My Hobby Page

Electric Bike

1. The bits and pieces...
2. Assembly of Components

Some time in Fall last year (2008) when the weather was so lovely rainy and foggy here in Geneva, we (Robert Becker and I) had the idea that it would be nice if we would spend the next summer riding around in Geneva with an "electrified" beachcruiser (because those bikes look cool and are incredibly comfortable) that can make a top speed of ~50-60 km/h (because we want to actually get somewhere with it... to work and back, to downtown and back). So we set out and did it. What follows now is a summary of our experience, not as detailed as a do-it-yourself guide but I tried to point out the major decisions and the procedures we used. It took us about 6 months (from around Jan. 1st until beginning of July) from the order of the beachcruiser until putting the last part on it to make it ready for the road. The most part of that time we spent with finding and ordering the right parts and building the battery box. 
  

The bits and pieces...

In choosing the right parts for the bike, we were led by two main factors: the weight of battery and motor and the top speed. Finding the right parts took us essentially the first half of our time(!). That's why I am a bit more detailed in listing the places where we obtained the parts. Since we are both skinflints, ebay.de was our best friend there; most parts were found and ordered there.


1) Brakes

Most of the brake force is on the front wheel (I heard ~80% somewhere). => we need good (at least hydraulic) brakes on the front wheel. On the rear it is not so important (see below, disc brakes would be difficult to install on the kind of bikes we are looking for; as they don't usually come with disc brakes, the frame in the rear is quite narrow and a disc doesn't usually fit in).
Front disc diameter: at least 180mm (make it large to maximize breaking power and heat dissipation)
From our experience, mechanical MTB disc brakes do not have enough clamping force at speeds of 50 km/h on an electric bike.

Since the weight of the brakes doesn't play a role (the batteries/motor are much heavier, see below), we could even use scooter brakes. One needs to make sure, however, to buy one-sided brakes as the double sided brakes are too wide to fit between fork and wheel. Since scooter brakes of course have to be custom-mounted on the bike frame, we decided for Shimano Deore hydraulic brakes on a 180 cm disc for now and collect some experience.

   

The brakes were overall straightforward to install, apart from making the disc fit right in between the brake pads. The brake was so close to the fork that the fork obstructed the disc. So, we not only inserted washers under the screws that fix the disc, but also had to under the screws that fixed the brake on the fork. It took a while to figure out the right number of washers on either side, disc and brake. Here a photo of the matched disc/brake system and the whole wheel:

   



2) Front fork with suspension

Since the bike will be very heavy we decided to use good suspension to make sure the frame does not brake when we ride over uneven roads. In terms of suspension space, 100mm is good enough. The fork has be made of steel to be able to weld something on it... just in case... a double-crown fork looks really good, so we went with this one.
Note that the fork has to fit to the wheel of course... so, it needs to be for 26" wheels. Also, the one we bought has a 20mm axis, as most heavy suspension forks, which affects the kind of wheel that we have to buy.

 


3) Front wheel

The wheel size of the bike we bought (see below) is 60-559 (26 x 2.35). We decided to buy a rim that can take this kind of wheel to withstand the heavy weight. Second, it has to be able to withstand the strong brake force =>
1) need high number of spokes: 36 or even 40 (32 is standard)
2) need stable rims => use e.g. double eyelets (from experience singel eyelets can rip open!)
3) need hub with 20mm axle diameter due to fork specs (see above)
Downhill rims are usually built to withstand strong forces.
It also has to fit the brakes, so it needed 6 holes to mount disc brakes.
After a long search, we finally decided for: "26" Dirt Sun Single Gold Track VR 20mm Steckachse". Not ideal but still OK.

 


4) Crankset

For the high speeds we want to ride we need to get the biggest gearwheel we could find (53 teeth) so that we can still benefit from pedaling; at low speeds we presumably want to use (mostly) battery power. In fact, we bought a completely new crankset to make the installation easier. Criteria for the choice of purchase was that the axle has the same number of edges (4 sides) as the crankset since we don't want to change the axle on the bike. We decided for a "SUN RACE Kettenradgarnitur 2-fach Rennrad 53/39 Zähne" (ebay.de) that was straightforward to install. We used a hammer to take off the old fork. Here some photos (on the left the package, on the right the mounted parts):

   

5) Batteries

The voltage of the batteries, along with the motor, really determine the power of the bike, for more details see below. Top speeds above ~40km/h can basically be achieved with a voltage around ~40V and above. We use two packs of 24V NiMH batteries (which consists of 20 1.2V type 2D cells with ~20Ah capacity in series) by nexcell (this company was mentioned on the ebikes.ca webpages). There are various reasons to use this type... they have a good Wh/$ ratio, the number of recharge cycles lie in the 1000s ... and finally we got them cheaper than the others (Li-Ion, etc). We decided for 48V simply because US safety norms consider higher voltages as hazardous. With ~2Ah per mile it looks like 20Ah is sufficient for a few short trips (see First Experiences below). The charge basically determines the length of the cells, hence the large size.

