Miles per Bar/ Range / Trip Planning Discussions

[jray3]

I know that this has been discussed at length, but the search function is so lousy that I didn't find a decent thread to resurrect. (where is that thread where we were posting RR meter photos?)
So, now that Spring has finally sprung in the Northwest, with multiple days in a row in the 60's, I'm remembering what easy living is like. The wife's mellow motoring has always gotten better range than Yours Truly, but we were both amazed when her 24 mile outbound commute, which is a combination of traffic jam and 60 mph highway, consumed only 4 bars, after requiring 6-7 bars all winter with occasional defrost only. This was a tag-team commute, so the battery was already 'warmed up' by my 16 mile return home. At 6 miles/bar(kWh), that'd be a range of 96 miles and efficiency of 167 watt-hrs per mile, or 55% better than the EPA rating. :mrgreen:

 

[randy3]

Are the bars (rr bars, I think you called them) all of equal value on the iMieV? In other words, all else being equal, will the top bar give the same miles as the middle and bottom bars?

 

[jray3]

Are the bars (rr bars, I think you called them) all of equal value on the iMieV? In other words, all else being equal, will the top bar give the same miles as the middle and bottom bars?

Yes, they're supposed to each be the same amount of energy, one usable kWh. It often seems like the first bar lasts longer than the rest, but I think that's because the first bar is usually consumed at lower speeds. I logged the odometer readings for each bar on a wintertime trip, and got 4.8 and 6.1 miles/kWh on the first two bars, but only 2.3 to 3.9 miles/kWh on the next 11 bars. Guess which portion of the trip was on the highway!

 

[Don]

Don't think you can say that since one fuel gauge bar gave you 'X' miles, then the total range is 16 times 'X' - It's not that kind of meter

I too have noticed that the first bar always gives me more miles than any other, even though any trip I take begins with the first 3 miles at an average of 45 mph - The second bar never gives me as many miles, even though that bar is usually done at more like 30 mph

I'm not sure if the meter uses a combination of measured pack voltage and watts consumed, but that would seem logical. Remember that a deep discharge followed by a full recharge recalibrates that meter. It's intended to be a 'fuel gauge' and just as any gauge on an ICE isn't completely linear (first 1/4 tank gives you 100 miles, but your actual range probably isn't really 400 miles) it doesn't seem like our meter is completely linear either

I seldom look at it, but usually do check the RR meter when I have 8 bars left - 'Normal' for me is about 40 miles left it seems

There *are* those who have driven this car an actual 100 miles on a single charge - Not that hard to do if you're in an urban environment where you're seldom above 35 or so

Don

 

[randy3]

Thanks. I'm hoping the i-MieV is more straightforward than the LEAF.

When I first got the LEAF, driving steady, the top bar would get me about 4 miles, then the other bars would get about 7 miles (12 bars total). Then they redid the software for it. Months later, I'm still not used to the change. The top bars disappear really quick and bottom bar is like a double bar. I'm looking forward to having each bar be a little more equal.

Nissan also put a second row of bars (small ones) right next to the longer (like rr) bars. These show how much your battery has degraded. Those bars (battery capacity bars) have caused considerable heated discussion among LEAF owners. In 2.5 years, my LEAF has lost one capacity bar, but I don't really understand if that means it's capacity is down 6%, 8% or 15%, and Nissan reps don't tell me.

 

[jray3]

Great to see you here Randy. Very few folks own both a LEAF and an i, so your perspective will be valuable. I prefer the i for local errands and my commute EVen after driving a lot of carpools in friends' Leaves. I think that the SOC meter is counting more than just amp-hours, because if it was, the miles per kWh would steadily decrease as the charge is depleted. (Takes more amp-hrs to make a kWh as voltage decreases). Even if all the Coulombs are being counted, no meter is perfect, so I don't feel bad about getting below 2 bars o charge for a rebalancing slightly more often than the once per year now recommended in our maintenance schedule.....

