Arduino sketch, library, BOM, and Gerber files for i2/x2 Segway battery diagnostics
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Latest commit d69167e Feb 5, 2019


I2 Battery Diagnostics

Arduino sketch, documentation for i2/x2 Segway Li-ION battery diagnostics ( also works with NiMH )

There have been a number of closed sourced solutions for battery diagnostics and management for the Segway I2/X2 and related batteries. Many of these solutions have been sold with "per use" lockouts such as "battery gauges/revivers" which work around the battery saftey systems to bring low-voltage batteries back above 50V to allow charging.

Even simple diagnostics tools to read the temperatures, the four on-board thermocouples, the voltages and capacities of the parallel battery clusters in each pack, or just the serial number and battery revision can cost hundreds of dollars/euros.

This git repository is designed to open the world of Segway Battery management to everyone, make the cells understandable and useable by the greater community of battery recyclers, powerwall, e-vehicle creators, or just people who want to have a deeper understanding of the battery systems in their Segway PT/I2/X2.

Included here are resources to help you such as:

  • Arduino .ino sketch with a simple menu system to read real-time diagnostics information from the battery
  • A breadboard schematic as well as pinout diagram for the Arduino and Segway battery to connect safely to the battery

I'm working on:

  • A schematic and PCB layout in Eagle format, along with Gerbers and Excellon drill files for an example Arduino shield
  • A schematic and PCB layout in Eagle format for an Arduino Mega & Adafruit 3.5" TFT display + STL to 3D print a case
  • A schematic and PCB layout in Eagle format for a Raspberry Pi + Python code command line diag tool
  • A BOM ( Bill of Materials ) with sources and links to purchase parts
  • An STL file to 3D print a compatible connector to the Segway battery and instructions on how to assemble and use it safely.

I'll be releasing a beta of the software and hardware schematics mid-January 2019. For information, please contact me here on GitHub. I generally respond within 1-2 days.


Feb 5, 2019

The battery voltage and temperature sensor code has been decoded, and the code is merged into the master branch.

The data in register 12/204 is being worked on now, and I have a couple people helping to decode the data found on register 198 as well. If you have a theory or suggestion as to the data, please submit an issue here on GitHub, or just modify the code and submit a patch request.

Jan 28, 2019

The Segway battery exposes interesting data on the following registers on i2c when read in the same way as the battery voltage values ( 3 bytes read, discard first byte, data encoded on 2nd and 3rd byte )

Register 12 ( 0xC ) reads 31 triplets. Byte 0 ( unknown ) , Byte 2 counts from Hex 0 -> 1E, Byte 3 ( unknown ) Register 204 ( 0xCC ) reads 31 triplets. Byte 0 ( unknown ), Bute 2 counts from Hex 0 -> 1E, Byte 3 ( unknown ) 1st and 3rd values repeat after 31 reads, both registers show the same data

Register 198 ( 0xC6 ) reads 37 triplets. Byte 0 ( unknown ), Byte 2 counts from Hex 0 -> 25, Byte 3 ( unknown ) 1st and 3rd values repeat after 37 reads

Example of the data - register number in <>, values in hex

<12> [C3:0:B0] [F1:1:1] [BE:2:33] [3F:3:31] [37:4:38] [3A:5:34] [C:6:61] [34:7:38] [A8:8:43] [27:9:43] [A6:A:43] [25:B:43] [37:C:30] [33:D:33] [A3:E:42] [A2:F:42] [21:10:42] [20:11:42] [31:12:30] [2D:13:33] [3F:14:20] [3E:15:20] [3D:16:20] [3C:17:20] [BB:18:20] [BA:19:20] [B9:1A:20] [83:1B:55] [82:1C:55] [D5:1D:81] [DC:1E:F9]

