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Charging Question

Discussion in 'Roadster' started by Pantera Dude, Feb 5, 2013.

  1. Pantera Dude

    Pantera Dude Member

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    Is it harder on the battery to charge in range mode or to drive until the battery is low or empty? I know from what I've read that the range charge hurts battery life and I think driving the battery to a low state of charge is harmful? Can you guys shed some light on this?
     
  2. Doug_G

    Doug_G Lead Moderator

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    Either is bad for the battery. That's why Standard mode hides the bottom 10% and the top 10%.

    There is increased degradation over time when the cells are very high or very low.

    Driving is a different story. When the battery gets low the cell voltage is lower. In order to maintain the same power, the car has to draw more current to compensate. So driving with the pack low is harder on it than driving on a full pack. (This is why Tesla recommends you keep the car plugged in.)

    Therefore I would strongly recommend doing a Range Mode charge before a long trip, rather than risk getting very low. Besides that there's less risk of running out if you run into a detour, get lost, get unexpectedly cold weather, etc.

    If I'm going to do a trip I usually charge Standard overnight, then in the morning I get up and flip it into Range mode, then go have breakfast, etc. As soon as possible after charging is complete I start driving. That way the car is in the 100% vicinity for a very short period of time.
     
  3. Pantera Dude

    Pantera Dude Member

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    Thanks Doug! How low is very low? I read where someone doesn't drive hard below 40% charge. I have run my car into the yellow a couple of times and into the red once. I would guess that the red is very low? If we run the car to zero miles in standard mode, is there more charge left in range mode and if so does the car switch to range mode automatically or does the car stop and require switching to range manually?
     
  4. Doug_G

    Doug_G Lead Moderator

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    If you run to zero miles in Standard mode, it will force you into Range mode. IMHO if you're anywhere near that you should have put it in Range mode long before that. You want to know as accurately as possible how much range you have left!

    There's no hard and fast rule, but it's probably a good idea to limit "spirited" driving when you are under half a pack. When you get to Yellow territory I would definitely be taking it easy.

    Red is very low, but not about-to-stop-dead low. I get there routinely on long trips. When you get VERY low, under about 25 km (15 miles), the car will start going "Danger! Warning! Will Robinson!" on you. It will also stop giving you range estimates. I'd suggest resetting your trip odometer (or at least note the reading) at 30 km (20 miles) so you know approximately when you'll be dead in the water.

    Unlike the Model S, when the Roadster gets to zero, it stops. I've never got it there. I did get a little bit into the "Danger Warning" region once (due to an insistent TV reporter) but I would personally recommend avoiding that if at all possible.

    Dead in the water is to be avoided at all costs. You'll have to call Tesla for help getting your car going again, and it's definitely not good for the battery. Whatever you do, don't leave your car in that state for a protracted period!
     
  5. Pantera Dude

    Pantera Dude Member

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    When driving, does range mode do anything other than limit performance, is there anything else it does that would protect the battery?
     
  6. Doug_G

    Doug_G Lead Moderator

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    Range Mode does a few things on the Roadster:


    • It allows 100% during charging
    • It chills the battery pack during charging, so it starts the trip at a lower temperature (reduces need for cooling)
    • It allows you to see the top and bottom 10% of the range
    • While driving it reduces the cooling power provided to the pack, allowing it to get warmer (to save power)
    • While driving it limits acceleration power (50% IIRC)

    (Please note that Model S Range Mode is completely different.)
     
  7. brianman

    brianman Burrito Founder

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    I didn't realize I was reading the Roadster sub-forum when I read this.

    Doug_G, have you experienced something like this in your Model S? Right around the 30 mi. mark (some time after the dashed acceleration limiter kicks in) the car pulls back on climate control as well, which feels like "ranged driving mode". Have you experienced this as well in your S yet? I don't recall reading this behavior documented anywhere, but it sure seems consistent in my S.
     
  8. Doug_G

    Doug_G Lead Moderator

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    I duuno... I never get my S anywhere near 30 unless I'm already in Range mode, and have been for hours!
     
  9. bolosky

    bolosky Member

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    I'm pretty sure this is wrong. There are two different levels. First, the car stops running. At that point, there's still enough charge in the battery to run the computer and auxiliary systems, so if you can get the car to power (or haul a generator to the car) then you can recharge it, no Tesla needed. This is not good for your battery, but it's not a disaster, either.

    If you let it sit for a long time after it stops running (say, by running the battery very low and then putting it in the garage unplugged for a few months) then the battery really runs out of charge and Tesla is required to recharge it. You've also likely done serious damage to the battery at that point. This is what people call "bricking" the car, and it really is to be avoided at all costs.
     
  10. Doug_G

    Doug_G Lead Moderator

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    Have you actually run to zero? I know someone who has and he needed Tesla's help to get going again.
     
  11. tennis_trs

    tennis_trs 2010 2.0 Roadster Sport

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    Anyone have any first hand experience, to give us input on this?

    I also thought that the Roadster should charge fine again if plugged in within a reasonable amount of time (I'd expected at worst within a couple days would be fine, but not waiting as long as months).
     
  12. ggr

    ggr Roadster R80 537, SigS P85 29

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    I ran down to the point where I had to push it home. Plugged in via an extension cord at 110v for a couple of hours. Then drove it uphill on the driveway to get to the 240/40 charger. I think it cost me a mile or so of permanent range, so I don't recommend it.
     

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