Inside a Tesla Model S Battery Pack

Post by snarfy » Fri, Sep 12, 2014, 4:06 AM UTC

jacquesm wrote: post #38

hellgas00 wrote: post #35

Earlier quoted context omitted.

Not sure where this myth started, the idea that somehow AC is less dangerous to handle at high voltages over DC. Wall socket AC alternates at ~50Hz, that's an oscillation every 0.02sec, for perspective, the average human reaction time is in the range of 0.15 to 0.3sec [Wikipedia]. There almost no chance that you willingly disengage a circuit once it's made for both high voltage AC or DC. Be careful whenever handling…

That's not a myth, it's a fact and reaction time has nothing to do with it. You're not consciously pulling back, your muscles will simply stop contracting for a short bit after which you (hopefully) disconnect. The DC damage is a condition called 'muscular tetanus'. The main risk with AC at medium voltages (say 40 to 250 V) is that your heart goes haywire. Though those voltages could easily kill you too. Yes, you sho…

Post by bigiain » Fri, Sep 12, 2014, 4:41 AM UTC

toomuchtodo wrote: post #51

bigiain wrote: post #28

Earlier quoted context omitted.

His copyright notice and explanatory paragraphs make it clear he's trying to keep some level of control over those photographs, while still sharing them with "his community" - which means I feel a little uneasy about having archive.org unilaterally slurp the images up like that... I know it's kind of a losing battle, but "publicly available" does not mean "in public domain".

Hey bigiain! I'm the one who initiated the archive against the page(s) in question. While I understand copyright is important, I also believe in the preservation of digital history on the internet. The page in question isn't password protected, nor were the images prevented by the Internet Archiver's archive process from committing the page to their archive. The author still receives their attribution, and The Archiv…

Post by idlewords » Fri, Sep 12, 2014, 5:36 AM UTC

hemancuso wrote: post #40

DanBlake wrote: post #27

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).

Isn't that the type of cell the 777 use(s/d)? I think Elon Musk very addressed the issue pretty well. http://www.flightglobal.com/news/articles/elon-musk-boeing-7... "Large cells without enough space between them to isolate against the cell-to-cell thermal domino effect means it is simply a matter of time before there are more incidents of this nature," he adds. "Moreover, when thermal runaway occurs with a big cell,…

Post by mozilla » Fri, Sep 12, 2014, 6:44 AM UTC

Varcht wrote: post #53

jacquesm wrote: post #38

Earlier quoted context omitted.

That's not a myth, it's a fact and reaction time has nothing to do with it. You're not consciously pulling back, your muscles will simply stop contracting for a short bit after which you (hopefully) disconnect. The DC damage is a condition called 'muscular tetanus'. The main risk with AC at medium voltages (say 40 to 250 V) is that your heart goes haywire. Though those voltages could easily kill you too. Yes, you sho…

Reminds me of two major events in my youth. Like you being shocked by the HV rail of an old tube radio and another acting as the ground for an old floor polisher in my grandpas shed. I guess I preferred the 115v AC, I remember it kind of like a massage chair but all through my body. Luckily my brother knocked into me long enough to let go, not sure I could have otherwise. The radio was brutal, knocked me back across…

Post by jacquesm » Fri, Sep 12, 2014, 7:05 AM UTC

SpacemanSpiff wrote: post #57

jacquesm wrote: post #31

Earlier quoted context omitted.

Where is the actuation mechanism for that that though? There does not appear to be any circuitry for that here. At a minimum you'd need something that would engage/disengage the cells, either a FET or a IGBT. (the voltage drop on other devices would be too large).

Take a look at http://files.wizkid057.com/teslapack/update2/Tesla%20BMS%20M... For cell #1, my guess is that the 4 parallel resistors (R3) are the balancing resistors and that Q1 is a small logic level MOSFET which enables cell balancing. On a BMS project I'm working on balancing current is only 250mA, so a small SOT-23 MOSFET is all you would need.