crossbreak
1 MW
dont make him poor.. even if he'd own a printer it would take years ankd cost $$$ to make a piece of that size...good idea, but 3D printers are not so far yet..sadly..
Battery assembly kit for 18650 cells - first prototype
- Thread starter circuit
- Start date
Exactly, 3D printing isn't much of a solution here at all. There's far more practical methods to produce plastic parts in quantity.crossbreak said:
It looks great, very clean. What would be the ballpark costs for laser cutting tabs to accommodate something like a 20s14p (single rows of 14) pack?
3D printing would be way cheaper than milling you can even print metal these days, but that would very expensive. As for printing large volumes printers can be very quick. As for cost you can buy you own hobby printer that uses ABS wire and holds a good tolerance 0.02mm for £600. For large production you would injection mold, but that’ll cost thousands to make and design the mold.
Yes, nickel.crossbreak said:
Well, my target selling price for 12s6p is $89 (which I still have not reached yet). For 20s14p it would be proportional to cell count, so... $346.trevc2 said:
However, there is one problem. Above price is calculated based on higher quantity production, no lasers. For a one-off prototype, it is more economical to laser-cut and that would come to around $480 in total (tabs+trays).
I will not be using laser for production, because of the cost. Optimal quantity to get sane price would be around 300-400 tabs. I am currently manufacturing 100 pcs. 8p tabs, still waiting for feedback from the factory. Success is not guaranteed here, because usually they are not doing such work and it is a bit "new" to them. I was warned about possible bad results, but since there are not many alternatives, I took the risk anyway. I mean, bill will have to be paid regardless of end result..
I have been reading your thread as I am building the same thing but to use not sell. Must say I wish you luck on this and feel it will payoff at the end. If I had to do it all over again I wish I could just order and not deal with all the time investment to make it myself. Well worth a few hundred dollars to me and many others. So I wish you the best of luck. Today I tested my cheap $189 eBay Chinese spot welder and was amazed it worked well and was very easy 
auraslip
10 MW
- Joined
- Mar 5, 2010
- Messages
- 3,535
Is it possible to work out a solution that doesn't require welding or soldering the cells? Some sort of spring system?
The reason why I ask is... well, used 18650 cells are basically free if you know where to look. If there was a system that allowed you to easily swap out bad cells, building a pack out of recycled cells would be a cinch. 18650 cells are ubiquitous around the world. If there was an easy system to turn used 18650 cells into ebike battery packs, this rich man's hobby might suddenly become viable for everyone with a bit of spare time and a little bit of knowledge.
I'm imagining some madmax post-apocalyptic world where I'm digging through rubble looking for 18650 cells to swap into my pack to replace the dying cells.
In seriousness though, after riding ebikes everyday for four years, the most annoying thing to deal with is bad cells. It basically kills the bike for months while you take apart the pack, test it, wait for new cells to come in, put it all back together, and then test it again. And the thing is, even Tesla deals with bad cells in their packs. Luckily for them, they have enough capacity spread across enough cells that some bad cells won't be noticeable. For us ebikers, a bad cell is a bad battery pack. Honestly, I think a hot swappable low capacity cells are probably the best way to go.
The reason why I ask is... well, used 18650 cells are basically free if you know where to look. If there was a system that allowed you to easily swap out bad cells, building a pack out of recycled cells would be a cinch. 18650 cells are ubiquitous around the world. If there was an easy system to turn used 18650 cells into ebike battery packs, this rich man's hobby might suddenly become viable for everyone with a bit of spare time and a little bit of knowledge.
I'm imagining some madmax post-apocalyptic world where I'm digging through rubble looking for 18650 cells to swap into my pack to replace the dying cells.
In seriousness though, after riding ebikes everyday for four years, the most annoying thing to deal with is bad cells. It basically kills the bike for months while you take apart the pack, test it, wait for new cells to come in, put it all back together, and then test it again. And the thing is, even Tesla deals with bad cells in their packs. Luckily for them, they have enough capacity spread across enough cells that some bad cells won't be noticeable. For us ebikers, a bad cell is a bad battery pack. Honestly, I think a hot swappable low capacity cells are probably the best way to go.
I wouldn't have considered those "basically free", and certainly wouldn't want a bunch of used Konions on any of my bikes
I assumed you were referring to things like recycled/discarded laptop cells, etc. There's been cases of ES members buying these in bulk and then expecting to build a new battery for their bike.
