Attention to Battery Charge Remaining or Miles Remaining?

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Dobeman2000

New member
Joined
Nov 14, 2014
Messages
4
Location
Northern IL
First, just want to say I have had my Leaf for about 6 months now and absolutely love it. I have encouraged all my friends to purchase one of these. They are efficient, tax incentives are terrific, plenty of power for the purpose, roomy, and many features. That being said, I have searched high and low for this answer but can't seem to find it. Basically should I pay attention to the percentage of battery I have left or the miles I have left? I am in Northern IL and it has started to cold here. This has in some way affected the range indicators. My battery indicator will say I have 80% battery life, but my remaining mileage indicator will say something like 45 miles left. What should I generally be paying attention to-the battery % or the miles remaining. Thank you very much for any info. you could provide.
 
miles you have left is not an option in the true sense of the word. The number is based on your continuance to drive in the future exactly as you have in the very recent past.

this means sometimes it will be relatively accurate. But changes in speed, direction, altitude, traffic, terrain, weather, etc. will affect this number as well

using percentage remaining requires you understand the route and its affect on the amount of power the LEAF must use to negotiate the course.

My advice is not go unless you feel you will have at least 20% of your charge when you reach your destination. the weather is simply too severe too often to risk it. The other thing is of course knowing your car, your route AND the weather forecast
 
DaveinOlyWA said:
miles you have left is not an option in the true sense of the word. The number is based on your continuance to drive in the future exactly as you have in the very recent past.

this means sometimes it will be relatively accurate. But changes in speed, direction, altitude, traffic, terrain, weather, etc. will affect this number as well

using percentage remaining requires you understand the route and its affect on the amount of power the LEAF must use to negotiate the course.

My advice is not go unless you feel you will have at least 20% of your charge when you reach your destination. the weather is simply too severe too often to risk it. The other thing is of course knowing your car, your route AND the weather forecast

So, with all that said when the car's battery reads say 30% and the mileage is at 10 which should I pay attention to?
 
Dobeman2000 said:
DaveinOlyWA said:
miles you have left is not an option in the true sense of the word. The number is based on your continuance to drive in the future exactly as you have in the very recent past.

this means sometimes it will be relatively accurate. But changes in speed, direction, altitude, traffic, terrain, weather, etc. will affect this number as well

using percentage remaining requires you understand the route and its affect on the amount of power the LEAF must use to negotiate the course.

My advice is not go unless you feel you will have at least 20% of your charge when you reach your destination. the weather is simply too severe too often to risk it. The other thing is of course knowing your car, your route AND the weather forecast

So, with all that said when the car's battery reads say 30% and the mileage is at 10 which should I pay attention to?

you are missing my point. Knowledge is power. do not discount either reading nor rely on either reading too much. your LEAF does not tell even half of what you should know about range.
my real advice would be to ignore both and get LEAF Spy but its not that simple.

If you are gung ho, you might want to start charting your drives. distance driven, miles/kwh, SOC remaining, general weather stats, etc.

like I said above, you really should know whats ahead and I mean weather....
 
IF you watch your % remaining and keep mental note of how fast it is going down (i.e. if you go 10 miles and it goes down 20% that may mean something to your estimates). But also be aware of things like heater/ac/defrost use. These will impact how fast the battery is used. i.e. if you drove that same 10 miles but had the defrost running with ac and heat but just turned it off, I would expect the next 10 miles to take materially less than 20%. Of course that works both ways.

I believe the "miles remaining" is an attempt by Nissan engineers to do what I just said - but it cannot know what the future holds in terms of your use of accessories/heat or the terrain you are about to travel.

For my drives that I regularly do I now know about what to expect. I kept a log (literally) in the car for teh first few weeks and I plan to do it again when it is cold to update my understanding of things.

