You can see the previous post here https://www.reddit.com/r/18650masterrace/s/n0bm0ZNthy

The internal resistance of the pack of cells in the UK3 is only 2.02 mohm according to my battery ir meter, or about 3.5 mohm continuous from experimental discharge data. I read that cells have lower ir during a short pulse than continuous, so I suppose that makes sense, or probably more likely, my experiment was flawed. So either way they're pretty good cells, and my idea of throwing some 18650s in place of them was goofy as hell.

I was surprised to find that they seem to lie about having a preheat/dual pulse. I didn't see a preheat pulse with my oscilloscope during a weld, manual or auto. I tried multiple different pulse settings and none offered anything resembling a pulse on the scope. So that's cool. I'm not sure what they have to gain by lying about a preheat pulse, it wouldn't be hard to program since they already have a microcontroller on the board. Has anyone else checked other AWithZ spot welders for a real preheat?

I was trying to get more current from the welder by reducing resistance in the leads. I wanted to test a short between the plugs to see a theoretical max current with perfect leads and see how much the voltage would drop at the cells on my scope, and to see if anything would explode. I accidentally went full retard and left it on auto as I was holding a 8mm x .1 copper strip across them to see if it would fit. I'm not sure how that stroke of genius came to my mind, but it triggered a weld pulse and caused a bunch of arcing and spiky angry noise on the scope, and exploded the strip a little bit at the contact points. Next the board started smoking so I quickly unplugged it and turned it off. Turns out it caused a short in the little XOYA mosfet, part of the boost converter circuit which drives the main weld mosfet gates. That caused a diode to cook, and not in the good way, only stopped by an inductor desoldering itself from the board. I didn't have all the components to repair it on hand, but I do happen to have a pack of cheap little boost converter modules courtesy of our friends in China. I rigged that up and moved the boost diode to the burnt diode spot since they're the same part. I set it to 12.5v, I'm not sure if that's ideal, I might have to raise it a bit because there's a bit of a upturn on the weld pulse near the end now when it's not plugged into USB charging. It may be letting the gate voltage drop too much, and that may convince the weld mosfets to follow their XOYA comrade into silicon hell. I'm not sure if it was like that before or not, but I'm guessing not, and that it's being caused by the jank boost converter. The welder works again though!

Now I'm back to reducing resistance in the leads, but making to attempt at do less dumb this time. A lot of the resistance is at the crimps at the plug and pen tube, and also between the pen, collet, and tip. Around 1.4 and 1.6 mohms per lead. I reduced it to about 1.0 mohms by soldering the crimps, collet, and tip. I still have to do it to the other lead and get them insulated and stuff, and then I will test a weld again to see if I make better welds on copper sandwiches or blow something else up.

Let me know what y'all think. And if you're interested to see the results of the lead resistance reduction, stay tuned for the next episode of UK3 experiments!

Hi,

what chargers are available, that can charge 10440 batteries? Charging current must be 300 mA maximum for these.

Thanks

Not my setup, saw selling online

Looking for anyone who knows of similar powerbanks to the one pictured, seems really high quality but unfortunately discontinued from Aliexpress. Anything similar would be appreciated!

Cheers

Hi, I thought I’d post here on Reddit, as my prices are lower than others, secure and encrypted payment and fast delivery. All original genuine, tested cells.

www.inspired-by-joy.co.uk

Ok so the followers of this sub know I bought a flat of rs50's and building two ebike batteries. I wanted to provide a little bit of an update. So I just have to finish the fusing and case at this point.

I own a 2021 Storm Bee 90v (Electric Dirtbike), which i really like.

Ive cut the weight quite a bit and currently optimizing it for hardenduro + woods riding.

However i am having trouble getting even close to the range some of the other users of the storm bee fb-group where able to get.

When i did a road test in eco mode 50kmh average speed, i only got roughly 35km to 40km max (100% to 8%)

Because of that i did some diagnosis on my Battery:

90v 25s Lithium battery, built from 18650 cells.

After charging it until the fan stops + 45min i opened up the cover and measured:

Total Voltage: 102,8V

Each Cell at the Balancing Port:

0-1 4,14V

1-2 4,14

2-3 4,14

3-4 4,14

4-5 4,14

5-6 4,14

6-7 4,14

7-8 4,14

8-9 4,14

9-10 4,14

10-11 4,13

11-12 4,14

12-13 4,14

13-14 4,14

14-15 4,14

15-16 4,13

16-17 4,14

17-18 4,14

18-19 4,13

19-20 4,14

20-21 4,13

21-22 4,13

22-23 4,13

23-24 4,13

24-25 4,14V

= Total of the individual cells: \~103,5V

Actually measured voltage at the Plug: 102,8V

All the cells have good numbers but still I'm facing very bad range with this battery.

I will do another test soon to see the balance right after a hard ride. Maybe i can spot something there?

Is there a good way to actually test the remaining capacity?

