Model S

What is the expected frequency of home charging turning on and off?

Hi -

I have a 2015 Model S 70 which I bought used about 6 months ago and about 67k miles. It has had one or two issues that resulted in the digital aspects shutting down and visits to the service center, including replacement of a "daughter board". One of the symptoms that led up to this was that charging was starting and stopping in my garage somewhat frequently. Over the last couple of months, I haven't had such severe issues, and the worst seems to have been one or two screen resets needed.

However, once in awhile the charging will start and stop a bit more than I expect in the garage. Last night, for example, my phone told me of two or three points when it just started and stopped maybe a bit later. It's been a bit cold here (in the 20s at night) so maybe that is somewhat related? I don't think any miles are being added. If I happen to catch the vehicle doing this sort of thing during the day, I have once or twice simply unplugged it, just on general suspicion that it shouldn't be doing that too much.

So I thought I'd ask a question of fellow drivers as to how often they expect the vehicle to start and stop charging when it is just sitting plugged in. My charges station is an old Clipper Creek CS-40 (about 7 kW) that has powered a Leaf and then a Volt since 2013, without incident, once I got something worked out on the initial install.

Comments

  • I wouldn't know. My car is never plugged in when I am not charging it.
  • Once charging starts, it shouldn't stop until it reaches the charge level you set. Then, after the charge level drops 3-8 miles from parasitic drain, it will top it off.

    If you are getting multiple start/stops during a regular charge cycle, that's not normal. It could be a loose connection somewhere along the circuit, causing heating. Or, it could be a problem with the onboard charger.

    If you can do a level 2 charge away from home, see if it happens there. If not, it's probably your 240V line or the external charger. If it does, it's probably within the car.
  • There is always a 12v draw, and when the 12v battery voltage drops to a certain level, it will start to charge it until it reaches the cutoff voltage. This may cause your car to draw from your clipper creek.

    This may be normal, but If the 12v battery is weak or failing, it may do this more often, exasperated by the cold. Weak or failing 12v batteries usually trigger a warning message in the car - replace 12v battery.

    Just a guess.
  • Teslafi will tell you how many times you car is charging, and how much power is being consumed.

    This can be useful in diagnosing vampire drain and problems with the 12v batt and on board charger.

    With the car unplugged, should not be loosing more than 3 miles or 1% a day.

    If you are, the most likely culprit is a failing 12v. Easy DIY for a 75D.
  • Main battery doesn't charge 12 v battery.
  • > @barrykmd said:
    > Once charging starts, it shouldn't stop until it reaches the charge level you set. Then, after the charge level drops 3-8 miles from parasitic drain, it will top it off.

    I see my Model S 75D charging any where from 1-5 minutes at a time maybe 6 times in a 24-hour period. I keep the car plugged in all the time to a 9.6 kW EVSE, charge level set to 80%, but only drive 50-100 miles 3-4 times a week. I attribute the short, frequent, charging periods to parasitic (aka 'phantom') drain.

    I have the Teslfi app active, and I used to have many more brief charging periods with less than an hour of 'sleep' time per day. I adjusted the sleep settings in Teslafi and got more sleep time and fewer short charging periods. This supports my sense that parasitic drain is the source of the issue.
  • > @WW_Icefree said:
    > Main battery doesn't charge 12 v battery.

    What does charge the 12-volt battery?
  • > @"Yodrak." said:
    > > @WW_Icefree said:
    > > Main battery doesn't charge 12 v battery.
    >
    > What does charge the 12-volt battery?

    When I had mobile tech over installing Homelink in model 3, I asked him if 12 volt charges from main battery he said no. I have no clue why would he say that.
  • > @WW_Icefree said:
    > > @"Yodrak." said:
    > > > @WW_Icefree said:
    > > > Main battery doesn't charge 12 v battery.
    > >
    > > What does charge the 12-volt battery?
    >
    > When I had mobile tech over installing Homelink in model 3, I asked him if 12 volt charges from main battery he said no. I have no clue why would he say that.

