So im in the planning fase of building my new board and is going to build my own battery pack 10s3p.
Problem is im getting lost in all the battery discussions.
What i’velearned so far is to use alot of fish paper.
Would it be a good idea to use these smaller strips as fuses. If so im planing just to use nickel strips instead of the pcb. Would this be a good idea?
Is this the best way to make it? and how do you make the best solution for the middel part. Between 1-2, 3-4 and so on? Or should i go with the usual bending in the middel, without nickel fuses?
I don’t like the idea of fuses. Someone will correct me if I’m off base here, but the “fuses” will burn thanks to resistance past a certain point. Basically, if a cell has an internal short, it will burn that fuse. Does this happen a lot? Or do we use a ton of fishpaper to protect against other than internal shorts because that’s a lot more common? Plus, resistance of those thin strips… Any resistance adds to voltage drop. People say it’s insubstantial, but take all the thin strip your using and line it up… (Then divide by the # of cells in each P group) and that’s the length of extra resistive strips adding resistance and sag. I personally go ham on my nickel, layering to reduce resistance as much as possible, insulating positives and going ham with fish paper a d kapton where it makes sense and under full load, I can tell voltage drop is as small as it is thanks to bulking up rather than slimming down to fuse it. Use a calculator to see how much resistance those “fuses” will add, and how much sag that will mean for your pack in particular. It’s a debate… what do these really do for esk8? You get an internal short and you stop a fire. If this is a serious concern for you than do it for sure. But, I’d have some way to test and know for sure when and how quick they will burn up to be sure. Cells rated for and pushed to 20A? Maybe a fuse that will burn in 0.5S at 40A load would be good. But still, isn’t a fuse only ensuring that the one internally shorted cell doesn’t carry all the other cells in the P group with it, so only one cell vents in the end? If a fuse ever did its job, your pack would still be toast until at the very minimum you disassemble, replace that cell and fuse strip. I dunno… I really don’t know.
As for bridging / making the series connections, a couple 12AWG silicone wires or 10AWG if you are pulling more than 100A total… That’s what I go by personally. Flat copper braid can be good for a thinner pack just solder quick, pre-tin, don’t let it wick too far into the braid or it will lose flexibility, become brittle and tear.
My only advice is to wire your batteries in a “U” shape so P-groups 1 and 10 are right next to each other and groups 5 and 6 connect at the other end. Right now if you traced a path from pack negative to pack positive it would be making an “S” shape with a weird diagonal jump at groups 4 to 5.
Hope this makes sense - don’t change the physical cell layout, just the wiring
Reasons to use silicone wire or braid can be to do with flex, but depending on size, they carry more current than nickel strip.
In the layout that @eBoosted posted, there would be no real need for fishpaper in between the connections as they are all series connections (I have often wondered if folded nickel between S connections is prone to arc though?) . You would want fishpaper in between the seperate P groups and between cells and balance wires.
@glyphiks the thought with the arc is exactly the reason im asking. So you would suggest braid or silicone wire instead of a couple layser of nickel?
Bought plenty of fish paper. Just need kapton tape and some wire or braid.
I don’t think that it would arc, but Im not sure. Plenty of people build packs with folded nickel S connections, as long as they are held tight together with tape I think it should be pretty safe.
I even fishpapered the S connection… kapton, fishpaper that folded over the sides, then folded
The only thing I would do differently if I did this pack again, would be to run the copper braid from the center of each p group, rather than end to end. Would reduce the load on the single nickel strip of the p group
It would only arc if that is the lowest path of resistance and a voltage difference. I wouldn’t worry about it even if it arcs it will cock up and insulate it self but if that’s happening you got bigger issues.
Edit: this is in relation to + fo one group to the - of the next
just with 10s3p instead. Do you have fishpaper on top of the balance taps?