 

[JoeS]

I know that this has been discussed at length, but the search function is so lousy that I didn't find a decent thread to resurrect. (where is that thread where we were posting RR meter photos?)...

jray3, know what you mean. Found it: maximum range remaining. This should prove of interest so some of our newer members where the challenge still stands: show us a photo of your RR (Range Remaining numeric) readout that exceeds the presently-claimed record by TaosEV of RR=103 miles (166km). http://myimiev.com/forum/viewtopic.php?p=2290#p2290

As far as fuel-gauge non-linearity, after getting to the sixteenth bar the iMiEV absorbs not only the (roughly) 1kWh but also the additional energy during balancing, and perhaps that reflects some additional distance for it to drop the first bar? In my case, I'll never know because my first 4 miles are all downhill and the fuel gauge sometimes stays at the full 16 bars well over the first 10 miles.

As far as non-linearity at the bottom end, comparing the miles driven to bar depletion I haven't noticed any significant difference: perhaps it's just a little bit of concern beginning to set in as one gets down there? If anything, it should stretch out because we unconsciously ease up a bit?

 

[RobbW]

I understand that the bars and miles do not have an exactly linear relationship, but any guess as to how far off the two are? Joe, it sounds as though you don't believe there is that big of a difference. Would that mean, in general, we could probably take the miles driven divided by the bars used to get an average miles per bar and "roughly" apply that to all the bars?

On my way in to work this morning, I measured exactly the miles driven over the entire course, 15.3 miles. Once I parked at work, I saw that two bars had been used. Granted, I have no idea if the second bar had just dropped off or if it was very near to dropping the third bar or halfway between. In any case, doing the math and assuming a linear relationship (which it isn't), I would get roughly 7.5 miles per bar if I continue driving in the same style as I did this morning. Being kind of iffy on the state of the 2nd/3rd bar, my total range on this charge would be anywhere between 80 miles and 120 miles. Obviously, it most likely is NOT going to be close to 120 miles, but if I can safely assume 80 miles on the low end, I would be happy with that.

 

[RobbW]

Okay, so it turns out it was closer to dropping the third bar as it did so shortly after I headed out for lunch. So, in a linear world, this should equate to roughly 5 miles per bar, or 80 miles per charge.

I also understand there is not a very good correlation between the power bars and the RR gauge. However, another fun little game I've found myself enjoying is how far can I drive while keeping the RR at the same mile?!

 

[Don]

I understand that the bars and miles do not have an exactly linear relationship, but any guess as to how far off the two are? Joe, it sounds as though you don't believe there is that big of a difference. Would that mean, in general, we could probably take the miles driven divided by the bars used to get an average miles per bar and "roughly" apply that to all the bars?

That would give you an average 'range per bar' . . . . but it still wouldn't tell you anything about how far you can drive on any one given bar. If you were going rapidly uphill, you might only get one mile to the bar, whereas if you were driving slowly downhill, you might get 30 miles

I generally don't watch the 'gas gauge' to check the bars very often just for this reason. The RR display at least gives you an educated calculation based on how and where you've been driving for the past 15 miles, so it's much more useful to me. I almost always glance ad the 'gas gauge' when the RR reads 40, and almost always see 8 bars remaining . . . . sometimes 9 bars just getting ready to switch to 8. On average, one bar equals 5 miles of range for me . . . . but the next bar might take me 2 miles or 15 - No predicting

Don

 

[Pier]

Yesterday, I wanted to get the most RR by driving as slow as possible for the last 30km (20miles). Not more than 40 kmh (25 mph). To my surprise I got only 155 km RR, about as usual.

Concerning the km to bars, I am firmly convince now that the first bar gives more km than others and even the 3 first more than the 3 at the middle. On the flat, same speed and wind, I got avg 14 km/bar for first group of 3 bars and 12 km/bar for second group.

Pier

 

[JoeS]

I understand that the bars and miles do not have an exactly linear relationship, but any guess as to how far off the two are? Joe, it sounds as though you don't believe there is that big of a difference. Would that mean, in general, we could probably take the miles driven divided by the bars used to get an average miles per bar and "roughly" apply that to all the bars?