LeafSpy is an excellent tool though. As you can monitor your miles/kwh (use the dash control if you desire, just reset it periodically so you have current info) you can input this into LeafSpy and it will give your remaining miles based on actual power in the battery. Manually adjusting the miles/kwh for conditions or expectations (I lower it when the wife is driving...) can then allow you to estimate more easily.
 
Dobeman2000 said:
So, with all that said when the car's battery reads say 30% and the mileage is at 10 which should I pay attention to?
The only number that really matters is the % State of Charge (%SOC) because that is a measurement of the amount of energy left in the battery. The miles remaining is simply a guess by the car how far you can go on that energy left based on your recent driving pattern. That's why we call it a "Guess-o-meter" (GOM) here. If you were to drive at higher speeds, or the weather got colder, snowier, windier, you might get fewer miles than the GOM reports. If you were to slow down or turn the cabin heater off, you would likely get more miles than the GOM reports.

The problem is determining how far you can go on that "30%". And that takes experience. As the weather cools you will get fewer miles per kWh in the battery, meaning fewer miles per % SOC. Driving faster will give fewer miles/kWh. Driving in snow or in windy conditions — save for trips all downwind — will give fewer miles/kWh. Using the cabin heater can significantly lower the miles/kWh you get.

You can get an idea of how efficiently you are driving by resetting your dash miles/kWh display before each trip. The number you get in summer will be significantly higher than the number you get in winter. You need to adjust your range expectations accordingly.

To give you a rough idea of how far you can go under a given set of weather conditions you can do some arithmetic: A new LEAF has roughly 22 kWh usable charge (actually more like 22.5 kWh but most people don't want to get to a low enough %SOC to use it all). So, each kWh is about 4.5%. If you are getting about 3.5 miles/kWh on a trip, that means that 30% would be something like (30%/4.5%) x 3.5 miles/kWh = 23 miles. Not that you would want to take the car all the way to 0% (I think it only goes down to 1-2%, but am not sure). But that gives you an idea of how far you can go.

So, it all depends on what sort of mileage efficiency you are getting. And only you can determine that by measuring it. Besides the mileage efficiency meter on the dash you can also keep an eye on how far you go for a certain amount of charge. If, for example, you charge to 80% and drive 35 miles to get to 30%, you used ((80% - 30%)/4.5) = 11.1 kWh to go 35 miles, which is about 3.15 miles/kWh. However, please bear in mind that the %SOC readings aren't completely linear, especially between 80% and 100%, for reasons I'd rather not try to explain.

Nevertheless, just keeping track of how much charge (in %) you use to go a particular distance will give you a rough idea of how far you are going to be able to go under the same driving conditions (speed, weather, heater use, and the like). If it looks as if you might not make your destination you have some options:

1) Slow down. This will increase mileage efficiency by a lot.
2) Turn off the heater, if it is being used.
3) Find a charge station.

It also helps to become a more efficient driver, but that takes practice and isn't something that can be learned at the last minute.


Don't know if that really answers your question, but it was a little vague...
 
Dobeman2000 said:
First, just want to say I have had my Leaf for about 6 months now and absolutely love it. I have encouraged all my friends to purchase one of these. They are efficient, tax incentives are terrific, plenty of power for the purpose, roomy, and many features. That being said, I have searched high and low for this answer but can't seem to find it. Basically should I pay attention to the percentage of battery I have left or the miles I have left? I am in Northern IL and it has started to cold here. This has in some way affected the range indicators. My battery indicator will say I have 80% battery life, but my remaining mileage indicator will say something like 45 miles left. What should I generally be paying attention to-the battery % or the miles remaining. Thank you very much for any info. you could provide.

Nissan and EVs in general, put a lot of effort into obfuscating the essential information so it's easy to see why people get confused. "Which of two incomplete and undefined displays should I pay attention to"? Indeed.

If we shovel away the bullcrap, it's pretty simple and they're the exact same concepts for a gasoline car:

Question: how far can I go?
Answer: Miles = total energy / energy per mile

Two answer this you need 2 pieces of information

1 - how much stored energy do I have?
2 - how much energy will I use per mile?

