7 Steps On How to build The Safest DIY Li-ion Battery 

1. Know the maximum draw of your motor 2. Match the current output of your batteries to the motor 3. Ensure bus bars can handle the current 4. Create space between cells to allow cooling and avoid short circuits 5. Know the maximum output of your fuses (Use a fuse from cell to bus) 6. Isolate the entire pack from exterior elements and causes of short circuits 7. Temperature control and insulate the battery pack thermal threars

Thank you for making this video. I think you've saved people from potential injury. Cheers

I appreciate what you have done here. I've seen lots of people making videos but none really explaining so far

Thanks for your info

What a great video. Thanks tons for the info.

The theory in the video is good but it just does not explain what a DIY hobbyists should do. You said to not solder the fuses but unless you have one of those machines you can’t really do it in another way. For small packs it’s okay to not have cell level fusing and just spotweld the pack without fuses. The fuses add additional resistance to your pack and make it a bit more fragile.

many thanks for info 👍👍👍

that fuse machine is amazing

Excelent video!

bro killer video very informal thanks for taking the time to create this.

There'll be a revolution in battery assembly fairly soon. Cylindrical contacts that fit into drilled holes in a sheet is the easiest straight forward way. Cylindrical contacts are basically insulated cables or wires engineered into being electrical contacts. I've been working with a company in the US to bring their contacts to the battery space. Their contacts are originally used for pcb testing in industry. Custom cylindrical contacts can have enough conductors to reach currents as high as 60A. Imagine battery construction like this, 1. Place cells all in the same orientation(positive side up) into a cell holder. 2. Place sheet with Cylindrical contacts which has cell holder features bellow it for alignment and a pcb(pcb can have built in fusing) or foil above the sheet with contacts. Cell holder, sheet with cylindrical contacts, and pcb/foil can all be joined together(bolts or laminating meaning adhesive) becoming one assembly. 3. Screw down assembly with a cover and batteries built with all connections to bms already made. No fancy robot or time consuming welding process needed. Similar cylindrical contacts making contact to cells can also make contact between batteries final pos and negative aswell as voltage sense to a bms within batteries cover. No wires or ribbon cable coming from battery except pos and neg out of bms and something like a couple wires for communicating with an inverter or the like. SSA or single sided assembly, negative connection is made to cells rim on positive side. Allows for one cell holder, contact sheet, and pcb assembly per battery instead of two like with DSA or double sided assembly. DSA is good for high current builds but SSA can also be quite high current just not as easily. Also the cylindrical contacts within a sheet will be many times cheaper and smaller footprint than contacts like leafsprings and aren't soldered to pcb.

Very great video, thanks for that 👍👍

6:55 I could watch this all day

appropriate cell level wire for 2170 packs? best method to put those into a bus size vehicle EV conversion?

Really informative and useful video. Though now I know what not to do, how am I supposed to do it?

Hey great video do you know where I can get these fuses wire

can i ask you recomendation gloves when build battery pack?

So many great points. I can't believe people hot glue their batteries together for ebikes that are going to vibrate down the road, it's an absolute recipe for disaster.

Outstanding video! So many "cheap" no-name commercial batteries DO NOT follow much of this advice! Take a shortcut and burn your house down?

Could please you make a detailed guide on how to make it right?

I was thinking about making a battery pack specifically for powering a computer away from the house, do you think I could use this to get away with that (I'll need a few extra pieces to control the voltage and amperage as well but as far as the battery goes what do you think)

What is the machine that is connecting the batteries with the tiny wire at the end?

Thx!!

Hey! does anyone know if I can actually connect a 12S battery pack with a 13S battery pack in parallel? I think the BMS of the 12S stops loading when it is full while the 13s will still charge up. And when I've run the 13s empty enough, the Bms from the 12s starts up again and both batteries discharge, right? Sounds like it could work, or am I wrong somewhere?

