I got 18 ni-cad 1.2v 5000mah cells from my dad's work in hvac. I normally make portable battery packs with USB c and wireless charging. There d battery size and I don't know if it's worth it to try and use. Open to ideas.

I managed to score a lightly used 10S3P ebike battery with genuine MJ1s as faulty for £15. Of the 30 cells, 22 were OK (6 were dead and 2 I damaged during extraction), and capacity is basically reading same as a new MJ1. Not bad for 68p per cell!

I want to use them to build a 10S4P pack of MJ1s, with BMS of course. I'm wondering what the best way to match them is. I know for a new pack you want to match on mAh within parallel groups. Should I keep the salvaged cells and the new cells in separate groups - i.e. 20 salvage cells + 20 new cells, with the first 5S4P being salvage and the second 5S4P being the new cells?

I have a couple of 36V battery packs for power tools, as well as two 36V ebike batteries in the household, so it makes sense to be able to use these as powerbank. Espcially the power tool batteries, the ebike batteries are large, still on a camping trip or emergency, it would be nice to use them as a power source.

I have a few USB PD charging boards, but sadly noone that can handle up to 42V input voltage, and I have been unable to find any that does. So I bought a DC-DC buck converter from aliexpress. It's a cheap item, but it works - /item/32693058807.html

However, there is a spark anytime I connect it to a battery. This is probably due to a high inrush current to charge the input capacitor, googling tells me. Apparently you can buy special anti spark XT90 connectors that are popular in the RC community for just this reason. But that adds another connection in the flow which is unnecessary, and as I want to make a somewhat proper adapter, that slides onto the 36V battery it would not work with that.

As the DC-DC converter was very cheap, I don't mind replacing it. Does anyone have a tip for a DC converter that has some inrush current protection? It does *not* need to be adjustable. I only need it to accept up to 42V, output of somewhere between 22V and 24V and handle 5A. ideally as small and efficient as possible, but rather <10$ than super efficient.

I have unprotected 18650 cells and want to use them in a parallel configuration such as a 3.7v 1s3p for use with a little esp32 lora board.

Started out thinking this is simple enough to safely put together but..The more I search for answers the more confused I become.

Essentially I want to safely use 3 cells in parallel and the search results have me wondering what is the BEST way to assemble this pack.

Some things I've read in my search for the best answer are:

• don't do it , buy a bigger battery

• it's fine as long as they're good cells with same internal resistance

• wire the cells together and use a tp4050 charge module

• use protected cells

• fuse the cells

-wire them together and get a bms (when I search 1s3p bms for example I don't get results. Mostly for 2s or 3s etc which I don't want)

Some of the things I've learned throughout my searching is that:

• over charge & under voltage protection is important

• short circuit protection & current limiting is important and should be spec'd slightly higher then load's max current draw

• cell balancing occurs by virtue of the parallel configuration (unlike series packs) so using closely matched cells is important.

So, what to do? Is there a clear cut answer or am I missing some "key word or phrase" in my search.

Hoping to find a solution , thanks on advance!

Is it considered faulty?

I bought a device that requires a 18650 battery and I can't figure out if it needs a flat top or button top. Product information only states 18650. Is there a way I can tell? Like does the connection part look different for one or the other?

TIA

I’ve recently learned about 18650 batteries, as we have a client whose costume requires these batteries to operate. The costume has a battery pack that accommodates 6 of these batteries. We purchased some 18650 batteries from Amazon, but they don’t hold charges for long.

I’m looking for more reliable batteries and discovered this subreddit. Could you provide a link to where I can purchase suitable 18650 batteries for this pack? I’m particularly confused about the different top and bottom designs. For instance, would this Panasonic model fit the battery compartment: https://www.imrbatteries.com/panasonic-ncr18650b-3350mah-4.87a-battery—protected-button-top/

7s5p 10ah. Yes I know it's not pretty. I leave the tabs on the recycled cells so I can use them to solder to so I don't heat up the batteries too much. I wanted to fuse the cells in parallel, as well as series. I think this accomplishes both. Still waiting on a bms. Max draw for this pack will be 30 amps. I used 30 awg fuse wire which pops around 9 amps so the series fuse would be rated for 45 amps. Cheers

I followed many recommendations and bought an Opus BT-C3100 on Amazon. It came today, I tossed in some cells, and all seemed fine.

While they were charging, I decided to do something for my own peace of mind, and probed the cells in-situ with a multimeter to make sure the voltage reading on the display was accurate. Lo and behold, the actual voltage of all the cells was around 0.12V higher than what the display on the charger was reading. This included a cell that the charger said was 4.10V, but was actually at 4.22V, all while the charger continued to charge it. I tested with a second multimeter to confirm the readings.

I'll be doing an exchange and hoping I get a properly-working unit this time. I'm glad I manually tested the accuracy of the charger, and invite others to do the same!