Here some more links:
http://www.houseofbatteries.com/articletoc.php
http://en.wikipedia.org/wiki/Rechargeable_battery#Table_of_rechargeable_battery_technologies
http://en.wikipedia.org/wiki/Electric_vehicle_battery
http://kokamamerica.com/

We used two of those batteries (left), along with two chargers (right):

      

Weight of one battery: 7.6kg
Size: 6cm x 18cm x 25cm

6) Motor, Throttle and Controller

At the time of this writing there are various choices on the market, like ecospeed, crystalyte, ... see here for a list and description. A nice performance comparison between a few systems is shown here. We used the ebikes.ca simulator to estimate the performance of the hub motor, in particular to find the right combination of motor and battery voltage for the top speed we want to reach. Then we used the more realistic bike simulator at kreuzotter.de (if this is down, an alternative is at bikecalculator.com) to estimate the actual top speed for the power we get from the motor. The values we get are 50 km/h (55 km/h) for 1.5 kW (1.8kW). We finally decided for the CLyte 5303 brushless hub motor and a 35A controller (Crystalyte 24-72V 35A Start Immediate Brushless Controller, Analog, IRFB4310 Mosfets), both from ebikes.ca, along with a 48V battery which gives ~1.7kW. With additional pedaling we can probably reach the ~55km/h we want. This is actually the same motor used at Electric Rider for the Phoenix bikes, so that looks promising :-) . Here the motor (rear wheel):

 

There a few (weak) arguments of rear vs. front wheel but it doesn't really matter. I use a rear motor because I thought it looks better.

... and here the controller:

   

The advantage of ordering from ebikes.ca is that all connectors of the controller fit to the connectors of the motor and the throttle. To install the throttle, I simply removed the gearshift grip for the chain ring on the left side of the bar, because we won't use that anyway, took off the rubber grip of the right handlebar and cut it a little shorter. The gearshift grip on the right side (for the sprockets) I then put on the left side of the bar; the throttle I then stripped on the right bar and then the shortened rubber grip. Here some photos of the handle bar, the throttle and its cabling and connector after the installation:

 


7) The bike

We decided for a steel frame for two reasons:

• the battery box and motor are very heavy
• Robert made bad experience with aluminum frames using a test-mountain bike: When steering into curves, the steering part of the aluminum bike shaked/vibrated a lot and generally feels as if it would break any moment... so this felt a bit unstable which is scary especially at the higher speeds (>50 km/h) we want to achieve...

Apart from being beautiful bikes, beachcruiser bikes also have the advantage that they are built a bit sturdier/heavier. Also, on some bikes (e.g. the one we ordered) the upper frame pipe is not round but slightly stretched in vertical direction such that it's even more resistive to torsion. This we felt is important as the light steering part is around the front wheel and quite light, but most of the weight is around the rear wheel from battery and motor.

That being said, it took a loooong time until we found the right bike. It's worth to mention though that on my trip to Chicago I got lots of helpful advice by "transit bycicles" who pointed me to companies that sell custom made steel bikes and bike parts, like "ingliscycles.com" who produce beautiful steel cruisers with disc brakes, or "waltworks.com". However, buying custom built bikes is very expensive, so we tried another solution. We finally ran across the "Beachcruiser 26" Lowrider Chopper Shimano 7Gang Retro" by "Guenter's Zweiradshop / radversender.de" on (guess where?) ebay. Here a few pictures (Robert's is in black, mine is with the label):

     

Aside from being on the cheaper side, there were various reasons for buying those:

• We needed 26" or 28" wheels since this is the size of the wheel that has the motor.
• With a dynamo for the front and rear light one can save buying separate batteries for those and have the lights instead (indirectly) run off the battery power of the motor.
• While beachcruisers aren't usually shipped with disc brakes, we needed at least attachments for mounting those on the front fork
• Curved frame. Just 'cause it looks cool.
• 7 gears on the rear wheel - the same number of gears the motor has
• Wide tires, especially in the back as there is no suspension
• The ability to easily change the front gearwheel

