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Tips for charging on 120 volts?

Discussion in 'Roadster' started by smorgasbord, Sep 27, 2014.

  1. smorgasbord

    smorgasbord Active Member

    Jun 3, 2011
    SF Bay Area
    I'm currently away from home, staying at a relative's, and only have 120 volt access (20 amp outlet). While I'm able to hit up Level 2 chargers on the road and such, it seems prudent (not to mention habit) to charge fully overnight. I've noticed that the car doesn't really cool the battery until it get to about 94% full (Standard mode). Before that it lets the battery hang out at 90F, sometimes even hotter.

    Is there something I could do to get the car to cool the battery before it gets close to full? I know I need to get some Level 2 charging going, but is there any sequence (or some special OVMS mode) that would enable me to cool my battery? I watching my CAC drop almost daily...
  2. supersnoop

    supersnoop Tesla Roadster #334

    Mar 24, 2014
    You could text the COOLDOWN command to your ovms module. But I don't think it will work with 110v.
  3. wiztecy

    wiztecy Active Member

    Apr 29, 2012
    Santa Cruz, California, United States
    #3 wiztecy, Sep 27, 2014
    Last edited: Sep 27, 2014
    The HVAC will run if ESS temp is greater or equal to 40C and turns off once it hits 36C. Still, you still won't be able to ever drive temps down to 26C off a single 110V connection nor anything less than 12AMPS on 220V. Best cooling you can do with this condition is 36C once the 40C threshold has been triggered. However if you pump in 150+volts you'll be able to cool down to 26C like 220V behavior. That Quick 220 box you mentioned in your other thread would be the only reasonable way to drive down the temps to where you want them.

    Don't know why Tesla didn't allow the HVAC system to run longer so it could drive the pack down on temps better, but that's the way Tesla designed it. Possibly not having enough current stresses the HVAC. Don't know. Well actually I guess I do, if the HVAC is running, that alone would be gobbling up the charge which isn't much on 110V. They must have made a trade off to put in as much charge as possible but fire off the HVAC system only when things get really hot!

    I already had this conversation with a Tesla engineer so I could do cooldowns at work but he concluded the HVAC algorithm is too limited under 110V.
  4. pharma5

    pharma5 Roadster F#25, Model 3 #36xx

    Nov 22, 2011
    central NJ
    On 120V it can actually go to 40C (104F) at lower SOC before cooling... as you hit the end of charging cooling kicks in to bring it to about 25C. Not a big deal to do it once overnight, as I've done this many, many times.

    Best bet is to have the car in a well ventilated area (outside garage) if possible. Makes a big difference on cool nights.

    Do not recall for sure but initiating in range mode may cause it to cool first before charging in earnest...I think (?) that's part of what cooldown command does on ovms or tattler. Might have a shot on true 120V 20A. If you try it manually, stop after cooling, switch back to standard mode, then reinitiate (?).

    Of course, if you don't really need the juice just wait until tomorrow - far more (and better) public charging options on the left coast than here...
  5. Roadrunner13

    Roadrunner13 Member

    Oct 16, 2013
    I only got my 240v charger recently and I was trying to do cooldown cycles before that on 110v.
    I didn't have a lot of success but I seem to remember having some with the SMS command: 'acc param'.
    The Acc command comes with a default of 'no charge' though and even if you set it to charge, the 'cooldown' portion slowed the 110v charging down to an even lower crawl!
    So be careful, overnight charging like this, will not give you as much charge!

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