"Full" battery levels dropping daily

[boltage]

I think you guys are missing the point. It's not that I NEED 230 miles (most of the time), but that the thing is dropping off at a precipitous rate for no reason. Seems like either a battery problem or a software problem.

And, I will at times need to get close to 230 miles, so I want to know that I have it. 6 months young is way too short to have lost that much battery capacity--and to keep losing it on a daily basis.

Have you been using the heater more now compared to before? Or driving faster on the freeway? Or now have a roof rack?

Also, check the air pressure in your tires. Fall season means that tire air pressures fall with when temperatures fall. Underinflated tires have more rolling resistance, leaving to worse electricity economy.

 

[TimBolt]

You (and everyone) should use Hilltop Mode to limit the charge to about 90%. Your battery will last many more years if you do this.

Of course, take it off Hilltop Mode when you need all 100% battery, like for a road trip, but put it back on when the road trip is done.

I have no use for Hilltop Mode, and I only charge at home about once a week, or as needed.

I see no reason to charge every night or to artificially limit the charge capacity of the car. If I lived at the top of a hill I guess it might come in handy, but even with a full charge the regenerative braking in “L” drive works perfectly after just a couple of miles of driving.

If anyone has evidence supporting the claim that not using Hilltop Mode is detrimental to the Bolt’s battery longevity, please cite it. Also, any evidence that daily overnight charging leads to increased battery longevity versus charging on a less structured schedule.

I’ll consider changing how and when I charge my Bolt if there is credible evidence supporting an optimal method.

 

[EddrivesEV]

Patronus, Thank you for the explanation of "guesometer." Makes a lot of sense.

Guess-o-meter" was a pejorative term given to the gauge in the Nissan Leaf. Its underlying algorithm is apparently so bad as to be very misleading.

On the other hand the computational math underlying the Bolt's Mileage Gauge is much more accurate. The use of that term to the Bolt is an insult to its Mileage Gauge, used, I suspect, by drivers of other vehicles.

A good guess is still a guess.

Guess-o-meter is far older then the Leaf. Yes, it applies to the Bolt and any other car's range estimation. Electric or anything else.

If nothing else, it should be a GOM to remind you that the range estimate doesn't apply if you are driving fast into a 40 mph headwind. Or through 4 inches of fresh snow. Or up a mountain pass. To keep safe the brain needs to be making a range estimation on it's own.

So under your theory, the fuel gauge in an ICE is a "guess-o-meter!"

You thought that the 3/4 fuel remaining would get you as far as you normally would get, but driving fast into a 40 mph headwind or through 4 inches of fresh snow or up a mountain pass, 3/4 of a gas tank just ran out! Nice guess!

I still maintain that Bolt drivers should not call the Mileage Gauge a GOM; and that all of those that do, drive something else. What do YOU drive?

PS: I googled "Guess-o-meter" and came up with a lot of articles about the LEAF. Where was its use before the LEAF?

 

[CTBolt]

I've had the same issue of the "full" battery levels dropping daily and my Bolt (had it less than 3 months) has gone from 360+ per charge to 188. One of the other reviewers made a very insightful comment and that is that the large indicator on the left of the panel actually represents a calculated estimate of how many miles you will get on a charge, based on your driving pattern. I believe he's correct, and here is an experiment that we can all get involved in to prove it; and, hopefully regain our confidence in the fine little care we are driving: If the "guessometer" (love that name) is simply based on our driving habits two things should happen - 1) assuming our driving remains constant, the drop should level off. More importantly, if we make a concerted effort to drive more conservatively (and we can monitor this by the yellow/green bar indicator on the right) we should actually be able to make the number increase. I'm going to go through a few full battery drains and charges and see if I can get the number to increase. Anyone else in for the challenge?

 

[CTBolt]

The more I think about it, this little Bolt packs a powerful 200hp, and is darn fun to drive. I believe I've seen several posts stating it's the best car the person has ever owned. Speaking for myself, it's pretty likely that in the first few months I've enjoyed the hp a bit too much, not realizing it's causing my estimated mileage per charge to decrease. My car is with the dealer now; but, I can tell you, no one I spoke to there (sales, mgmt or service) would acknowledge this as any issue. Then again, they offered me two free oil changes when I bought it. Am I the only person to find myself educating the dealership?!

 

[EddrivesEV]

I have already done this experiment:

When I drive off-highway, or on highway at bumper to bumper speeds around 35-55 mph, for a great percentage of my battery capacity, my mileage goes up.

When I drive consistently at 75+ MPH from city to city, for a great percentage of my battery capacity, my mileage goes down.

