Interesting links

http://www.electricbicycleworldtour.com/en/

http://www.ev-network.org

Battery pack received

On Tuesday July 28th we have received the battery pack (48V) and the charger.

It has taken 15 days, but it was actually shipped 3 days after the kit, so shippments from Shanghai to Spain take around 10-12 days.

The material seems to be in perfect condition. The battery voltage is 53 Volts, so we decided not to charge it before using it.
The only drawback is that the battery pack does not fit in the bag that was provided with the kit. I guess the bag is thought for the 10 or 15Ah battery pack, not for ours (20Ah).

The wheel was already mounted, so we have connected all the wires and needed components (brake levers, thumb throttle, regular controller) and the battery pack, and have switched it on for the first time.
It works perfectly! And how powerful the motor is! It's virtually impossible to stop the wheel, even with the whole weight of our body.
You should have seen the EV grin in our faces... (EV stands for Electric Vehicle).

But a lot of things are still pending: looking for a proper way to hold the 11kg battery, trying out the pedelec sensor, trying out the regenerative controller, ...

We are having fun!

Disassembling the gear bearings

Once we got the tool to unscrew the gears from the wheel (picture), we confirmed that the bearings were completely damaged.

We couldn't find a set of 5 gears (as the original one) to replace the damaged one. We've only found sets with 6, 7, 8 or even 9 gears, but they wouldn't fit because they are wider. So we have finally mounted 1 gear only.

It's quite strange to see a mountain bike with only one gear in the rear wheel, but this is what we have right now.

Next surprise: the gear we have mounted is wider than the chain. Did you know that bike gears are available in different widths? Neither did we. We are actually asking ourselves if we really got a bicycle gear... Anyways, the width of a gear is nothing that a miter radial saw cannot reduce...

After some hard work, finally the wheel fits in the bike (and the chain in the gear;)

Just waiting for the battery, now.

How a brushless motor works.

This is a good document that explains how a brushless motor works and how to design a sensorless driver.
Despite our driver is a conventional driver, with several extra wires, this document gives a good description of the motors used in electric bikes.
http://spsis.com.ar/electronica/back_emf_tesis.pdf

Material received

On Thursday July 23th, we have received the kit: rear wheel (26'') with electric motor and 5 gears, 2 controllers (regular and regenerative), thumb throttle, pedelec sensor, brake levers, and a bag to carry the battery and the controller).
It has taken 10 days. Not bad.
Everything seemed to be in perfect condition, but when we have started assembling the components, we have had two problems. One is a small issue, but the other one is a show-stopper:

• The rear wheel, when mounted, was not exactly centered. It was slightly shifted to the left (the gears are on the right hand side), so it was not possible to mount the rear brake (the left pad was always in contact with the wheel). We have been able to solve this problem (at least partially) by smooting out the hole that holds the wheel axis.
• The big problem is that there is something wrong with the gear bearings: the gears are stuck to the wheel. So, the only way to ride the bike is not to stop pedalling (not very nice in an electric bike, by the way). We need now an special tool to disassemble the gears... Damn!

Following the shippment

Today, I got the confirmation that the kit (without the battery pack) has been shipped.
However, it seems I'll have to wait some more days to get the battery pack. This is their explanation: "because this month we have a lot of battery order,so the battery need waite some days send to you".

Material already ordered

Finally, we have ordered the following material from an ebayer (daoji666):

• 1000W 48V Electric Bicycle kit with 26'' rear wheel (5 gears) and thumb throttle.
• Pedelec sensor.
• 48V Regenerative braking controller.
• 48V 20AH LiFePO4 battery.
• LiFePO4 48V battery charger.

About $800 including shippment (from China to Spain).

Can't wait...

Learning about batteries

We have taken the decision to get the 48V 1000W motor, so now, we need a 48V battery pack.
There are several options, between 10Ah and 20Ah, and two main technologies:

• LiMn2O4 (Lithium Ion Manganese Oxide): 3,7V cell. Recommended for up to 15Ah.
• LiFePO4 (Lithium Iron Phosphate): More expensive. Recommended for more than 15Ah. Flat discharge curve. 3,2V cell.

We have decided to take the big one (LiFePO4 48V 20Ah), so that if we add a second motor (front wheel), we don't need a second battery pack.

Twist throttle or thumb throttle?

This is another decision we have to take before ordering the kit.

My bicycle already has a twist gear shifter, so we'll need to choose the thumb throttle.

Wheel size

First step is to check the size of the bicycle wheels to know which kit to order.
It's not as simple as it sounds. I've measured the diameter of the wheel (including tire): 64cm = 25,2''.
Kits are available for: 10", 16", 18", 20", 24", 26", 700C, 28". Mmmmm, not maching...
I take again the wheel, and on the tire I can read: 26 x 2.00 (54 - 559).
Well, it looks like it is a 26'', but now, I want to understand the meaning of all the numbers.
Thanks to http://www.sheldonbrown.com/tire-sizing.html I've learnt that:

• 26: diameter code of the wheel (including tire), in inches. In the past, 26'' wheels were 26'', but nowadays, there are many variants of 26'' rims and tires, and you can even find 26'' wheels that are less than 25'' in reality. I understand now why my 26'' wheel is actually 25,2''...


• 2.00: width code of the tire, in inches.


• 54: width of inflated tire, in centimeters.


• 559: ISO Bead Seat Diameter (see picture), in centimeters.

So, we know now, that we have to order the 26'' option.

Looking for components

We will start with a powerfull electric bike conversion kit for the rear wheel.
There are lots of options in Internet and ebay:

• The 48V 1000W model in Sanny's camp Ebay Store looks great.
• daoji666 in ebay seems to be a bit cheaper.
• Another option is goldenmotor.

Defining the project

Roberto and I have decided to convert a bicycle to electric.
We will start with my bicycle (Decathlon Rockrider).
The main goal is to have fun while we learn about electric motors, controllers, batteries, ...
The project may finish with the development of a two-wheel-drive electric bicycle.