(Edit: Number typo)

I just picked up 6 of these button top protected cells that I was intending to use as an upgrade for a few flashlights that take 18650 batteries. All the safety documentation that came with them have me second guessing myself about how to go about actually using the cells. Besides the documentation stating that they shouldn't be used individually is there any other reason why putting these in a flashlight would be a bad idea?

Had two 10s2p blocks fall into each other creating a sparking/welding event. After getting them separated I checked voltages and most were .1 to .2 volts lower than what they had been; from 3.5 to 3.4 or 3.3. plenty of scorch marks and burnt plastic coverings. Should I assume these cells are compromised? Or is there a way to check?

Application for the battery pack would be a 1wheel so I don't want to put a pack in that could suddenly die on me at 50% due to a bad cell.

I bought this thing on AliExpress: https://www.aliexpress.us/item/3256805947360847.html?spm=a2g0o.order_list.order_list_main.5.70a21802qMy8Xy&gatewayAdapt=glo2usa

I put batteries in it, turned it on, only to discover that it has a timer built into it! It will not STAY on. Meaning, whatever devices I have plugged into it also won't stay on (or charging).

It's infuriating. Whoever designed this thing should be shot.

I don't have the tools or the know-how to buy the parts and put one together myself.

Does anyone have a recommendation?

Good evening.

I am building a replacement battery pack for Phat Scooter. The original battery pack is 18650 20s5p, but an unusual form factor - so I could not find a replacement.

So I decided to build it and increase the power a bit. The original cells were 2400mAh, I am using Samsung 35E, 3500mAh. Also opted for JK BMS as they seem to be highly rated.

Assembled it using kWeld spot welder, so far so good. All seems reasonable, except - the pack seems to be loosing about 0.1V a day - with no load connection. Is this normal?

(Also, the BMS is making very quiet ticking noises, but nothing loud). see the attached photo of the pack (I did not wrap it yet) and a screenshot of BMS App.

I would appreciate any comments or suggestions.

Thanks!

https://preview.redd.it/k236h80l6qwc1.jpg?width=1080&format=pjpg&auto=webp&s=b9b871cc5cf4681a16a744360fc5b59696e69de2

https://preview.redd.it/mpkw770l6qwc1.jpg?width=2016&format=pjpg&auto=webp&s=10b2631846b47bcf665a01699e56863783843a97

I bought 2 new 18650 from onlybatteries.com and one is 3.83v and the other is 0.9v. What should I do. I'm trying to connect them in series

Update: I charged it up to ~3.3v and then connected them and they appear to be working. I also called them and they said to just charge it.

I have a 6S battery pack. The spec sheet for the individual cells says they have a “Standard Charging Current” of 0.5C (1.25 Amps) and a “Peak Charging Current” of 1.0C (2.5 Amps). For various reasons, the pack is not balanced.

For my 6S pack, is the standard charge current still 1.25 Amps or is it 6x (7.5 Amps)?

edit: fixed units. Thanks /u/Baselet.

I'm using Liito cells. Overall package comes at half the price as a store bought battery.

Like the title says. I have a 13s Daly BMS that I would like to use on a 10s pack. I think Daly supports this I just don’t know if you leave the last three wires disconnected or connect the top most wire leaving a gap for unused wires. Any suggestions would help.

I'm wanting to put some 18650 rechargeable batteries in a few guns but I don't know what BMS to get can someone give me some recommendations? Each gun takes 6aa.

Battery tray.

Choosing batteries for a 20s4p build. The continuous current will be 30a (from one cell 7.5a), short-time current 75a (18.75a).

Which one is better to choose molicel p45b or samsung 50s.

The second option will win due to higher capacity. But it seems to me that at short-term current 75a, voltage sag will be more in 50s. In the end the distance traveled will be about the same, because at 5% battery charge 50s will give bms shutdown faster due to higher sag?

p.s Charger with what current is better to take, for example, under molicel (4.5a normal), 4.5a x 4p = 18a, 18a x 0.7 = 12a? Is it possible to charge with a lower current of 5a?

Sorry for my English, I'm writing through a translator

Hello! I'm fairly new to this stuff but have been wanting to try to disassemble an old portable charger to repurpose the 18650 battery. Currently the battery isnt charged.

For some reason I cant post the pictures, so I'll have to describe it I guess. The battery is pink and labeled: ICR18650-26H M SAMSUNG SDIEM TEW3

The device itself is very similar the one shown in this video ( https://youtu.be/nidrrMN7I9I?si=jSKZlCWjC1SNAd2H ), however the wire to the negative end is shorter and soldered to a long metal strip thats bends to be stuck to the negative end (not attached to the side of the battery). The positive side wire is similarly soldered to a metal strip stuck to the battery, but the strip is short, roughly the the length of the battery's radius. I'm unsure how the metal strips are attached to the battery as they are seemingly just stuck on flat with no signs of spot welding.

My main question is how could I go about getting everything off the battery safely/is that even possible? I'm aware these batteries can cause a fire/explode, so I want to be careful! Sorry if this is a dumb question!