkuti, good to see you on here again. I have a couple of those that I got a year or so ago from either Illumn or Liion Wholesale here in the US…looks like the same cell (same model, same button). I have not see the self discharge in my pair that Limsup did. I don’t use them a lot but have been impressed with what they can deliver. I only have maybe 8 or 9 cycles on them so I can’t offer anything there.
For the love of God, for the love of God… 
That you are saying there is terrible.
Long ago I once tested a bunch of old laptop pack scavenged 18650s for self discharge, leaving them to rest for a couple weeks after being charged in parallel to a non-stressful voltage level (can't recall the exact figure, but fairly sure it was between 3.8 and 3.9 V). Some of the cells in that laptop pack were initially found slightly below 2 V, and besides a capacity check I did that self-discharge test to determine which cells to discard. I discarded a couple cells which lost very few mV, keeping only the ones whose voltage was rock solid set at the initial value.
I do not expect any decent quality li-ion cell to lose any significant amount of energy from self discharge, that is the reason I think what you say is really piss poor performance. Comparatively speaking, low self-discharge NiMH cells do a lot better than that!
Hello :-) Correllux. Yes, I do no longer post here very often; I don't feel the need and I certainly have much more imperative things to spend my time at now.
Its nice to hear that their discharge performance is good, but I have binned cells with much less self-discharge rate if I am to take Limsup's figures seriously… 
I certainly do not want to buy cells like that.
So, could you make a test for me? Correllux or whoever is willing to who purchased the cells from a reliable provider (I really hope Simon gets top quality cells). A simple test like charging a cell or cells to 3.8 - 3.9 V, measuring their voltage at rest and noting it down, and a week later repeating this last step. One week of wait time can be enough to check if there is any discernible loss of voltage and energy in the cells.
Thanks and cheers. ;-)
I can probably do that but it might have to wait until this weekend. I don’t have a bench supply so I’ll have to eyeball the display on my MiBoxer and pull them. I’ll try a 0.2C charge and take voltage right off the charger and after an hour…unless you’d like some specific procedure.
0.2C charge? That's 220 (200?) mA for a ≈1100 mAh capacity cell, which model of MiBoxer do you have? This is slightly off topic, but the second channel in my Lii-500 suffered a malfunction months ago and ended up literally cooking one of my AAA Ni-MHs, as it didn't terminate and kept pumping the full current until I stopped it many hours later. The cell ended up so hot that its wrap melted and there was plastic debris over the positive terminal of the charger. :FACEPALM:
It does not really matter which device you use to charge the cells, so eyeballing the charging voltage in your MiBoxer is fine; just let it charge the cells until you see ≈3.9+ V on its display. Since the voltage is measured somewhere in the charger's PCB, the voltage at the cell terminals will be slightly lower because charging current times rail and contacts resistance is a voltage difference. So, you will measure slightly lower voltage at the cell terminals once removed from the charger. I suppose you have some decent multimeter. O:)
Measuring the resting voltage after an hour or a little more off the charger is adequate. Thanks.
Ouch about the melted wrap on your cell! I watch my NiMH cells carefully…actually just recently started to use a slightly higher charge current for them than I traditionally have. I usually use the Maha for those, though, but the MiBoxer seems to do ok. I have the first version of the C4-12 that had the single grey button (the second version had two yellow buttons). I’ve been really satisfied with it other than the IR readings (typical, though) and I don’t usually let it run automatic since it likes to choose high currents if the cell’s IR is low. I’d buy another if MiBoxer were still in the charger business…I’m hoping the new Vapcell S4+ will have improvements and take 26800 cells.
This charger will let you select 200, 300, 500….on up. I think it might even do 100 on li-ion but maybe not (it will for NiMH though). Pretty versatile. Yes, I do have a decent meter that I trust for 1/100th of volts…lately I use it more than my others. It’s the Brymen-made EEVBlog unit from a few years ago. Nice features and more accuracy than I usually need…well suited for general electrician and automotive use and enough features/quality to handle the majority of hobby and electronics uses.
I put the cells on my desk at home so I won’t forget about this.
The EEVblog multimeter, Correllux? That should be either a 121GW or a BM235, both of which are out of my league O:) and needs; but it's nice to know that the voltage measurements are going to be accurate.
Concerning the next Vapcell charger, I hope for the best but I won't place my bet on it. Are you following the suggestions thread which vapcell Dennis started in that regard? }P Too much complaining and little actual knowledge about cells or batteries, vapcell Dennis.
And what I just said is also common with other brands of chargers (like Liitokala), its like if they have or hire n00bs or ignorants to decide what to implement in a charger, because one way or the other their devices always end up having some hiccups or inconveniences (like trickle charging cells, what the hell?). Its hard not to be judgmental with all of this. :-|
I'll be patiently waiting for the self-discharge test results, Correllux, it's going to be a 10+ day wait. No hurry at all from my part, by the way. Thanks again.
date(mdy) v
11/6/2022 4.1876
11/14/2022 4.1072
11/17/2022 4.0954
11/25/2022 4.0734
11/29/2022 4.0582
12/4/2022 4.0314
12/7/2022 4.0062
12/26/2022 3.8913
12/29/2022 3.8808
1/30/2023 3.7539
Here are my measurement data on one of my cells. I used YR1035+ for the measurements. I don’t think this is normal, but I noticed it too late to file a dispute or ask for a replacement.
