Turtle range

[TonyWilliams]

I found the famous range chart to be inaccurate for me. Now I drive without range anxiety because I know how far I can go.
Dale

Dale, I also found the chart inaccurate for me too, but for a different reason. Even at his "exactly" speeds, I always exceed the m/kW h and the miles. He did his testing and based his chart on CA roads, which is much different than here. Also, they're based on set speeds once you reach the freeway/Interstate which isn't realistic because most people have to travel a ways to get to those freeways/Interstates which can really boost your miles and m/kW h. To tell drivers to 'reset' their dash meter when they reach the freeway is ridiculous when they are trying to see how many miles they can go on their WHOLE trip. You should only reset your meter IF you want to just do some of your own research. Like I said, I did reset the meter when I reached the freeway (for comparisons), drove all freeway at a set speed under his ideal conditions, and STILL exceeded his figures every time.

That seems very unfair. The range chart can be used to plan a trip (5 miles at 30 mph, 23 miles at 65 mph, etc) to get an idea of whether it is feasible. The idea that it is necessary to integrate changing speeds and compare them to the range chart while driving misses the point of it IMO..... Since the Phoenix area is rather higher than sea level and often quite a bit warmer than 70º, are you considering those factors? They make a substantial difference.

This has been pointed out to LEAFfan many, many times. As we can easily tell, Phoenix is higher and MUCH hotter than the baseline data on the chart.

For example, we know that Phoenix is 1100 feet-ish, and with a 120F degree day at standard pressure 29.92 (adjusted to sea level, as is the custom) and 20F dew point in that parched area is over 5000 feet in density altitude. The chart is based on sea level.

How to calculate density altitude

I estimate a 1.5% increase in performance per thousand feet raise in density altitude, therefore a 7.5% increase in range overall above the chart data with the above given criteria. Naturally, LEAFfan makes no adjustments and merely says the same thing over and over. I offered this post to LEAFfan to help him.

The best way to handle the multi segment trip is with simple math, explained in this post. Also, the iPad / iPhone app at the Apple Store helps a bunch with this, but does not have multi segment calculations yet:



I thought I'd expand a bit on how to determine range with a composite trip of city and highway driving.

It's relatively easy to get on the freeway, set the cruise control on 60 mph, and there's not much more to do. Assuming the conditions meet the parameters of the chart (level, etc), you'll knock out performance that matches the chart.

If conditions do NOT match the chart, you will have to use a bit of wisdom to determine how that might affect you. Going up hill, into a headwind, very hot or cold outside, and running the heater or a/c will reduce the chart data. Unfortunately, we do not yet have a chart formula to estimate how those parameters might specifically affect range.

Other issues extant to the above parameters are "cell balancing", which seems to affect how full the battery may charge (only affects 100% charge), and is easy to determine when the 12th fuel bar quickly disappears during your trip after a 100% charge.

The other end is more troublesome. If any one cell (of the 96) is not balanced, you may loose the last 5 to 10 miles of your range. I predict we'll have a way to measure the cells to determine whether those last miles are available. For now, however, it appears that the odds are overwhelmingly in your favor that you will make it, but planning a trip to the last mile is bad form anyway. If you find yourself in a situation where you need those last miles, you'll have to roll the dice a bit.

Another issue is battery degradation, which there's not going to be a measurable amount yet, but that will be an issue a year or more down the road. I think we can expect 2%-3% reduction in range per 10,000 miles. The higher value if you work the battery hard (leaving the car with 100% charges, numerous DC quick charges that heat up the battery, high ambient heat that heats the battery, and running the battery to low energy levels regularly).

City driving can only be logically derived from average miles/kWh. My typical suburban southern California, non-freeway driving is about 4.5 m/kWh, so I'll use that for most of my planning. I'll adjust that for conditions that are not normal to me, and unfortunately, it will be tough for you to judge without a little seat time in your car to determine what's normal.

So, here's the composite part of using the chart. Let's say I'm planning a 90 mile trip. 10 miles will be suburban driving to the freeway, then 70 miles of freeway at 60 mph, and finally 10 miles of heavy city stop on go on a Friday evening before a national holiday.

For the first 10 miles, I'll use 4.5m/kWh.
For the next 70 miles, 3.9
For the last 10 miles, I'll use 3.0

So, here's the relatively simple [edited] math:

10 miles / 4.5 =  2.22 kWh
70 miles / 3.9 = 17.95 kWh
10 miles / 3.0 =  3.33 kWh
           -----
90 miles total / 23.50 kWh = 3.829 kWh average

Can I make it? No, because a 3.8-ish m/kWh average will take me about 80 miles. Also, the total used of 23.50 kWh exceeds the 21-ish kWh usable battery capacity.