<204> [C:6:61] [34:7:38] [A8:8:43] [27:9:43] [A6:A:43] [25:B:43] [37:C:30] [33:D:33] [A3:E:42] [A2:F:42] [21:10:42] [20:11:42] [31:12:30] [2D:13:33] [3F:14:20] [3E:15:20] [3D:16:20] [3C:17:20] [BB:18:20] [BA:19:20] [B9:1A:20] [83:1B:55] [82:1C:55] [D5:1D:81] [DC:1E:F9] [C3:0:B0] [F1:1:1] [BE:2:33] [3F:3:31] [37:4:38] [3A:5:34]

<198> [AA:0:4F] [F7:1:1] [45:2:32] [46:3:30] [3C:4:39] [3E:5:36] [3C:6:37] [42:7:30] [41:8:30] [40:9:30] [BF:A:30] [3D:B:31] [2C:C:41] [24:D:48] [BA:E:31] [BA:F:30] [38:10:31] [38:11:30] [AE:12:39] [32:13:34] [2E:14:37] [A1:15:43] [33:16:30] [B1:17:31] [31:18:30] [AA:19:36] [AE:1A:31] [AA:1B:34] [2D:1C:30] [2C:1D:30] [AB:1E:30] [21:1F:39] [A1:20:38] [83:21:55] [2:22:55] [5E:23:F8] [27:24:AE] [D4:25:0]

Register 23 ( 0x17 ) reads 4 triplets. Byte 0 ( unknown ), Byte 2 increments 0x1,0x11,0x21,0x31, byte 3 ( unknown ) Register 215 ( 0xD7 ) reads 4 triplets. Byte 0 ( unknown ), Byte 2 increments 0x1,0x11,0x21,0x31, byte 3 ( unknown ) 1st and 3rd values repeat after four reads - these are likely the temperature readings on two registers

<23> [7F:1:68] [F3:11:64] [4E:21:79] [4A:31:6D]

<215> [7F:1:68] [F3:11:64] [4D:21:7A] [4A:31:6D]

This data parses to the following binary:

0001 0001 0110 0100
0010 0001 0111 1010
0011 0001 0110 1101
---- Measurement index nibble
     -------------- Possible A/D conversion of the temperature ( 12 bit, or 10 bit? )

And of course, registers 150 (0x96) and 86 (0x56) contain the battery voltage data encoded as:

Byte 0 (checksum) : Byte 1, Byte 2 are the MSB and LSB of a 16 bit integer. Top 3 bits are the battery index. Lower 10 bits are A/D converted battery voltage data, where each tick represents 8 volts / 1023 steps.

Jan 27, 2019

After debugging the code with @gmulberry's input and live experimentation by feeding arbitrary voltages to an opened battery, we have determined that it's likely a 10bit ADC and that the voltage scaling factor is 8V ( 8000mV ) divided by 1023 steps ( 10 bit ADC ) to calculate the value of the voltage on the pack.

The code has been changed to reflect this, switching variables to the 32-bit long type to handle the math. Each step of the ADC represents (8000/1023) or ~7.820 milivolts.

Jan 26, 2019

First check-in for the Arduino code! You can read the voltages from the cell groups with the currently checked in code. I'll be updating the code with more functions as I clean up my research code.

Also added:

  • Screen snapshot of the i2c bus communication to the battery when reading the voltages
  • My notes on reading the voltages, and an explanation of how the protocol works
  • Updated pinout of the connector, with proper location labels and functions for all pins -Connector Pinout
  • A terrible photo of my messy desk, that shows how I wired up the battery. Embarrasing, but useful... -Messy Desk

Jan 20, 2019

Thanks to Segway Nation Tours in Austin, TX - I once again have access to a supply of both good and red-light batteries to continue the development and research! I have had about a month of downtime, so am catching up. I now have an Arduino Uno connected to a battery and can read all 23 cells in the pack. As it turns out, 12V is needed to "wake" the battery up and I have modifed the picture to reflect that.

Initial Arduino -> Segway Battery pinout : Only four wires are required

  • SCL -> SCL pin on Battery
  • SDA -> SDA pin on Battery
  • GND -> GND pin on Battery ( CAREFUL! Don't connect to Segway Battery POS terminal )
  • +12V -> BAT ENABLE on Battery ( You can use VIN if you use a 12V power supply for your Arduino )