Nissan does not give you #1. Stored energy is not "bars" or "percent". It's kilowatt-hours. If you know the degradation level of your battery, you can estimate this from the percent display. To get that information you need one of the "scan" devices and apps that get that info from the CAN bus. A new battery these days seems have just over 22.5 kWH of useable capacity.

For #2 you can get a pretty good idea from the dash. Reset the miles/kWH display daily before you set off and it will give you decent info after some miles of driving.

Paying attention to your efficiency over time you will come to know how terrain and weather affects your efficiency, and also how to modify your driving to achieve certain efficiency goals. For example you have an 80 mile trip and 22kWH available. Averaging 4miles/kWH will get you there with a cushion.

Don't worry it's not as hard as it sounds. And even if you don't opt for a scan device you will intuitively begin to understand, control and predict these factors. After a few weeks it becomes second nature.
 
Thank you all for your help. What I am noticing however is that since the weather has gotten considerably colder this week the battery % and mileage estimate are far apart (which they weren't until this cold weather). Do any of you think there is a malfunction, or is normal due to the weather change?
 
Dobeman2000 said:
Thank you all for your help. What I am noticing however is that since the weather has gotten considerably colder this week the battery % and mileage estimate are far apart (which they weren't until this cold weather). Do any of you think there is a malfunction, or is normal due to the weather change?

I suspect that many would consider the GOM a malfunction in the best of circumstances LOL.

However - as I understand it there is some sort of averaging in the algorithms so give it time - if the weather and your driving habits are consistent it may well settle down... whether the numbers mean anything will still be up for debate...
 
Dobeman2000 said:
Thank you all for your help. What I am noticing however is that since the weather has gotten considerably colder this week the battery % and mileage estimate are far apart (which they weren't until this cold weather). Do any of you think there is a malfunction, or is normal due to the weather change?

The mileage estimate is not particularly useful. For example I can drive up a local mountain and when I get to the top it will tell me I have 13 miles remaining. What does that mean? It means if I drive up a mountain for another 13 miles I will be out of power. It has no idea that I have reached the top of the mountain, will now descend and gain 6 kWH of regenerated power. Furthermore when I do get to the bottom it will then tell me I have 70 miles remaining, which is equally ridiculous because it's assuming that I'll be descending for another 70 miles.

Now... if your driving conditions are consistent then yes the Guess-O-Meter can show the effect of other influences with some measure of validity. For example, cold weather usually results in less range. It takes battery power to run the heater, the battery stores less energy, the air is denser and the tires have higher rolling resistance. So all else being equal, 80% might take you 80 miles on a comfortable day and 50 miles on a cold day.

The bottom line is that most LEAF drivers learn to ignore the Guess-O-Meter. Some go so far as to simply cover it up so they don't have to witness it's delirium. Personally I find it somewhat useful in some ways, but not because of its accuracy in predicting the future. It's full of **** but I know the ways in which it's full of **** and thus compensate.
 
My first EV, a Mitsubishi i-MiEV, had a "guess o' meter" too. However, I turned it off and used the 16-segment battery display to let me know how much batter is left. I can't turn off the meter on the LEAF, but I still look more at the 12-segment battery display than the range remaining number.
 
Thanks again to all of you-very helpful info. When I drove home from work the battery was reading about 70% with about 50 miles to go, looks better. I will just basically ignore the "GOM" and pay attention to the power bars. I learned a lot today. Will read over a number of the posts within the forum to pick up some info.
 
Dobeman2000 said:
I will just basically ignore the "GOM" and pay attention to the power bars. I learned a lot today. Will read over a number of the posts within the forum to pick up some info.

