how the hell do i charge this thing without it blowing up?

Hello 18650masterrace subreddit !

I am currently in the process of building my first 18650 battery pack. I have a AOVO ES80 (Xiaomi M365 replica) and I've had it for 2 years now but the battery simply doesn't hold the charge anymore.

I have decided to build a new pack instead of buying a pre-made chinese pack (cost 130-150€), I figured might as well build my own. I have a background in electronics (took classes in highschool) so I am familiar with soldering, basic electric knowledge, etc...)

The old pack is a 10S3P 36v 10Ah pack. Composed of 30x 18650 cells. Reference : ZK-INR18650 - 3.7v - 9.25Wh - 2500mAh (that's what's written on the cells.)

I've bought the following stuff :

• 30x INR18650-30Q 3000mAh 15A cells on nkon.nl
• Kapton tape
• Shrink Wrap (for the pack)
• Insulator Rings
• Insolator Paper
• Foam pads (to wrap the pack)
• PURE nickel strips (not nickle plated - 0.8mm wide, 0,2mm thick)
• Portable spot welder (tested - works well)
• Glue gun

stuff I bought

I am only missing 18650 holders, I wanted to print them but I need to configure my 3d printer properly first.

This is the old battery pack

top side

bottom side

current bms

I intend in using the current BMS in the new pack. I think it provides a max output current of 10-20amps. Shouldn't stress the batteries since the pack can theoretically output up to 36v 45A.

I come here for advice before building my pack and I will take any help I can get !

Thanks

So here I have a sanyo NCR19650GA, it’s under a year old and today I noticed a weird stain on the battery sleeve/wrapping it looks wet but I have never got this battery anywhere near water or any other liquids What do you guys think about this

I got a bad batch of outdoor motion activated solar security lights and they all have bad purple cells marked Hongli logo. No other markings. They all eventually refuse to discharge to full amps but show a voltage of fully charged. If I plug them into the solar light the light glows dim. Same for swapping them into a flashlight. If I swap them for a good cell the light is fully illuminated. So these are trash and Im now in the market for some more good cells but the internet either wants $6 a cell or acts like I want drugs.

So I am looking to retrofit an old 80's toy (big trak) with 18650's since I have a ton of them kicking around and chargers etc.
Originally they took 4 D cells in series so I am assuming best case/best original batteries 8000mah
I can easily fit 6-9 18650's with plenty of room left for a voltage conversion board without having to modify the original battery compartment.
So the question is....worth it? I remember being a kid and it would tear through a set of Alkaline D cells fairly quick so I figured maybe it would be worth switching in something rechargeable that I already have lots of (I have probably 50'ish 18650's.
Also any suggestions on best theoretical arrangement of series/parallel and decent V conv board would be awesome.

I regularly use unprotected cells, so I typically have one or two on the charger most of the time. I have a decent charger, but I'm cheap so I probably use some cells longer than I should (I did finally get some silicone sleeves for transport, so that should reduce damage anyway).

I know it's not recommended to leave cells charging unattended, but that's hard in practice. What are good safety solutions so that the place doesn't burn down? Putting the whole thing in a metal toolbox?

I guess I've probably answered my own question, but anyone have any better solutions, or other experience?

I got a vacuum robot with a broken battery, the cells where around 1V and it was from 2013 so I figured they died because of age. I replaced the 4 cells but not the 4S BMS, and the robot was working for around an hour before needing a charge.

Fast forward around 20 charging cycles and now the vacuum has to recharge every 20 minutes or so. What could be the cause of this? Thanks.

I recently bought a Towild BR-800 bike light 4 month’s ago. The stock battery that came with it won’t charge anymore. Meanwhile an older 18650 no brand cell from an old bike light (now broken) since 2020 still works and charges on the Towild bike light.

Hi, I know this is the 18650 subreddit but have a relevant question on sizing nickel strips. But I may make up 18650 packs some day. How do you actually size them appropriately? Do I need a calculation or is there a chart somewhere? I'm replacing the AA cells in a ski boot heater. Its 4 cells, 1.2Vx2000mah cells. I think I need to know the total amps the pack is capable of.. Any ideas?

Thank you

Edit: I forgot I need a spot welder too, looking for recommendations on some that are relatively affordable. My battery pack came with 4mmx0.2mm strips, but a lot of people say their spot welder won't work well at 0.2mm thick.

