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I've wondered, so I presume others have wondered. How does the car actually behave at the end.
So... Armed with a "You don't know me but I'd like to borrow some electricity" speech, an extension cord, and a little spare time, I decided to see for myself.
At 20 miles, I got the suggestion to switch to 'Low Power Mode', and the nice green guess-o-meter turned orange
I kept on truckin', staying within walking distance of the house, and hitting the go pedal pretty hard a couple of times (still pulled hard and showed over 120 kW on full acceleration.)
At 11 miles, it switched from '11' to 'Low' and said 'Propulsive Power is Reduced'. 2 orange bars showing.
I headed for home and started rehearsing my speech, just in case.
By the time I got home, about 1 1/2 miles later, I had zero bars. Dunno how much further it would've gone, but I'm guessing not much. App said 9 hours to charge to 100%, hooked up to my Clipper Creek HCS-40.
Interestingly, I'm showing 10% more range after fully charging than I've seen in the last few months. I generally use Hilltop Reserve, only charging to full whenever I plan a trip of over 100 miles (usually 2 or 3 times a month.)
The last few "top off's" have shown 170-182, and this morning I'm showing 202. Same temps, same trips.
I tend to always trend up towards the 'Max' range rather than trend down towards the 'Min, so I never worry about taking off if the anticipated trip is less than the average range shown.
Being a pilot, I always plan to get where I'm going with an hour's worth of fuel, whether I'm headed to the coast in the Stinson or to Brussels in the 7X, so this experiment goes against the grain and won't be repeated, at least not as an experiment. :D I usually plan on getting home with at least 30 miles showing.
But... I found it interesting and thought those of you who haven't been really low on juice might also.

Just after range went from "11" to "Low", 2 bars. Changed to 1 bar about 60 seconds later:


At home a mile later:
 

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I too wanted to know exactly what happens with low battery levels and have run the car down to near 0% a couple times to figure it out. I "cut it close" on many of my trips and I want to know if I should be factoring in 5% or 15% safety margin for my drives. Confidence in your battery level can be the difference between driving in comfort (73F heated interior, 80 mph) or DWF (driving while freezing).

The trip I have my most complete data on occurred a couple weeks ago during a 39 degree dark, wet Michigan afternoon. This trip was 90% highway at 72-80 mph speeds with climate control on auto at 72-74F. I actually reached my destination with 4 bars remaining but continued to drive on country/city streets for the sake of collecting data.

I hit 3 orange bars (15% battery), at 113.4 trip miles with 24 miles remaining. Trip: 2.9 miles/kWh, 345 Wh/mile.

I hit 2 bars (10% battery) at 121.7 trip miles with 17 miles remaining. I traveled 8.3 miles on the 3rd bar using 2.7 kWh.
So far there has been no change to the car's driving or regen behavior, and 140kW acceleration and 80+ mph driving is still possible.

The "Propulsion Power is Reduced" warning came on while at 2 bars with 6% battery level (checked with app). The range display changed from 8 miles to "Low" at this warning. This warning brings a re-mapped throttle curve, making the throttle response and acceleration of the car feel sluggish. Highway driving is still possible, but rubber burning 140kW power draw is no longer an option.

I hit 1 blinking orange bar (5% battery) at 133.1 trip miles. I traveled 11.4 miles on the 2nd bar using 2.4 kWh.

My 2% battery "low power mode" warning happened at 141 trip miles. Between 5-2% I traveled 7.9 miles using 1.8 kWh. I learned that "low power mode" just asks you if you want to turn off the radio. This warning is an option in the energy settings named "radio power down". You can select off,2,4,6,8%. I happened to have mine set to 2% which gave me an accurate pop-up warning at that exact time. This is a handy way to get another low battery warning exactly when you want it.

I did not take the car down to 0% as I did not want to waste time towing the car home. I suspect the car would go dead on me with no further warnings when the first battery cell hit the LVD low voltage disconnect point as monitored by the BMS.

My conclusions: The last 3 battery bars may disappear slightly quicker than you expect because the car's BMS is calculating the best it can to give you the most accurate 15%,10%,5% warnings that it can. I also feel confident driving the car down to 1 blinking bar (5%) without risking dead/shutdown. Below 5% is a game I'm not ready to play yet until the temps rise above freezing. I am not a fan of the cold, yet I live in Michigan.

