r/18650masterrace

Partner let their battery sit uncharged for months. Almost tossed it out.

I was looking at the new EU Battery Regulation (EU 2023/1542) coming in Feb 2027. Under Article 11, portable tools will basically have to move to user-replaceable batteries without destroying the casing.

Look at the most frequency use mini 4V Tools like electric screwdrivers, hot glue guns and mini rotary tools, they all sealed in batteries.

It seems US doesn't have anything like that yet , I honestly think this is the right direction to go.

Swappable packs solve three problems in my book. First, you don't have to stop what you're doing and wait for a charge, just slap in a fresh battery and keep working. Second, with a built-in battery, if the charging port breaks or the cells eventually die, the whole tool becomes e-waste even if the motor is still perfectly fine. A removable pack avoids that entirely. Third, just like the 20V platform, you'd only need maybe two or three 4V packs total, because you're rarely using several 4V tools at the same time. Plus you don't have to pay for a new battery every single time you buy a new tool.

The only trade-offs are a slightly chunkier handle and having to buy that first battery pack upfront when you get your first tool.

Do you think a unified 4V swappable pack makes sense, or is 4V just too small to bother？

I posted this on r/tools yesterday, some DIY experts strongly recommend designing the tools to allow direct replacement of the 18650 cell itself, rather than making a proprietary pack. But is it really practical to have 18650 cells in power tools swapped out like AA/AAA alkaline batteries? I know that people with the right skills can easily replace a cell with a soldering iron and a spot welder, but what about the majority of users who don't have that equipment or those skills?

0.15 copper and 0.1 nickel plated.

8AWG and AS150 connector

JBD 100/300A

made for Ninebot G3

I did a bms swap from the old JBD 100/300a to the JK 200/350A BMS, the main reason was bottleneck issues, the Tenpower 50XG were never warmer than 35° on the jbd and on the first run with the jk they reached it, so they dont feel as wasted. But my jbd was in fact also defective showed 100mV difference the entire time while everything was fine on the JK. Also redid a lot of bad soldering and have thicker wires now (from 10awg to 8awg). I also redid balance leads and now my vescs fit better in my scooter and I can probably decrease the spacer size!

Also left a small easter egg ;)

No balancing, crappy design. This one was unnecesary hard to repair. Positives: samsung 30q, copper cell links.

I bought 14 of these packs for about €40 in total, which gives me 280 cells. Each cell is rated at 2,000 mAh and around 10 A, I think. Every single cell seems to work, and they all held their voltage for a month.

Now I want to build something useful with them. I can buy used women’s or commuter e-bikes without batteries for around €100 on flea. They usually have a 250 W front- or rear-wheel motor and are limited to 25 km/h with pedal assist . There is also bikes with mid drive motor but i thing they are more prone to fail and dont want to gamble on them

My idea is to build a battery pack for these bikes and install a different controller with a throttle, removing the pedal-assist system.

I also have a spot welder and know how to make battery packs, how many volts and and how many cells should i use

A neighbor of mine had their electric mower battery charger flash red and green on them after mowing, signaling battery fault. He started taking it apart thinking he could fix it, but couldn’t. It sat on his shelf for a year or two. I disassembled it to salvage the cells and found that all except three batteries sat at 3.5V +/- 0.5. Three of the 30 batteries were at 2.9V, which probably caused the charger to indicate a fault.

I’ve graded 12 of the 30 cells, and they all have between 15-30 IR, and 1800-1950 mAh capacity. The 2.9V cells show no difference from this average. No idea what could have caused the imbalance in the battery originally. The 3x2.9V were in bank 7 of 10 in the Ryobi battery. I’m going to let them sit for a week or two at 3.6V and see if they self discharge.

Now I have a bunch of lion cells with nickel tabs spot welded on them.

What do?

I’ve got a question about nickel tabs. I’m designing and building a 13S9P pack for an e-bike conversion and I’ve got the pack and cell holders designed but I’m down to the tabs now. I’ve got access to an industrial spot welder at both work and home. Work has a nicer welder than what I have and mine isn’t set up yet. It’s a Miyachi Unitek 250 dual pulse. The pack I am making should be able to put out 40 amps. I’m looking at bafang mid drive conversion kits at either 750w or 1kw. Due to how custom the pack I’ve designed is, I’ll likely need to have tabs custom made for me. Would 0.5mm tabs be plenty of material across three contact points? I had originally planned for 0.3mm tabs but after some extra research I don’t know if those will suffice. I’ve already practiced welding a stack of x3 0.15mm tabs and it welded it nicely. It welded x2 a lot better and it had a much better weld though. Each bank of cells will be in a 3x3 square connected to the next 3x3 square either in a straight line or in an “S” shape.

here is what the model of the pack and tabs look like: https://imgur.com/a/ouvjzHy

Have to do like 8000 welds for my ev battery so ergo mod for the welder

This is taken from the deep dive trailer today. I can’t tell if it’s reskinned heatsink or something else

Are those plastic rings enough? Or do I need fishing paper for Extra insulation?

This is a Li-Ion battrey holder I got online and both of them have a copper thing missing. I am sorry if this a stupid question, this is my first time working with circuits.