Sounds like the right conclusion. Over time you get used to just how far you can get given the battery percentage remaining under different conditions. You've probably already figured out that driving at freeway speeds over, say, 60 mph will reduce range. As this is your first winter with the LEAF you'll soon learn just how much of a range penalty you'll pay in cold temperatures and under different conditions. If driving through snow (which adds resistance to the tires) or against a strong wind you'll also see a range penalty and you'll learn to adapt to that. As you're in Illinois you probably don't have to worry about the impact of hills on range, but if ever you do take your LEAF up a big climb that also will have an impact on range.
 
I drove 10 miles to the zoo today starting from a 100% charge, with the last few miles being up the hill. Once parked I had an estimated range left of 37 miles and ~75% charge (9 charge bars). After driving 10 more miles home I had about 60% left and an estimated range of 55 miles.

The GOM is pretty useless on a good day. It starts with an inflated estimated efficiency than is completely unreasonable toi display a big range that you can only achieve by cruising on flat ground at <40 mph, then gradually adjusts it to your recent driving history (think <5 miles), then fudge it on the low end to be pessimistic to avoid stranding you. I think they designed the algorithm to maximize anxiety. It gets your hopes up that you can go 100+ miles when you first sit down, drops that 20% after a few miles of even gentle driving, then halves that going up the first hill, finally it randomly fluxuates around a number that is earily close to the distance to your destination keeping you in a needless sense of panic the entire time. It should have been been set to display the range using EPA efficiency (roughly 3.5 mi/kWh) and not taken any recent driving into account. A smoothly dropping number is better than a boneheaded algorithm the gives a number that flops around like a dying fish.

All that said, I have seen some very odd things at <50F. Some days I get to work with 92% left (just one charge bar down), other days I am down 3 charge bars and down to about 80-85% after only 7.5 miles of relatively constant traffic. If I am well pre-heated I have a lot more left than if I don't preheat even if I keep the climate control off the whole drive in and have fairly similar mi/kWh efficiency numbers. It seems like the battery management software has some sort of schizophrenic top end in cold and changing weather, or that something under the hood doesn't like being cold. Still pinning it down.
 
Moof said:
The GOM is pretty useless on a good day. It starts with an inflated estimated efficiency than is completely unreasonable toi display a big range that you can only achieve by cruising on flat ground at <40 mph, then gradually adjusts it to your recent driving history (think <5 miles), then fudge it on the low end to be pessimistic to avoid stranding you. I think they designed the algorithm to maximize anxiety. It gets your hopes up that you can go 100+ miles when you first sit down, drops that 20% after a few miles of even gentle driving, then halves that going up the first hill, finally it randomly fluxuates around a number that is earily close to the distance to your destination keeping you in a needless sense of panic the entire time.

Well, that doesn't match what I've observed, but then most of our trips are predominantly downhill away from home and uphill back, so what we witness are pessimistic numbers turning to wildly optimistic numbers going out and somewhat optimistic numbers coming back. (Coming back we figure that if the GOM shows twice as many miles as we need to get home then we're safe.)

One thing to remember is that it is MUCH MUCH harder to estimate distance-to-empty on EVs than it is for ICEs. In your gas-powered car the engine runs all of the time. Going down a steep hill, when it's not needed to produce any energy, it still consumes gas. (This is true even on hybrids above certain speeds.) Furthermore, a large percentage of the fuel consumed is just waste overhead. By contrast, and EV uses little more battery than it needs to get you where you're going - and if going downhill may actually add to the stored energy.

Thus, while factors like hills, headwinds, highway speeds, higher resistance tires, extreme cold, and resistance caused by snow or rain on the road affect the mileage of both ICEs and EVs, they have a much greater impact on EVs as a percentage of the total energy used. Imagine, for example, that your trip involves factors such as hills and winds which combine to require twice as much energy to get your car the same number of miles under "normal" circumstances. In an ICE car this may require only 10 or 15% more actual fuel, since so much of the fuel burned in the ICE car goes to overhead waste, but for the EV it will require 100% more battery energy. Then, on the return trip, the combination of downhill and tailwinds means that you end up using net zero energy - your energy usage is exactly 0% of what it be under "normal" circumstances. But on that same downhill trip your ICE car would still use 70% or more of the fuel it would anyway (depends on the car - hybrids in general would be a lot less) because of overhead/waste.

