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Tesla Updates Model S Software As a Precaution Against Unsafe Charging
zlives writes "Tesla Motors has maintained that the most recent fire involving one of its Model S electric vehicles isn't the result of a vehicle or battery malfunction, but the company is still addressing the situation with a software fix, according to Green Car Reports. The California-based automaker has added a software function that automatically reduces the charge current by about 25 percent when power from the charging source fluctuates outside of a certain range, Green Car Reports says, citing the Twitter feed from an Apple employee, @ddenboer, who owns a Model S. You can read the text of the update below."
Here is the actual article, not the article about the article... http://www.greencarreports.com/news/1089292_tesla-updates-software-to-cut-charging-if-wiring-may-be-bad
Much of the us infrastructure was built prior to 1900, when end uses we're capped at 110 volts for reliability. Much of the European infrastructure was built after 1900, when the end use limitations were solved. So they did 220 v since it w as more efficient.
First mover problem.
The *proper* fix would be to redesign the charging circuit to continuously monitor feed impedance.
They already do that, by monitoring the voltage drop when the load is applied. That doesn't cover all cases though, because fires are more often caused by high resistance or intermittent junctions. If you get say a 5% voltage drop because of wire resistance it's probably no big deal because the heat dissipation is spread out over the length of the wiring. A similar drop caused by a poor junction might glow because it's concentrated in one spot. I believe that poor junctions often exhibit short term fluctuations because they're loose and intermittent, and that's the additional thing that this software mod looks for.
This isn't an issue specific to Tesla vehicles, but it is something that any electric vehicle owner should be aware of and an issue in general for home electrical distribution systems.
The first house I lived in when I got married had the entire house on a single 20 amp circuit (supposedly installed by a professional, but I'm not sure which decade with the tar & cotton wiring I ended up spotting as I went through the attic), and the house I grew up in was only rated with the fuse box for 40 amps (again the whole house, but there were multiple circuits with that house). Even the house I live in at the moment is only rated for a maximum of 100 amps, and I'm not really sure how close to that limit I care to push the issue even though the wiring gauge does look sufficient for those power requirements. I know some new home construction can be rated for as high as 200 amps or more, but it is something to be discussing with contractors when the house is being built currently in terms of planning for potential needs of future power needs. IMHO it really needs to be added into the NEC (National Electrical Code) as assuming something like a stead base power load of 40 amps in a standard socket should be found in a garage or something like that.
That doesn't even get into the neighborhood power distribution systems that would need to be updated in a serious manner if electric vehicles became quite common. It most definitely will become a major issue for electric utility companies in the future if these vehicles become popular.
Tesla actually slowly ramps up the current draw. When I hook my car up to the 80A charger it will slowly ramp up to 40A, pause, then slowly ramp up to 80A (there are two chargers in the car, each rated at 40A). It monitors the change in voltage as it does this.
This post is encrypted twice with ROT-13. Documenting or attempting to crack this encryption is illegal.
I hate to break the news to you, but Ohio is out-doing Texas.
#naabhaprzrag, #sverubfr-000, #agi-fcbafberq, negvpyr[pynff*=' negvpyr-ary-'] { qvfcynl: abar !vzcbegnag; }
and for a higher voltage you go line-to-line, which is only 208V
That's not how they do it for residential (at least in my neck of the woods - not sure if it's universal). It's split phase. The secondary of the transformer feeding your house is single phase 240V with a center tap connected to neutral (nominally an earth ground). 120V lines are between either side of the secondary and neutral. You get 240V by connecting to both of the "hot" sides of the secondary (i.e. you don't use the center tap).
You never see 208V measured from hot-hot in homes unless you have severe voltage sag - only 240V single phase with 120V measured from each hot to ground.
208V is commonly seen in commercial 3-phase situations, though, where you tap 2 out of 3 hots and each hot is 120V measured to ground.