How to calculate range - Jaguar I-Pace EV400 Forum
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post #1 of 4 (permalink) Old 09-08-2019, 12:29 AM Thread Starter
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How to calculate range

Here are two plots based on 39 trips where I recorded starting SoC, miles driven, and ending SoC.
Reassuringly (because you never know with those JLR software people), SoC and kWh correlate extremely well, presumably because JLR directly calculates SoC from the same kWh charge estimate they make available via their API.

So: for those of you who don't have access to the kWh figures, going to your MyEV panel and looking at the percentage SoC is a fine surrogate for kWh and you can calculate your range based on current consumption (or historical consumption if you want an average) with this simple formula:

miles_traveled / (StartSoC-EndSoC) = Predicted total range on a full charge
[remember to convert the SoCs to a fraction, i.e. 40% = 0.4)]

Two use cases:

1. You want to know your average consumption for past trips. Just add up all the miles traveled (numerator) and add up all the SoC differences (denominator). Then do this calculation (which is the same as above): Total_Miles / SoC_Sums = average range.

2. You want to know whether you're going to make it to your destination and you've had a headwind since you started. Do the calculation. It will tell you your total predicted range, assuming the current conditions don't change. Then take your current SoC and multiply by the predicted range. That's how many miles you have left. Example: I started at 80% SoC. Have driven 30 miles and it dropped to 65% SoC. Range = 200 miles. That means that now that I'm at 65% SoC, I have 130 miles left in the tank. The GoM shows 150 miles. IGNORE THE GoM. You have 130 miles left. Good thing home is 100 miles away so you're fine either way.
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post #2 of 4 (permalink) Old 09-13-2019, 12:46 AM
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Yes. This has been my argument, too. Forget comparing to other vehicles. Just use your miles per % of charge - which for me, in the heat, on the highway at 75 is about 1.9 to 2.1 - which means my real world range is 190 miles ... MAYBE 200.

In the city, my miles/% of battery used is closer to 2.4 - or 240 miles range.

Yo Jaguar - you should make the % charge NUMBER visible on the speedometer at all times (don't make me go into a special screen and hide the media screen). And, you should make miles/% Battery an option on the Trip Set display.

Excellent post!
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post #3 of 4 (permalink) Old 09-13-2019, 02:41 PM
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Quote:
Originally Posted by WattAJag View Post
Yes. This has been my argument, too. Forget comparing to other vehicles. Just use your miles per % of charge - which for me, in the heat, on the highway at 75 is about 1.9 to 2.1 - which means my real world range is 190 miles ... MAYBE 200.

In the city, my miles/% of battery used is closer to 2.4 - or 240 miles range.
Those are my 'mental benchmarks': 190 Hwy and 240 City. Based on applying the 'fuel tank' ratio (% full) to those figures, I've dismissed use of the GoM.
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post #4 of 4 (permalink) Old 09-15-2019, 12:05 AM
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Range Spreadsheet

I can't seem to upload the file as an attachment, but I can give you instructions to build a simple, but useful spreadsheet you can use with the Google Sheets app (readily available to download to your phone) to more accurately calculate range than the GOM while you're driving.

Note: Take great care using your phone while driving & maybe while you're using auto-pilot or have a passenger enter the data.

One-Time Build Instructions:

1. From the Google Sheets click the circular + button to start a new sheet.

2. In Cell A1 enter text: Starting Battery %
In Cell A3 enter text: Miles
In Cell B3 enter text: % Battery
In Cell C3 enter text: Rem Range
In Cell D3 enter text: Total Range

3. In Cell C4 enter Formula: =A4*B4/(C1-B4)
In Cell D4 enter Formula: A4+C4

4. Click the 3-dot menu in the top right corner, select Share & Export, select Save As and name the sheet EV Range.


To use the sheet.

1. Put in your starting battery % at the beginning of your trip at the top of the sheet (Cell C1).

2. Zero out your Trip Odometer from the button on the top of your I-Pace turn signal, so you can track the miles you've driven.

3. Then, periodically, you can enter the miles you've driven from the Trip odometer and the current battery % (from the ECO screen) into cells A4 and B4. The remainder range you can expect, and your overall range (based on your starting battery) is calculated.

This is the REAL range you can expect given the conditions you've been experiencing in today since you started off. Provided the rest of your trip is in a similar speed/temperature/direction/elevation change that you have already been driving, the range estimate will be very accurate.

If you charge the battery during your trip, start over at step 1.
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