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Hack a Day: Tesla Battery pack breakdown

Elixer

Elixer

Lifer
Tons of bolts & Torx screws and each has a specific torque amount which must be adhered to.
A total of 16 battery packs, each of which contain 444 cells with a total of 24V, for a sum of 5.3 kWh.
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Lipos have better power density.
They WILL go violently if crushed or even slightly deformed though.
The cans are much more stable and thus safer.

I wonder how long it will be before mechanical mod mfrs make tubes fitting these. Big fat mechs (30mm) and velocity style atties will get popular again especially given the 45A upper current limit.
 
brainhulk said:
why are they making flashlight size cells? why not just make 1 large car size battery? Would save weight and manufacturing materials or it will have a larger energy capacity, right? If it explodes into a fiery inferno, I would rather be vaporized instantly.
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Heh, that would have to be one huge battery to be able to vaporized you instantly 😉

*edit, n/m, was thinking of something else
 
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brainhulk said:
why are they making flashlight size cells? why not just make 1 large car size battery? Would save weight and manufacturing materials or it will have a larger energy capacity, right? If it explodes into a fiery inferno, I would rather be vaporized instantly.
Click to expand...

You understand that the way you get higher voltage out of batteries is to run many cells in series, yes? You know those 9V batteries? Do you think they're one cell? Nope, they're six 1.5V cells in series. You know why a battery is called a battery? It's because it is (typically) a battery of cells.

A Li-ion cell is ~3.6 volts. It's always around that voltage. If you want ~400V that's a lot in series that you need to make, so there is one requirement. The cylindrical cells also allow for some space between for expansion and cooling. You put enough cells in series to get the voltage required, and then you use those modules in parallel to reach your current requirements. The large number of cells also allows each individual cell to charge slowly, but allows the overall battery to charge quickly.

You asked why they don't make "1 large car size battery". That's precisely what this is. You just didn't know what a battery actually is and assumed a battery means a single cell.
 
That guy has lot of interesting battery related videos. Pretty much most battery packs work this way, from cars to hobby RC. Basically a number of 18650's connected as a pack. It's just the thing of adding cells in series/parallel to get the right voltage and capacity. Lithium ion is tricky to charge though, as you need to charge each cell group separately so that they are balanced. Not like lead acid where you can give it 2.25v per cell and call it a day. (at least for float charging) That's why hobby RC packs have two connectors, the big one which is all the cells in series, and the small one which splits up all the cells for charging.

I would have thought the Tesla modules would be more servicable though, that first metal cover looks like you pretty much need to destructively remove it. Would be neat if they made it so all the individual modules just slide into the big pack and only require a few bolts. They will really want to come up with a proper way to recycle this stuff if we're going to go this route and making it modular would help as if one pack goes bad you don't want the entire thing to be considered a single FRU, but rather have each individual cell be accessible by the dealer to be replaced.

brainhulk said:
why are they making flashlight size cells? why not just make 1 large car size battery? Would save weight and manufacturing materials or it will have a larger energy capacity, right? If it explodes into a fiery inferno, I would rather be vaporized instantly.
Click to expand...

I'm guessing thermals has a lot to do with it. With smaller cells there is more surface area for dissipation.
 
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