Yep, recognizing that these are all averages and coarse approximations, anyway, and a function of speed and terrain and headwinds and lead/featherfooting and... My own rule of thumb is 4miles/bar, knowing that I can very easily up it to 5miles/bar if I need to. I use the RR gauge, the Fuel Gauge, and my Garmin GPS DTG (Distance To Go) to give me a warm fuzzy feeling on extended trips, with pre-planned contingency backups if intended charging points become unavailable. Friends scattered around the SF Bay Area usually have dryer outlets close to their garages: except for actual visits with friends, I haven't unexpectedly had to call on them for a charge, yet...

The RR display at least gives you an educated calculation based on how and where you've been driving for the past 15 miles, so it's much more useful to me. I almost always glance ad the 'gas gauge' when the RR reads 40, and almost always see 8 bars remaining . . . . sometimes 9 bars just getting ready to switch to 8. On average, one bar equals 5 miles of range for me . . . . but the next bar might take me 2 miles or 15 - No predicting

I agree with Don and also prefer the RR Gauge. Ah, living in flat country is sooo much more predictable … Don, you're pulling our leg with those last two words as you are much too astute and know the outcome of leadfooting at 80mph (<2miles/bar) or featherfooting at 25mph (>6 miles/bar). It's the 20-mile downhill which can even increase the fuel gauge by a couple of bars that makes watching the iMiEV's gauges really fun.

 

[PV1]

I noticed that the first bar almost equals 2, so there's more energy hidden at the top. However, my last few bars disappear quickly. This could be that I need to re-calibrate. Driving to work, I use 1 bar and part of another, and on the way home, I use the rest of that second bar and two additional ones. Another route I travel, I got 8.5 miles before losing the first bar, 2.2 miles off the second bar. This equaled 2.3 kWh.

I'm tempted to spend a few hours and calculate how much energy each bar contains/represents.

 

[fjpod]

I noticed that the first bar almost equals 2, so there's more energy hidden at the top. However, my last few bars disappear quickly. This could be that I need to re-calibrate. Driving to work, I use 1 bar and part of another, and on the way home, I use the rest of that second bar and two additional ones. Another route I travel, I got 8.5 miles before losing the first bar, 2.2 miles off the second bar. This equaled 2.3 kWh.

I'm tempted to spend a few hours and calculate how much energy each bar contains/represents.

I've noticed this on my car as well. So, make sure you don't drive out too far before starting your return trip. Leave at least 60% of your pips for the return. And don't forget to take hills and elevations into account.

 

[aarond12]

I noticed that the first bar almost equals 2, so there's more energy hidden at the top.

I agree. From a full charge, I can get to work in 1 bar. On the way home, it's 2, possibly 3 if I want to get home faster. (9 miles each way.)

 

[JoeS]

A couple of days ago I was a panelist in a local public discussion forum about Electric Vehicles. The main presenter made the case for Solar + EV. The Tesla owner raved about it's performance. The relatively-new RAV4EV lady owner pointed out the usual EV attributes and allowed as it's good for 100 mies on one charge. The Leaf owners did the usual with emphasis on QuickCharge ability. The FordFocusEV owner loved its looks, but said little else about it and recounted his experience of arriving at SFO and finding zero available EVSEs.

After pointing out that it was a normal car with all the modern features and over-80mph top speed, I gushed over the i-MiEV's practicality: huge flat-floor cargo capacity, the small outside dimensions, our super-tight turning radius, etc.

What really caused the the crowd to gasp is when I tackled the issue of range: "Even without a QuickCharge port, my i-MiEV easily goes 150-200 miles per day". Thought I'd share the example I used, based on living in Los Altos, CA. For us, I'm including the fuel gauge status as well -