It makes complete sense.

The trick is to not drive 50 miles and expect the Gauge to be accurate as to what the true capacity of what your Bolt's battery has.

Take a nice leisurely drive one afternoon: go visit a nearby town that is less than 50% of your battery's capacity away and come back home and recharge your battery. See what your real capacity is.

Then see what the Mileage Gauge tells you for your next drive.

 

[michaellax]

When I drove experimentally from Los Angeles to Las Vegas, just to prove it could be done in the Bolt EV, heading northbound out of Victorville, I drove 200 miles at approximately 55 mph and arrived with 55 miles on the Mileage Gauge and returning southbound I drove 190 miles back to Victorville at approximately 65-70 mph with 3% left in the battery when I arrived at the EVGo station there.

At that point the Mileage Gauge had gone to orange LOW MILEAGE with no numeric reading.

 

[oilerlord]

I have no use for Hilltop Mode, and I only charge at home about once a week, or as needed.

I see no reason to charge every night or to artificially limit the charge capacity of the car. If I lived at the top of a hill I guess it might come in handy, but even with a full charge the regenerative braking in “L” drive works perfectly after just a couple of miles of driving.

If anyone has evidence supporting the claim that not using Hilltop Mode is detrimental to the Bolt’s battery longevity, please cite it. Also, any evidence that daily overnight charging leads to increased battery longevity versus charging on a less structured schedule.

I’ll consider changing how and when I charge my Bolt if there is credible evidence supporting an optimal method.

For those that lease their Bolts, drive more / worry less about the battery. Seriously. I would. Heck, you only have the car for 36 months so why sacrifice range? Make sure you charge it to 100% and do your utmost to keep it fully charged all the time just in case you need all of those 238 miles or more on a moment's notice. Discharge it all the way down to 0%, and charge it to 100% because you can. DC fast charge to 100%, and preferably on the hottest of days. Blast the hell out of the battery because in the end...it really doesn't matter. You don't own the car - GM does. In the magic of leasing, the next EV you drive will include a fresh new battery.

However, for owners that do intend to go well beyond 3 years / 36,000 miles with their EV (or those waiting to pick up a Bolt off-lease), have you ever wondered why GM assumes that a Bolt's battery that has degraded by up to 40% is just normal wear & tear, and not covered under warranty? Answer: GM knows the battery will degrade, and that battery pack is expensive to replace.

There is credible evidence supporting optimal methods in extending your battery's lifespan. Hilltop mode is one way of helping to limit depth of discharge, and thus allowing the battery to last longer:

http://batteryuniversity.com/learn/article/how_to_prolong_lithium_based_batteries

 

[TimBolt]

The chart you posted represents empirical results from a lithium battery with a different chemistry than the battery used in the Bolt. The authors have developed a model that they believe will produce accurate battery degradation estimates for other lithium battery types, but their model requires actual empirical data for each battery type, as each type performs differently.

However, considering this graph at face value, under the worst case scenario in the graph, I’ll only be at 85% after 2000 discharge cycles. Considering that I charge about once a week, that’s 38 years from now. Sounds like the battery will outlast me.

Most of the sample charge-discharge data points on the graph are fairly clustered up to the 1000 cycle value, with capacity readings of between 90-93%. Only the 75%-65% and 75%-45% examples show significantly less degradation, and it seems unlikely that most Bolt owners would reasonably be expected to keep their actual battery use within such a narrow real world range.

Also, is any Bolt battery ever charged at 100% ? My understanding is that the battery management system keeps a certain reserve at the top and bottom of the battery capacity, so the battery never charges all the way to 100% or down to 0%. Conjecture is that about the top 5% of capacity is limited by the battery management system, which would make the highest possible battery charge 95%, not 100%. The Bolt also goes into limp mode when nearly discharged, so discharging to 0% also doesn’t seem possible.

Considering the meager hypothetical performance gains in this academic model, I’ll continue to fully charge my Bolt as needed, and use its full range capacity down to a prudent minimum before recharging.

 

[boltage]

Also, is any Bolt battery ever charged at 100% ? My understanding is that the battery management system keeps a certain reserve at the top and bottom of the battery capacity, so the battery never charges all the way to 100% or down to 0%. There’s a footnote at the bottom of the graph that states that EVs use an 85-25 cycle, not sure how accurate that is, but it makes sense that GM has built-in limits, since they’re on the hook for battery failures.

There is speculated headroom, but no confirmation from GM. Although even if there is 10% more battery than the nominal 60 kWh, a full charge-discharge would be something like 95-5, not 85-25.