I assumed you were referring to things like recycled/discarded laptop cells, etc. There's been cases of ES members buying these in bulk and then expecting to build a new battery for their bike.
auraslip said:The "basically free" cells won't be capable of any meaningful output power in the numbers we're fitting on a bike, unless you're running a 250w system
tell that to doc and all his happy customers
Anything is *possible*. However I there already are at least couple solutions on ES, also I am targeting more professional users. Digging around in laptop junk, disassembling old batteries, testing each cell an then replacing them one by one each month is just not an option for them.auraslip said:
If you often have issues with cells, maybe you are doing something wrong? Using old cells? Not using a proper BMS?
Bob K
10 W
This a good time to ask a question about using 16-18 gauge wire on UR18650FM4 cells.
From all of the wire sizing charts/programs I have seen, a cell that puts out 2.5 amps
continuous and 5 amps maximum only needs a small wire to connect it to the main parallel bus.
I see you have 4 small "traces" connecting the positive electrode to your bus.
Do you have a total cross sectional area of the metal making up those 4 " traces" that you could share?
I ask , because I am in the process of making a pack that will use 6P modules of UR18650FM4 cells.
I would like to use 16-18 gauge wires soldered to the cells for numerous reasons . Including
less heat stress on the cells during soldering!
thanks!
Bob K
From all of the wire sizing charts/programs I have seen, a cell that puts out 2.5 amps
continuous and 5 amps maximum only needs a small wire to connect it to the main parallel bus.
I see you have 4 small "traces" connecting the positive electrode to your bus.
Do you have a total cross sectional area of the metal making up those 4 " traces" that you could share?
I ask , because I am in the process of making a pack that will use 6P modules of UR18650FM4 cells.
I would like to use 16-18 gauge wires soldered to the cells for numerous reasons . Including
less heat stress on the cells during soldering!
thanks!
Bob K
I had to do that to lower manufacturing cost. Still good enough, I think.
OK, not ideal, just first batch... Some details still need improving from my and manufacturer's side. Price, for example. I was quoted big and, after delivery, bill turned out to be twice bigger. Bummer, quite large investment already.
Anyway, this first batch is good enough to assemble first prototypes. As you can see, these are for 8p packs. So: 8p, 6p and 4p configurations are available. These are designed for spot welding, but are soldering-friendly as well.
I have also improved plastic tray's design to bring cost a little lower. Looks the same. So double yay!
All what remains now is to order some paper spacers. Will do that shortly, probably will be in my hands in one week.
So... Is it time to start a selling thread? Or would you like to see my own pack being assembled first?
OK, not ideal, just first batch... Some details still need improving from my and manufacturer's side. Price, for example. I was quoted big and, after delivery, bill turned out to be twice bigger. Bummer, quite large investment already.
Anyway, this first batch is good enough to assemble first prototypes. As you can see, these are for 8p packs. So: 8p, 6p and 4p configurations are available. These are designed for spot welding, but are soldering-friendly as well.
I have also improved plastic tray's design to bring cost a little lower. Looks the same. So double yay!
All what remains now is to order some paper spacers. Will do that shortly, probably will be in my hands in one week.
So... Is it time to start a selling thread? Or would you like to see my own pack being assembled first?
circuit said:Guys... Check this out!!
Guess what that is... Yup, that's a pure awesomeness!! As you can see, fuse design is different. I had to do that to lower manufacturing cost. Still good enough, I think.
OK, not ideal, just first batch... Some details still need improving from my and manufacturer's side. Price, for example. I was quoted big and, after delivery, bill turned out to be twice bigger. Bummer, quite large investment already.
Anyway, this first batch is good enough to assemble first prototypes. As you can see, these are for 8p packs. So: 8p, 6p and 4p configurations are available. These are designed for spot welding, but are soldering-friendly as well.
I have also improved plastic tray's design to bring cost a little lower. Looks the same. So double yay!
All what remains now is to order some paper spacers. Will do that shortly, probably will be in my hands in one week.
So... Is it time to start a selling thread? Or would you like to see my own pack being assemble first?
At what amperage would they break connection?
We can put them together for larger parallel packs no?
Well, I am making and most people I am working with high power packs. 22s10p of 18650 cells, the packs will be hitting about 70amps max so 8 amps per cell, so this will not work. At least 5 of us would want a 10amp per cell fuse, so do not know if that is a hassle from a manufacturing point. I do see a market for these as it makes total sense but different gauges would be a reality. Maybe for now you might want to stay with in the most popular gauge and as business grows offer different gauges. Just giving you feedback. I would be a customer with the right product for me if that helps.
