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Quick urgent question about charging rate

Discussion in 'Roadster' started by MileHighMotoring, Apr 8, 2016.

  1. MileHighMotoring

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    My car's fully-charged rated miles is exactly what I need to use tonight for a book signing (Nick Offerman!) so I'm thinking I'll leave early, plug it in somewhere and eat dinner for an hour.

    I've never charged my Roadster in the wild before, and I have the Tesla-branded J1772 adapter. How many miles can I be expected to gain with one hour of charging at 30 amps (typical L2, Chargepoint maybe). Is it only 15 miles? That's what my rudmentary math is telling me. Might have to suck it up and take the ICE tonight :(
     
  2. gregd

    gregd Member

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    Probably closer to 20 miles, especially for the first hour or two of charging. Most of my experience has been charging at my office, where there is a ChargePoint station that gives 30A at 200-ish volts (208 minus sag). My 60 e-mile round-trip commute takes about 3hrs 15 minutes to get back to full on a standard setting. Only the last 15-20 minutes are tapered.

    Not all charging stations offer 30A, though I have seen 32 in the wild (wasn't ChargePoint, though). If it's ChargePoint run, see what their website claims, or give them a call to verify.
     
  3. ChadS

    ChadS Petroleum is for sissies

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    30A * 208V (typical at commercial site) = 6.24kW. Actual power going to the battery can vary significantly be temperature, and range varies greatly by temperature and driving style, but assuming 4 miles/kWh you can expect a little over 20 miles per hour after accounting for standard overhead.
     
  4. MileHighMotoring

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    Thanks guys. Would you say that the Ideal miles is fairly accurate? I'm happy to try and hypermile a bit, but it's 95% highway miles. I can keep it around 55.
     
  5. gregd

    gregd Member

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    It really depends on how you drive, and what the terrain is. If you have a lead foot, no; at 55 on level ground, you can probably do better than ideal. My commute has a 1,000 foot elevation change. Heading down hill to work, the 25 miles costs me 20 e-miles. On the way home, it costs closer to 40. This is mostly 65+ mi/hr freeway driving, no heat or A/C. Bun warmers and headlights don't cost anything.
     
  6. strider

    strider Active Member

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    I can verify that your standard Chargepoint hooked to 208V/30A commercial power will yield right at 20 mi/hour.
     
  7. hcsharp

    hcsharp Active Member

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    That's what I get. Sometimes a little better. What are you running for tires? I get better than ideal miles at 55 mph on Yokohamas if it's at least 45 degrees with only mild hills. Drive the Roadster and take your time eating dinner!
     
  8. wiztecy

    wiztecy Active Member

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  9. MileHighMotoring

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    Thanks for the help, the trip went perfectly, I hypermiled it so much on the way there, I ended up at home with 20 miles on the clock and no charging needed! I was impressed many miles I "saved" by being so easy on the accelerator and keeping it at the speed limit (or a little less). I drove the first 10 miles and lost only 2 miles on ideal (and estimated went through the roof as it learned my new driving style)
     
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  10. slcasner

    slcasner Member

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    Congrats for having the nerve to go for it!
     
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