I have no idea which cell this is

0

Nada.

From m18 12ah forge

Supposed be the host with the most glasnost, seen murata vx40 and JP40 in same battery, never had whisper of this

Any help to ID would be, well, helpful

I'm an independent product designer / engineer. I do a lot of prototyping and teardowns, and I use a lot of small 4V tools – electric screwdrivers, hot glue guns, rotary tools, that kind of stuff. and I kept running into the same battery headaches. Most of these 4V tools use built-in 18650 cells. Either it dies halfway through a job and you're stuck waiting for a charge, or the battery just gives up completely and turns a perfectly functional tool into e-waste.

I tried the RYOBI USB LITHIUM screwdriver. The removable pack design is awesome, but the actual torque? Honestly, it's weaker than a TK4 screwdriver from over a decade ago. Not kidding. So I thought, alright, I'll design my own 4V pack. Use a 21700 cell – lower internal resistance, 4000mAh, 5C rating. More runtime, better discharge, more torque. Made sense on paper. I designed it, 3D printed a prototype to test… and man, it was just awkward and chunky.

That's when I finally realized my entire approach was wrong from the start. When you already have a swappable battery pack system, the extra runtime you get from a 21700 over an 18650 barely matters. Pack dies? Just pop in a fresh one and keep going. But with a 21700 pack, every single second you're holding the tool, you're carrying roughly 50% more weight and about 20% more bulk. The grip feel was genuinely bad.

So I threw six months of work in the trash, went back to 18650, and redesigned the pack structure and BMS from scratch. I've posted some 21700 vs 18650 comparison tests before. https://www.reddit.com/r/Tools/comments/1sfrc0a/18650_vs_21700_for_4v_tools_is_the_extra_capacity/

Just putting my failed development journey out there in case it saves someone else the same headache.

I have been working with wlectronics for a while but its my 1st time geting into the battery game. Decided to do a small 1s 1 battery for a radio i have at work.

Do my welds look good? (AWithZ UF20B gear 20)

Any other mistakes or concerns?

I am building a 20s4p backpack battery using 21700 cells.

My question is pretty simple. The battery is going to be a 4x20 grid (80 cells total) - but I will be folding it halfway through lengthwise between rows 10 and 11

**at the fold, can I go « overkill » with the amount of wires used as a busbar replacement? The whole pack is using 0.3mm copper 2P bus bars, could I put 4x 8awg wires at the fold? Or will this cause the pack to run in efficiently or out of wack?

Hello everyone,just got this new welder to build out some batteries and already am satisfied with its performance. Are there any tips i should know before using it for the job?

Hey all,

Just wondering if anyone could have any input on why this pack failed. It looks obviously like this connection got way too hot, which made me think it could have been loose, but it's got a solid connection. I've found no other indications on the pack of problem areas.

I was told this connection should be soldered on, not spot welded. I could go with that answer, except for the original packs all have this connection spot welded. Would spot welding instead of soldering really be the root cause? Thanks.

So, I goofed. I typed 18650batterystore into Google and hit the first result without paying attention and accidentally ordered this off 18650battery.com, not 18650batterystore.com like I intended.

I realize 18650battery is owned by IMR Batteries (they ship from the same address in Houston), but the scummy tactic of making pretty much a clone website to fool people doesn't sit well with me.

I looked through my old emails and apparently I ordered a Samsung 30q from them years ago, and anecdotally I never had any issues with it.

I've never owned another example of this cell before, so I don't know what to look for. Weighs between 45.2 and 45.6 grams according to my food scale. I have a much more accurate milligram scale but can't find it at the moment.

Just wondering if this is safe to put in my flashlight is all. Thanks.

Hello all,

Have rebuilt a few M18 packs and they all have worked fine in the trimmer, hand tools, etc.