Mammalian04
100 kW
Very nice Circuit.
EDIT: eCruz just snapped me back to reality. I didn't think about the fuse capacity. As such, I think I would be in the same boat as him...
EDIT: eCruz just snapped me back to reality. I didn't think about the fuse capacity. As such, I think I would be in the same boat as him...
If we are talking about 22s10p pack, multiplied by 5... You know, that looks possible. Quantity maybe not enough to make any money, but really possible to do.ecruz said:
Higher current rating is also possible. Maybe not tomorrow, but after 6-8 weeks. Can you wait so long?
Mammalian04
100 kW
circuit said:
I edited my previous post to reflect what eCruz has noted. In my amateur excitement, I didn't think about the fuse capacity. Put me on the waiting list with him!
Also Circuit, I see you noted that you aren't interested in doing the assembly. Do you have any assembly recommendations for those of us without the skill (and spot welder)? I don't really want to get into it for just building the occasional pack for a new eBike build.
I could assemble the packs, however there are two strong reasons not to:
1. Shipping lithium batteries is a real pain... Chinese people 'rebrand' them as Ni-MH and provide fraudulent safety datasheets to get cells shipped, however I can not do so, due to the risk of a fine and covering of whole expenses (for example crashed plane) if fire happens...
2. Shipping is quite expensive. I mean, shipping from China to me (EU), assemble and then ship to you would mean almost double shipping costs.
3. Minor reason - I would need to buy a spot welder, design and build a suitable head for it. For small quantities, like DIY project, it is okay to use simple one-day builds as work tools, but at higher quantities that gets very painful.
I will work on this, but it will take some time.
If welding is not possible, you can solder those tabs. I personally don't like heating my cells, but many have good results this way.
1. Shipping lithium batteries is a real pain... Chinese people 'rebrand' them as Ni-MH and provide fraudulent safety datasheets to get cells shipped, however I can not do so, due to the risk of a fine and covering of whole expenses (for example crashed plane) if fire happens...
2. Shipping is quite expensive. I mean, shipping from China to me (EU), assemble and then ship to you would mean almost double shipping costs.
3. Minor reason - I would need to buy a spot welder, design and build a suitable head for it. For small quantities, like DIY project, it is okay to use simple one-day builds as work tools, but at higher quantities that gets very painful.
I will work on this, but it will take some time.
If welding is not possible, you can solder those tabs. I personally don't like heating my cells, but many have good results this way.
Thanks for this review. Unfortunately such welder only covers a "buy a spot welder" part, but not "design and build a suitable head for it". I mean, that welder is okay to weld 2 or 3 cells together, but when it comes to large battery.. Hard to reach in to middle of pack, so external "mobile" head would be required. With replaceable tips, springs for pressure equalization, etc... It gets quite complex project to get good results.ecruz said:
I'm not saying it is not possible or very hard to do, for example existing arms could be extended ant that's it. Anyway this is just a minor issue against other two: shipping prices and shipping generally.
Whilst you are still early in the design phase, can you change the cell spacing to use the U type spacer where the battery cells sit vey close to each other like in the dewalt 18650 tool packs ?
The normal round clip lock 18650 holders still leave a 1-2mm space between the cells, so why not make them as close as possible, i.e cells nearly touching, heat will get out from the air voids anyway. The pack will be more compact if so.
The normal round clip lock 18650 holders still leave a 1-2mm space between the cells, so why not make them as close as possible, i.e cells nearly touching, heat will get out from the air voids anyway. The pack will be more compact if so.
parabellum
1 MW
So, you mean, everyone using your assembly kit should buy professional cell welder assembly bank?circuit said:
They are as close as possible already, touching each other, where safety allows. In some places there is a gap to prevent short circuit due to sleeve wear.Gab said:
Nope. Professional tools are not required for one-off project.parabellum said:
There are several options:
1. Solder it
2. Buy cheap welder from China
3. Build one yourself - lots of info online, can get as simple as two parts.
4. Borrow or rent professional tool for couple of hours
5. Take it to a shop for professional job. The kit fits together and hold in place quite well even without welding, so you can carry it around already assembled. Very convenient for shop to just make some welds and don't care about assembly.
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