Could I make it?

Yes, if I slow down to 43 mph (not recommended, but instructive here) on the freeway.

Now I have:

10 miles / 4.5 =  2.22 kWh
70 miles / 5.2 = 13.46 kWh
10 miles / 3.0 =  3.33 kWh
           -----
90 miles total / 19.01 kWh = 4.73 kWh average

90 miles total now equals a 4.73 m/kWh average, or almost a 100 mile range on level ground. Yes, we can make 90 miles, with almost a 10 mile reserve. Also, 19.01 is significantly below 21 usable.

Easy money, and easy math when done correctly.

 

[smkettner]

Take a generator with you and test it out yourself. I tried it once.

Test the generator for an hour charge before you rely upon it out on the road.

 

[nosuchthing]

I've done turtle twice. Both times got a minimum of 1 mile at 35 mph. I suspect it can do up to 2 miles at 35 or less on flat surface.

VLBC with three lines blinking comes on at 3 miles on GOM at which time there are minimum of 6 freeway miles left at 65 mph. The LBC comes on at 7 miles on GOM. Do that all the time.

Once in turtle -- just drive, in eco. No stopping, no turning off power or that car is dead -- as the book said.

 

[surfingslovak]

I believe that you have less than 0.5 kWh usable when the first power bubble disappears. By the time the turtle fairy visits, you have about half of that left. If you feather the acceleration pedal, you might see about 6 or 7 mpk energy economy. This might be enough to go about a mile, but I wouldn't count on it. Watch the power bubbles, and before the last one goes, pull over and park.

As Tony said earlier, there is no point in killing the car. I'm nearly certain that he is our turtle champ, and if I were you, I would pay attention to what he says. I've done a fair number of tests, and got myself to a point where I had to push to get to an outlet or charging station three times. I wouldn't recommend it.

If you wanted to try a different approach, have a look at the spreadsheet I've compiled a few months ago.


Click to open

 

[LEAFfan]

But I'm willing to guess that even you can't do 100 miles at 65 mph[/quote
Even if I had a few miles to drive to the freeway, set the CC for 65mph, there's no way that the car could go 100 miles, so your guess is correct.

 

[davewill]

LEAFfan, I look at the mph numbers in the chart strictly as rough guidance. Any LEAFer who has had his car any length of time knows what mpk numbers they can sustain during a drive, and that's how I use Tony's chart. I know I can sustain 3.9-4.0 mpk driving @ 60-65mph around here, so that's the column I use from the chart for my planning. If I'm trying to do a trip close to my max range, I reset my mpk readout, and keep an eye on it. If it's falling below the number I know I need to make it (from Tony's chart), I either slow down, plan to stop for a charge, or both.

There's no need to rely on his mph results unless you're a newbie, and even then, you need to use the mpk number to make sure you're staying on plan

 

[ShawnInStL]

After testing it out for myself, I will add my experience to the low end of expectations. I turtled at the worst possible point on my test loop and made it a hair over 1/2 mile before forced shift to N. What surprised me, however, was contrary to some of the pictures I've seen on the forums, my power bubbles did not start to diminish over time. They went from full to 1 bubble over coast as soon as the turtle appeared.

First thought, "Finally! Turtle!" Was driving on VLB for what seemed like forever. Pretty sure it was around 13 miles due to very efficient driving. I was working on the 100 mile club, too.
Second thought, "Crap! Only 1 bubble available?"
Third thought, "My wife is gonna be PO'd when she finds out."

As well as I planned out my intentional turtle, it still caught me by surprise. 1.5 hours on a generator and I was back home.

 

[DaveinOlyWA]

during my only trip to turtle with a GID meter, i lost first power circle then drove .5 miles to turtle (8 GID) then another .8 miles and parked it. 5 circles gone. speeds at this point 20-25 mph

 

[spike09]

New owner here... I want to test the limits of different driving styles and end the run in turtle mode around my charger. I know there are a lot of factors involved, but generally what has everyone seen being the "range" once turtle takes over? Do I have 1, 2, or 3 miles to find power?

I have now "brodered" (intentionally run out of charge) my LEAF twice. I did it the second time to make sure my data was reliable.

First Attempt
VLB to Turtle - 10.7 miles
Turtle to dead - 0.3 miles

Second Attempt
VLB to Turtle - 10.4 miles
Turtle to dead - 0.2 miles

My speed was below 35 MPH at all times.

 

[garsh]

I managed to go 1.2 miles after turtle the one time I unintentionally got that low.
But I kept my speed at about 12mph to maximize range. And the car shut down a few seconds after I parked.