WARNING: The above is just my test results, observation & opinion. Your results may vary, try at your own risk.
 

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I ran so low ... after "low propulsion", after the single blinking bar, after no bar, the radio shut off warning with 1 mile to home. I made it ! (radio powerdown in my car is %2)

at 250 mile aprox range . I am thinking %2 would still be 5 miles of range.
 

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i was more cautious during the same experiment. I happened to use up the battery until I almost had the first battery orange icon hit (at 20%). It was -28C outside and I did not want to risk it, so, when it turned orange, I turned around and went home. But I am glad to know in case of emergency I have from 20% to 5% battery to get home or find a charger...
 

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Better that than the opposite extreme, I guess. Imagine, pounds of *really angry* protons trying to get as far away from each other as possible and steal electrons from anything in their path... :)
 

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so does onstar tow you to a battery charger if you kill it somewhere? i've started wondering how you'd handle that. So far I've barely gone 40 miles without charging overnight. Just I've had a habit of rolling into a gas station at zero a few times, curious what happens when you can't go walk for some electrons.
 

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I thought if I ever mis-calculate after leaving the last bar (pun intended) and Bolt hits the wall energy-wise and comes to a stop. I’ll just call Roadside Assistance (free for 5 years) and ask them to send a truck with a generator. So as to put a few kilometres/ miles in Bolt’s battery sufficient to get to a charging location.

Potential problem with above plan: per Bolt owner’s manual P246: “Do not use portable or stationary backup generating equipment to charge the vehicle. This may cause damage to the vehicle's charging system. Only charge the vehicle from utility supplied power”.

Why is this ? sine wave stuff…? Wouldn’t the safety & communications protocols in the Bolt-to-110v OEM trickler cord & plug prevent damage ?

Here’s a video showing a fellow renting a small portable generator at Home Depot and charging a BMW i3 with it: (skip to minute 2:00 showing generator piece)
https://www.greencarreports.com/news/1094356_how-to-recharge-any-electric-car-anywhere-any-time-video
BTW, the BMW i3 owner's manual doesn't say anything about don't use generator power.

Why does Bolt owner manual say don't use portable generator ? Anyone tried it anyway ?
 

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@Cehjun, instead of a generator, you can have a tow truck or friend tow your Bolt via the front towing eye-bolt. It's just like DC fast charging but you would probably want to keep it slow to avoid overheating the pack. I know some people have descended large mountains and fully charged their Gen 2 Volts with no issues (from 0% to 100% SOC) but am unsure how the Bolt handles it.

Someone already has done it (skip to 1:40 for the actual charging-by-towing):
 

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Towing: I wonder which is more risky: 1.) having Roadside Assistance lift up the front wheels and tow vehicle to charging location* or, 2.) pull vehicle in L mode using towing eye in order to self-charge (will Roadside do that?, or find a kind soul with suitable vehicle...)
* will Roadside take you to a place other than Chevy dealer ? (assuming standard Roadside coverage is valid for not-so-smart EV drivers:eek:)

Regarding 2.) above: Bolt owner's manual P.299 is goes against it in various phrases: “Incorrectly towing a disabled vehicle may cause damage…. The damage would not be covered by the vehicle warranty…. Consult a professional towing service if the disabled vehicle must be towed…. If the vehicle is equipped with tow eye, only use the tow eye to pull the vehicle onto a flatbed car carrier from a flat road surface.”
 

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The simplest way to get a jump would be from another EV. Don't know if on-board computers will allow it currently. All the OEMs are fooling with vehicle-to-home, and vehicle-to-grid, so it would work, if they'd allow it.

Without computers in the way, here is one nearly full Tesla battery jumping a nearly empty one. Starts at 54 minutes in. Like watching water run from a full tank, into an empty one.

https://youtu.be/44nMCFB4XgQ?t=3222
 

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@Cehjun, instead of a generator, you can have a tow truck or friend tow your Bolt via the front towing eye-bolt. It's just like DC fast charging but you would probably want to keep it slow to avoid overheating the pack. I know some people have descended large mountains and fully charged their Gen 2 Volts with no issues (from 0% to 100% SOC) but am unsure how the Bolt handles it.

Someone already has done it (skip to 1:40 for the actual charging-by-towing):
https://www.youtube.com/watch?v=JDLsKGNgOEE
I enjoyed watching redneck supercharging on that video :)

It's too bad that they didn't say on the video how many miles per gallon the truck got for that segment.
 

