It may seem odd, when I ask about fuel in regards to Tesla. I yet do not own one, but some acquaintance ( with Tesla Y Long range, with total battery capacity of 326 miles) has tole me when I asked about buying, per the person Tesla loose about 7-10% fuel every weekend if not driven. So if the person leave it at 55% on Friday evening and do not put the car to charge or drive the Tesla on weekend, then on Monday morning it will show fuel left at 48% or 47%, that is a loss of 7-8% ( or 22-26 miles), per the person Tesla says that is normal. Does the ICE car's EPA mileage v/s Tesla EPA mileage calculation take that part in to account.

I feel ( I hope I am not biased), that most of the buyers of Tesla are middle class+ so they are not taking that part in to account and not noticing the loss and hype.

Does other electric cars have the same issues ?

2 Answers 2


I think all electric/hybrids (which use a battery) have the same issue. Even lead acid batteries lose power over time. The problem is, all batteries self-discharge over time. All batteries are going to discharge at different rates (the Wiki article has some self-discharge rates), but it's pretty much a given all of them do it. I'm sure it isn't news to anyone, but most people I know who own plug-ins charge their vehicle on a regular basis, so probably don't notice. Also, I'm not sure about it, but I believe that if you maintain your batteries with a charger, it will lose far less power overall than with it just sitting stagnant.

  • Plus the minor loads from the various things still drawing power. Your car can't unlock itself as you approach unless it is always checking to see if your key is in range...
    – Jon Custer
    Commented Jan 17 at 13:30
  • @JonCuster - Good add! This, as well, affects all EV's, not just Teslas. Commented Jan 17 at 14:02
  • And any regular ICE vehicle - you just don't see it on a projected range display. If you vehicle will sit for weeks to months it should be on a trickle charger.
    – Jon Custer
    Commented Jan 17 at 14:04
  • @JonCuster - While you may be using the term "trickle charger" generically, I don't recommend them. A battery maintainer does a much better job. A trickle charger continues to charge without regard to the state of the battery, where a maintainer keeps it topped off and in good condition. Commented Jan 17 at 14:16
  • Tis true, I got sloppy. The $0.50 chip that turns an old-fashioned trickle charger into a battery maintainer is pretty common nowadays meaning there is no reason to not be sure it is a smart device.
    – Jon Custer
    Commented Jan 17 at 14:24

There are a few things happening here.

  1. Always-on technology. Teslas are packed with technology, much of which is on all the time, even when the car is unoccupied. I've heard them called rolling iPads, and just like a tablet the car's computer is always on and running background tasks which require power. Syncing data to the cloud won't drain a car flat, but it will impact the range.
  2. Normal discharge: As @Paulster2 points out, all batteries discharge over time, it's unavoidable
  3. Temperature: lithium ion batteries perform best in a specific temperature range. Cars.com did some testing on Tesla Model Y range at different temperatures and found that at the extremes of temperature the batteries' range dropped

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65-70°F (about 18-21°C) was about optimal, there was a gentle decline below 60°F then it decreases more sharply below 10°F.

So, much of the decrease could be likely to the simple fact that it's colder in the morning than the evening. It would only take a difference of 15°F or so. It's just one of those things EV owners have to get used to, no matter the make.

  • I liked both answers, how can I know if EPA ( en.wikipedia.org/wiki/…) took into consideration of all these parameters . Which forum to ask that question.
    – puzzled
    Commented Jan 18 at 0:01
  • What would the EPA have to do with EV range calculations?
    – GdD
    Commented Jan 18 at 8:36

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