YamaGo (3rd party battery support mod for Yamaha ebikes systems)




 
Yamaha GoFree (3rd party battery support mod)

This device has two uses: 

  • Yamaha battery hacking dongle to use any 3rd party battery instead of the original Yamaha battery.
  • Wireless battery Fuel Gauge / Watt meter


Hacking the Yamaha battery

As with other brands, the Yamaha PW series motor doesn't allow to use any 3e party battery. But with the use of the dongle described here, the Yamaha ebike will be hacked so that you can use any battery instead of the original expensive Yamaha battery.

At electric bicycles, only a battery of the own brand can be used, that is product tying and is prohibited. 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. 

To develop a hack, GamerPaddy re-engineered the Yamaha mid-drive motor at the Pedelec-Forum. The battery dongle described here is based on the hack from GamerPaddy, but has several improvements such as the fuel gauge with the LTC2944.

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.

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.

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 absolute maximum voltage is 50V, that corresponds to so-called 36V batteries.
  3. The battery capacity is measured very accurately with an LTC2944 fuel gauge IC, not just simple voltage measuring.
  4. Fuel gauge indication with 6 LEDs on the board
  5. The dongle turns off automatically when the Yamaha ebike is turned off.
  6. The battery capacity is stored in an EEPROM so that it is not lost when switched off.
  7. The data signal output has a short circuit protection.
  8. A NRF24L01 wireless module can be soldered for use as a battery monitor / fuel gauge / Wattmeter.
  9. Note that Giant ebikes with a Yamaha motor can’t be used with the dongle because they use a CAN-bus which is different from the one described here.

All Yamaha drive units X2 ST TE CE X2-45

Here are all Yamaha drive units as of April 2021.


Dongle installation

Remove the aluminum foil if present. The first dongles don't yet have a protection case. You can electrically insulate the dongle with duct tape or heat shrink tubing. Make sure that the dongle is protected from water.

Yamaha battery dongle wiring

Attention: in case of wiring errors or reversed battery voltage, the dongle and the Yamaha system will immediately break. So double check the wiring with a multimeter before plugging in the battery.

Note that the charger cable can no longer be plugged into the charge input of the battery. Because the dongle contains the coulomb counter for measuring the battery capacity, the charging current must also flow through the dongle. It is best to use the anti spark XT90S for the charge connector.



F.A.Q.

  • Is it necessary to dismantle the motor?
    Not, the wiring is on the outside.
  • Which Yamaha motors are suitable for the battery hack?
    The dongle is till now just tested on the PW-X2 and the PW-SE motor, but it should work on all Yamaha mid-drive motors. If it unexpectedly doesn’t work on your motor, you will get the money back.
  • Which Yamaha motors are NOT suitable for the battery hack?
    Yamaha motors used on Giant ebikes.
  • Is it waterproof?
    The first versions will not yet be waterproofed, you have to take care of that yourself.

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.






Protected data output circuit

The Yamaha PW-SE data output circuit is not protected against short circuit to the battery +, the transistor TR320 will be blown up then. That's why I reverse engineered the data output circuit. The dongle has a protected data output that is protected against short circuits.













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