[HN Gopher] Giving EV batteries a second life for sustainability...
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       Giving EV batteries a second life for sustainability and profit
        
       Author : prostoalex
       Score  : 26 points
       Date   : 2021-04-07 00:26 UTC (22 hours ago)
        
 (HTM) web link (techcrunch.com)
 (TXT) w3m dump (techcrunch.com)
        
       | elihu wrote:
       | This seems like it would be complicated by the many different
       | chemistries and form factors available, and the wide variability
       | between packs depending on how old or well-taken-care-of they
       | are.
       | 
       | If one were to set out to create a single large battery out of
       | massive array of extremely heterogenous individual battery packs,
       | what would that look like? I guess you could pair each battery
       | pack with its own individual charger and inverter so they can all
       | feed into some common bus at a given voltage and frequency --
       | sort of like the "microinverter" setup for solar panels.
       | 
       | You could cut down on heterogeneity by only using one type of
       | battery in one installation, and trade batteries between
       | installations or even with external companies so everyone can get
       | matching sets. Sort of like the card game Pit. You could also bin
       | the batteries by quality, like how manufacturers of vacuum tubes
       | have a hard time replicated electrical characteristics exactly
       | from one tube to the next, so they sort them into bins after
       | manufacture and ship them out as matched sets that came from the
       | same bin.
        
         | rektide wrote:
         | Making heterogenous individual packs sounds like an absolute
         | disaster. That's why this is various car companies teaming up
         | with specific folk: because they'll have big quantities of
         | cells from each individual vehicle they get, and there will
         | only be so many different types of cell. There will be big
         | supplies of a couple different cells, ready to go in to
         | applications of all different sorts.
         | 
         | As it so happens, there's already a lot of agreement. Many many
         | cells are either 18 mm, 21mm or 28 mm diameter cylinders &
         | 650-700 mm long. "18650" cell is very common. 28650 used to be
         | a "big" cell but it's not around as much I feel like. "2170" is
         | a "21700" that is increasingly popular. Most of these cells
         | have similar charge behavior, of applying a fixed amps up to a
         | point, perhaps with temperature sensors to detect problems/slow
         | down, and then a slower finishing charge, that ends around 4.2V
         | per cell.
         | 
         | Using solar grid-tie micro-inverters would probably work fine
         | to join together a bunch of different packs.
        
           | Reason077 wrote:
           | And now, Tesla are developing an even bigger "4680" cell:
           | 
           | https://evannex.com/blogs/news/tesla-s-4680-cell-is-a-
           | stroke...
        
         | sokoloff wrote:
         | Some modern LEDs are also binned parts, as are CPUs.
        
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       (page generated 2021-04-07 23:00 UTC)