I have been playing around with electric bikes for about 8 years now. I don't know what it is but I seem to have a habit of motorizing everything that comes into my possession. I found bikes to be a fun candidate.
E bike one was actually a snap decision eBay purchase when I was living in Melbourne. Most times I like to build things myself but this e bike was sold for under $100 less than I could gather materials for. I purchased the used e bike from a guy in Gelong who had imported it himself. He had way to many toys so some had to go.
The e bike was a Ezip made by Currie Technologies (a few years later they were actually sold in Kmart for about 6 months) Cheep Chinese Steel frame MTB with nasty rubbish components. Although the frame was over engineered. Over sized thick walled tubing and dam heavy. especially with 24v 12ah of Agm lead, A 25A Dc speed controller and a small Dc motor.The motor was a little MY1018 that has a reduction gearbox built into the motor case. It mounted just above the the rear axle on a a 5mm thick steel plate and drove the left side of the rear Hub through a sprocket and chain.The hub basically had a 7speed freewheel on the right and a single speed freewheel on the left. Enameling the bike to be peddled like normal without driving the motor. A hall-effect twist grip was used for the throttle .
This bike was fun (relative to what I had ridden at the time) Top speed about 25kmh with Lots of torque. It soon got boring though at 25kmh. I started doing research and found the same motor was actually sold in a 36v kit . It didn't take me long to open the speed controller cover and discover the caps were good for 50v. I started of purchasing another 12ah agm and trying the bike at 36v
. It now had a top speed of around 35kmh and with 36v x 25A controller I had around 1000w hot off the charger. This felt good for a while but the need for speed had taken over and I wanted more. So another 12ah agm was purchased . I now had 48v and 1250w hot off the charger. This was good for about 40-45kmh and it felt real good
.With that little My1810 screaming its guts out. The fun didn't last long as I had overlooked the fact that hot off the charger the battery's now exceeded the speed controllers 50v caps and the controller eventually let out the magic smoke.
In a moment of madness I actually hard wired a large switch to the handle bars to bypass the speed controller.This didn't last long as the contractors in the switch welded them self on. I had a runaway bike at 45kmh
good thing I wasn't hurt and a lesson learned.
It was Time for a rethink and a new controller. I found the weight of the 48v of lead was an issue with balance to. So to ebay I went and purchased a new 48v 35A DC speed controller and 48v battery charger. I purchased a little one wheeled clip on boby trailer for the bike and towed the battery's behind the bike in that. I now had 50v x 35A - 1750w hot of the charger and a ton of torque. As the rides become longer and the hills I was powering up at 35kmh steeper. The single stock My1810 motor was getting real hot - toasty hot! I had to do something. My solution was to purchase another My1810 motor and extend the mounting plate to hold both motors. Extending the chain over both sprockets and wiring the motors in parallel. I was able to 1/2 the load on each motor. This dual motor setup could handle all the abuse could throw at it. It was a very reliable bike for a long time.
One thing I didn't like about the bike was the Noise. The little My1810's had metal gears and when over vol ted they were making a real racket. I played around with different lubrication methods but nothing really helped. It was time for something different in the motor department.
I started researching AC hub motors and was impressed by the efficacy of AC. I purchased the largest most powerful and (dam heavy) AC in wheel hub motor I could get my hands on at the time.It was a crystalite 5304 Direct drive in wheel hub motor. I also purchased a powerful AC speed controller rated at 72v 50A 12 x 4110 fets and 100v caps
This motor weighed just under 20kg and a I had to lace up a seriously strong rim and spokes to keep it all together.I fabricated large SS torque arms to stop it tearing its way out of my bikes rear dropouts.This motor was smooth, quiet and a torque monster
(how ebikes should be). I added another two 12ah agm battery's to the boby trailer and I now had 3.6kw of power and 70kmh !! top speed hot of the charger
This thing actually had to be driven with a little respect as it was getting dangerous. All that weight of motor and agm bricks and still the stock Izip china brand rim brakes to stop the thing. Rolling the throttle on to hard could get the you in trouble to. Great for rolling on the throttle and passing guys riding road bikes in full Lycra outfits
The look on there faces as i waved pretending to peddle.that $6,000 carbon fiber bike wasn't much good to them now
This bike was ridden like this for about a year before some of the AGM's started to give up under the load.It was time to rethink the battery's. Around this time lifepo4 lithium battery's were just hitting the market. I few guys were taking chances with pouch style packs from ebay. Quality was hit and miss. C rating was 1 - 2c at best and BMS systems were very unreliable getting the nick name of (b
ystems). I got lucky and found a direct contact in china for cylindrical style 10ah cells from a company called headway. Rated at around 5c continuous and packaged with a beefy and relatively reliable BMS system and 5A charger. I purchased two 36v 20AH packs. This gave me the option of running 36v or 72v.
I took the opportunity to upgrade the Bike frame with very high quality but secondhand triple clamp down hill suspension fork and front disk brake. New front wheel, rear brakes and quality tiers front and back. The little bobby trailer was becoming a pain to tow. It made it difficult to turn around in tight spaces, Drew attention to my over powered e bike and a host of other issues.
I decided to mount just one 36v-20ah lithium pack into the frame of the bike. This got the weight in the center of the frame between my legs. I was finding that lithium battery's didn't suffer from voltage sag and held around 40v for most of there discharge capacity. This was good for 40kmh. A happy medium between speed, safety and battery size. This configuration was kept for a few years and thousands of KM. I had around 60km range from the 750 whr pack with some very light peddle assist. Although I usually most rides were around the 20km mark with little to no peddling. I also purchased a little e bike cycle computer called a cycle analyst. Its basically a digital LCD back lit display you mount to your handle bars. It has a wire that runs down to your battery's and a small shunt. Another wire to the front wheel like a traditional bike speedometer. It can show pack voltage, AH in-out, Whr- KM, Max min Amps,. Great for checking up on how many Ah you have consumed from your pack. You can also program it to over ride your throttle signal and limit speed, Max Amp's and a host of other features.
This bike was nice I could climb any hill peddling or not. I was pushing around 2000w max into the hub 10 x the legal limit in AU . I did program the cycle analyst to 200w so I had the option to switch to legal mode or 200w mode. I found keeping a low profile and stealthy look to the bike. Along with not riding it like a idiot I drew little to no attention. I could still use the boby trailer now just to tow cargo around when need be. My daughter rode with me on this bike in a child seat form 1yo until around 4yo. It was a very practical ebike and had come a long way over the years.
Next up is ebike Two the ultimate ebike project.....
Offgrid 2008, Selectronic PS1 6kw/48v inverter, x 2 Midnite solar classic 150 MPPT, 3960w NE PV 24 x 165w BP panels, 4200w NW PV 21 x 200w DAQO PV, 16x400ah lithium.