Here’s What Happens When You Run A Tesla Model S Battery Down To 0 – Video

NOV 29 2016 BY ELECTRICCARSTV 31

Most electric cars have some sort of buffer built in for the estimated/remaining range figure hits 0. The Tesla Model S is no exception.

Battery At 0

Battery At 0

Seldom do electric car owners push their vehicles past this 0 figure, so few of us know what really happens after the goose egg pops up.

The story below (and video above) tells the tale of what happens whne you go past 0 in a Model S.

“What happens when you run out of power in your Tesla? Range anxiety – especially at Nordic winter time – is prevalent to all EV owners and this also includes Tesla owners.

As most EV’s use battery capacities of around 20 KWh, Tesla’s generous capacity of up to 100 KWh dampens this anxiety somewhat but not entirely. And for this reason you have a tendency NOT to explore the full capacity of your battery as you have to make room for any discrepancies (traffic, delays etc.) in your calculation of your trip’s ideal power need. As nobody wants to be in the dreaded situation with ZERO power somewhere on the highway you typically add 5-10% on top of your calculated power need – just to be sure, don’t you?”

“Tesla encourage us to not exceed the zero power mark on our Teslas, but what exactly happens if you do? Tesla fanatic Bjørn Nyland tried this by accident in 2015 with his Model S P90 (7.x software) where he ended in the roadside with a completely depleted battery pack shortly after passing zero power and he had to be pushed(!) to nearest power outlet.”

“Now, on my 85D (8.0 software) I made a deliberate “run-out-of-power” test late October, 2016 to see what happens when you continue to drive when you have zero left on your dashboard – and of course to share this useful knowledge with all fellow Tesla enthusiasts. Look into the video and see what happened…”

If You'd Rather Not Watch The Video, Then Here Are The Results In Recap Form

If You’d Rather Not Watch The Video, Then Here Are The Results In Recap Form

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31 Comments on "Here’s What Happens When You Run A Tesla Model S Battery Down To 0 – Video"

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Since all Teslas are always calliing home, I would have expected Tesla to send a message asking why the driver was intentionally running the battery down and even offering to help avoid the situation.

They don’t have staff monitoring it at the time data is collected to be able to offer this assistance.

I disagree. A Tesla sitting stranded on the side of a highway during winter with a dead battery is a big deal – especially if the driver starts tweeting about it…

You could make the same argument about gasmobile drivers running out of gas, which happens a lot more frequently.

Oddly enough, gasmobile makers appear to assume that drivers should be responsible adults, rather than children who need a nanny constantly watching them.

Real-time monitoring would require a sizable paid staff doing nothing else. OnStar does that sort of thing. But then, OnStar charges a monthly fee for its service. Do you actually think Tesla should offer that for free?

Don’t count on the extra 20km being there… The guess meter on Teslas is very good, but I have heard of ppl running out at 0 (0 was indeed 0)…so, always have a buffer!

So he did NOT actually run the battery down to EMPTY! WHY not???
That is the interesting part…

Most likely because Tesla, like many other EV automakers, deliberately keep a tiny portion of power “hidden” away from the user, so as to avoid completely draining the battery for real, and causing long term damage to the battery.

So while the display says “0 miles left”, in reality it probably still has 3-5 kWh worth. Notice that even after his battery was “empty”, the displays were still working.

Because, in the first place, it’s really hard on battery life to completely drain the battery. As both comments above correctly state, even when the Tesla car’s range meter says “0”, there still is some reserve power in the battery pack. There is a difference between usable capacity and actual capacity. A “0” reading means 0% usable capacity, but not 0% actual capacity. This applies to all production BEVs, not just Tesla’s cars.

Secondly, and worse, you actually risk “bricking” the battery if it’s run completely flat and allowed to remain that way for an extended time. Bricking means the pack is dead, cannot be recharged, and has to be replaced.

I don’t think I’ve ever read about Model S/X packs being bricked, but there were a few incidents of Tesla Roadster packs being bricked until Tesla did a software update to prevent it.

OK, I did not mean to drain the battery to 0% SOC. I meant to drive the car until it actually STOPS.

My LEAF would do another 5-8 miles. The Focus and i3 only about 2 miles.

Running a lithium ion battery dead is the worst possible thing you can do to it, other than charging when the battery is below freezing. Why would anybody do this? Totally pointless.

Some people are genuinely curious as to what happens when an EV, especially a Tesla with its fairly sizable range, runs out of juice. And better that this guy shows us rather than people find out the hard way.

Hi @Warren

Two things…

1) When the Tesla reaches “0 miles left” and eventually stops moving, there is still some amount of power left in the battery. The remaining power is kept to prevent the battery from “bricking”.

2) It is true that Li-Ion batteries “prefer” to be kept in the 20%-80% SOC range. However, simply going up to 100% or down to 0% is not necessarily damaging unless you leave it there for long periods of time.

Running down to 0 right before charging is actually fine, since he was only at “0 miles left” for a few minutes. I would NEVER do that and then leave it sit for a week however!!!

Forgot to add… others have done this intentionally (down to 0 then back to 100) not to see what the reserve is (which in itself is interesting) but to help balance the cells and improve the pack capacity.