Awsomeeee information

Thanks for the video. Where can i buy this kind of battery

.. From Italy...great intro... 👍

Great info. How do you look at commercial packs manufactured by the ebike manufacturers and their suppliers (such as Bosch) that do not use individually fused cells but instead connect them in parallel using thicker strips and have a single overcurrent protection circuit on the BMS?

Was curious about that large water cooled motor at minute 3:10. Could you tell me the name of the motor/supplier? Thanks

I saw a snip of my video in there. Would have been nice if you asked before using it but that's up to you. I agree cell level fusing has it's place but I think it could do more harm than good with DIY builders who can't achieve the same precision as on an industrial level. Your basically filling your battery with a bunch of resistors that will create more heat on top of what the battery is producing normally.

May you take similar approach to BMSs topic as in this video? The cheapest one are only resistive and that is just loss of energy and I'm wondering how does tesla do the balancing for example - I'm sure not the resistive way. Cheers

I'm doing a tiny house project and would a battery that can be charged by solar panels. How much would it cost to have you build a battery for me that can support 2x PlayStation 4s , 2x small TVs and an air conditioner.

Do you consider problematic if receiving new li ion cells at 3.44v? I've received my new 21700 Samsung INR 40T3 4.000mA, 35A cells with 3.44v. Is that too low? I've builded an 2.8 kw 24s8p battery for an electric paramotor and has a huge voltage drop at 10-17kw full throttle and it should handle it like other similar batteries. I'm trying to find out why. Thanks.

Excellent video but will BMS's make a difference in preventing thermal run off or no?

4:30 Whoa... so there is no need for trial and error projects, huh? The fuses follow the same principle of amp vs capacity

you talked me out of modifying a battery pack I have. Probably for the best. Thanks!

That's good theory on how to build safe Li-ion batteries, the problem is when you buy commercial products like laptops or e-bikes/scooters with batteries that clearly don't follow those steps.

Can you fix my battery pack it had a couple bad cells

Your first statement is completely false and misleading.

3:35 Okay so the type material and size of material holding the current is directly associated with the amount of energy passing through it... 🤔

Avendo un po di batterie 18650 da 3.7v E volendo costruire un pacco batteria per un scooter elettrico La batteria che monta lo scooter E di 60v 20ah Come li devo montare..... Quanto batterie mi servono e con quale schema montarle E poi o trovato un controllerxhe protegge 60v e 35ah i rete Va bene Grazie dell'aiuto.

Someone should make diy wire bonding machine for cells that didn't cost much

hy where are you located? could you build me a 150- 300kwh boat battery pack? for a 12kw engine. i have to stay under 3.5 tonnes everything included, but for transfer i could swap out the motor, clothes some movable stuff, liqueds and even the battery if possible :)

El problema no siempre es la batería, el problema también es o puede ser causado por los mosfet, todo controlador brushless estan conectados en paralelo los mosfet y el capacitor, que pasa cuando un mosfet se pone en corto? Pues va directamente a la batería y más cuando el fusible no adaptado a quemarse a un corto circuito, deberían de poner en serie un diodo en el + por si hay un corto, así ya no va directamente a la batería el corto circuito.

I store my cells in my bedroom. over my bed. in a cardborard box. no electrodes toucing. any tips? can I store them outside in minus 25 C? I want to make a safe system.

The video isn’t clear enough, It’s understandable but the edit is very choppy. But overall, it is defiantly informative

The thing is we all want more speed and range so I expect to see more videos of battery fires.💯

Nice & Thanks :)

So I want to build a battery pack for a camper. It will see extreme temperatures. My first thought is I need to climate control the batteries. Very little is mentioned about this anywhere. Another thought is that I want it repairable. Something that battery packs wrapped really tight are not. Thirdly, I want the system to be self diagnostic. Not something that is common with battery packs let alone with DIY builds. Sadly it looks like I will need to engineer my own solution. Thanks for the video.

Dont forget to use BMS, and always a plus to have a load balancer, my cells stay super healthy and balanced :)

Seems like it should be common sense, but since it's not... Great video!