8) Relay

A relay is needed as an on/off switch. The important feature of the relay is that it must be able to withstand currents of >30A, so it needs good contacts. Just because it is impressive to use, fun and unusual :-) we decided, instead of a key+relay system, to use a magnet that switches the relay on. As a basis we use an electromagnetic relay that is big enough to make modifications: "BACHOFEN -CO BCKR 11S".
I took the coil for the secondary circuit out, soldered the plus and minus side cables on the relais, and glued the relay box with double-sided tape on the inside of the aluminum box. Since a magnet on the outside of the box pulls the contacts outwards, (not inwards like the coil used to), I had to reverse the on/off position of the flexible piece, i.e. connect the "minus" cables to what used to be "plus" and vice versa, and wrapped a rubber band around the flexible piece such that it pulls the flexible piece into the relais box ("off") on the one hand and on the other hand gives way if a magnet pulls the flexible part out ("on"). To increase the metallic surface (to benefit more from the force from the magnet) I screwed a washer on the flexible part and sawed open a part of the relay's plastic shell to increase flexibility... it was definitely a piece of work. On the left a photo of the original part, middle and right after the modifications:

           


9) Circuit breaker/Fuse

To avoid current spikes that can harm the batteries, we were thinking about using a circuit braker that can be re-activated with a simple button-click, just in case those overcurrents happens more often than we think. We had a cheap thermal Carling CLB breaker rated 25A lying around, however a look at the specs showed that it takes ~10s of seconds until it triggers if the current is 50% over threshold, which is far too long for us. So, we finally decided for a Carling fuse holder, along with this 40A glass fuse:




10) Recharging Equipment

The batteries are recharged with these chargers from nexcell that came with the batteries. That was convenient because the chargers and the batteries were shipped with the right connections so there was nothing that we had to modify. We bought the 24V charger listed on that webpage One charger charges one battery (24V), so we need two chargers that charge in parallel (which is quicker anyway). Because of that, I soldered both cables, that go to the power outlet, together so that I only need a single power socket for both.
To access the battery connectors in the aluminum box I made a little door on the aluminum box that can be opened to pull out the battery connectors and connect them to the charger. Since the batteries are kept in a tight aluminum box, they heat up very quickly. And since the recharger switches off the recharging current if the batteries get hotter than a certain temperature (~55 degrees), a cooling mechanism has to be installed. For this I used a computer fan from my old Dell Optiplex in series with a 1kOhm resistor (see below). On the left the charger (unmodified), on the right the complete, modified charging equipment: (Dimensions 190*95*50 mm)



Experience: Total recharging time is, as expected, ~4.5 hours (~20 Ah/4A).


11) Bicycle computer "Drainbrain"

To keep track and measure of various quantities (voltage, current, used Ah, power, etc.) we had bought a standalone drainbrain (the older model of the standalone cycle analyst), version 1.0.1. More info on the ebikes.ca webpage. This is very straightforward to install:

  YYY more images


12) Lighting

First off, the dynamo that was shipped with the bike was apparently kaputt. And since the bike goes higher speed we anyway need a good, bright front light that (a) shines a long distance and (b) it should draw only little current. LEDs seemed to be a good option. Basically, after some browsing of this webpage, we finally decided for the SOLAROX High Power G4 LED bulb white. Since these LEDs run on 12V DC we put two of them in series and plug them into the battery cables one (24V) battery. Each LED is 3cm in diameter, so two of those fit next to each other into the 7cm diameter front light case that was shipped with the bike. To protect the LEDs from overcurrent we put a resistance of a few Ohm with 1/2 W power rating in series with them.
Most of the work here was to shell out and "cannibalize" the original bike lamp, i.e. to remove the light bulb and the "mirrors" that focus the light. I actually used a mill machine to remove the mirrors and to smoothen out the transparent plastik front plate(!). I then used hot glue to fix the LEDs on the front plate next too each other. I also had to use hot glue on the back side of the LEDs because the connector-pins easily came off the LED board otherwise...
It took me actually a few hours of biking around to find a little round on/off button switch. Farnell has nice ones but they ask for a ~15 Euro shipping fee(!). So, after looking for them at car electronics dealers (too expensive) and other bricolage places, I finally got them at Media Markt for 5 CHF. Hurray!