On the other hand, batteryuniversity.com documents that fully charged li-ion batteries can lose 20% of its charge in a month. (See Table 4 in the first link) According to the website 70mV drop is is roughly 10% of a li-ion battery capacity, so 140mV drop in a month in my data can be considered normal in the batteryuniversity standards. However, I have not noticed these kinds of voltage drops in other batteries. Maybe recent li-ion batteries have significantly improved self-discharge rates.
Average self-discharge rates documented in batteryuniversity.com are about 1~2% capacity in a month for a half-full li-ion battery at optimal temperature. (See Table 3 and 4 in the first link) That is roughly 7~14mV per month. The monthly self-discharge rates on my cell on sub 4.0v voltage is above 100mV, so my cells have high self-discharge rate even according to the website’s numbers.
To summarize, self-discharge on my “fully” charged UH1835P is in the normal range, but the self-discharge rate is very high when the battery is half-full (below 4.0v).
Hello! 
Just dealing with this new forum engine and layout. Having a single powerful editor is a big plus, and it saves the input text while typing; but concerning the remaining 
stuff… the old site was better (LoL!).
Back on topic, how are these UH1835P cells doing, Correlux? Having the measurements after a week is adequate for me, I could wait two weeks but it’s enough already and you are entitled to recover the service from your cells.
And with regards to Limsup, all I have to say is that the self-discharge figures in your previous post are rather bad, in my lightful opinion. Modern low self discharge NiMH cells do much better. I just hope that is a bad batch or any other issue, because if it’s the norm… 
Barkuti, sorry for the long delay but I’m back with numbers and a happy report! Wow, this new forum platform will take a little getting used to. I rather like the old layout - less busy, easier to function, lots of little details - but I can see areas with a lot of great improvement here on the new one.
Ok, so last we talked I’d planned on starting on that upcoming weekend. I ended up charging them up the next night I think, but made an oops and just let the charger top them off as usual. So that provides another data point for a few days’ worth after full charge. I drained them and charged them up to the right spot, then took daily readings over the next - well now it’s been a week and a half.
I kept the notes in a draft email, and as a test I’m just going to copy/paste from there and see how it formats. Bottom line is that these two cells have stayed stable the whole time after the expected initial slight drop with rest after the charge. I’m going to keep this going for a few more weeks just to see what they do. These are the only two of this cell that I own and I think they only have maybe 9 or 10 cycles on them (not a popular cell for my own uses). I have some of the higher capacity Vapcell F14 cells as well and will probably do this test on them soon (they seem to be stable, but as with these Keeppower that’s mostly anecdotal until actually observed/measured over time).
Ambient room temps were 20°C most days, but from 19°-22°…don’t think that matters here really.
Initial accidental full charge was started from the cells drained-in-a-light down to 2.783v and 2.831v followed by a 30min rest period.
Miboxer C4-12 (single button version) charged to 4.2v at 300mA. Cell ends and charger contacts were scrubbed and cleaned with IPA before charging.
Input at termination (for what it’s worth) showed 1048mAh/1030mAh
IR is totally not accurate or trustworthy on this charger, but it settled on 110mOhm as charging progressed (was 183 and 200 mOhm at start)
Immediate voltage reading after pulling off charger was 4.157v / 4.156v
One hour voltage 4.155v / 4.155v
After four days 4.149v / 4.150v
==========================================
Now for the real test.
Noting the slight undercharge at termination on this charger, I tried to gauge when the right time to pull them would be so they would end up at the 3.9v you requested. I actually hit it spot on - not sure how that happened!
Drained-in-a-light down to 2.979v / 2.944v with a one hour rest period.
Charged at 300mA to 3.94v (I tried to give them the exact same charge time/time delay before pulling them after reaching that voltage - because science).
Input 774mAh for both
IR settled 98mOhm for both cells (used slots 2, 3 this time because slot 1 always seems erratic…initial on both was 220mOhm)
Temp reached 24°C (21°C ambient)
Immediate voltage reading of 3.900v and 3.902v
Voltage after one hour rest was 3.895v / 3.894v
Over the days we lost just a few millivolts, mostly on that first 24 hour period. Something interesting was that when I would read on Cell #1 the voltage would usually climb just like a single millivolt or not at all, after the usual few seconds’ wait. Cell #2 always seemed to climb up 3 millivolts, every time except the last couple where it was one or two. I don’t know if that says anything about the cell (would be curious if it does) but it’s not the meter. Daily results as follows:
Day 1 3.891v and 3.890v
Day 2 3.890v and 3.890v
Day 3 3.890v and 3.889v
Day 4 3.890v and 3.889v
Day 5 3.890v and 3.889v
Day 6 3.890v and 3.889v
Day 7 3.890v and 3.889v
Day 8 3.890v and 3.889v
Day 9 3.890v and 3.889v
Day 10 3.889v and 3.889v
I really expected to see just a bit more drop - initially and over the days - but I’m glad to see that these are this-much stable and happy. I’ll keep noting the readings and post back here in a few weeks.