While charging and the battery gets near full charge, cell group 9 gets a higher voltage then the other cells. When stopping the charging cell group 9 instantly drops back down to the same voltage as the other cells. The cells are brand new. Why does this happen?

I have a light installation with 200 individual devices running on two 18650 batteries each. From spring to fall i set it up about once a month it runs for one to five days, then i take it down, charge the batteries, set everything up (put the batteries back into the devices) and set it back up a few weeks later. But now it is november and i‘m not doing anything til at least april. Now: what is a) the best way of storing them? Is „in my bedroom closet“ fine or is there a better place? b) a good storage container? I don‘t want to accidentally burn my house down because two batteries shorted each other while lying in a pile..

I have a bunch of Sofirn 21700 with

• Max discharge: 10A
• Max charge : 3.5A ( Base on website )

I saw on Aliexpress has the diy powerbank can support 100w+120w+120w input and output. They said it can hold 24 x 21700 in 4s6p, and I have no idea how to calculate the total input and output my batteries can support. Please help me. Thank you all

Hey everyone, incredibly new to this hobby. I've recently swapped out my scooter battery and would like to convert the old battery into a battery bank, ideally with USB charging and AC out for charging a laptop. I swapped this battery out since it couldn't hold a charge (assuming a few of the cells might be dying). Does anyone have recommendations for me to learn more? Thanks!

The case from AliExpress, 21 harvested Panasonic NCR18650 (Lenovo batteries), BMS the cheapest from Ali, 100A. DC to PD from CNEX6 (nice and neat), PD to NUC. Power consumption on the standby is just 6W. Will test some software later.

Has anybody done that? The cells are inside a two-piece plastic shell, which I cannot open for the life of me.

https://preview.redd.it/8nm0luba5kzd1.jpg?width=3024&format=pjpg&auto=webp&s=9675e08512b03922e5839fb61288cf13cc0978a5

hi, im working on a project that requires a lot of energy...
i need a huge 12S40P pack, and since it's so big heavy i want to split it into 4 packs of 12S10P

to make it safe i want to give each pack it's own BMS and then i can take 2,3 or 4 packs and connect them together in the system.

my issue is that i can't just plug them together cause if the packs have a voltage difference then one pack will charge the others, the currents will spike, and the BMS of the packs that are getting charge will reach shutoff. that is in case the balance between packs isn't managed

i also don't want to include ideal diodes between the the batteries because the system will generate alot of regen current when running and i want it to return to the batteries...

is there a product like some sort of master BMS that can balance and manage energy between complete packs?

Pulled the one on the right out of a flashlight after no known abuse, and flashlight should have protection circuitry. Surprised to see it from vapcell

I bought these from my local vape shop 5 for 75cad and I'm wondering if it's a okay deal or not I'm in canada

i really want to make two 18650 power banks (one to power a raspberry pi and another to have in my backpack that can charge my laptop/phone) i got a whole stash of 18650s and soldering stuff/wires so that part is covered but im still looking for a case and charging module. i found a module on amazon w a digital display but dont know enough about electrical engineering to know if its the right one.

https://www.amazon.com/gp/product/B0C135H3QG/ref=ewc_pr_img_1?smid=A2PKC8LJIH43BW&psc=1

id appreciate other tips/input or a guide for making one of these lmk.

I have multiple "diy devices" with bms that accept 18650s as power source by mean of mounting it with through hole leaf spring battery holder. most of them pulling max 2A continuously but a electric drill will pulling like 7A for a sec (max allowable current from bms).

my idea is, I can use those Devices with all battery that i have by swapping it between devices and not buying battery for all of the device i have since I don't use all of it at the same time, and a bit of monetary constraint.

but over time it is eating the battery wrapping and should be changed after like 10-20 pulling it off from the battery holder to charge or to swap with other device.

my question is, is there any alternative battery holder that won't eat up my wrapping given the constraint (2A cont, cheap) or there is a way to somehow not damage the wrapping on the positive side everytime i pull the battery out from holder. Also, unfortunately i don't have immediate access to 3D printer.

Currently building a 7s scooter battery. Previously built a 7s4p but the voltage drop was fairly significant still. Motor pulls a max of about 250w at 24v when going up an average size gradient, which sometimes brings the voltage down as far as 21volts. Would another 1 or 2 parralel do the trick?