Really? So they performed the contactor replacement and replaced your drive unit and rear brake rotors at the same time? Did you have issues that warranted those replacements? Please expand.
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Really? So they performed the contactor replacement and replaced your drive unit and rear brake rotors at the same time? Did you have issues that warranted those replacements? Please expand.
> According to Michael Faraday's law of induction the collapsing field will generate a very high voltage in the bar to induce a current in the same direction as the original flow path. This very high voltage is what creates a fireball flash-over arc as the current is trying to compete the circuit . . [kennybobby]
Doubt the collapsing field from the bar itself could contribute much to the flash-over pyrotechnics that chew at and untimately destroy these contacts. The energy would mostly be coming from the motor windings and/or drive circuitry. L of bar <<< L of windings.
The design failing here might simply be too small a C across the contacts; TM could be installing more C in lieu of installing some miraculous new contactors.
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Doubt the collapsing field from the bar itself could contribute much to the flash-over pyrotechnics that chew at and untimately destroy these contacts. The energy would mostly be coming from the motor windings and/or drive circuitry. L of bar <<< L of windings.
The design failing here might simply be too small a C across the contacts; TM could be installing more C in lieu of installing some miraculous new contactors.
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Otmar
EV Modder
Motor windings are downstream of bus capacitors and therefore not an influence here. The cables and bars are the inductance of concern in this situation. It doesn't take much inductance at high currents to cause issues. That said, during normal use the electronics will stop drawing current before turning off the contactors and so no arcing happens then. It's only in the safety shutdown case that breaking the arc is an issue.
My understanding is that capacitance across the contacts would be undesirable for safety concerns since they can carry AC currents. It is reassuring how Tesla isolates the pack so well when the contactors are off.
HankLloydRight
No Roads
Just as another data point, my 15639 VIN is scheduled for this service later this week as well, so it seems like the 15XXX range seems to be targeted. Perhaps this only affects certain cars, although I would have thought A packs would be on the list. I have a B pack.
KB's comment re right hand rule now seems to me to be about the pulling of plasma off the contact points. This is accomplished with only the small L of the bar, carrying huge Amps. Now makes sense.
These are DC-carrying contacts usually protected in EVs with diodes in parallel. In this case they are protected by normally closing/opening with zero current applied. Except for 'safety shutdown', at which time protective diodes might help.
I would have used a pair or more of these contactors in order to avoid all these dead-in-the-road failures. Plus I would put them either outside the battery or inside but with a removable cover plate (to simplify replacement). But this is not the usual AC ~f propulsion system as found in everyday DIY EVs, if there is such a thing anymore.
Best wishes with your Stretch project!
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HankLloydRight
No Roads
Maybe something to do with just one person's workstation that assembled or installed the contactors incorrectly before it was caught/detected.
I was told that the drive unit sounds that I had mentioned indicated a lubrication problem, and that the rotors were warped and rusty.
artsci
Sponsor
Gizmotoy
Active Member
Wonder if they're collecting contactors from a smattering of potentially-affected VINs to determine if wider action needs to be taken, and if so, where the cutoff is?
Got mine replaced today. Pretty uneventful. The new contactors do sound a bit different though. When they engage, they sound pretty much the same with a clack-clack sound, but when they disengage, the sound is much more muted than the previous contactor. It's a much lower-pitched and softer thud sound for lack of a better word. It's a very different sound.
Some Sigs are having their packs shipped to Fremont for more extensive repair. Was that your experience or did they do it all locally at the SvC?
I have an S85 I bought from the original owner last month with VIN in the 36000s that is now having the contactors updated although this was not based on a proactive call. This morning, we received a 12v failure message and the car would not move. Tesla had a flatbed out within 45 minutes and was able to pop nose and supply power to the 12v battery to start her up and back her out to the flatbed.
It's not entirely clear, but it sounds like the Palo Alto SC is able to do the work on this unless they spot some other issues that need to be repaired in which case the main pack is shipped to Fremont and in that case they said they would put a loaner pack in the car until Fremont is done with the repairs. We had more than 165 rated miles remaining, and we checked app and they were able to charge up the main pattery to 90% at the SC before they called us to tell us about the contactors needing to be updated.
It's not entirely clear, but it sounds like the Palo Alto SC is able to do the work on this unless they spot some other issues that need to be repaired in which case the main pack is shipped to Fremont and in that case they said they would put a loaner pack in the car until Fremont is done with the repairs. We had more than 165 rated miles remaining, and we checked app and they were able to charge up the main pattery to 90% at the SC before they called us to tell us about the contactors needing to be updated.
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