👌🏼👌🏼

They need to make the solid state batteries because they don't catch fire when they are punctured.

Assuming that the poles won't contact the opposite is the first reason that causes short circuit Most battery explosion happen due to dangerous design flaws I've been using li-cells for a decade for many applications but never had a single short circuit incident

Very interesting. I know nothing about batteries, but it seems the battery industry, and the raw materials used to build them, is going to grow even more with the auto industries push for electric vehicles. Which I suppose is good, but what about the environmental impact of mining for the raw materials, and the human toll?

sodering cells is fine. listen to this i did a test on a brand new 1500 mah " samsung" but it wasa chinese fake i think. anyways i decided to find out how damaged cells would get whe heated to just below thermalk runaway, multiple times. I used a blowtorch a held it on both the positive and negative ends of the cell, then out it back into the tester. AFTER DOING THIS 7 times witha blowtorch the results were that the mr increase by 10 and the capacity ddecrease by 50, basically nothing, even with a blowtorch I didnt damage the cells. But I have experienced thermkal runaway 4 times now and I know hoew scary it is but unless you pass that threshold heat does NOT damage the cells

Spacers. Not absolutely required... And not possible to use on every scenario. (try to build a pack for a Laotie Ti30, the original battery doesn't have any spacers). Fuses. That's why BMSs exist... Surely a fuse is much much safer, but putting fuse wire on every connection is unrealistic, especially if you don't have a awesome spot reder... Tesla is a battery factory, don't expect DIYers to do the same kind of a good job without the necessary tools... Hot glue is fine :) As long as the pack doesn't get oo warm, it's perfectly fine...

I am always watching your video. I am running an electric board club in Korea and have 17,000 members. I want to collaborate with you when I have a chance.

I just want to make a 60v 20amph battery for my bike so I can put on a better controller and motor

So wait a second. Why the categorical dismissal of hot glue? If the cells are appropriately spaced, say with silicone o-rings, there wouldn't be anything inherently unsafe about keeping them together with hot glue would there be? Of course, assuming that everything is well isolated with fish tape or whatever.

wonder if someone actually have a battery at the size of building

aw man. It ended too soon 😅.

I remember when companies were going to make hydrogen powered cars and everyone screamed about how dangerous it was. Now cars are being powered with Li-Ion batteries, and no one is saying anything.

"Because Tesla does it" is not enough to justify the bold statements in this video.

Josh

What are you talking about? Lithium batteries have under one mega joule per kilogram energy density while TNT has 4.6. gasoline has 46.

alot of things work to build lith ion batts, there's is not only one way to make them....?

Why i should watch Tesla Videos.Thos Cars blowing up too

My super expensive bosh battery pack does not have individual cell fuses...they are solid spot-welded 6P in 10S config...go figgure...

I can see why most people pay 3-4x more for premade lifepo4 batteries. I'm wayyy too dumb for this.

After dying from my apartment exploding from my DIY battery, I would highly recommend You listen to these warnings & be safe!

TNT has an energy density of 4.6 million J/kg ->4.6million J= 1.278KW hour, lithium-ion batteries' energy density ranges between 260-270 wh/kg. TNT 1kg = 1.278kw/ hour, lithium-ion batteries at most 1kg = 450wh/kg Why are you saying lithium-ion batteries have more energy density than TNT?

think we need a lot of sand deposits near every road when electric cars gets more popular, as sand is the only way of make the fire more controllable

not to downplay safety concerns, but LI batts are only mildly dangerous. not extremely so as stated in the vid. extremely dangerous is the level of household mains

Dude no, cell level fuses are not practical or even a good idea. If the fuses pop you are very likely to lose control and crash at high speed. I would rather try to slow down a burning board or scooter then be thrown off at 40 mph Please don't spread miss information about electric vehicle battery's. Cell level fuses only make sence in much bigger packs or with reclaimed cells where the failer rate is much higher

Just more propaganda, move along