Bend it over a pencil or a drill bit. (4mm?), and do it slowly so the wire doesent heat up.
*I’m serious.
While that might help, it doesn’t really solve the issue of the the fuse wire being more of an unnecessary mechanical weak point than it needs to be and the idea would also be to try and completely remove the need for soldering fuse wires.
Fuse wires also end up sticking out from the rest of the side of the pack just slightly because they’re thicker than nickel strips which means that you need to take this into account when shrink wrapping the pack etc as the fuse wires will end up digging outwards slightly and become the first point of contact with external objects in the case that your battery isn’t 100% secure etc.
Fish paper, is the adhesive used flammable? I know that was a concern raised about the circle isolators.
I have well over 4000 miles on this type of battery pack and it is still holding up. Most builders go wrong by not stabilizing everything inside their enclosure with a dampening material like natural cure silicone. My guess would be that you had excessive movement or you did not fix the buss bar from moving. Batteries should always be 100% secure. Any movement at all will eventually wear through the battery casing over time due to vibration.
I lay down strips of foam rubber and lay beads of silicone to fasten the pack inside my decks. A second set of strips go on top of my packs to allow for a compression fit once the hatch is on.
@trigger4point7 the batteries are like little flares when they go thermal, the whole point of this is to stop that from being a possibility or at the very least limit the extent of the damage if the board is compromised by an accident. If you are worried about the adhesive flaring up just be sure to buy from a reputable distributor and stay away from Alibaba for your insulators.
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A fuckload of flex. I could pot an entire sled in silicone and if i arancged things correctly i could mount it on a loaded deck and bounce around all day.
the problem is that silicone is soft so a damage and puncture resistant shell is still needed, but no reason it couldn’t be scaled like armor to allow flex.
shit that sounds like an idea there. If you properly footed the silicone into the deck you probably wouldn’t even need fasteners of any kind, just clever ridges and etchings to give it some grab.
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THIS. 1000000x THIS.
I’ve been using silicone to pot the packs into the fiberglass boxes for about a year now and it has eliminated all issues concerning vibrational damage and wear on packs.
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I should add this also.
@Rinzler tested the narrow nickle strips as fuses like you mentioned earlier in the thread. They basically turn into space heaters without breaking connection, I wouldn’t use them.
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Yeah that whole thing seemed sketch to me. i’d rather use a thin gauge superworm because i’ve seen what happens when those smaller wires, 22 guage and below, do when they wick up inside that silicone sheathing during a hard short on an 18650 pack. It’s awesome to watch. You can see the light from the melting copper travel up through the center of the silicone tube and then nothing. MEanwhile, the insulation is 100% in tact and the wire looks as if nothing has happened to it at all. The fire was completely contained, so to speak. Burned up copper safely inside the silicone sheathing.
what gauge do you think would be appropriate if we tried that as a fusing technique?
I wouldn’t use a multistrand wire for a fuse. I do use a small section of 12awg silicone sheathed wire to make my series connections. The short length, 1.5", makes the 12 awg overkill but it is good for the peak currents. Longer runs necessitate the use of 10 awg from the battery main terminals.
Is 0.15mm x 18mm busbar thick enough? I have a chance of spot welding up to that thickness
In my opinion .15mm is not thick enough to carry the load, I use .015 inch thick buss bars. You can spot weld onto the buss bar using the thinner nickle.
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Yea I’ve gone with a new design for my new board where I’ve used your original cell level fuse design as inspiration. My packs are two cells thick so I run the bus bars on the side.
One of the things that’s made designing my packs more difficult is that I wanted them to be able to be easily removable from the enclosures and split up into sub 99Wh packs which makes securing them more difficult.
Atm I have the batteries wrapped in kapton tape, then a thin layer of felt for vibration dampening and then shrink wrapped and stuck to my enclosure with velcro. They didn’t come out as cleanly as I’d liked, but so far they’re holding up really well but I guess we’ll see how things go.
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Don’t wrap in kapton
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Why’s that?
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Traps in heat which is what you want to Avoid your cells from having
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so dont wrap them fully in it but still better than electrical tape
Fair point. Interesting to note that it seems to be a fairly common practice on these forums. This being a larger 10S6P pack, I don’t think I really push these cells particularly hard though so shouldn’t be an issue
I think it looks sexy that’s the only reason I use it plus a little bit around certain areas can be for strictural integrity, but too much and it builds up heat
It’s advantage is that it’s heat resistant and non conductive, compared to fish paper non exactly sure, I have both along with the obligatory heat shrink and glass fibre tape
glass fiber tape?