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ESS Cool Down Procedure *WITHOUT* Using OVMS

Discussion in 'Roadster' started by Roadster, Jul 7, 2017.

  1. Roadster

    Roadster Member

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    As I patiently await the release of OVMS 3.0 so I can remotely make use of its thermal management features, I was hoping someone could document what's needed to perform a "poor man's" cool down of the ESS. From what I've gathered reading previous posts, the car needs to be plugged in and I should kick off a Range Mode charge just long enough to get the HVAC to turn on and run for a bit.. but for how long? I believe it was also mentioned that a 220V EVSE was needed so I should be fine there as I've got an old ClipperCreek TS-70 (limited to 40A / 220V output). Thx in advance for the guidance.
     
  2. Stefan T

    Stefan T Member

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    Have the AC on in coupe with car on, with driving
    I have seen that the ESS cool down realy good if i drive carfull, in sunny wheather and the AC on.(can be too cold. 5-10C below outdoor temp)
     
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  3. supersnoop

    supersnoop Tesla Roadster #334

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    Start a range charge. The first thing it does is cool down the battery before it starts charging. Keep an eye or ear on it so you know when to cut it off.
     
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  4. wiztecy

    wiztecy Active Member

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    Depending on if you want your battery to charge or not dial your amps in. If the battery is around 55-65% SOC I dial the amps down below 30. If you want it to charge then keep them at 30 or 40. Also leaving the Roadster in standard mode will allow the Roadster to cool-down, only time I select Range Mode is if its a very very hot day which the cooling needs to be aggressive to drive the ESS temps down. Over time you get the feel of it.
     
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  5. gregd

    gregd Active Member

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    Ditto what Wiztecy said. Summer temps would top out around 100F. When I would drive up the hill after work (1,000 ft elevation gain at freeway speeds), the ESS would be quite warm by the time I got home. At the time, I was limited to 24 amps charging current, 240 volts. I would plug the car in and start a Range mode charge for about 30 minutes or so, then stop it manually. That would cool the ESS down enough that the circulation pump would shut down, otherwise it would run all night. If it didn't stop the pump, I'd give it another 15 minutes of range charge. The A/C does cycle a few times during the cool-down, so I couldn't go just by ear for when to stop the charging. I also couldn't monitor the actual ESS temps, so observing the coolant pump shutting down after stopping the charge was my measure of success.

    No idea if this was the best plan for ESS health, but this was my logic. My primary charging would occur at work each day. This would show that the charging ports were appreciated, and to give the ESS a cool-down during the day, vs letting it sit in the hot parking lot unpowered after the commute in from home (25 miles). That prevented it from needing an unattended cool-down without being powered. I don't think that actually occurred, but that was my concern at the time. Also, a full charge and cool ESS for the return trip up the hill in the hot afternoon would be easiest on the overall system. And charging at work was free, so no point finishing the charge at home.
     
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  6. Roadster

    Roadster Member

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    Thx for the direction everyone. Sounds like the key is to get the ESS to a temperature where the coolant pump turns off; a good thing for keeping the batteries happy and, more importantly, the pump components from addl. wear. Does anyone know the range at which that happens? I also like the idea of dialing the charge rate down to 12A or 15A but if a higher amperage is needed to ensure the HVAC comes on, pls lmk the minimum there as well. Thx again.
     
  7. wiztecy

    wiztecy Active Member

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    The target ESS temp your shooting for is 26C or 78F. If you can drive it lower, great. However if the ambient temps are high, the HVAC system will be battling to bring the ESS temps down but won't succeed, there's a point of diminishing returns here. So when I see it at 26C I'm happy and weigh how much the system is working vs how long the HVAC will have to run if I want to drive it any lower. Note that usually the temps will bump up a degree after settling in. Just get a feel for it and from my experience it will shut the pump off. However if its really hot it hot and that circulating pump will continue to run.

    As for amps, I believe the lowest you can dial the 220V amps down is 12amps as you mention, that's enough to cover the HVAC. I go up to the next amps since its not much more but enough to cover the HVAC overhead and then some. Doesn't really matter I'm sure but it makes me feel better just on how the system runs.

    And charging of the 110V line, the Roadster will only activate the HVAC to cool down the ESS only and only at the end of the charging profile or when the target SOC has almost been reached.
     
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  8. Roadster

    Roadster Member

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    Fair point on the diminishing returns; esp. in hot climates. Sadly, my garage temperatures are pretty gnarly at the moment so the system continues to pump and blow throughout the day as you mentioned. I try to open my garage door from time to time to let the accumulated hot air out but ambient temps are just as bad. Can't imagine what @shrink, @skadax, and @bpangburn have to go through in their climates as discussed here and here.

    Ah, good to know about the caveat for 110V charging as well. L2 it is then.
     
  9. markwj

    markwj Moderator, Asia Pacific

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    The OVMS and TATTLER systems also have some fancy logic to monitor the HVAC. OVMS cooldown does a range mode charge at 13A. It looks for the HVAC stopping, then toggles to performance mode for a few seconds before switching back to range. That seems to happen about once every ten minutes or so. I've always been dubious whether it makes any difference - the HVAC is controlled by the VMS and we have no direct on/off control. We can definitely get it to kick in by stopping and restarting the charge, but that is considered detrimental to the health of the contactors.

    So, if you want to do it manually, I suggest range mode, 13A for 30 to 60 minutes.
     
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  10. bpangburn

    bpangburn Member

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    I ultimately framed in a bay of my garage, insulated, and added a window unit. Probably not the greenest solution, but not quite ready to move north.
     
  11. ViviV

    ViviV Member

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    @markwj What is OVMS cooldown and how do I do it?
     
  12. jeremyz

    jeremyz Member

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    I was going to do the same thing, but I never got around to it. It's probably cheaper to do that than to pay for the wear and tear on the expensive A/C components in the Roadster.
     
  13. markwj

    markwj Moderator, Asia Pacific

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    There was some discussion back here, and this post has the specifics:

    OVMS Module and Cooldown
     

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