So this is why the DTE (distance-to-empty) gauges we're used to with ICE cars tend to be relatively accurate - usually a bit pessimistic to help people avoid running out of fuel - while on EVs we call them "guess-o-meters". Imagine your LEAF had just climbed Pike's Peak (which a few LEAFs have) - what the heck is the GOM supposed to do with information that shows a recent driving pattern of getting a ridiculously low miles/kWh over the last 30 minutes? Should the GOM programmer assume that will continue or assume a that this was a temporary low and that you'll soon return to a normal consumption rate? Then after the return trip you've actually regenerated 25% of the battery back - what should the GOM do knowing that you've actually increased battery capacity for the past half hour? Estimate infinite miles to empty?

The simple truth is that without knowing the route and the driving conditions you can't know how much battery an EV will use. There are a few pretty good tools which guess at this, like Leaf Energy, but you have to input the route and conditions.
 
cgaydos said:
In an ICE car this may require only 10 or 15% more actual fuel, since so much of the fuel burned in the ICE car goes to overhead waste, but for the EV it will require 100% more battery energy. Then, on the return trip, the combination of downhill and tailwinds means that you end up using net zero energy - your energy usage is exactly 0% of what it be under "normal" circumstances. But on that same downhill trip your ICE car would still use 70% or more of the fuel it would anyway (depends on the car - hybrids in general would be a lot less) because of overhead/waste.

Ah!!! Thank you! Excellent point! Said another way, "your ICE car is generally only 20% efficient at actually driving the wheels, but when other factors make it harder to drive the wheels, since most of the inefficiencies have already been borne out, it doesn't take much more additional fuel". In essence your ICE car become more efficient just when you need it to.

cgaydos said:
The simple truth is that without knowing the route and the driving conditions you can't know how much battery an EV will use. There are a few pretty good tools which guess at this, like Leaf Energy, but you have to input the route and conditions.

...Which is why I've been wondering why no one has created an integrated nav system that knows the route you are planning to take, knows the elevation changes, and with internet access it even knows a bit about the weather you will likely encounter in the next half hour of driving.

Heck, I can't even seem to find an EV trip planner that does what I need it to do. They don't even ask your car's EPA rated range. You see in my area, public charging is so rare, showing the charging locations along my route is basically worthless. I have to plan my route to get to the charging stations available, and if I don't, there is no point in showing the route beyond my range. And ideally I do that with a "B" plan, where if the first location is none functional, then I can reasonably drive slowly enough to get to another. But I never know how fast to drive. Once it's gone it's gone. I find I have a decided bias towards what I know and I've seen. If I've never been to a location, I basically seem to try and treat it as though it does not exist, until I know otherwise. I suppose as I continue my 100% success rate with public charging, I'll gain more confidence in the system.
 
i dont have a leafspy or other tool.
my effective method for estimating range on a trip is to understand how many miles i am getting per bar.
how?
i check the mileage as the first two bars disappear. if it is 4.5 or 5, i just multiply that by the number of bars remaining.

i average 4.5 or 5 these days. in the old days it was 6.
 
thankyouOB said:
my effective method for estimating range on a trip is to understand how many miles i am getting per bar.

Just for another perspective, I travelled yesterday in 22(F) temps. I had never done the route before, so I was going 45MPH on back roads to ensure high efficiency and range. There was some slush on the roads in spots, wet in others, dry much of the way. Between the temperature and the slush, I had trouble averaging over 4Mi/kWh. The first 30 miles I averaged 4.4, the next 30 miles took my average down to 4.0 (so was running at 3.6) even at a steady 45MPH. Partly because just before LBW kicked in, it started sleeting. The droplets were splashing to larger size and instantly freezing to my windshield. Thus the need for defrost (not in my plan, guess they changed the forecast on me, or there was high variation between forecast for my origin and my destination). I'd never been to my destination charge station before and ended up missing a turn. This, and another missed turn on the new route with less than main-road signage, added about 7 miles to the length of the trip.