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interesting on the tow option .. you could have a tow up a big hill ...
Wow qué cojones ! Trying for a “double dip”: faster self-charge on the way up the hill. Then opportunity for yet another regen charge on the way back down.

Q: if the tow rope breaks part way going up, can one engage R and catch some regen kw’s going backwards on the way down ? :p
 

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I ran so low ... after "low propulsion", after the single blinking bar, after no bar, the radio shut off warning with 1 mile to home. I made it ! (radio powerdown in my car is %2)

at 250 mile aprox range . I am thinking %2 would still be 5 miles of range.
Yesterday, I had miscalculated how much juice I needed for my day. I got the “low propulsion” light 3 miles from home (Going uphill with heavy traffic all the way). Shut off AC and put radio in low energy mode just in case. Made it ok.

Since that happened and I happened to have a nearly empty battery, I decided to charge to 100% for today. Not sure if that was a good thing to do, but I only charge to 100% once a month.
 

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I've been trying to get comfortable driving with fewer bars (basically gaining confidence in the GOM). Today is my biggest test. I have 4 bars left with a GOM of 47-59-70. My SOC is 18% according to the app. My drive home is 16 miles, but it is mostly downhill and my range usually only drops about 5 miles. It will be interesting to see where I end up. Well, I mean I know I'll get home - where the GOM will end up. :)

I have 1963 miles on the car and this charge I've averaged 5.1 miles/kWh. I'm currently at 227 miles on the tripometer.
 

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Don't even think about 'getting a jump' on your drive battery, esp. from another EV. Getting a jump on your 12V battery won't get you anywhere either. Both could yield explosive results.

It has been said that completely discharging the drive battery is a bad idea, especially if you do it repeatedly. Rechargeable batteries typically do not like being fully discharged. Charging to 100% is also considered inadvisable, but Chevy seems okay with it. There may be some safety margin on 'topping off', but I am unsure if there is any margin on 'draining the tank'.
 

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There is a safety margin at the bottom too, but I assume it's less of a margin as the top, since running to zero almost never happens, whereas charging to full frequently happens. You're not going to kill an otherwise healthy battery running to zero, just don't do it frequently.
 

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The arguments have raged back and forth about this on this forum. ;)

IN GENERAL, Lithium-based batteries do not like being fully charged or fully discharged (meaning it lowers capacity more rapidly, or even kills them). The issue is what "fully" charged or discharged means.

I believe that GM built in safety margins at the top and bottom simply so that they wouldn't have to do a lot of warranty repairs - giving away expensive batteries for free. What those "%" might be ... nobody really knows.

IN GENERAL, it is "better" with Lithium-based batteries to :
* discharge/charge between 10%-90% (than it is to repeatedly do 0-100%)
* discharge/charge between 20%-80% (than it is to repeatedly do 10-90% or 0-100%)
* discharge/charge between 30%-70% (than it is to repeatedly do 20-80% or 10-90% or 0-100%)

HOW MUCH of a difference it makes is debatable (and has been 'debated' {beaten to death} on this forum repeatedly).

Frankly, my take is that :
(1) ONE such cycle (*allowed* or *nominal* charge on the Bolt) to 0% or 100% isn't deadly
(2) GM probably put a larger buffer at the top than the bottom, seeing as 100% would happen more often than 0%
(3) 15 or 45 seconds a day is worth the time investment even if it really has no effect
(4) try and keep the battery between 20-80% (heck, 35-80%)
(5) So set "hilltop" to charge to 90% (or use the new slider option to 80-90%) unless you need the charge for that day
(6) don't freak out every time you can't manage #4 - it's not that big of a deal if you aren't doing it every day


I managed to do the above when I had a 84 mile range Spark EV, it's not that hard to do - like I said, 15-45 secs a day. I've probably spend more time arguing about it on the internet than I did in *years* of 'just doing it' with the Spark. My battery lost about 6% (total) in two years with my 'babying' it. Maybe what I did had no effect. But even if that were true, I still think it was worth the effort. ****, it was worth it just for the "I'm probably doing the right thing" feeling I got out of it.

Edit: crap - I just noticed that 'hashtags' are tracked by this site. So I am adding hashtag #LiIon ...

Edit2: well, it din't track #LiIon, maybe a certain minimum number of posts needs to be done with a hashtag before it 'tracks' ... ???
 
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