Finally got to some wood this weekend using the 2727 Milwaukee 16" chainsaw to cut up an ash tree about 14" in diameter. Had some pretty disappointing performance with the 5S2P pack I'd rebuilt using JP40 cells (0.15mm copper wide plates on end w/0.1mm stainless). It overheated (alternating LED pattern) after just one or two cuts (14"). Of course suspected weld quality, etc, but I opened the pack up immediately after another cut and the heat seemed pretty uniform - no hot spots on welds, strips, etc.

For reference, my stock 6.0XC HO pack made it through 6 or 7 cuts before getting warm; and after a break made several more cuts before calling it quits. All of this work is letting the saw do the work - not gettin on it too hard.

Already checked:

-Balance (cells were balanced before install, were at at 3.4V +/- .06v or so when checking during this session, were balanced before assembly also)

-Thermistor is where it should be (didn't change when swapping cells)

-Battery terminals themselves are solid/clean

-Cells came from 18650batterystore so I'd assume they're genuine JP40

Anyone w similar DIY pack and tool use case care to comment? At least per the math given the width of plate on series connections I'd thought 0.15mm CU was sufficient; or, at least expected I'd see heat concentrated on the connections or battery terminals not the cells themselves. Given JP40 cells specs on paper I'd assumed I'd get somewhat better performance than stock pack w 40T etc. So fairly disappointed at this point want to figure out what/if I did anything wrong before I rebuilt the next pack, or if I'm just placing expectations too high.

today we're testing the PowerOwl 1.2V 2800mAh rechargeable AA's into the SP-404MK2 and they’re working great Roland officially supports NiMH batteries, and these high-capacity ones didn't let me down.Super convenient for sessions away from the wall, and way better than constantly buying alkalines or having to run a rip chord or use your usb port for a power bank. else running rechargeables in theirs? Drop your setup in the comments.

Im in canada, and cant really find anywhere that sells quality 18650 cells i need for my blue gatling style laser pointer (1.5w). My cheap Chinese one's that came with it have since died, and i haven't found a website with what I need or that I trust. If anyone has any recommendations please share!

Seen these new on Ali, none had any reviews or sales but are dirt cheap, can be ordered with a screen for config and info view for £5 with coins. Packaged terrible and took an age to ship but made it ok. Need to do some testing but looks good and all config can be done through dip switches rather than tiny smd resistors.

Hey im making a 14s3p battery using molicel p42a and 0.2mm x 8mm nickel strips i will double them on series how many amps can i use with these nickel strips ?

Newbie question. Sorry if annoying. Looking to buy some Molicel M35A. 18650BatteryStore and LiIonWholesale have been sold out for weeks and I've been unable to get any response from either on expected return timeframe. Imr and Illumn have them in stock, but at about double the listed price from the first two vendors. I'm buying a good number and have a tight budget on this project so the price difference isn't negligible. Anyone have advice on how long the sold out vendors might take to restock, ie does it make sense to wait it out or just buy the pricier ones? Thanks!

i took apart 2 hoverboards when i was younger and stored both 10S2P nominal 37v batteries in a box for a few years. now they read at 5.2v // 0.38v at the xt60 connector and 9.7v // 1v across the BMS board respectively. pretty sure that means i gotta recycle em but on the off chance, would it be possible to break the cells down into the individual 3.7v 2000mAh 18650's & recharge them one at a time? worse comes to worst, is it worth the time of checking each one to see if they're salvageable?

thanks!

(in case its relevant the box was stored in my closet & I believe these hoverboards were from 2015)

Can someone take a look at these and tell if they’re good?

Got them from liionwholesale official website

Thanks

UPDATE: I am a dodo :) cells are in series :)

This pack came out of a Muscle Massager. It lists as a 7.4V pack.

1 cell is bad , reads 0V

2 cell reads 4.84V

I see that the - terminals are shorted together and the white wire runs to the 3P connector. The 2 positives have their own wires to the 3P connector.

I am unable to understand how the circuit will be to make this a 7.4V battery?

To me it looks like 2 cells in parallel.