   


For the rear light I bought a simple battery-powered bike light at Jumbo.

Assembly of Components

Basically there are two time-consuming parts: A box that holds the battery and any other "power-equipment" along with connecting and building the parts that go in there, and the assembly of the mount that holds the box on the frame.

1) Front fork

This is the old fork:




The "star bolt" (size 1 1/8"), that simply holds the cap on the steering pipe, was not shipped with the fork. Below a view from above:

   

I also mounted a star bolt to the bottom side to hold the headlight. It turned out that a bolt for a 1" pipe fitted well. It was straightforward to install the fork - one only has to be careful to remember the order and the way the washers and ball bearings for the headset, that fix the fork on the frame pipe, are placed onto the steering pipe, below and above the frame. Here the installed fork:



I took the stickers off later...


2) Battery box

The wheel is delivered "ready to install", the controller is shipped inside a box, so the batteries are really the only electronics part that we received "raw". Since they have to be protected from rain and packed in a sturdy way, we decided to put them into a metal box... somehow... The first question was: where to place the batteries on the bike?? Criteria were:

• Low center of mass for balance reasons (=> on top of the luggage holder is probably not ideal)
• Weight of the bike should be equally distributed (=> close to the axle of the rear wheel is probably not idea, if we want the motor to be on the rear wheel)

So, we decided to mount it in between the bike frame, "between the legs". This implies that: (a) the box has to be narrow enough to still allow for pedaling and (b) the batteries have to fit in. To satisfy (a) we required it to fit between the arms of the pedal, so the pedals have to be able to turn around. From simply holding the batteries by hand in the frame space it dawned on us that we have to shape the box to exactly fit inside the frame pipes, to use maximum space in order for the batteries to fit in(!). And that we did...

Other battery box contents/requirements:

• on/off switch: relay
• an overcurrent protection: fuse
• can attach two battery chargers, one for each battery => this means that (a) we need to mount connectors on the box for the charger cables or (b) need to be able to open the box somehow to pull out the charger cables. Sincethe cable connectors are non-standard and have to be protected from rain somehow, we decided to go for option (b).
• no messy cabling to outside; use proper connectors for a clean look and user-friendlyness
• some way of attaching it quickly and robustly to the bike frame

Note that the box has no insulating material around the batteries that protects the batteries from heat/cold; during the first test rides it turned out that the aluminum reflects sun enough, even if the bikes stands in the plain sun, such that the box stays cool. For the "deep temperature test" we have to wait till winter I guess, but it is probably better to keep it inside that time anyway.

So here goes... as a reminder, this is how the bike looked like before we started with a box, with the crankset and the fork mounted:

  

First, we took the steering off and put the bike on the ground as shown on the 4th photo in the series below; we lay a big piece of paper underneath and drew the shape of the inside frame pipe with a pencil. Note that the crankset has to be installed for this, since the box has to be adapted to the shape of the biggest gearwheel!
Then we took a piece of wood (as shown on the leftmost photo) that was thick enough to hammer the aluminum around its edge to make a rounded edge (see here) and cut the wood with a mill along the pencil line. (To make sure that the paper doesn't move we glued it on the wood using double sided tape. I should say that double sided tape turned out to be very useful for holding... anything really... temporarily). Since that was not precise enough we had to do some refinements on the sanding machine... well... if I say "we" I actually mean Robert in this case. Here some impressions:
 
        

Then he rounded the edge of the piece with a router:

 

The next step is to cut the aluminum plate. We bought a 1m x 3m aluminum plate, 1.5 mm thickness; that was on the one hand thick enough to hold a good weight, on the other hand thin enough to bend it with a hammer. The idea was to make two side plates and connect them to a middle piece (with rivets or screws). Below a few impressions of making the side pieces. We drew a line along the shape of the wooden form, in a distance of 5 cm to have enough room for bending around the edge, and then cut out the aluminum along this line with a saw. here you see Robert cutting out his piece... note the corners of the cut-out piece on the figure (3) below: they are cut out such that when we bend the aluminum piece, the edges close in the corner (see also further below).
 
   

Then we fixed the aluminum on the wooden form, and both of those on a table, with a screw clamp. Then we bent the 5cm overflow around the rounded edge of the wooden block using a hammer.

