Scooters for Sale/Electric VTronic and Ebretta scooters
Electric VTronic and Ebretta scooters
We decided the initial prototype was to be based on the Indonesian produced Vespa Excel model which has a striking similarity to the Italian Mk1 T5 and the VTronic was born. We chose this chassis for a number of reasons, including a sportier, modern look and the large frame. A number of companies and suppliers were approached over the next couple of months to source the smallest but most powerful battery cells we could find which we could fit into the Vespa design without losing the classic look by altering the shape with extensive modifications.
Looking for all the components to build an electric scooter is a maze of information. There are details and technical information that is not fully explained and so more research had to be done on just what was being used. Do we go with a bushed motor, a brushless motor, or an induction motor? Do we go with a direct drive, a transmission drive, or a hub motor? So we decided to maximize space and minimize power loss, the brushless hub drive is our best option. Now came volts and watts; the focus of the drive is to have enough speed and power for urban travel. But we wanted the whole system to be robust, but not completely drain the batteries in five minutes. The 48v motor gives you strength without being too strong; the majority of electric vehicles are 48v.
We had the choice of three types of batteries: lead-acid, silicone , and lithium. Lead-acid and silicone are quite tempting do to the low price, but the drawbacks are numerous. Lead-acid and silicone are large, heavy, and lose charge at a faster rate. These batteries also have a habit of dropping off power gradually as the batteries drain. So if your batteries are 20% full, you may only get 80% performance from your scooter. The last thing a person needs is a scooter that does not perform at its peak due to low battery. The lithium battery is expensive, but it holds more electricity in less space. When I say “lithium”, we actually mean lithium iron phosphate (LiFePo4). The LiFePo4 battery is stable, strong and the standard for most advanced electric vehicles. The LiFePo4 battery has a sharp decline at a much lower capacity, so you will get more power for a longer period, but the drop-off is sharp. After a long period of research, the first batteries were individual cells that were 4.2v each with 40Ah. That means we have to stack 16 together to power a 48v device.
The system still needs a controller, a throttle, and a Protective Circuit Modules (PMC) . A controller is the system that pushes the power from the battery to the motor. It is a computerized system that switches the coils in the motor on and off to spin the motor and control the speed. But with this system there is a computer link that allows you to adjust top speed, torque, and acceleration. So you can tweak your bike with a few clicks of the mouse. The throttle is needed for the system to go, any vehicle needs a throttle, otherwise it is go at full speed or stop, something that is acceptable in a toy, but not in a motor vehicle. We had the choice of a foot pedal, thumb push (like what is used in a snow mobile), or a twist throttle. The choice was obvious, a twist throttle to replicate the same control and feel of a gas powered scooter. And lastly is the PMC, which we will describe later in the article.
By putting all these components together we decided to use top of the range components to fit with the quality of the chassis. The V-Tronic motor is a brushless 13” hub motor that is 48v 5000 watts. The motor will reach a top speed of over 60 km/h and has the torque of 180 Nm. The rear hub motor is built to carry a person in an urban environment. It has enough torque to accelerate uphill and carry a larger person.
The mk1 version has a total of 16 cells and the set up includes a top of the range (computer link up) controller unit and a Protective Circuit Modules (PMC). The PMC serves a number of purposes including monitoring battery levels and avoid over charging. The purpose of the PMC is to ensure that the batteries can be charged over 1500 times without losing effectiveness. The batteries are LiFePo4 (Lithium Iron phosphate) batteries that hold 40Ah, these batteries are lighter and hold more charge than lead acid or silicone batteries and are safer than the lithium ion battery. The charge time is 2 to 3 hours from empty to fully charged.
The run time of the V-Tronic varies due to driving conditions but during road testing we’ve been easily exceeding 40km’s before re-charging. Battery level is monitored by a toolbox mounted voltmeter, this simple and basic model has since been upgraded to a computerized model.
We carried out extensive fabrication work on the Vespa Excel chassis to incorporate the battery system and also the new swing arm assembly and double-sided shock absorbers to fit the brushless motor hub. The area that held the gas tank was used to hold the central battery packs of 8 cells and both side panel spaces hold the other 8 cells (4 cells on each side). The controller unit and PMC were built into the false bottom of the seat and the charger unit was fabricated into the rear arch with easy access via a hinged rear light unit. Finally a rear disc brake kit was fitted on the rear motor. The handlebar controls were modified to reflect a more modern system since there is no clutch. Now both handlebar controls are used for the braking and the foot brake was discarded.
Now the extensive fabrication work on the Vespa Excel chassis was only half the challenge. We assumed that the components that we bought would have quite simple wiring of input and output. We fit all the parts into the system and hoped that the wiring would be a simple matter. What seemed simple turned quite complicated in a very short period of time. The instructions were very vague and many times not even correct! , but the online assistance was available and good, but at the same time, not helpful since neither of us had a good background in electrical systems. The system was built so that “the batteries” would not overcharge or any possible shorts could happen along with several fuses and redundant safety systems. The strength comes with installation of all the correct wiring and using higher gauge wires to make sure enough power was reaching all the systems.
Approximately a year later we started work on the prototype Lambretta style conversion called the Ebretta. This was built from scratch and although we used traditional Lambretta styling the chassis is custom made. The original prototype was improved upon during construction and the Mk2 version has a lowered centre tube to allow maximum area for the battery compartments. We also decided to widen the centre arch and also extend it slightly by 15 centimetres. The external modifications are not noticeable and the classic look is still retained. The motor unit, electrical components, and swing arm assembly is identical to the VTronic assembly. This means that the same power and performance of the V-Tronic is also inside the luxurious and class chassis of the Ebretta.
The Mk2 VTronic improvements are numerous. The battery system now includes an integrated PMC unlike the prototype which involved extensive electrical engineering. The cells are both smaller and more powerful. The old style voltmeter has been replaced with a SevCon digital display unit and the settings can now be changed directly through the controller rather than by PC link up. The addition of a DC converter also means standard lighting can be used although we’ve upgraded all new systems to LED lighting units. The same large lithium batteries that power the motor can power the lighting and signals. We are looking into adding accessories that allow you to charge your phone, tablet, or laptop while you drive.
We are also currently working on a Vespa small frame model with a brushless 10” motor and also a complete “conversion kit” for DIY fitment.
We will have the first production models available August 2012.
The Word Magazine June 2012 - Vietnam's First Electric Vespa and Lambretta (Read the article PDF 1 PDF 2)