However, most people do not wait until very low charge levels before recharging (just like they do not wait until the last drop of gasoline before refueling a gasoline car). So they may recharge when the battery gets down to somewhere between 25% and 50%. If a Bolt owner has hilltop reserve mode on, a recharge will bring it up to 87% to 90%. So an 87-25 cycle in this case would be close to 85-25.

Hybrids (e.g. Prius) and plug-in hybrids (e.g. Volt) may limit battery usage to allow for much greater buffer to extend battery life, since maximizing usable electric range is not as high a priority compared to a fully electric vehicle.

Remember also that the graph is in terms of charging cycles. But note that while the 75-65 cycle results in less degradation per charging cycle, you would need to charge 6 times as often as charging in an 85-25 cycle.

 

[LeftieBiker]

The NiMH version of the Prius limits charge to 20%-80%. That's why the packs last so well despite the generally poor track record of NiMH batteries.

 

[michaellax]

I enjoy the Grande size Starbucks coffee but it tends to splash out when driving through the cover's drinking hole.

I used to have them not fill it to the top to avoid this problem, but then over the long run, I was wasting money getting less coffee than I was paying for.

Finally, I ordered a Grande coffee in a Venti sized cup and the problem was solved. Then they developed a plastic green stick to plug closed the drinking hole in the coffee cup's cover and now I am back to my Grande cup again.

I waited for the Bolt EV because I wanted a 238 mile capacity car not an 80-100 mile capacity car or a 150 mile capacity car.

I find that most, if not all of those members of this forum who criticize full charging of the Bolt EV drive a different EV; ask them!

Nobody knows what engineering GM has provided to protect the battery but anecdotal evidence from drivers of the Spark EV and Volt suggest that those cars have suffered from low battery capacity loss over the last few years; ask them!

While the Leaf is the main capacity loss culprit for the last few years.

I am sticking with full charging my 238 mile Bolt EV.

 

[DucRider]

There is credible evidence supporting optimal methods in extending your battery's lifespan. Hilltop mode is one way of helping to limit depth of discharge, and thus allowing the battery to last longer:

http://batteryuniversity.com/learn/article/how_to_prolong_lithium_based_batteries

This is good info for cell phone batteries with no thermal management.
The 1,500mAh pouch cells for mobile phones were first charged at a current of 1,500mA (1C) to 4.20V/cell and then allowed to saturate to 0.05C (75mA) as part of the full charge saturation. The batteries were then discharged at 1,500mA to 3.0V/cell, and the cycle was repeated.

We don't generally routinely charge or discharge our EV batteries at a constant 1C (60 kW for the Bolt). Nor are EV batteries charged to 4.2V (unless GM really did leave 0% buffer, but the EPA stats indicate otherwise). Throw in no thermal management and different battery chemistry and this study means... who knows? Too different to draw many conclusions.

 

[oilerlord]

My understanding is that the battery management system keeps a certain reserve at the top and bottom of the battery capacity, so the battery never charges all the way to 100% or down to 0%. Conjecture is that about the top 5% of capacity is limited by the battery management system, which would make the highest possible battery charge 95%, not 100%. The Bolt also goes into limp mode when nearly discharged, so discharging to 0% also doesn’t seem possible.

Considering the meager hypothetical performance gains in this academic model, I’ll continue to fully charge my Bolt as needed, and use its full range capacity down to a prudent minimum before recharging.

Tim, you asked for "credible evidence" and I provided a link to it. Clearly this wasn't a study specifically about, and limited to the Bolt, but only as one research data point about how different depth of discharges (in general) affect the lifespan of lithium ion batteries. I'm not going to debate battery fade, or what does or does not affect a lithium battery's lifespan because scientific research is available online should you choose to read it. Again, I plan on driving my EV for a long time, and a LOT of miles, so I have a keen interest in learning all I can about the subject, and steps I can take to extend the life of the $38,068.30 main traction battery. Returning the car back to Mercedes isn't part of my deal. It's mine, and as such, I have a vested interest in preserving it's range for as long as possible.

If you're in the majority that chose to lease their EV, you may, understandably, have arrived at the conclusion that battery fade doesn't matter and/or doesn't apply to you. I respect that. To each their own.

 

[michael]

Four years ago, I was active on the MYFOCUSELECTRIC web site. I was preaching the same thing I still do: take care of your battery: it WILL fade, but you can do things to minimize the degradation.

Almost everyone there told me I was full of crap. Ford did a wonderful job of engineering. The battery has liquid cooling. There are adequate reserves top and bottom that you don't have to worry. The studies you are quoting don't apply to this kind of battery. etc etc etc.