  
  
Here the ready-made piece, along with the tools used (on the right). Note again, that after bending the edges, the corners close up and there is no gap:
 
   

Here a photo of the sanding machine that gives us nice streaks across  the surface, i.e. a "grained" look:

 

We then make a "connecting piece" that we want to fit onto the "cover" above as shown here:



To do this we measure the circumference of the "cover" piece and the thickness of the batteries (~12 cm for both) and take this as the length and width of a square piece of aluminum that we cut out with the cutting machine below which makes very nice rectangular, clean cuts:



Then we have to bend the square piece wherever it matches with a corner of the cover piece using a sheet metal bender. Note that this has to be adjusted to the thinckness of the metal and the radius of the edge):

 

Then we arrive at the photo above. So far the center piece has not been that difficult, however it turned out that, when we put the cover pieces together, the box was about 2 cm wider than the batteries. Since we have to make the space between the legs as narrow as possible to be comfortable, we could make the box a bit narrower. For this we had to take off 2 cm from the long side of the center piece using a nibbling tool:



... which was a pain to use and caused many blisters... I then got tired of all that and effectively put the whole project on ice for a few weeks after I was through this part...! I eventually (luckily!) returned back to it and continued... next step: make holes on center piece and covers to connect them. For this we put the parts on an even surface and used a caliper to make holes at a constant distance (1 cm) from the rim of each:

 

We then made holes at a more-or-less even distance, 3-4 holes on each side. Then we used this tool to punch holes of size M4 at the marked spots:

   

One cover we fixed with screws and nuts (nuts that seat themselves into the hole when tightening the screw; "ecrou a sertir" in french), that we fixed as shown below with pliers:

   

... and the other cover we fixed with pop rivets (what kind? YYY) - well, we did this at the very end, but this is how it looks like:



It turned out the the rivets were easier to insert than the screws. So, if we took the box apart we used the rivet side (only happened a couple times anyway).

Now that one side of the box is closed we can think about the equipment inside the box:
We need a circuit breaker / fuse to prevent us from overcurrents, a watertight connector for the line to the controller and the "on/off" switch (= relay).
The photo on the left shows all parts of the "power line" soldered together: battery - circuit breaker (later substituted by a fuse) - relay - power connector to the controller. Especially the soldering of the relay took a long time. The photo in the middle shows how the breaker and the power conector are placed on the box. This is pretty much determined by the space left by the battery and by the (would-be) location of the bike frame once the box is put on the bike. For the hole of the power connector we used the nibbling tool again and for the hole of the breaker/fuse a drill with a big-diameter bit. The relay is simply glued on the inside wall with double-sided tape which holds surprisingly well on the aluminum. On the 3rd photo a zoom-in with everything installed (if you look closely you see a fan installed as well - this was actually installed after the first "putting things together" but the photo has been taken more recently), the last photo shows how the relay is attached:



Note that the metallic little box of the power connector was cut off later because there is a 6A-rated circuit inside that blew up at the first ride... (it was pretty messy inside with a mixture of circuitry and plastic and I had to cut it off with a combination of metal saw and screwdriver...).
Then we have to put some packaging foam padding around the batteries so that they don't bounce around and to distribute their weight:



Now that all essential electric parts are in, we could think about mounting the recharging equipment:
I wanted to screw to the inside of the box an old computer fan (NIDEC BETA V TA225DC) from my Dell Optiplex computer that runs on 12V DC, with a 1kOhm resistor in series. This combination consumes ~100 uA which is small compared to the 4A charging current.
So, first I determined where to mount the fan:



Then I made a hole that's big enough for both fan and to pull out the recharging cables, at a place where none of the other connectors were in the way, using the "evil blister making tool" again:



And the piece I cut out makes the "door"... essentially I bought a hinge and a locking bolt for wooden doors at Jumbo and took a drill to make a few holes in the box (doesn't need to be very precise). The screws used here were pretty small; M2 for the lock, M3 for the hinge, each with bolts on the other side. The black rubber to make it somewhat watertight was actually lying around in the workshop area - no idea where I could have gotten this from otherwise; it fit nicely around the edge of the "door". I glued it on the aluminum using super glue:



To make sure that the fan creates some circulation inside the box I glued two ~1 cm thick aluminum strips ("space holders") between the batteries using double sided tape:

 

Now we have to think about the powering of the fan that has to come from the charging cables between charger and battery. Since it is a 12VDC fan, I only connected it to one 24V battery. Since I wanted to make sure that the fan is disconnected when we stop charging, I connected the "minus" cable of the fan to the cable coming from the battery and the "plus" side of the fan to the "plus" cable on the charger-side connector. (That means, we are forced to disconnect those cables when the rechargers are taken away.)


