Improved GOM. Check My Reasoning/Math

My Nissan Leaf Forum

Help Support My Nissan Leaf Forum:

This site may earn a commission from merchant affiliate links, including eBay, Amazon, and others.

PianoAl

Well-known member
Joined
May 16, 2016
Messages
239
After owning our LEAF for 1.5 months, I understand why they call the range meter the Guess-o-meter. I would prefer to estimate my remaining range based on my typical efficiency of 3.9 miles / kWh (instead of the very recent efficiency that the GOM uses).

However, the one crucial number I need, the energy remaining in the battery, isn't available without LEAFSpy. The display shows SOC, but the energy remaining will also depend on the SOD (state of degradation).

If I want to use my system, I can either run LEAFSpy all the time or create a spreadsheet and print it out. Here's the formula I'd use.

Energy Remaining = SOC% / 100% * kWh / Full Charge

Miles Remaining = Energy Remaining * Miles/kWh - Margin (Where Margin= Margin of safety (# miles remaining when I get home))

or

Miles Remaining = SOC% / 100% * kWh/Full Charge * Miles/kWh – Margin

Here's a spreadsheet that uses that formula:

JnP8vCA.png


Ignore the "Multiplier" column.

If I use a Margin of 0 miles, this is the spreadsheet:

7XY9ZsB.png


So, to have an improved GOM in my head, I simply multiply the SOC by .9 and subtract the margin. For example, if SOC is 80% my remaining range is about 80 * .9 - 8 = 65 miles. Or, I could print out the spreadsheet and keep it in the car.

I'd have to recalculate as the battery degrades.

Is my reasoning and math correct?
 
Kind of misleading to have both a 100% and 98% option the way you have it on the print out. Your max charge will be between 93% and 97% depending on a ton of factors. Might as well call the range available at 96%, 98% and 100% the same (combine them / eliminate a couple). My car never sees above 94% SOC so I'd chop off the 96% option as well.

I'd also be concerned that you get 3.9 miles per kWh. Tire pressure low? I'd suggest raising tire pressure to 40+. Driving very fast? Maybe slow down a hair on the highway portion of the trip. Crummy tires? Buy LRR tires as soon as range is an issue for you.

On the OEM rims with crappy summer tires I was getting a 4.4 miles per kWH average.

On my lightweight 15" rims with LRR tires I'm getting more like 5.2 miles per kWh average (though I haven't driven them a full year, I expect the average to rise after I get to drive fall and spring. Partly due to climate control draw, partly due to initial inefficiency of new tires wearing in and getting more efficient).
 
dhanson865 said:
Kind of misleading to have both a 100% and 98% option the way you have it on the print out. Your max charge will be between 93% and 97% depending on a ton of factors. Might as well call the range available at 96%, 98% and 100% the same (combine them / eliminate a couple). My car never sees above 94% SOC so I'd chop off the 96% option as well.
Good point, I'm guessing since PianoAl's Leaf is relatively new it still shows 100% SOC at full charge and still may for a few years. My '13(put into commission in '14) still charges to 100% but my '12(put into commission mid '12) generally stops ~91% although at times I see as high as 94%. Still for now the chart should be a quick handy reference point for him, for sure more accurate than the GOM :D
 
When the battery degrades, does the SOC% top off at a lower percentage? If so, my statement of "the one crucial number I need, the energy remaining in the battery, isn't available without LEAFSpy" is incorrect.
 
PianoAl said:
When the battery degrades, does the SOC% top off at a lower percentage? If so, my statement of "the one crucial number I need, the energy remaining in the battery, isn't available without LEAFSpy" is incorrect.

While I admire your effort (and in the end it's all fun), I think the "fatal flaw" of your algorithm is battery degradation. If this were a multiple choice question:

1) The GOM is not accurate
2) 100% SOC is not always 100% SOC
3) Battery degradation has a non-linear affect on GOM and SOC
4) all of the above

The answer would be 4)
 
Stanton said:
PianoAl said:
When the battery degrades, does the SOC% top off at a lower percentage? If so, my statement of "the one crucial number I need, the energy remaining in the battery, isn't available without LEAFSpy" is incorrect.

While I admire your effort (and in the end it's all fun), I think the "fatal flaw" of your algorithm is battery degradation. If this were a multiple choice question:

1) The GOM is not accurate
2) 100% SOC is not always 100% SOC
3) Battery degradation has a non-linear affect on GOM and SOC
4) all of the above

The answer would be 4)

I agree. My idea is that I would frequently revise this as LEAFSpy a new, lower value for the energy in a fully charged battery.
 
I don't respond to people who don't post their location because nearly every answer is highly dependent upon knowing what kind of climate you are in
 
Hey all,
I'd like to add a discovery. May be already discussed but I didn't find it.
On the Zero Emissions menu accessed from the blue button of the same name, there is a driving range screen. It has two circles of range. One is from the GOM. The outer circle. The White inner circle is labeled Normal. I have found it correlates pretty close to the Leaf Spy reading for miles remaining if you enter your current miles/kWh. A pretty simple screen to tell you if you will make your destination or not. None of there seem to take in elevation and driving conditions but this one seems the most reliable.

I made a trip from Montpelier Vt to Boston MA in a day and used that to gauge my range through a long stretch of road without any charge points. It was a 67 mile piece but had a lot of elevation change. The temp was cool and snow and wind were expected on the way. I was charging L2 so I wanted to be sure I stayed long enough to get the the L3 in White River Jct VT without just sitting there to 100%. I watched that range display and when I had a 20 lime buffer I left. It worked out almost exactly. This was traveling at 55 mph on an interstate with climate control on set to 70 F.
I have a 2016 Leaf SV with the 30 kWh battery.
The only real advantage to this is it's in the car and doesn't require running and app or leaving a dongle plugged in all the time.
LeafSpy is a great tool for sure. But daily it is a bit of a pain if you just want to drive somewhere and not do research all the time. Fun for those that do of course.
It would be interesting to hear other's experience with that display. Remember it's the inner circle not the outer grey one. That is just the GOM reading.

Thanks
 
gregn said:
Hey all,
I'd like to add a discovery. May be already discussed but I didn't find it.
On the Zero Emissions menu accessed from the blue button of the same name, there is a driving range screen. It has two circles of range. One is from the GOM. The outer circle. The White inner circle is labeled Normal. I have found it correlates pretty close to the Leaf Spy reading for miles remaining if you enter your current miles/kWh. A pretty simple screen to tell you if you will make your destination or not. None of there seem to take in elevation and driving conditions but this one seems the most reliable.

Good point; I have used that screen in the past (mostly before I had LeafDD).
One thing for sure: it's hard to beat the "idiot proof" nature of a range circle over an actual map (in real time no less)!
 
Back
Top