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Use L2 charger instead of Supercharger when battery is cold with very low SoC

Discussion in 'Model S: Battery & Charging' started by rypalmer, Jan 3, 2017.

  1. rypalmer

    rypalmer Member

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    I had a very frustrating charging experience on Sunday as part of my journey back to Toronto from Atlantic Canada.

    After L2 charging in Edmundston for 90 minutes, we limped toward the Rivière du Loup Supercharger. For a stretch of highway that we should have cruised at 110km/h, our average speed was 65km/r, average consumption 186Wh/km at -7.5ºC. 172m gained over many rolling hills, range mode on, heater off (brr). It was a tedious experience for my co-pilot, who had no prior first hand experience with electric vehicles.

    We arrived with 1% SoC, freezing cold, ambient temperature about -10ºC. I turned Range Mode off upon arrival. We plugged in at the SC, and the car gave no complaints and suggested a 1% to 100% Supercharging time of 1h20. I waited for charging to ramp up which it never did. I recalled other threads discussing the need to warm the battery prior to Supercharging, so for the first 20 or 30 minutes I wasn't too concerned.

    It cycled from 0 to 10kW at random (as others have described), and after 1h20 minutes on the Supercharger having gained only 1km rated range, I tried changing stalls to no effect.

    This was not the coldest temperatures I've attempted to charge in since owning the car, but it was my first very cold Supercharging experience. What felt strange, though, is that I have used L2 charging many times while quite cold soaked, and have never seen anything but full amperage/rated range charging.

    I pulled across the parking lot to a L2 charger, and to my surprise the car pulled the full 48amps, registering 48km/hr charging. My pack gained kms almost by the minute while I called Tesla tech support to seek further advice.

    They confirmed what was not at all intuitive to me: that L2 charging is a lot more effective at trickle charging than Supercharging. I have no idea why this would be the case. But if you find yourself in this situation and want to potentially save some time/grief, try plugging into a L2 charger if available, to bring up your SoC a few points while warming the battery, prior to Supercharging.
     
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  2. rypalmer

    rypalmer Member

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    Stats for the curious.
     

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  3. apacheguy

    apacheguy S Sig #255

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    Well a supercharger is just a bunch of onboard chargers stacked together. I can see no reason why the onboard charger had no difficulty delivering 48 amp while the supercharger could not.
     
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  4. brkaus

    brkaus Active Member

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    Really sounds like a bug, connection problem, or SpC problem.
     
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  5. rypalmer

    rypalmer Member

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    Not according to Tesla tech support. They indicated their own policy was to use L2 charging to trickle charge dead cars for the same reason. They recommended L2 charging in this situation (very cold pack, very low SoC).
     
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  6. brkaus

    brkaus Active Member

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    As noted above, given an SpC is just a stack of chargers, it makes little sense.

    They might prefer one use an L2 in such conditions, but there is no apparent reason that an SpC couldn't act same as internal charger.

    Do they make L2 available at all SpC locations that are in cold weather regions?

    Not doubting your experience or what support said. I just find it strange.
     
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  7. rypalmer

    rypalmer Member

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    I've never seen a HPWC colocated with a Supercharger. I can only think Drummondville that had a few Circuit Electrique L2 chargers at the same pad.
     
  8. Rocky_H

    Rocky_H Active Member

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    I have started to see several threads on this same behavior (merge them?) here on this forum. So while I do see a lot of reports of this and a lot of reports of the support people at Tesla saying this is normal, it is definitely freaking NOT normal or acceptable. There is no reason why a Supercharger should not be able to at the very LEAST run at a low level, supplying 6kW+ to the internal battery heater, for pete's sake to warm up the battery and get some low level charging ramping up slowly. This thing where it sits for over an hour twiddling its thumbs at 0kW makes no sense at all. This never used to happen with the old 85 and 60 kwh batteries, so I do wonder if it is some problem with the newer generation 70/75/90/100 ones that have the added silicon in the anodes to increase energy density, but perhaps at the cost of a temperature weakness in the charging behavior of the chemistry. Still, a Supercharger should be able to act exactly like a level 2 charger. No reason for it not to.
     