  


Now we can put everything back in. And here is how the box is finally being closed up:



Now that the box is ready we can think about how to mount it on the bike frame:
It took us a long time to figure out how to do this. On the one hand it should be easy to attach/detach e.g. for battery recharging, on the other hand it should sit firmly. Also, we wanted to minimize any welding on the frame. It was more-or-less obvious that (a) we need 3 points to fix the box to prevent it from wiggling, and that (b) the bottom part of the box should "sit on something" and that its weight will make it sit firmly on that point. So, we first constructed a support piece on the outside of the box (see 1st and 2nd photo below this paragraph) with a hole in the center and drilled a male piece with a lathe that fits into the hole and that is to be welded on the frame (see 3rd and 4th photo). The male piece we decided to be a little cone so that, if the box is too far away from the frame, we'd only need to drill out the hole on the box a bit more. The support on the outside of the box are simple aluminum strips with a length that's equal to the width of the box and 3 cm width. We used a milling machine to mill a ~1 cm wide "track" on the strip on which we could lead the cone when we slide in the box:



After that was done, we inserted the box and thought about what we could use for the other two connections. We finally decided to weld a little "fork" each on the frame on which we would slide quick clamps. These are, on the box side, screwed into a support piece (again, we made aluminum strips as described in the previous picture), this time inside the aluminum box. Since the thread on the quick clamps does not go far enough in we made thick aluminum cylinders from a solid piece and drilled a hole through the center, as space holders.



 
This mechanism turns out to hold the box very tightly and it also makes it easy to take out the box.

Since the space for the box turns out to be so tight, the fuse is actually obstructing when we take out the box and we have to take it out every time we remove the box (this is something we have to fix some point). Also, we had to sand away a protruding part of the recharging "door"...
  
In terms of the look of the box, I left it as is and didn't bother painting it, mostly because the metal reflects the sunlight and prevents it from heating up in the sun too much.


4) Controller mounting

The controller is mounted on the back side of the rear frame pipe, simply because there was space and it doesn't obstruct the driver there. The metal box of the controller already has holes in it and it is not so heavy, so we simply made a thin strip of aluminum that we bent around the frame pipe with a piece of rubber underneath to prevent the frame pipe from getting scratches.

     

This photo shows the controller with its connections. The battery connection was modified and a computer power connector was soldered on to fit to the connector on the battery box:




5) First attempts to lower the friction on the rear wheel

The rear wheel is not of the best manufacturing quality, e.g. there is simply a hollow, cylindrical plastic piece, for some reason, between the moving wheel and the still rear fork. Since this rear wheel is a little wider than regular rear wheels, this piece pushes on the wheel and the fork and creates friction... Since the part inside the plastic piece (at inner radius) does not move, we manufactured a steel piece like in the figure on the left, that pushes on the inner, still part of the wheel and the still fork and prevents the plastic piece from touching the fork. See the right photo to see how it looks like when it's installed.

   

To make this steel piece we started out with a hollow steel pipe of suitable diameter and thickness that we found in the trash of the workshop, and sawed off a few centimeters, as well as the little gap (roughly, eye-measured). Then the piece was clamped in and tightened to a smaller radius until it fit (trial and error).



6) Spray-paint the rear wheel

Since the housing of the motor in the rear wheel was in grey, I thought it would be nice to spray-paint it in the color of the bike (black).





7) Putting it all together


... and here is the end product: :-)
   


The box weighs: 16 kg
The bike itself (without box) weighs: 30.5 kg

Experiences

Here I want to briefly summarize my experiences over the first weeks. Overall the bike ran very stably and without makor issues.