I had planned (my "worst case" plan) to arrive with 22% charge. I made it with about 14%. That would not have been enough to make my "B" plan charging location (27 miles away). The 22% would have been really pushing it too. But the plan was to drive efficiently and leave both options open. But my efficiency never was as good as I'd predicted (hoped), and then got worse along my route.

I say this just to point out that these other variables can create wide variability in range, and difficulty in estimating range. The slush adds weight to the car and also disturbs the carefully designed drag. The temp. reduces available power from the battery and causes rain to freeze to your windshield and lots of defrost to thaw it.

When you combine that with the lack of charging infrastructure in my area, it is VERY important to make your destination because the "B" plan is even farther away. You can't just say "oh, I'm running a bit low, I may have to divert 5 miles from my route here and choose a location to charge for an hour or so to make up the difference." You're stranded on your backroads, in your 22 degree, sleeting weather. Or you are driving up to every farm house, hat-in-hand, hoping to get a trickle charge for 4 hours to get you back on your plan.

So you can see, I had to plan very carefully with lots of cushion in my estimates. By the time I started out and measured two bars of miles, it would have been too late to take the correct route.

I should also point out that the charge bars are not all the same capacity. The first two are 16%, next two are 13.2%, next two are 12.8%, then 16.6% then 12.1%. So that's upwards of 25% overestimation on your range. On the other hand, it always seems like the top 10% of SOC goes rather quickly, so perhaps the two roughly equal out.
 
If you don't need to squeeze every mile out of your battery, it doesn't really matter. After two years, I barely look at the gauges. In summer, I charge every other day at most. In winter, I charge every day so I can blast the heat all I want. But I only live 10 miles from work and we have L2 at work.
 
kikngas said:
I should also point out that the charge bars are not all the same capacity. The first two are 16%, next two are 13.2%, next two are 12.8%, then 16.6% then 12.1%. So that's upwards of 25% overestimation on your range. On the other hand, it always seems like the top 10% of SOC goes rather quickly, so perhaps the two roughly equal out.
The instrument cluster is really optimized to confound and confuse. The fact that leaf Spy exists is a testament to just how awful it is. SOC on the 2013 and later models is a good thing, but really should be kWh remaining.

I sympathize with the designers, since their target audience is everyone from non-technical grannies or frothing at the mouth petroleum haters, not to mention MBA brainwashed managers reviewing every detail. As the technology has increased in cars there is a weird attempt to showcase some details, while arbitrarily hiding the rest.

Carwings shows you information in kWh, including accumulated regen power, while the car does not. So there is an odd dichotomy within Nissan itself. I am still baffled as to why Carwings is consistently optimistic over the car dash for miles per kWh. I get the impression there is a bug where they accidentally double-count regen power, but it is only a guess. My guess is the whole thing was contracted out and nobody within Nissan knows the code, just another feature used to sell the car while having no intention towards making it ever work well.

In a perfect world I would love to have:
1) kWh remaining, along with kWh used and kWh regen'ed as displays
2) DTE based on a fixed number (EPA efficiency, or manually set).
3) kWh total AC/heater power
4) Regen available
5) Battery temp in degrees, not super chunky bars
6) SOH in percent, not bizarrely irregular bars (needs to be mandated and regulated, IMO)
7) Single button reset for distance, speed, and efficiency averages (including the nav efficiency)
8) An "instantaneous" efficiency meter that smoothed out the number by factoring in kinetic energy storage, and potential energy storage from GPS and speedometer information. Right now the display is only useful if you are at a perfectly constant speed on a perfectly flat road. Call it a dissipation meter.
 
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