I’ve just finished building an 18650 Samsung 30Q pack with these nickel strips.
I had to spot weld two layers of nickel strips, since one layer will only do 3A continuous without getting warm and will blow fast at 8A per cell.
Now with two layers I have 6A continuous and 16A fusing. Times 14 cells this is 84A and 224A max.
I’m running the pack with a 200A Smart BMS…
Here are the pics:
I become depressed when I see the job needed for building a pack…
Anyway nice job to all people that have build their own pack
SaltyPaws - your calculations are interesting, with 1.36V drop in a 58V pack at 150A (with 14 parallel cells). It makes sense that the battery will voltage sag with an inch of fuse wire on every cell, totaling 30cm of high resistance wiring across the pack. All the other wires in our setups are chunky gauge to minimize losses and allow current to flow.
Runtime is precious, which is why I went for wide and reasonably thick nickel between my cells in a 6p pack, so as to avoid wasting power into heat. The losses would be much worse than 1.36V if I used similar gauge cell level fusing with 6p while pushing 150A.
I guess if you did have an individual cell fail with a short circuit, then a fused serial connection would prevent shorting the entire parallel row - but hopefully that won’t happen if we’re using good cells. It seems more likely that the balancing wires short onto each other, or a connector/plug shorts out - which can be mitigated with careful construction and a pico fuse where it the balance wire joins the cells
I can imagine some ways an individual cell could fail would include:
-salt water in the battery pack
-a piece of stray solder on the positive terminal
-a jagged square corner of nickel bridging the positive terminal to the outer can
Good quality +ve terminal insulators seem essential, and full battery waterproofing. I’m not sure I would trust a shrink wrapped pack which is only separated from the ocean with a single waterproof case.
Yes. That looks correct. The voltage drop of my pack is super low. I did a bunch of testing when I first built it a year or so ago. I’ve set my VESC amp limit to 250A and Towed foil boarders into the surf. No voltage drop issues.
I think fuse wire on just one side of the cells is a good idea. Nice improvement over my first gen of these packs.
I get 1h30min run time and average 20 miles on this battery. No noticable voltage drop.
Really clean build, do you have a link to that battery box your using?
… and to anybdy;
How and with what to replace a blown fuse? Soldering ?
For an 12s 10p, what price should I expect? I am a bit lost with the 18650, the 18650 30q are maybe on the limit with their 20a discharge on 10p pack… But they are already expensive (18$ here and 10$ on Bangggood)
If I built it would be 2x 6s 10p and I use my RC hobby charger.
Cross that hurdle if it were ever to happen.
How much power/amps do you need to tow your friend?
How much amp do you usually need when foiling and starting?
Thanks mate!
Here’s the link to the case:
https://www.bopla.de/gehaeusetechnik/product/euromas-polyester/gehaeuse-8/p-339.html
I would strip of the nickel band of the complete row, change the cell and weld a new nickel band over it.
A really nice battery case, with nice inner dimensions to accommodate a 14s14p setup : 342 x 342 x H79.8 (70.8 + 20 - 5 - 6)
How much is it sold (no visible price) ?
IP 66 protection: did/will you do sthg to improve that a bit ?
Yeah, I’ve done quite some research to find a case that would both accommodate a 14S14P Setup or more and fits in the cavity…
The actual price is around 200€, I haven’t done any additional waterproofing. But I’ve submerged the finished case without battery for 30 mins under 50cm water and no drop inside!
For the next box, consider asking your buddy with the CNC to machine an Isogrid in the 1/2" acrylic to remove a lot of weight at little cost of strength.
What kind of plugs are these? Do you happen to have a link? Thanks
Hey guys I really like your cell packs,
are there any guys from austria who can assemble such a 18650 pack for me that fits into those cases?
And which smart BMS do you think works best? Dali or maybe ANT BMS?
https://www.youtube.com/watch?v=c7PGLFgkdf4&t=2s&ab_channel=DamianRene!
I have been thinking about a SPC (safe parallel connection) video that I saw on the eskate builders page and at first I loved it and I thought it was genius! But now I’m thinking it has some issues…
I made a fake battery pack out of much safer AAA’s showing the series and parallel connections. My understanding is that the whole point of the design is to protect against internally shorted cells so I replaced one of the cells with a wire. In theory SPC is supposed to solve this problem by braking the small Nickle strip “fuse” and keeping the battery safe but it does nothing about the series connection on the + and - sides of the dead cell. I believe this will cause an imbalance of voltage between the series cells. The upper right cell would be at lets say 10.8V if these were Lion and the upper left cell would be at 7.2v. I think the 10.8v cell will act almost like a charger and push a missive amount of current into the 7.2v cell to try and equalize the voltage. this will then cause the next parallel ‘fuse’ to brake up the line. I think this will continue to happen going up the battery pack until the line of series cells with the dead cell is completely severed from the pack? Or the next fuse doesn’t blow and it over charges the cell above the dead one causing a fire?
Also how would you terminate the ends of the pack to your bus bars? That can’t be made out of fuses or it just will instantly fail when you use the pack for the first time.
Does anyone else know what I’m talking about this has been driving me crazy?
The batteries shocked me!!!
After you did this test - how did you get the lid off? The 3m tape is sticky but not permanent?
Also, did you fasten the cells into the case in anyway or does the sheer weight of the battery pack mean they don’t move around very much?
Thanks!
