Model S

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Long term storage advice

edited November -1 in Model S
I'm about to enter a new phase of my Tesla ownership with my June 2016 AP1 MS90D. After it being my daily driver and 50k miles, I'm taking an ex-pat assignment and it will be unused for likely 2-3 months at a time. I know there are several other threads on this, but looking for more for reassurance than advice.

My plan is to leave the car plugged in set to charge to 50%. I know once the SOC drops down to something like 47% it periodically top itself up.

Normally I charge at home using my UMC connected to NEMA 14-50/50 amp circuit. Are some reasons it would be more convenient if I park the car in the side bay of our garage and my UMC won't reach my dedicated 14-50 outlet. Any concerns or bad experience if I plug it into normal 120V outlet, potentially via an appropriate heavy gauge extension cord? Is an alternate outlet I could use without an extension cord, but have an irrigation system control plan running off of it and don't want to share circuits.

I talked to my service center first of the month and they didn't have any specific advice on storage approach.

Comments from those that store car ~3 months at a time without anyone waking it up??




  • What you said in the first paragraph is I would recommend. Set the car to a 50% charge. As far as 14-50 Vs 120V set the amps to 12. That way it trickle charges.
  • edited September 2019
    I would try and plug it into an outlet/circuit that has/will not have anything else running on it. There is no harm in leaving it plugged in.
    edited September 2019
    Technically this is not trickle charging, but the effect is the same. The battery will discharge a bit, and then the car will turn on charging to bring the battery back to the maximum that you have set. With the smart design of the Tesla charging system it is very safe. @jordanrichard makes a very good suggestion because if the Tesla system sensed a momentary fault it may set a lower charge rate than desired, or even disconnect.
  • edited November -1
    Using 120V is far less efficient. Your electric bill will be higher doing it this way rather than the UMC at 240V.
  • edited September 2019
    I store mine over the long winter moths. Set it to 50% and have the timer to go on at midnight with low peak hours. Loses 1% a day and will top up after losing 4%. I do wake it up now and then and open the door. Not sure if I have to but just in case if it has to wake up to charge the 12 volt battery every week or two.
  • Months. Dang autocorrect strikes again.
  • edited September 2019
    I agree charging off of 120V is not trickle charging. It will periodically charge when drops 3-4% below the set point, so every few days as kerryg states.

    I also agree and am aware that charging at 120V is less efficient than charging at 240V as barrykmd states.

    Reason I would charge off of 120V, not 240V is due to potential desire to park the car in the third bay of our garage and the UMC not reaching from the 240V outlet to the third bay. Since my MS90D will not be driven regularly, makes it more convenient for the others in the household to get their cars in/out of the garage if I park the MS in the far bay of the garage which requires maneuvering a slight dogleg versus pulling straight in.

    Based upon some tutoring today, I think I have my wife a little more willing to take my MS out for a short spin around the neighborhood every few weeks. We have a couple cars now that do not get driven frequently (family minivan, daughter's car who is in NYC, plus now my MS). I think I have her convinced to do a weekly rotation and drive a different car one day each weekend. This will keep the 12V batteries in all three from draining down too much. Will likely follow that strategy at least over the next 3 months and then will reevaluate when back in US over the holidays.

  • edited September 2019
    You may return to a dead 12V battery. It's not easy to access, but if you can, try to trickle charge your 12V battery. It will deep cycle when your car is not "in use", and that will seriously shorten it's life.
  • edited November -1
    I'm about to leave my car for 6 months and the 50% on domestic (240 volt) sounds a good plan.
    My question is: can I leave the Sentry Mode switched on for the 6 months?
    Tesla seem to think it will automatically be disabled so the car can power down occasionally.
    I can live with this if I can remotely turn it back on with the app.
    Anyone have experience with this?
  • edited November -1
    Considering Sentry Mode uses 300W, that's about 5 cents/hour in electricity cost. Over 6 months, that's $216. Without considering the shortened life of the 12V battery from the wear and tear of the extra charge cycles, you might as well buy a real dash cam, which uses about 5W and has greater functionality.
  • edited October 2019
    If the car is in your garage, why would you want or need Sentry mode?
  • edited October 2019
    To the OP, consider topping off the tires and either jacking up the car or putting saddles under the tires to prevent flat spots.

    I left my car parked for two months and had no problems.
  • edited November -1
    I wonder if it might be better to set the charge to no more than 20%. 20% is the threshold for maximum power saving to begin. This 300 w hourly drain is disturbing. Suppose you only drove 10 miles per week but lost 70 miles during parking. Further suppose your Tesla Model S is rated at 100MPGe with 1/7 efficiency that's say 14 MPGe.
    Even a polluting big pick up parked for a week and then driven 10 miles would be more efficient.
    This is hypothetical but there was nothing efficient about overnight parking. Now I shouldn't complain Sentry mode was a free feature and I think the drain has been fixed in V10 2019..32.12.2 I just got it this morning and so far it looks good.
  • edited October 2019
    @AERODYNE - I didn’t want to jack the car up as I wanted it to be easily movable in case my family did need to move it out of the garage for some reason. I also think I have convinced my wife to drive it for a few miles every 2-3 weeks. If there was no chance any of my family needed to move it then I would have looked at doing something lik you mentioned plus put a trickle charger on the 12V battery.

    @dougk71- RE setting the charge to no more than 20% - Lowest you can set the charging set point is 50%.

    Not sure which has been more stress inducing - knowing that I have a software update ready to be installed (likely V10) and not going to be back to my car for 2 months or having just weathered out a typhoon yesterday equivalent to a Cat 1-2 hurricane.
  • edited October 2019
    @reed_lewis My garage is in an out-of-the-way hamlet in rural France where there have been break ins over the years. If someone breaks into my garage, which is also a workshop with some expensive tools, I'd like to be able to identify them.
    It's a pity to learn about the amount of drain caused by Sentry, because it seems to be the perfect burglar alarm and identification system.
  • edited November -1
    The perfect burglar alarm would be a burglar alarm.
  • edited June 2020
    I'm not concerned with the fine points of trickle charging or Sentry mode - my concern is that when I leave the car unused for 3 months over the summer, I want to be confident that when I get back the battery will work and there will be no significant damage to the car or battery. It sounds as though leaving the charger on, scheduled to charge at midnight each night to 50%, should work. Does anyone disagree?
  • edited June 2020
    No disagreement, but you might want to bump it up a bit, say 55%, so it will not go below 50% (it tends to drift down a few percentage points before starting a charge.
  • edited June 2020
    What I’ve found that works well for me is that before I leave for 2-3 months I’ll typically have charged to around 80%, driven some around town last day or so, and be in the 70ish% range. I’ll then set the charging set point down to the minimum allowed 50%. Leave with car plugged in and let is slowly lose 1.5-2 miles a day. After about a month I’ll see the car is nearing 50%, so whenever convenient, I’ll remotely bump it back up to 70% and let it charge.

    This keeps my battery in the 50-70% range, average over the month about 60%, and when it does charge charges for a couple hours, not the few minutes every couple days.

    Not saying something wrong with just setting at 50 or 60%, plug it in and leave it, but I prefer the periodic charge for 20% or so. That tends to mirror my normal charging style when I am back in US and driving my car regularly.
  • One of the risks of long term storage when it is plugged in is tripping the breaker. 12A is very close to the 15A most 110v sockets have. If another appliance happen to use that same circuit, it will trip the breaker and you will not be there to reset it. Best is to use a dedicated 110v or at least cover with black tape all 110 outlets in that circuit...something visual for the rest of the household.
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