Solar Electric Bicycle Project

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This project was a way of using the ongoing power I am producing both from my 100w wind generator and 5w solar panel.

The basis of the project was a second hand Sinclair Zeta II bought on eBay for 21 ($40) - originally manufactured from 1997 - 2000

The Sinclair ZETA II consists of a rechargeable battery pack, which powers a lightweight motor unit over the front wheel. Touch a lever, and the unit pivots to bring a pulley-mounted belt into contact with the tyre. Press a switch, and the belt drives the wheel. This belt system is patented by Sir Clive Sinclair. When you no longer need power assistance, a flick of the handlebar switch takes the belt out of contact with the tyre.


 Battery 12v 7Ah Yuasa sealed lead acid.

Motor 12v dc - 168 W max (thermal cut-out)

Charge time 14 hrs@ 500Ma

Max speed 11mph

Range Approx 5 miles on level road - no headwind.



Handlebar motor controls.                                                           12v 7ah battery and fuse.


Zeta motor disconnected from tyre.                                                               Zeta motor engaged.


The addition of my 12v 500Ma (5w) solar panel with a 1 amp inline fuse connected was all that was needed to charge my bikes battery.

A silicone blocking diode connected to the positive terminal of the solar panel is necessary to stop reverse current from the battery.

If on a cloudy day I need more charging power I hook the battery to my 100w wind generators battery through a controller box to limit the current

to 1.5 amps and that takes 4.5 hours to fully charge from flat. I check the voltage regularly with my digital multimeter, a charging regulator could be

used if the bike is left for long periods of time in sunshine, they are available from maplin electronics price 9.99 code N82AU  wiring example here

I use it daily to travel the 2 miles to work, however as expected the power from such a small motor is not great, best not to rely on the units power solely.

Best to consider it as pedal assistance, it really helps the old legs. I have read the zeta 3 (again no longer made) had a more powerful motor and quieter gear train.


No licence, tax or insurance needed (in the UK)  + No fuel costs or parking fees or queuing in traffic!

This project cost me 30 ($50). I now have completely free powered transport - it can be done.

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