dogman wrote:My impression is that each case should be a paralell group.
pwbset wrote:dogman wrote:My impression is that each case should be a paralell group.
Yes! Absolutely make them parallel enough for ebike use and for BMS simplicity etc. etc. Even 4p is too small in my opinion because of realistic ebike loads and I would highly doubt those tenergy/ultrafires etc could handle higher C rates for long term... if you design a really easy modular/snap together structure then you can parallel as many as you want I suppose. Is there a realistic design you can think of that would allow endless 1s1p snap together possibilities? I know for the konions I'm working on 1s10p is going to be the minimum realistic parallel that I'd be looking for personally. Please let us know how we can help!! This is a very exciting project you're doing! 18650s really need an option like this... looong overdue.
pwbset wrote:Pretty different direction really but maybe these will give you some layout ideas for your molds... like brick vs. circular etc. etc. I plan to re-use the Makita cell dividers/holders and fabricate some sort of compressive tops/bottoms that can tighten with two screws or whatever and have subpacks in 1s10p and make 14 of those wired in series in a triangle enclosure. Anyway... around 15ah at 52v nominal and less than 20lbs is the goal. 1s10p subpacks would seem an ideal size for ebikes... 3 for 12v, 6 for 24v, 10 for 36v, 12 for 48v etc. etc. depending on the chemistry... LFP would be a little lower obviously.
GGoodrum wrote:If you could do a snap-together block, like the ones shown below, but make it for a123 cells, I think you'd sell a crap-load. I know I'd personally buy hundreds of them. This one below is for the large format 40138 PSI LiFePO4 cells, which already have screw terminals on the ends of the cells, What you would need for an a123 or 18650 version is either one of those 211 springs, with a screw that holds it to the block, or with the other tab-type ones if you can leave room to solder to the tabs.
leamcorp wrote:By the way, where did you get the holder thing there. I could use something like that to make the mold also.
leamcorp wrote:Where can I get one of those block? It gave me a good idea to incorporate the fastening mechanism.
I don't know about going commercial though, I'm making some for myself and some if anyone here is interested. It will be a low volume - probably spin casted parts using fire proof urethane plastic vs injection molding.
leamcorp wrote:Anyway, I've just did a quick prototyping to do a proof of concept. Please understand that I spent less than 1/2 hour making this - so, its horrible looking prototype. The final model will need to be super thin, much shorter, etc.
I'm envisioning that there will be two different pieces - An end piece that will be used to fasten the entire pack and middle pieces for actual cells. I still think clip on tabs will be easier to work with but we'll see how that works. I do have a source that could make copper strips with correct holes.
Tab version. Turns out that tabs have as much, if not more, force/coverage as the spring. The good news is that its easy to put the tab clips. The bad news is that you'll either have to use a copper wiring or do soldering on the back. Also, it maybe difficult to make since the back section will have to be fairly thin, which make it difficult for all but injection molding.
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