I don’t expect much from these tiny cells that also aren’t made by the major manufacturers, but hopefully these will give a pretty good cycle life and capacity retention. Who knows if they’ll still be available for sale in a few years’ time, but it’s good to share the data points.
I wonder what Limsup’s cells are suffering from…maybe poor storage before he got them, or perhaps Keeppower isn’t very stringent about cell selection? I suppose that isn’t the worst drop over nearly three months for these tiny cells, but I wouldn’t be very happy with that either. China-brand or major OEM, I’ve never had cells drop that much in storage until they were already very well used and not liking a full 4.2v charge anymore and some capacity loss was clearly apparent.
Now…a question for you. Why did you specify 3.9v for the test? Obviously there’s more loss initially from the full Overcharge we tend to give these. Just curious.
1 Thank
Thank you for all that detailed data Correllux, it’s sort of like if I had done it myself. 
Notes:
Internal resistance readings cannot be accurate because these chargers do not only measure the cell resistance, but the sum of the resistances of all what is connected to where the charger measures the voltage drop difference used to calculate the resistance. R = V / I, where V is the measured voltage difference and I is the current. Chargers measure this voltage somewhere in the PCB via some microcontroller chip or some other specific integrated circuit, and between it and the cells are the connecting wires which go to the rails themselves, then the rail springs and rail sliders in between contributing to the large variability in the IR readings. plus any contact resistances. So this is the reason why these measurements are far off the actual cell resistances, being much larger because they add much other unrelated elements into the equation. They are still somewhat useful, though, as they serve to indicate if the cell is more or less well seated in the rail and contacts are clean. If rails and contacts are clean the constant voltage phase of the charge will be as short as possible (faster charging) and overall it works better (less resistances, less losses, less heat).
Your measured capacity numbers let me know that even if I charge these cells to just ≈3.92 V, there is still above 70% capacity in them, and around 2/3 of their maximum energy.
The reason I did specify around 3.9 V is because your cells live better at these voltages. You can read BU-808: How to Prolong Lithium-based Batteries for more detailed information. I also use this advice for my smartphone battery, but since smartphone batteries are high voltage types I’ve boiled down or summarized the lesson into a proportion: 14:15, which is exactly 3.92/4.2 (V). So, the limit voltage I set for my 4.4 V smartphone battery is 4.106 V for maximum lifespan.
By the way, there are pretty good battery manufacturers in China. Unfortunately, there is also many junk and overall a bad press mainly due to dishonesty: dishonest battery rewrappers, dishonesty and ignorance in general, and etc. Not long ago I bought a drill battery pack for a friend, made with Ni-MH sub-C cells, with a claimed capacity of 6800 mAh. I did it reluctantly (I saw it coming), and in the end I filed a dispute against it because out of 3 test charges and discharges at 1 A it only delivered an average of 1100+ mAh. I got the money back, of course.
To finish off, I like the self-discharge figures, so I think I’ll very likely build a custom drill battery pack with them. 
Thanks and cheers.
You are most welcome! I’m detailed and methodical like you are, I just don’t usually show it.
I had to ask about the 3.9v because aside from maybe obvious reasons, you could be up to anything - anything at all! I missed your original comment about using these for a power tool. That sounds like an interesting application for such little cells! If you end up doing it, please post and let us know how it performs. Would this go in a relatively dumb tool, or will there be challenges to address with any onboard electronic controllers and such?
Reminds me, one of these days I need to try and source a good bi-axial led to put into my drill. Some of the newer drills/brands are finally using warmer emitters and flat chips instead of ye olde colde bleue junk…a nice change, about ten years late to the party.
Wellp, today I spoke with the fellow of me which was considering a battery overhaul for its old DC735 drill, but since he is surprised by how well the aforementioned knock-off or lesser quality battery 
performs, and he also knows about the BU-807: How to Restore Nickel-based Batteries which I can do for him on his oldest battery… he’s not very enticed by the major overhaul that the li-ion modification implies. I guess that he has enough, particularly with its main battery which I built for him long ago with top quality Ni-MH cells, balancing connector and also a battery balancer following this guide: Balancing Ni-MH Battery Packs @ Electro Schematics. He told me he always uses the battery balancer with that battery (made with “Turnigy 4200” cells), and now I can see the difference because I also built another battery pack with cells from the same provider/rewrapper for him (with “Turnigy 5000” cells) and that one died due to multiple cell reversal and etc. Of course more than likely he screwed up with the battery (without BMS protection, you have to know when to cut and its best to put a discharged battery inmediately in the charger for at least a small while, to quickly undo any possible cell reversals), but I also think that keeping these high performance cells regularly balanced is of great importance, particularly if cell consistency (in both capacity and self-discharge) is less than desirable.
In any case, thanks again for the provided data Correllux (and 
Limsup too).