I have no idea if that is still relevant with Tesla and all their software updates though…

I’ve seen a lot of argument, especially on Leaf forums, over whether draining the battery pack and fully recharging it actually increases the pack’s capacity, or whether it just resets the software to give a better estimate of actual remaining charge.

I don’t know that I’ve ever seen this addressed by anyone who was able to give an authoritative answer. Certainly it’s not rational to think that any individual cell could suddenly recover more capacity, but — and this is pure speculation from someone who isn’t an electrical engineer — perhaps a pack which has gone slightly out of balance might be rebalanced by this method, and that very well could result in improved usable capacity.

Draining and recharging a Li-ion does nothing to the battery. (Or at least nothing good.) It does help calibrate the battery monitoring system, which may result in the SOC displayed to the driver appearing to have more capacity than it had previously. Ni-Cd batteries do benefit from full discharges, which is where that theory stems from. What happens chemically when a battery discharges? Some batteries, like lead acid, lose voltage at a constant rate as this discharge happens, so it is fairly easy to tell where in the state of charge the battery is sitting at any time. Li-Ions do not do this. Their voltage during discharge drops quickly, and then levels out for the vast majority of the cycle. At the very end of the cycle, the voltage starts to drop again. Most batteries have a safety system that interferes at this point to stop the battery from discharging any further to prevent damage to the battery. What kind of damage? Chemically, when being discharged Lithium ions that were attached to a piece of copper foil anode detach from the foil and move over to an aluminum foil cathode. Once enough of the lithium is moved, the copper anode… Read more »

BMS = battery management system. I’m too used to acronyms to remember what they actually stand for…

“The moral of the story – full discharges help the BMS, but are harmful to the battery. Do them at your own peril.”

Yes. Exactly!

Thanks, Sopfu.

Yeah, I should have included a caveat that at best, this is hard on battery life, and shouldn’t be done often, if ever.

+1 Thanks

There are DIY converted EVs that may need occasional full discharge to balance cells, but I don’t think that any mass production EV would have so poorly designed battery management.

There are different kinds of balancing. Top balancing means you actually use some form of cell balancing (the vehicles I work on have switchable resistors) to cut the voltage of the higher cells so they all hit the top voltage at roughly the same point. Bottom balancing involves running the batteries down to the low point (this is not the cascade point of the batteries, at which point the battery is damaged, it’s much much higher than that) and burning off the high cells (using the same resistors) so they all start off from the same “zero” point. Typically you bottom balance the pack when you build it and get it operational, and top balancing happens during the final phases of charging. These techniques utilize the “guard bands” around the battery curve to prevent over/undercharging of the batteries– you typically have a 5-20% guard band at the low and high point. In other words, the 0-100% INDICATED battery capacity is more likely 10-90% ACTUAL battery capacity. Allowing these “guard bands” to change over the life of the battery can (and usually IS) used to “hide” the fact that battery depletion and wear is a real thing– you might have a… Read more »

I guess if you hit zero, then you would stop and call for help. Most people would use what’s still available to reach the nearest charger.

I wonder if the car only allowed this because there was a destination to a charger in the NAV?

Exactly my first thought!

would be interesting ,how much kwh he loaded until 100%

Do any of you guys know how much actual capacity the Tesla uses of it’s battery? I know the Volt uses about 10 of 16 in the Gen 1, Now like 13 of 18 in the gen 2, the LEAF uses about 20 of 24, and so on. What about the Model S and X? Do they have a “usable 85” of 90? If so.. then I can see some battery degradation possible running it super low could do.

Tesla doesn’t give out that info, and apparently there is some controversy over the actual figures.

Here’s the gist: Someone claims to have done extensive testing of the cells in a Model S85 pack, counted them, did the math, and claims the so-called 85 kWh pack has only 80.7 kWh. He further claims there is ~77 usable kWh.

77/85 = 90.59%; 77/80.7 = 95.4%

Please note that I make no claim that this info is accurate. If the tester’s test methodology doesn’t match Pansonic’s test methodology, that alone could account for the apparent discrepancy. (And in fact, this wouldn’t be the first time I’ve read about
“nameplate” capacity, as listed in a battery manufacturer’s specs, being a bit, shall we say, optimistic as compared to what electrical engineers actually measure as the battery’s real-world capacity.)

If we assume that this is the case, then what he’s measuring as ~77 kWh usable capacity would actually be rated (by Panasonic, at least) as ~81.1 kWh usable capacity.

Anyway, those interested can read the discussion thread for themselves:

https://teslamotorsclub.com/tmc/threads/teslas-85-kwh-rating-needs-an-asterisk-up-to-81-kwh-with-up-to-77-kwh-usable.61896/

My Leaf shifts into neutral if you ignore the low battery warning, the very low battery warning, and the turtle. I have seen the turtle many times, but have only coasted down my street and up my driveway a few times. Only once did i have to physically push it a few feet to get the car plugged in.

How many miles past zero range? I think the LEAF new is about 21.x usable of 24kWh. The Focus is about 19.8kWh. The i3 about 18.9kWh of 22kWh.