Overnight - fully charge the iMiEV using Level 1 (120vac)
0630 - Starting with 16 bars - take neighbor to airport (40 miles round trip).
0730 - Arrived home with seven bars. 4.4 miles/bar. Plugged into L2.
(No problem with rush-hour traffic as iMiEV qualifies for single-occupant HOV lane use)
1030 - Starting with 16 bars, but not fully charged, drove 45 miles to San Francisco to watch the America's Cup racing.
1130 - Arrived with 6 bars. 4.5 miles/bar. Plugged into L2 EVSE at Crissy Field (the world's most beautiful EV charging station location)
1430 - Starting with 15 bars, drove the 45 miles home.
1530 - Arrived home with 4 bars. 4.1 miles/bar. Plugged into L2.
1800 - Starting with 12 bars. Drove 40 miles to Capitola (by the ocean) over the Santa Cruz mountains for dinner with friends in rush-hour traffic.
1900 - Arrived with 4 bars. 5 miles/bar. Net altitude reduction of 600ft. I love the see the fuel gauge go UP on that long downhill!
(Plugged into friends' dryer outlet in their garage - they're now used to me doing this, although there's a free public EVSE less than a block from their house).
2200 - Starting with 13 bars, drove 40 miles home. Minimal hypermiling.
2300 - Arrived with two bars. 3.6 miles/bar. Plugged into EVSEUpgraded L1 for 120vac 12A overnight charge.
Total mileage: 210 miles

Of course we'd like to have larger battery packs, but it would be nice to have a pack size vs. cost alternative when buying the car (e.g., like Tesla). In my case, anything much over 50 miles one-way results in my taking the Gen1 Insight hybrid anyway, so a 100-mile range car wouldn't change my driving habits at all. Sure, I'd use a 150-mile range car a bit more, but still wouldn't drive it 400 miles to Los Angeles. I think Tesla has the long-range EV market sewn up for years to come...

As an aside, I drove my Gen1 Insight for the first time in a while up to SF yesterday to watch the America's Cup (only because I was given a non-EVSE reserved parking spot). Have to agree with alohart: we've become so used to the silence and wonderful instant torque of our EVs, that any ICE vehicle (even one as superb as the Gen1 Insight) now seems ancient in comparison. In addition to the iMiEV, I've been driving my Sparrow which I recently converted to Lithium - shedding 450lbs; need to take it to a dragstrip to quantify, as I had to remove a battery pack to reduce the voltage from 190v to 145v just so it would now be manageable (barely) - I won't let anyone else drive it. :twisted:

 

[GdB]

I have an excel spreadsheet I used to figure this out and I thought this little table would be useful:

Assuming little or no AC, and no heater!

MPH miles/bar
25 9.5
30 8.6
35 7.6
40 6.7
45 5.9
50 5.1
55 4.5
60 4
65 3.5
70 3.1
75 2.8
80 2.5

 

[genec]

When getting low on bars resist the temptation to get to your destination in a hurry. Instead, remember that the slower you go the farther you will go. The i-miev gets the most mpge at around 20 mph. Yeah, it seems like a crawl but it may get you back home where otherwise you're in the middle of nowhere.

 

[Phximiev]

I have an excel spreadsheet I used to figure this out and I thought this little table would be useful:

Assuming little or no AC, and no heater!

MPH miles/bar
25 9.5
30 8.6
35 7.6
40 6.7
45 5.9
50 5.1
55 4.5
60 4
65 3.5
70 3.1
75 2.8
80 2.5

Assuming a highway trip at 75 mph, then by your table the maximum travel distance for a full pack would be 44.8 miles. Now to add an additional variable, elevation. The elevation of Anthem, Arizona, is 1,863 per wikipedia. The elevation of Cordes Junction, Arizona, is 3,700 feet. Plugshare says its 34 miles on I-17 between Anthem and Cordes Junction and there is some up and down, so some regen is possible. There are no other realistic alternative routes for making the trip. Can I make it, or do I stop in Black Canyon City and use a NEMA 14-50 campground charge to re-charge?

Or do I just drive at 70 or less and risk aggravating the other drivers? (Driving at 70 by your table gets me 49.6 miles).

Best guesses accepted!

:?:

 

[Don]

I have an excel spreadsheet I used to figure this out and I thought this little table would be useful:

Assuming little or no AC, and no heater!

. . . . and no hills plus little to no wind I might add

Don