Extrema EV project

Aprilia 125 RS Extrema conversion to electric propulsion  

Rapidly write and not ordered, will make better later...


I choose to write this project in english because major part of my EV knowledge is due to American Ev Album list,  my turn to share.

I'm a motorbike rider since youngest, in fact it was my first driving license. The idea of an EMB (electric motorbike) came from an article in a technical ICE motorcycle magazine. It was about the JC2 electric motorbike. What is JC for ? is for "jamais contente" which translate to "never satisfied", the 2 is for...second edition, why ?
because the first French car to pass 100km/h top speed was electric and named "la jamais contente".
This EMB purpose was clearly breaking records and it did:

records détails coming soon

You can see a Web copy about the article here


You now why so time to find HOW ?

I bought a running 1994 RS for 900 euros, not brand new but a good deal.



Range targeted ?
I have a 30 km commute, it is my range goal with a safety margin to be defined.

Performances ?
Eh, it is a RACE motorbike !!!

The electric motor will be a pancake style permanent magnet DC brushed motor capable of about 10kW continously and 24kW peak power, it should do the trick.
There is 3 choices here:

Original well known Lynch motor (Lemco), price is high, near 1000 euros, 60V continuous power is 10,5kW giving 3900 rpm / minute.

Deutch Perm-motor, price is about 600 euros, similar to LEMCO

Brigg and Stratton Etek, price is about 450 euros, similar to LEMCO

I had a deal on first choice: a new first generation Lynch motor at 475 euros, weight is 10.5kg.



The naked bike:


More soon


To maximize batterie cargo capacity, motor will be here


I started with a belt drive design but had to quickly forget this idea , chain transmission  is cheaper and easier !
Original ratio is 16 X 39 with 520 chain.
My max power will be 25Kw so maybe a 420 reenforced would be a good compromise to minimise losses, still not enough data to decide.
I'm targeting between 4,5 to 6,5 gear ratio.

First design was Gates, Polychain GT2 with 22/90 teeth drive.


The batterie choice is still in progress, all are "available" to me but still price, power, capacity, life time issues.

High power deep cycle AGM (Hawker, Chinese, Optima, maybe Exide Orbital XCD though will not fit)

aircraft starter type Ni-cad (Saft)

EV sized Ni-MH (Chinese)

Nickel Zinc (French company not ready to produce and Evercell)

Li-ion (Thundersky and other china production)

This is Thundersky Li-ion 100Ah and 90Ah cells mockup and at right 4 modules of four 100Ah cells for a total voltage near 60V, it seems that opposite to 16 X 100Ah cells, 16 X 90Ah will fit. 


and the high tech cuting tool with very high tech light dimmer control ;^)




I have few spare SAFT STM5-100MRE and MR  for my electric car and scooters, there are exactely same but a plastic sheet added on MRE to stock cooling water in this tiny space:

STM5-100MR (air cooled) 3 Peugeot Scootelec modules STM5-100MRE (green coolant)

Maybe i will try fitting some of them (36V) for test but 100Ah is a big/heavy batterie, a 60V100Ah pack  will be about 130 kg and impossible to fit in the poor bike, need a 1100ZZR here :^)

I had a great deal on like new aircraft engine starting Saft batteries:

Some 1.2V 50Ah/1C NiCad cell, for 60V50Ah (3kwh pack) i need 50 cells in serie.

Part of Saft personal collection :^) 24V50Ah pack with both connectors male female

Simple batteries test with my "last"(story below) two 12V150W heaters:

Last charge was few months ago (i don't have date), rest voltage is 25.8V which translate to 1.29V/cell,  somewhere between 20 to 80% SOC, impossible to have precise State Of Charge out of  nicad voltage. My charger is not finished but i'm curious about voltage sag so here we go:

The bench
25.8V at rest
1.6 ohms loaded (heaters in serie)
Vsag = 0.9V/20 cells
0.4 ohms loaded (heaters paralleled)
Vsag = 1.8V/20 cells

I know it's not a very accurate way to do that but i don't have enough load power to test farther so i extrapolate which seems to be a linear equation:

95.8A load should bring down pack voltage near 20.4V, about 1V/cell, end of discharge here !

Voltage sag turn to be more important i was thinking, though still usable, the calculated EMB consumption on flat road is far under 1C 50Ah, but power should not be what i was planning, time to find more heaters...and achieve big Nicad charger to work on real numbers !



How to multi kill a lots of tiny heaters quickely:

I initially started with "a bunch" paralleled absorption fridge system heaters connected through a 500A 50mV shunt BUT whitout radiator... i was thinking about few seconds use with quick data readings... what a mistake !

The 200mV panel meter shawn briefly "1" (over range) this is more than 2000A instantaneous power BUT the 8 heaters immediately self destructed.
Unfortunately i was looking at AMPS when circuit opened not at voltage :^( because another mistake: using a digital panel meter over the shunt and near the batterie instead of my usual 2 DVM side by side "bench".

Accuracy is doubtful though still a good indication, Saft guarantied them for 20C, i will try a fluke test latter.

Time and preparation is important, quick test was not a good idea...



i found a deal at Ebay but it finally cost me more thanks to french customs :^( still a great deal though...
It is a like new Alltrax 72V 450A with serial interface for PC adjustment and monitoring, i translated Alltrax software to french et voilà ! will post few screens next time.


that's all folks...for the moment


Some questions ?