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  9. Boourns

    Boourns Member

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    If this is Tesla's recommendation, there should be a HPWC attached to every SC stall, at least in cold climates.
     
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  10. mrElbe

    mrElbe Active Member

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    I remember many years ago I had a FIAT 850 Spyder and on a very cold day in Vermont, I built a wood fire under the engine oil pan to get it started. I guess definitely not recommended for the Tesla battery.
     
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  11. andrewket

    andrewket Well-Known Member

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    I've been told this is a known bug. The current workaround is using L2 to get the SOC up and then supercharge, but by no means is this normal.

    The solution must be complicated otherwise I would have thought tesla would have pushed out a fix already.
     
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  12. apacheguy

    apacheguy S Sig #255

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    Pretty sure this bug didn't exist until the newer firmwares. The fix should be simple: revert back to the older code that is known to be stable.
     
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  13. Rocky_H

    Rocky_H Active Member

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    Oh, can I revert back to version 6.x, before the interface suckage?
     
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  14. ecobon

    ecobon Member

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    I have had charging errors with the red light at the charger port and the dash requesting that I unplug, depress the brake and try again. After a few times, my cold and 2% SOC started to charge very slowly at a supercharger. After about 20 minutes, it started to ramp up and provide a "supercharge"

    When I use an L2 charger there is also no taper up to 90% that I can recall.

    Park Meadows Mall near Denver, CO has 2 mobile superchargers (4 spaces) and 2 HPWC.
     
  15. Lanber

    Lanber Member

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    Arrived at Brokelandsheia last night with 0km range left. Drove last 50km without heater on. Battery was warm and took supercharging as normal. It was -12C outside! I charged up to 70% without cooling starting at all. When I unplugged and started car the active cooling went beserk a few minutes. So bad steeringwheel was vibrating.

    Last summer I ran battery low with a CAN bus monitor so I wouldnt get stranded, I took out 2.5kwh under 0. Then supercharging would only give me 3kw first 5-10 minutes before it cranked up to normal speed.
     
  16. Rocky_H

    Rocky_H Active Member

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    Well, it's the same taper curve. It's just that a level 2 power level is so low that it's far below the required taper level and doesn't need to get reduced. The behavior is exactly the same, but a level 2 is only about 6-20kW, which is so low that the taper curve won't hit it until it's in the upper 90's%. Supercharger is at 100kW+ so you see it much earlier as it has to come down to 80, 60, 40, etc. which is still far above a level 2. Most people just usually don't bother at a Supercharger to 97-ish percent when the behavior would exactly match the level 2.
     
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  17. sorka

    sorka Active Member

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    Since the heater and other stuff will draw off the supercharger feed, it might be faster for P models to enable the battery heater right after the plug into the supercharger.
     
  18. wozzinator

    wozzinator Member

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    Regardless of the input type, doesn't the battery heater use off-board energy to heat the battery pack (even if it's in range mode) while plugged in to something?
     
  19. TonyWilliams

    TonyWilliams Active Member

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    I had this happen on the Roadster. The car only had a mile or two left on the rated range, and it wouldn't charge very fast at all.

    After hours at a very low charge speed (less than 1kW I think), it finally sped up to normal speed. This was in Southern California, and it wasn't cold.
     
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  20. David99

    David99 Active Member

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    This happened to me at a recent road trip as well. It was cold, but since I had driven the car for 300 miles before, the battery was warm. I actually use TM-Spy to get the battery temperature reading and it was well over 30 degree Celsius which is definitely warm enough to charge the battery normally.
    So I do not think it's battery temperature. It could not have been. The battery was at 0% though. What's odd is that I have driven my car down to 0 several times. A few times even beyond that. The Supercharger always provided full power after a short ramp up time. This must be something they added with a recent firmware. I have never had this happen before. Lithium batteries have to be charged very slowly when the voltage is below a certain point, so maybe that's what happened. It still doesn't explain why there is virtually no power coming through to charge. Maybe it's just a bug. Maybe the combination of lower ambient temperature and low state of charge triggers it, but it's still wrong as the battery (in my case) was definitely warm enough to take the full power of a Supercharger.
     

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