texaspyro said:
I really wish they sold some of these packs as 1S (1S4-6P) so that they could be properly seriesed. Paralleling packs via the balance leads is a rather lame and sorry way of building a pack.
It's the plug-it-in-and-done way of building a pack, and a method that has been throughly proven in field.
texaspyro said:
Balance leads are not meant for handling large currents,
Balance tap leads would be a terrible thing to try to pull high currents through. It's a good thing they never see more than a handful of mA on a pack with decent cells.
texaspyro said:
plus a cell failure in a paralleled configuration wipes out all the packs in parallel. If you seriesed 1S packs, you can just remove that pack and live with a 3.7V drop until you could replace it.
It's not like it can quickly kill other cells grouped with it in the event you get a failure that causes high self-discharge on a cell, and the beauty of LiPo, is in the event of a short, they harmlessly vaporize the tab off the cell like a little fuse, which doesn't bother the other cells in parallel.
Either failure mode, if you're using any sort of cell-level monitoring, you get alerted (like the chargery HVC/LVC beeping alarms the size of your pinky that folks just leave plugged-in to each combined balance tap set) to a problem that is going to take many hours at worst before it can impact the other cells.
And then in the event of a single cell failing, it would be a hell of a lot harder to find which one out of the group of hard soldered 4-6p cells is responsible for bringing the group down, when series arranged groups makes it as simple as disconnecting the balance taps and checking which cell falls. (on it's own, or under load etc)
No battery tech, layout, design is perfect. In practice though, having them in series groups at a semi-useful voltage sure makes it a lot easier for average-Joe's to put packs together than needing to assemble 24 separate series connections, and then wire balance taps. The way they are, it's pretty much plug-n-play.
Fortunately, it doesn't seem like we need to worry about building batteries to last more than a few years anyways. The rate the technology is improving, it feels almost like worrying if your computer is going to last for 5 years or something. It's a situation where it doesn't really matter, because in a few years, the price will be cut in half again, and they will keep getting smaller, lighter, and with higher C-rates and more cycles.
