r/18650masterrace

Good %insert_time_of_day%! I bought an old e-scooter (moped?) kreidler florett 1.0, with a 3000w wheel-motor. It runs on a 48v acid battery pack. The battery no longer lasts more than 10 km, so I need a new battery and the price difference between 8 acid batteries and a new li-ion battery pack is not that high as to not to try my hand in spot-welding.
I ran the idea through some AIs, got the basic idea of it, but still would rather have a person give their opinion on it.
I have 13s8p pack of 21700, BMS 100A (120A got canceled and I was pressed for time). Printed a battery holder out of PETG (ABS was a beach to print, failed 8 times with enclosure and heat soaking),
My main questions are:

1. Do you need the fish/barley paper between the cells even if there is a 2mm gap between them?
2. Why do people silicone-glue the pack from all sides (water resistance?) even if they then put the pack into a plastic case and then, sometimes, into another metal case? There is no way that water will get into the battery, and if it does, then that means the scooter is in a river.
3. Is pure nickel strips (0.2mm) really necessary? It is a beach to find pure nickel strips, but AI says that I should NOT use Nickel plated steel.
   Looking forward to your input and thank you in advance!

So for a long time, I was debaiting wether or not to make/buy a spot welder.
I'm planning to build maybe 5-10 packs of different sizes, not too big (max. 6s4p).

I first tought of building my own spotwelder using an old microwave transformer and arduino to control. I'm not really sure if it's worth the danger if a 50$ device can do the same thing.
I heard about the AwithZ devices and that they're apparently great, but at 150$ I can't really justify the price as it wouldn't be worth it to build my own packs.

I'd be glad to hear you're thoughts, maybe I'm just not thinking it through, anyways thanks in advance :)

Ok this is so bizarre. I sell /service ebikes and this was the last of 10 identical bikes i unboxed and assembled this last one - it had sat in box maybe 3 years... plugged in charger and it was charging normally, voltage increasing. (oem charger that came with bike)

Came back to it after a few days (was super busy) and found the battery reading 78 volts.

Unplugged the charger and battery VOLTAGE STARTED CLIMBING AND KEPT CLIMBING UP TO 84 VOLTS!!!!

Yes I was absolutely ready with door open at this point to throw it out, half expecting bad things to happen.

nothing happened. battery is cold. no heat, no noise.

Tested Charger w/no load - 78 volts output!!! wtf? the others do not do this - should be 56v.

Im just posting this right after this happened. IM going out with a large resistor to discharge the battery but i have questions - hoping someone has seen this before.

Guessing this is due to faulty charger, not battery... will test further.

Is there any chance the cells are NOT damaged at this point?

Shouldn't the BMS have stopped the incoming high voltage? is that not a normal protection even on cheap bms?

(this is a cheaper chinese ebike but they do have high quality LG cells and the batteries are well constructed - i have torn one down before to know this).

Thoughts & warnings???

My ebike's battery is getting tired and it's time to get a new one. I was just going to buy from the manufacturer cause the amount I would save building my own 18650 pack is not worth it. But I recently learned that Samsung 58E 21700 cells can be had for half the price of the the 35Es that would be equivalent to what's already in my pack, have higher discharge rate and more capacity obviously.

I'm content with the with the capacity I currently have and so building a pack with only 39 cells instead of the standard 52 for 48v packs would be more than enough. I don't wanna design and print my own box, I'd prefer the space saving of a smaller case, and I'm weary of the structural integrity of partially filling a case.

Has anyone seen a box designed for 39 cells in the wild?

Where do u usually buy ur battery component (not speaking of cells) ? Speaking of pure nickel strip, spacer, battery case, .. ?

Needed a single cell today. Flat non protected 18650. Would have been $13 with shipping but paid $8.60 for the cell in person. Their wholesaler is 18650batterystore so I know it's a legit cell. Im just glad I can finally pick cells up when I need one. Getting them online is still the best option if I need multiple cells so this is more of a single cell thing.

Hey yall,

I am new to this sub and fairly new to working with these batteries. I am wondering if anyone has a decent charging module rec for a 3 cell pack. It is for a usb-c rechargable lamp that I am making. The lamp uses a G4 socket and while I have found one G4 that can work off of a single cellat 3.7v, It is just no where near as bright as a 12v G4 and I really want it to be as bright as possible while still being usb-c rechargable. I purchased a pre made 3 cell pack off of amazon that came with a barrel jack attached, but really need it to be able to charge off of a usb-c input on the lamp, or I will have to resort to the dimmer 3.7v circuit. If anyone has any recs for a decent charging module It would be a lifesaver!

Maybe welder was too hot but I blew a hole on a 18650 battery and I see blue.

How do I go about disposing of it. No jokes please, it's a real safety question

i'm planing to make 6s Li ion battery for my 5" drone. here is my setup:-

Mario5, F405 V5, v2207 v3 1750KV, weight 512g without battery and gopro, hover Amps 10-14A with R-line 1550mah 6s battery 256g (total=770g)

For battery i have 2 choice, EVE 50PL and JP30/Newbeedrone 3000mah. i am confuse which way should i go..

18650=> 3000mAh, ~300g

21700=> 5000mAh, ~420g.

Is this 2000mAh valuable over extra 120g weight? should i choose 21700 for high Amps discharge OR 18650 for lower wight. (cruising and sometimes fly with action camera)