ElectricScooterParts.com Support Center

I would begin by disconnecting the battery and removing the old control module and then follow the wiring diagram below to install the new relay and throttle. The battery should be the last component that is connected to the circuit after it is completed.

The original PC board was designed so the motor would not start until the scooter was pushed off to around walking speed. When replacing the  original PC board with a relay the scooter should be pushed off to  around walking speed before the throttle is engaged. If the scooter is  not pushed to walking speed before it is started the motor and relay  will have a very high Amp load placed on them which could cause these  parts to fail prematurely.

The terminal numbers on automotive relays are clearly marked on their bottom side. Either a four terminal SPST (single pole single throw) or five terminal SPDT (single pole double throw) automotive relay could be  used. If using a five terminal SPDT relay the middle terminal marked 87a  should not be connected to any wires.

12 Volt automotive relays are available on our Relays Page  and they are also available at all auto parts stores. If you need a new  throttle the original yellow finger-pull On-Off throttles are  discontinued and no longer available however we sell an upgrade On-Off  twist throttle on the Zappy Classic Parts Page.

This PC board to automotive relay conversion will also work on Zappy SX electric bicycles and electric bicycle conversion kits.

The original control board on Zap electric bikes had a relay that controlled the power, so replacing it with a relay will yield the exact same speed and mileage range as the original controller did.

To make it our THR-E20 throttle and RLY-1240 relay can be used which are available on the following pages:
http://www.electricscooterparts.com/throttlessinglespeed.html
http://www.electricscooterparts.com/relays.html