LeafRange

A better range "guess-o-meter" for early Nissan Leaf cars

This project follows on from (and compliments) my earlier LeafSOCdisplay project, which grew from CANa Display for Nissan LEAF © Copyright EV-OLUTION

The project uses an Ardunio Micro (or Mini Pro, or Mega2650) with a 160x128 pixel TFT display and a MCP2515 CAN-bus module to passively listen to the Car-CAN data bus and use the info to provide a more rational range estimate. The display is mounted in a 3D printed frame that fits inside the main dash unit and covers the old range estimate (ie., the "guess-o-meter") with a better range estimate based on battery capacity and temperature. There's also an optional frame that allows the display to be mounted in the corner of the dash, so you can see both the standard Guess-O-Meter and my range estimate.

YouTube drive demo: https://www.youtube.com/watch?v=xt2o3SWRRq8

YouTube hardware show & tell: https://www.youtube.com/watch?v=k4QYvayp_lU

Features

range estimate is not stupidly optimistic at the start of your journey (which is usually when you most want it to be rational). You won't see the range estimate drop 10 km after driving the first 1km like the built-in Guess-O-Meter does.
range estimate does not disappear when the battery dips below 20% (to be replaced by the flashing ---). You get an accurate range estimate down to 0 km. However; there's no buffer below that - so you can't drive another 10 km on "empty" like in a petrol car.
range chart that shows how well the estiimate matches reality (stores jouurney data in EEPROM over multiple drives)
shows battery pack temperature in Centigrate (more understandable than the temp "bars") when the battery is cold or hot
auto-starts a journey odo (multiple trips on a single charge)
range calculation factors in: battery State of Charge, battery State of Health, and battery temperature (see https://github.com/PaulKennett/LeafRange/wiki/Notes}

The significance of the range chart feature is that it makes it much easier to adjust your driving to achieve a desired range.

For example

Say you need to drive 75 km in your 2011 Leafster. You charge to "100%" which gives you a rage estimate of 82km range on my LeafRange display (not that bad for an old gen 1.0 Leaf). The guess-o-meter would be saying something like "103km" which would be a bold-faced lie.

So you head off, stopping at a few places along the way (my display saves range and odo data along the way). About half way there you notice that the chart is showing you're actually trending below the initial estimate line - meaning you should start to ease off the speed a little so that you won't run short.

On the other hand - if you see that you're driving above the initial estimate line then you know you have plenty of capacity to spare so can afford to drive faster.

Limitations

THe range formula is simple; it's only factors are battery capacity, battery SOH and batter temperature. It doesn't know about terrain, weather, driving conditions, car weight, etc. The key benefits are; (a) it's not stupidly optimistic at the start of a drive, (b) it doesn't stop working at the bottom end, and (c) the chart allows you to adjust your driving behaviour to achieve a desired range. All those things improve your confidence and reduce range anxiety.

The raw_Gids variable is stored as a single byte so can't go above 255. A brand new 24 kWh Leaf has about 281 Gids when full. This puts an upper bound on the range it can deal with of about 130 km (about 160 km on the GOM).

Hardware

Arduino Micro, Mini Pro, or Mega2560 (use a Mega2560 for development, use a Micro or Mini Pro for use in the car as it boots up much faster and uses less power)
MCP2515 (CAN bus module)
1.8 inch TFT display 160x128 pixels (like this https://www.aliexpress.com/item/4000016800528.html)
TXS0108E 8 Channel Logic Level Shifter (https://www.aliexpress.com/item/4001131536726.html)
10 Position Flat Flex Cable Assembly Receptacle to Solder Tab 4.00" (101.60mm) https://www.digikey.co.nz/product-detail/en/te-connectivity-amp-connectors/A9AAT-1004F/A9AAT-1004F-ND/137494
5V to 3.3V DC-DC Step-Down Power Supply module (https://www.aliexpress.com/item/4001039310587.html)
70CM 10P IDC Flat Ribbon DATA Cable 2.54mm (https://www.aliexpress.com/item/32891063802.html)
Male DC3 10 Pin 2x5Pin Right Angle Double Row Pitch 2.54mm (https://www.aliexpress.com/item/32945804425.html)
3D printed frame for the display (https://www.myminifactory.com/object/3d-print-nissan-leaf-range-graph-display-154555)
3D printed project box DRAFT (https://www.tinkercad.com/things/lRlt66oEZCM-leafrange-box-v16 - I'll provide a better link soon}
PBC motherboard for a Pro Micro or Pro Mini Arduino (Gerber file provided above or https://oshwlab.com/paulkennett/LeafRange-for-Micro)
PCB for level shifter module (Gerber file provided above - you could use https://jlcpcb.com/ to make them)
OBD2 plug (like this https://www.aliexpress.com/item/32865761651.html)
97% Mini DC-DC 15V 12V 9V 7.4V to 5V 4A Step-down Power Module https://www.aliexpress.com/item/4001313603033.html

Parts list with indicative NZ$ and US$ prices (as at 11 May 2022)

Note: LeafRange_v117.ino fills 99% of program memory on a Micro board, 85% on a Por Mini board and 11% on a Mega 2560 board. If I come up with any new fetures ideas I'll need to drop using the Micro board and foxcus on the Pro Mini.

Relation to the LeafSOC project

The LeafRange project started out as a fork of the LeafSOC project (with a larger 3.3V TFT display to replace the 5V OLED display). So the LeafRange motherboard has been designed to also be used for the LeafSOC project. The on-board jumpers allow you to switch between Car-CAN (for LeafRange) or EV-CAN (for LeafSOC).

Also:

the latest LeafRange motherboard also has the correct dimensions for the OBD2 plug holes. T
the LeafSOC project uses a 5V OLED display so you can leave the 5V-to-3.3V DC-DC converter off

Todo

see the Wiki Todo page https://github.com/PaulKennett/LeafRange/wiki/Todo

PaulKennett / LeafRange