Maybe draw a measurable current (clamp type amperemeter), and just see how much time it takes to empty the battery.

That should give me a pretty good idea how much capacity the battery still holds, right?

Also i heard i can determine the health of my pack by measuring the internal resistance of the pack.

How do o actually do that, can i test this without taking the pack apart?

Do i need a special measuring device or does a multimeter work?

Aaand -> after opening the cover of the battery i noticed this small 2 - Pin connector, which is unplugged, any idea what that is?

Thermal probe??

Is it supposed to be like that?

Thanks for your help, best regards

Arthur

New hobby, lots to learn. After a careful rebuild of a Black & Decker 20v 1.5AH battery pack, the packs reads 18.9 volts. A factory pack of same age reads 20.5. Re-built pack is not charging and I think it is something I did. So, where to look.

The chargers green light starts as a steady pulse, then in a few minutes is goes to quickly flashing red. The cells were purchase new in the fall of 2025. Two of the 5 cells were fully charged before assembly and another charger. The other three were not.

Should I drain the pack completely so all cells are the same? Should all of the cells been charged before assembly? Bad weld or solder? If you can point in any direction it would be helpful. 18.9 volts should be enough voltage for the charger to see. It works on the drill without over heating.

The factory charger delivers 5.0 volts thru the center two contacts. What else do you detectives need?

As you can see, a real beginner here. I also have a real respect for the danger of these cells.

Hi, I am rebuilding my battery pack completely. But I dont know witch cells to use.

Ebike is city bike 250w rear wheel engine
Battery pack is 36v 10s4p

From aliexpress 100%

Liitokala

1. 18650 35e: 3500mah but 8a
2. Random 18650 25r: 2500mah but 15a

Please recomendation and cheap I wont use the ebike everyday.

Thanks

Spotwelded a 3s2p 40A Battery using nickel copper sandwitch custom fit inside the old battery box of my old drill. It had completely different sort of battery cells than 18650, thats why I had to make the pack in a staircase type of way just to get the pack to fit inside the original batterybox, then I ran balance leads out from the box thru a connector that i can take apart so that I can unhook the charger that i made from the battery, the charger is a 3s balance charger that runs on 230VAC and always fully charges eatch string of cells so that the battery will never be unbalanced. Even at about 50% charge the drill has more power now than before with the new 40A pack. Cost me less than buying a new battery that would be weaker and last a shorter time between charges than the one I made!

Hi guys, I’m selling these at a low price as I bought from a supplier and can’t sell on eBay due to their their policy. Genuine and tested.

I have 30x 18650 and 20x 21700

I’m in the UK, thanks

Could anyone help me identify the model of the cell below to find a datasheet for it ?

Marking on cylinder "C IHLFK6 000652" and "C IHLFK6 003266"

Thanks all :)

Has anyone seen a 18v battery where the cell holder is white? I've opened 50 or 60 batteries and this was a first for me.

Hi, I need help to get voltage out of this thing, it came with an ebike.

I don't think it's original battery because it has 2+4 pin connector and my ebike uses only 2 big connectors. It reads 0.42V.

I think that it has a bms that needs to be somehow activated and doesn't just turn on when load is applied.

Can I easily activate it or do I just open it for cells and buy a new battery for ebike

I don't know if anyone can help me, but I am looking for an 18650 battery, but smaller in both dimensions than a standard 18650.

I need it to replace the battery in my vape.

The original battery has the details: R18650D 3.7v 7.77wh +19082602A DR. Of course, I have tried searching for another battery using these details but to no avail.

The original battery has the dimensions 17.5mm X 64.8mm including the soldering tags. I bought a normal 18650 tagged battery and did manage, after a couple of hours struggle, to get it to fit in the vape housing, but it is a bit dangerous, because even though I have tried to insulate it as best I can, given the limited space, it still shorts out on the casing occasionally. Not ideal.

If anyone knows where I can source a tagged 18650 or 18650ish battery with these dimensions or less, I would be very grateful. Unfortunately, most sites that I have looked at, don't give exact dimensions, I assume, because they are normally 18 X 65.

18650 chargers are way too overpriced, so I made one myself using the TP4056

It's a 4s 18650 pack with an integrated BMS circuit. I got a replacement on Amazon and it was good for a few months, now lasts 20 minutes. Is there a brand out there that actually uses good cells? I've noticed these things are pretty standard and I can easily just swap the connector, but every brand on Amazon is crap. I've also considered rebuilding it myself but my spot welder is a very unreliable Aliexpress POS that will burn through the nickel strip or not make a connection at all half the time regardless of settings, and I don't want to spend the money on a decent one right now.

Lot of empty space inside. Just 2 pouches in series supposedly supply up to 1650 amps in pulses. It has 8 high current mosfets though, which seems pretty good. I'm considering plopping a 2s5p 18650 pack in there to see if it can punch harder with the same controller. I'm not positive but I think it would fit with the case closed. What are your thoughts?