Copper busbar - electrical conductivity

[longhairedboy]

@Hummie

I was meaning that when the one cell has an internal short the other cells beside it in the same p will also be shorting through it until the fuse breaks the connection. A safety feature which makes sense only when shorting happens in a cell but when does shorting happen in a cell?

i have all the same questions.

my thoughts were that the fuses allow a gentle overload cascade to happen that will eventually burn up all the cell fuses in the p group, disabling the pack, and i have to assume burning up the balance lead as well if the BMS doesn’t sense some dumb shit happening and switch off.

so then what… you replace the cells?

so after reading this whole thread repeatedly while trying to take the occasional break in order to draw pictures of urinating esk8ers, i was lead to the conclusion that having cell “go dud” inside a welded p-group was somehow super-bad-time, either the cell would drag everything down with it and not accuratelty balance things any more, or something worse like extra heat …

except i’ve never seen any of this happen and i’ve had every kind of bad battery come across my bench conceivable. I’m not saying i’ve seen everything, i must assume that i have not. but i have seen packs with far less than adequate cells sitting in the middle of a 4P group doing nothing but mildly affecting range and full charge voltage.

[sash]

I am also trying to decide if cell level fusing worths extra efforts needed to build a pack (and also maintain it, replace fuse wires, etc.).

In the known cases of thermal runaway, would cell level fusing have prevented it? If one cell goes on fire, then I guess the whole pack will even if all fuses burn.

Does “internal shorting in a cell” happen to anyone?

But I am definitely going to do this:

@chaka

If you do not want to go through the trouble of fusing a pack at the very least you should be isolating the paralleled cells from the next group of cells with a strip of fishpaper and insulate the edge of the positive terminal if you are bridging cells with nickle strip.

[banjaxxed]

What’s nice with the @chaka method is that he left behind a nice thingiverse design for anyone to adapt it