When I turned in my car, the battery which had close to 20 kWh usable when new, was down to the low 15's.

If you look at this thread

http://www.myfocuselectric.com/forum/viewtopic.php?f=14&t=3663

you will see that lots of people are.s now seeing the kind of fade I predicted and experienced

It happens guys. The atoms are going to do what they want, they don't care what we hope they will do.

 

[michaellax]

When I turned in my car, the battery which had close to 20 kWh usable when new, was down to the low 15's.

So you lost 5 KWh from a 2013 Ford Focus.

Do you think the technology is the same in 2017 as it was in 2010-2012 when it was developed for the 2013 Ford Focus; or do you think that maybe GM has used their experience with the Spark EV and the Chevy Volt to improve their battery conditioning technology?

If I lose 5 KWh from a 64 KWh battery, I will have 59 KWh. But I am sure you will say that you lost 25% of your capacity.

But there is no evidence to support your theory that battery fade from "usage" is linear. That is, I am sure you used the maximum capacity of your Ford Focus, i.e. 78 miles, much more often than a Bolt EV driver will use the maximum capacity of our 238 miles.

You are comparing apples to oranges.

Also you are ignoring two other factors:

1) Battery fade in a 78 mile capacity vehicle to 60 miles is much more dramatic than it will be to a Bolt EV with 238 miles; and

2) Even if we choose to replace our batteries, and why do that for mere fade (?), the cost of batteries keeps dropping.

So, yes, I can chose to NOT drive my Bolt EV and have a pristine battery years from now. The engine and the tires will also be in much better shape, too!

Or I can get the bang out of my buck and use the vehicle for what I paid for: 238 mile range!

 

[SparkE]

When I turned in my car, the battery which had close to 20 kWh usable when new, was down to the low 15's.

So you lost 5 KWh from a 2013 Ford Focus.

Do you think the technology is the same in 2017 as it was in 2010-2012 when it was developed for the 2013 Ford Focus; or do you think that maybe GM has used their experience with the Spark EV and the Chevy Volt to improve their battery conditioning technology?

If I lose 5 KWh from a 64 KWh battery, I will have 59 KWh. But I am sure you will say that you lost 25% of your capacity.

But there is no evidence to support your theory that battery fade from "usage" is linear. That is, I am sure you used the maximum capacity of your Ford Focus, i.e. 78 miles, much more often than a Bolt EV driver will use the maximum capacity of our 238 miles.

You are comparing apples to oranges.

Also you are ignoring two other factors:

1) Battery fade in a 78 mile capacity vehicle to 60 miles is much more dramatic than it will be to a Bolt EV with 238 miles; and

2) Even if we choose to replace our batteries, and why do that for mere fade (?), the cost of batteries keeps dropping.

So, yes, I can chose to NOT drive my Bolt EV and have a pristine battery years from now. The engine and the tires will also be in much better shape, too!

Or I can get the bang out of my buck and use the vehicle for what I paid for: 238 mile range!

This is a rather aggressive post to someone who wasn't even responding to one of your posts. He has his opinion (based on prior experience) and you have yours. Everybody, please keep responses polite.

Thank you

(mod out)

 

[LOLady]

And, might I add, not even responding to my original question.

I am not talking about longer term degradation of the battery. I am talking about the "full" level being 40-50 miles less on a rather sudden basis. The car is only 6 months old

 

[SparkE]

And, might I add, not even responding to my original question.

I am not talking about longer term degradation of the battery. I am talking about the "full" level being 40-50 miles less on a rather sudden basis. The car is only 6 months old

The estimate of range is simply that - an estimate. It uses an algorithm that takes many things into account. For example, if you had full chrge and drove on the freeway at 85 mph until almost empty, your next full charge would show a much lower estimated range. It doesn't mean that is exactly how far you could actually drive (say, at 35 mph). Temperature, recent driving habits, and other things affect the estimated range shown.

 

[michaellax]

And, might I add, not even responding to my original question.

I am not talking about longer term degradation of the battery. I am talking about the "full" level being 40-50 miles less on a rather sudden basis. The car is only 6 months old

Sometimes the mention of "hilltop reserve" turns the topic to battery capacity degeneration and for myself, I apologize for hijacking the topic.

I see some good tips have been offered to you here in this thread.

I suggest you do what I do: Take an afternoon and go for a good 100 mile drive at modest speeds and turn around and head home. See what your capacity is like at the end of the drive.

Then do a good full recharge and see what the Mileage Gauge tells you.