What really happens when a BEV battery runs flat?

[i3an]

I checked with AAA who said they have no mobile charging capacity and I would be SOL with them if my i3 BEV battery ran flat whilst on the road, and as it can't be towed I am guessing a flat-bed truck would be required. Now we all know that a "flat" battery still actually holds a few miles worth of charge but is software inhibited from using it, so I was wondering if my i3 stopped dead a mile from home and I hit the God button in the roof, would She be able to send a temporary override and let me tap into some of that reserve?
A related question for anyone who has actually run flat: how honest is the GOM as one approaches the zero lower bound? I get the feeling that 5 miles GOM range is actually more like 7 or 8, and 3 means 5 or 6 .... and so so on down to zero - and beyond!
Anyone out there with first-hand experience?

 

[i3atl]

Here you go: http://www.mybmwi3.com/forum/viewtopic.php?f=10&t=1918

 

[Andrewd99]

I thought I would write a quick post here about my experience with the i3. Now, I haven’t actually ran it flat, but have had it down to as low as 2mile range...so pretty close.

My car is a 2017 i3 BEV (94ah) so the second model BMW has released. From a full charge in Comfort mode it displays a range of around 115miles and EcoPro++ it shows 130miles.

The furthest I have had out of the car on a single charge is 132.4miles. This was mainly driving on country lanes and traveling below 60mph.

I regularly drive it on the motorway and even though I’m in EcoPro+ mode still drive it at 70-75mph and get around 100mile fairly comfortably from a full charge. (Note: as long as no heating or air conditioning is on).

The closest I have come to running it on empty is 2 Miles, and even right up to that point the performance was as normal. But at that point it was doing 56mph willing the sign for the motorway services to quickly come out of the fog!

As you get to 15mi range you start getting alerts. These start off a amber warning and as you drop to 10mi it changes to orange and then at 5mi and below red alerts, constant flashing notices and ‘bongs’. The first time I took it to below 5mi I too spotted the satnav started to scan for nearest charge points.

When you run the battery very low it does take longer to charge the car again. This was really obvious when I was on a supercharger and it was charging it at 12amps when normally it’s 100+amps. I guess it’s similar to how the last 5% of the battery charges as that too seems to have the current drop and take a while.

One other thing I have noticed in the car is that in warmer weather (>25C) the battery definitely provides a better range.

Done be afraid to take it under the 15 Miles range as it still quite a long way. But my advice is certainly always be aware of where a Plan B location for charging could be.

Hope that’s useful.

 

[justanotherdrunk]

did just that yesterday down to 0 miles range / 2% battery life

experienced mushy throttle response

also noticed if i sit for a few minutes a small amount of range seemed to return

:lol:

 

[jadnashuanh]

Both excessive heat and cold affect battery capacity...by sitting for a while, things may have cooled off a bit, giving you a little bit of range. The internal resistance goes up as you discharge from heat.