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Increasing speed on Electric bicycle

A successful 45km/h e-bike project.

I was always curious how much speed and
power I can get out from my old Electric bicycle (Volto TDF 300W) and not to blow
something up.
One day a friend of mine, George, came around
with a story about how he added a 12V battery serial with the 36V lithium to
his foldable also Volto and it increase speed and power noticeably. The first
question was how far did he go on it and what about the controller? Did it handle
the 48V ok? He said he got from Ranui to Auckland city which is his route to
work and back. That’s 44km with not overheating, pretty good news! So it seems
the controller has enough reserves for extra load. It supposed to be 60V rated
and with heat protection and cost new $50.

How much power and speed we can get without doing expensive alterations.

Use only NZ or internet available parts.


The motor – Direct drive, less gear, less brush .It is simple and bullet
proof. Such a motor is very difficult to kill!


We discovered some fantastic hidden potential of the motor.

The coil- very easy to swap using a faster one from 20″ bike. It is inexpensive only $60



The trick No1

Use the 300W coil from 20″ bike and put it to 26″.
To swap it is quite easy job and increases the speed up to about 36km/h but losing a bit of torque. When I had done just this it was not really impressive because the bike had a lack of power it was equal to about 250W output so not really impressive if you have hills around.

The trick  No2

48V battery…. That was exactly what I need to do to get my power back.

After George tested the 12V lead acid battery in serial connection he found the capacity was not enough and the lead acid battery was getting hot and it blew up finally.  After some calculations we stated it could be used as an inexpensive occasional power booster (for short time only) otherwise the 12V battery capacity would have to be much bigger to handle the discharging current without heating up.

The battery solution

I bought 48V 9Ah lithium battery with a charger and a cable because there is a different plug for output connector because it is manufactured for different models of electric bikes.

 It is going fantastically 45km/h



New Zealand has specific regulations on using electric bicycles. The maximum legal motor power is 300W otherwise it has to be registered as a scooter. Also any information here could lead to bicycle damage, loss of warranty or personal injury/accident.

Enter discussion in forum.