Extrema EV project
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
This EMB purpose was clearly breaking records and it did:
records détails coming soon
You can see a Web copy about the article
You now why so time to find HOW ?
I bought a running 1994 RS for 900 euros, not brand new but a
Range targeted ?
I have a 30 km commute, it is my range goal with a safety margin to be
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
The naked bike:
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
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.
Simple batteries test with my "last"(story below) two
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:
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
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
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
MOTOR CONTROLLER NEWS
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 ?