    You didn't answer the question - what does charge the 12-volt battery?
  • Yes, I was mislead. My previous statement is wrong. I apologise.
  • > @WW_Icefree said:
    > I have no clue

    That sums up your knowledge of Tesla (and everything else, too).
  • > @"Yodrak." said:
    > I see my Model S 75D charging any where from 1-5 minutes at a time maybe 6 times in a 24-hour period. I keep the car plugged in all the time to a 9.6 kW EVSE, charge level set to 80%, but only drive 50-100 miles 3-4 times a week. I attribute the short, frequent, charging periods to parasitic (aka 'phantom') drain.
    >
    > I have the Teslfi app active, and I used to have many more brief charging periods with less than an hour of 'sleep' time per day. I adjusted the sleep settings in Teslafi and got more sleep time and fewer short charging periods. This supports my sense that parasitic drain is the source of the issue.
    >

    Thanks, I may give this Teslafi website a try, though it seems to have a fee. If this particular issue is addressable digitally with an adjustment, I wonder why Tesla does not just address the issue itself.

    Yesterday from sometime in the morning to around 8 PM I received about 24 notifications on my phone about starting, stopping or having charging interrupted. Of those notifications that have the miles on the car at the time of the notification, all indicate 173 miles. That is, the car never was at a point of adding back any miles (more than a tiny bit). I was not particularly doing anything in or around the car yesterday that I recall, though I did at one point forget that my key fob was in my pocket so the car woke up a bit, for a few seconds, until I took care of that. Finally I just unplugged it and will let it sit for a day or two. Under the pandemic I only go out 2-3 times a week anyway, and sometimes just to keep the car happy.

    So, with that frequency, it may be that there is something wrong somewhere outside the car in the connections, or maybe something else. I'll mention it to the Tesla service folks next time I am there. I like the idea that ultimately the solution might be in the 12 Volt onboard battery in that this would seem to be easily remedied and it would fit with my two previous EVs, Leaf and Volt, which both ultimately (if I recall) required 12 Volt battery replacements. However, even if there is a problem with the 12 Volt battery and it relates to this seemingly-overly-frequent stopping and starting of charging, I have to wonder if it is a symptom and not just an isolated thing.
  • Now that you have provided more info, I think it is unlikely to be the 12V system, good news.

    Try popping off the nose cone and connecting a battery charger at about 4A to the jump posts overnight, see if that helps.

    Teslafi is very much worth the 5/month fee, and I think it is free for two weeks.
  • > @josh_98457260 said:
    >
    > Thanks, I may give this Teslafi website a try, though it seems to have a fee. If this particular issue is addressable digitally with an adjustment, I wonder why Tesla does not just address the issue itself.

    Teslafi is a worthwhile app to help understand what's going on with your Tesla, so it's constantly interrogating the car to find out what the car is doing. Because of this, Teslafi actually contributes to phantom drain. The adjustment I made was to have Teslafi interrogate less often, allowing the car to sleep more and thus lessen the amount of phantom drain that Teslafi causes.
  • I agree with @Yodrak...

    One feature it has is battery report. Compares your range to all other cars of your type and mileage. Reduces worrying about the pack.

    Software update notices and release notes are nice too. Updates are like a cliff, no turning back, and I like to be the last "lemming" in case I get a firmware update push...

    With deep sleep set at 20 hrs a day, my vampire drain is 0.03 Kw per hour.
  • > What does charge the 12-volt battery?

    https://teslatap.com/articles/12-volt-battery-compendium/
  • > @ATPMSD said:
    > > What does charge the 12-volt battery?
    >
    > https://teslatap.com/articles/12-volt-battery-compendium/
    >

    Yes, Thanks to TeslaTap extended explanation.
  • note -
    For now I have solved the problem by plugging in at 120 Volts using a portable EVSE and a different circuit.

    I'll look into teslafi another time, sounds good, but I just didn't want to deal with it right now.
Sign In or Register to comment.