That was one very quick trip to the recycler, pack dates from August 2013. Crashed car?<p>Totally nuts to work with DC voltages this high without taking safety precautions. Anything over 50V DC is to be treated with very serious respect.<p>AC is different, you get a good number of opportunities to dis-engage, but with DC your muscles contract and that's that.<p>I'd rather mess with 2 KV AC than with 200 V DC.<p>Lovely engineering on that pack by the way, the number of safety features is very impressive. Sure looks a lot better on the inside than mine ever did!<p>( <a href="http://pics.camarades.com/d/90045-1/IM000398.JPG" rel="nofollow">http://pics.camarades.com/d/90045-1/IM000398.JPG</a> )<p>(That's only 48KWh but at 48V so much higher current)<p>I think I've found the source of the pack:<p><a href="http://www.teslamotorsclub.com/showthread.php/32687-For-sale-Tesla-Model-S-85-kWh-main-lithium-battery-pack-with-less-then-500-miles-SOLD" rel="nofollow">http://www.teslamotorsclub.com/showthread.php/32687-For-sale...</a><p>Original asking price was $29K.
I think he's wrong about one thing. A good BMS not only monitors cell voltages, it has the ability to bypass some charging current around individual cells. Not a lot, but enough to balance the charge of all cells over a cycle. That capability can do wonders for the reliability and life of a pack.<p>While I worked in EVs for 6 years, I have no knowledge of the Tesla BMS - they were not our customer and I worked mostly in motor control anyway.
Pictures wouldn't load so I used <a href="https://web.archive.org/web/20140910232549/http://www.teslamotorsclub.com/showthread.php/34934-Pics-Info-Inside-the-battery-pack" rel="nofollow">https://web.archive.org/web/20140910232549/http://www.teslam...</a><p>thanks again archive.org
Interesting to compare this to the ford fusion battery[1], which uses clever construction to prevent a technician from being exposed to high voltages during construction and teardown.<p>[1] <a href="http://www.etotheipiplusone.net/?p=3109" rel="nofollow">http://www.etotheipiplusone.net/?p=3109</a>
Asides from price, why not engineer a battery that did not rely on 18650 cylindrical cells? Seems like a bit of extra weight and lost capacity/space by using tons of 18650 batteries which each have their own casing instead of just making a 'brick' style battery, similar to those found in mobile phones (but obviously much larger).
I had a similar appreciation reading this that I felt for the original iPhone tear-aparts by ifixit and their brethren.<p>EG - looking at a truly innovative use of existing technologies pushed to their limit and engineered to a sum greater than their individual parts.<p>Makes me want a Tesla even more.
Anyone else notice that in the Tyco contactor picture it's labelled "Coil 3.14 Ohms"? It makes me think they only needed it to be 3 Ohms, but an engineer somewhere couldn't resist making it πΩ
One problem I've had before was if one cell in a pack is damaged and replaced, the BMS balance current would take forever to flatten the pack.<p>Do you know if Tesla has any way of improving or making this faster?
Seems like there is a lot of room for improvement?<p>Reducing the sheer number of casings on individual cells would radically reduce weight/volume.<p>Then with less groups of cells you could actually have the BMS monitor them like my lifepo lithium battery for bicycle.
That's pretty interesting and is testament to the versatility of the 18650 cell package!<p>I'm rebuilding ThinkPad X200 9-cell this weekend that is filled with 18650s and repaired a PBX about 15 years ago that had them in it so they appear literally everywhere.
Are the QR codes only used for manufacturing lines or tech support? It would be awesome if there was an open database where I could find replacement parts for particular devices.
From what I've read these packs have around 7000 3100mAH NCR-18650s. Over the years I've used these NCRs (or lower mAH versions) individually in special flashlights - and while they seem to have good reliability overall, one did fail on me while charging. Thats why often hobbyists charge these outside in fireproof bags.<p>I would be terrified to drive a car with this technology.