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Introduction

As with other brands, the Yamaha motor blocks if another battery is used. But a Yamaha ebike can be hacked because Yamaha doesn't use any encrypted authentication. To develop a hack, GamerPaddy re-engineered the Yamaha mid-drive motor at the Pedelec-Forum. I thank GamerPaddy for that. 

Because I initially wanted to use a Yamaha motor on my solarbike, the Maxun One, I made a battery dongle myself. My battery dongle is based on the hack from GamerPaddy, but I made several improvements. 

Who wants to finish the dongle?

I have stopped further development. I don't have time anymore and I don't have a Yamaha ebike to test the dongle. The development is done for 90%, the rest must be completed, see below. I have created a new theme at the Pedelec Forum here, please ask questions there. The files are open source on GitHub here. 

Things to be done ...

Hardware

The PCB v4 has to be finished. The PCBs can be manufactured cheaply in China, a stencil is necessary because of the small LTC2944 chip.

Software

The code in Yamaha.ino has to be changed with the newest code on the Pedelec Forum.

Fuel gauge

The fuel gauge works well on the laboratory table, see the video:

Nog doen.......................

But during driving on the street, error messages occur and the motor stops. If the battery capacity is set constant to 90%, the problem is gone. Change this to disable the fuel gauge software:
data[4] = procentLevel; // change this to: data[4] = 90;

Characteristics of the Yamaha battery dongle

  1. You can use any battery on your Yamaha ebike instead of an expensive original Yamaha battery.
  2. The battery capacity is measured very accurately with an LTC2944 fuel gauge IC, not just simple voltage measuring.
  3. Fuel gauge indication with 5 LEDs.
  4. The dongle turns off automatically when the Yamaha ebike is turned off.
  5. The battery capacity is stored in an EEPROM so that it is not lost when switched off.
  6. Data signal short circuit protection
  7. Very low power consumption
  8. The dongle can also be used on any other ebike to measure just the battery capacity.

Yamaha e-bike battery hack with very accurate Fuel Gauge v3

Yamaha e-bike battery dongle with very accurate Fuel Gauge v3

Prototype v3 of the Yamaha e-bike battery dongle

I built a prototype of the battery dongle and also developed the complete software. The fuel gauge with the LED capacity indication works fine.
The dongle works well on old Yamaha motors but on new motors problems occur. On the laboratory table, everything works fine, however, error messages appear while driving and the motor stops. Because I will not use a Yamaha motor on my solarbike anymore, I no longer continue with the development.

The communication part with the Yamaha motor in the software should be completed with the new findings in the Pedelec forum about the communication problems.

Circuit version v4

I have made a new schematic version 4 that still needs to be finished...
Version 4 has some improvements:

  • Data signal short circuit protection by Q1 ... Q3.
  • Connector J2 has 3 pins.
  • The processor is changed to the ATmega328PB.
  • ISP connector J9 for burning the bootloader.

Notes:

  • Resistor R13 is for indication, it will blown up, if the battery is being connected in reverse.
  • The ATmega328PB has a power consumption of just 2mA at a supply voltage of 3.3V and a clock frequency of 5MHz.
  • The zener diode D8 limits dissipation from the voltage regulator U3.
  • The switch S1 is for starting the test software

Connections

Take the cable from the battery to the Yamaha motor.
Cut off the connector of the Yamaha battery.
Connect the three wires to the dongle: 

M- Motor - Black
M+ Motor + Red
Data   Grey

 

Connect the new battery as follows:

B- Battery -
B+ Battery +

Yamaha battery hack

At electric bicycles, only a battery of the own brand can be used, that is product tying and is prohibited, see my article HERE. If the same existed for cars, the 12V battery could not be replaced by any other battery, which is of course very undesirable. As with other brands, the Yamaha motor blocks also if another battery is used. But a Yamaha ebike can easily be hacked because Yamaha doesn't use any encrypted authentication.

Example of use

On my solarbike, the Maxun One, I want to use a Yamaha PW-X2 mid-drive motor. The problem is that the Yamaha battery is not suitable for my solar bike because:

  • The PV panels can charge the battery with a current as high as 8A. Normal Li-ion e-bike batteries can’t stand this high charge current. I need LiFePO4 battery cells.
  • The battery must allow simultaneously charging and discharging, this isn’t possible with the Yamaha battery.

Battery authentication

As with all e-bike motor manufacturers, the motor blocks when another battery is detected than the same brand. Note that this is unallowed product tying, see my article Product tying.

Fuel gauge with the LTC2944

The Yamaha battery has a fuel gauge built in and the battery capacity is sent to the display via a data cable. If a battery other than the Yamaha battery is used, the capacity should be measured externally. Therefore, the dongle also measures the battery capacity.

Use as a Universal battery capacity meter with LED bar

The dongle can also be used universally as an accurate battery fuel gauge for any battery. The remaining battery capacity is continuously displayed with 5 LEDs. If the battery is switched off or disconnected, the capacity-value must be restored when it is switched on again. The battery capacity is therefore stored in an EEPROM. 

Eagle files

Yamaha battery hack schematic v3

Yamaha battery hack schematic v4

Yamaha battery hack v3 PCB

Connecting a second battery to a Yamaha battery

Instead of a battery hack, you can use the original (possibly worn out) Yamaha battery only because of the data signal and connect a new extra battery in parallel with it. I have described this in the article: Battery management system BMS.

Connecting an extra battery to a Yamaha battery

Yamaha PW SE data output circuit

While working on the battery hack, I blew up the transistor TR320 in the PW-SE Yamaha engine several times. The cause of this is unclear so far. That's why I reverse engineered the data circuit scheme.

Yamaha PW SE data output circuit

Blown up transistor TR320 (EMG9) PW-SE Yamaha

I have discovered that error messages occur when the battery capacity changed too quickly.

Dongle during development

Yamaha battery dongle development

 

Details

My name is Albert van Dalen and I'm an inventor. I have 40 years of experience in electronics and software. During the development of the Maxun One solar bike, I constantly needed special equipment, parts and software, and so I rolled from one project to another. In September 2010, I started this website where I share my ideas and designs with the world. On my webshop, I sell products that I initially made for myself, but that were also interesting for others, such as a spot-welder controller and a solder-paste dispenser.

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See the open source PCB Eagle files on GitHub.

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30x10mm ATtiny3217 Arduino breakout board in DIL24

I am looking for someone who can take over the production and sales for a small one-time fee. I will place a link to your shop here too.

The Dily3217 is an Arduino compatible development board of 30x10mm, easy to integrate since it has a breadboard-friendly narrow DIL24 package. It is powered by the new ATtiny3217 and it has 21 I/O lines. It can be programmed with an external USB FTDI adapter. It has more or less the same functionality as the Arduino Uno.

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All I/O pins are used: despite the small size, it has more I/O pins than the Arduino Zero or SAMD21 Mini/Dev Breakout: 34 instead of 21. Due to the very small dimensions it will fit easily into all embedded electronic projects, even in microdrones.

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These are my inventions up to now, see also the inventions in the pipeline. If you are interested, please contact Business Partners.

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I have inventoried my on-going projects, because I honestly speaking lost the overview. I had started many projects but many of them are on-hold because they, on closer inspection, cost years to finish and in the meantime other things had become more important and I keep getting interesting new ideas.

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