• Top speed achieved: 53 km/h (without pedaling). Pretty close to the estimated value! As for pedaling: that turned out to be impossible at that speed (need to pedal too fast), even with the 53-teeth crankset... that's simply because we use smaller wheels (26" instead of 28").
• The battery didn't deliver much charge first and recharging stopped early...; after ~2 recharges recharging happens more smoothly and is closer to the expected ~5 hours. 
  Range: roughly 40km. Of course, the discharge time depends a lot on what the driving style is. I can use one battery charge for ~ 2 days (2 x geneva and back (2 x 16km) + slow-up round (~10km) + to workshop and back (~8km) + 2 x to work and back (2 x 10km)) if used with no more than 1kW, but these numbers should be taken with a grain of salt...; If I always go full power, well, it takes me 1/2 hour * 50km/h (max. speed) = ~25km to empty the battery. When the battery is close to being discharged, power goes down rapidly (within a few ~10 seconds)! So, need a Ah-meter to keep track of charge and to be warned ahead of time.
• I mistakenly used a computer power connector that was rated 6A to connect battery and controller. It exploded with a lot of mess and bad smell at the first ride, so I took it out of the box removed the protection circuit. There were no more problems with this piece.
• I needed to tighten the spokes screws by a half turn because the weight pushed the rim towards the axis to much such that it actually made noise, more see below.
• I noticed that the wider rear wheel, that has the motor in it, is not completely centered. That means, that the mudguards andthe brake are a little off-center.So, I readjusted brake for the uncentered. Also, apparently I didn't tighten the bolts on the rear wheel axle properly and the rear wheel almost came off. I re-screwed the firmly and never had problems with it again.
• The drainbrain broke already after a few rides. In fact the shunt resistance got damaged, so I have to make my own... the guys at ebikes.ca were so nice and told me the circuit and what shunt to buy. However, it was hard to find a shunt that can stand a current of ~35A. Since we needed another drainbrain anyway, we ordered one and also a substitute shunt. 

Then my NiMH battery broke. Probably a short somewhere in the battery box. I ordered Ping batteries. However, although they make custom designed packs, a 20Ah pack equivalent to what I used to have wouldn't fit into my battery box. Also, Ping batteries can't draw more than 1-2C current, so I had to get at least a 20Ah pack. I eventually bought two packs with 15Ah each. One custom made pack that fits into my original battery box, and another one for which I made a second box (see photos YYY).

I had various problems with the custom made pack: First, the BMS I got did not balance all cells correctly and left one cell with a lower voltage. While I ordered a new BMS I shortcut the old one, so that it does not cut out at a too low voltage any more, and then this one cell died. I ordered and installed a new cell then. But then the new BMS showed the same problems so Ping sent me yet another BMS. With this one things seem to work - so far. Ping was very helpful during the whole process but this failure rate is still a bit too high in my opinion.


After having it in the garage over the winter, here are my experiences after a few months:

• after ~2 weeks the first spoke of the rear wheel "breaks": although I tightened the nipples before (since they keep rubbing on the aluminum rim), they screwed themselves off and fell off into the rim housing one by one => ordered a new rim (Atomlab YYY, where? photos! YYY) and new spokes (which ones? YYY), measured with ebikes spoke calculator
• Around the same time, the front wheel disk brake pads (Shimano Deore BR M555) are through => bought two new ones
• the front suspension is still annoying => ordered new front fork that works much better (Marzocchi Bomber, see photos YYY)

All the mechanics work has been done in the "CMS workshop" at CERN. Thanks to Christian Haller and Maurice to let us use it!
Parts have been bought at Jumbo, ebay.de, led1.de, ebikes.ca.
Thanks also to the amounts of trash at CERN, incredible how useful trashed parts are... that's where we got the magnet, the power socket and connector, and the small steel and aluminum pieces from...
And, of course, without Robert's good ideas I sure wouldn't even have started this project.

To do

• Repair Drainbrain shunt
• Need to move the fuse holder to another location so it doesn't obstruct the inserting of the box; into this hole I will insert a switch for the head light
• A bit less critical: handle for the battery box; cut away a bit of the cabling between controller and rear wheel
• I need to buy a new front fork or fix this one -> lower part moves when braking; it was really a low quality fork...
• rear suspension. It looks like the bike frame is made such that it is easy to add this...
• Mudguards and double kickstand (a single stand is not enough for this heavy bike): After some browsing on ebay.de etc I came across Classic Cycles that offer both beachcruiser mudguards (with a ducktail of course) as well as double kickstands.

Things to know about Lithium Batteries

This section collects wisdom that I found mostly on the endless-sphere forum pages...

My Old Electric Bike

What you can see on the following pages is a photo series of my old bike. Here is the technical data:

motor: crystalyte 408
controller: 36-72V 20A
batteries: NiMH 36V 15Ah
These parts are essentially lower-power versions of the parts described above, and were bought at the same places respectively.

... and what you get out of this is
top speed: ~30 km/h (without pedaling; didn't measure it precisely)
weight: YYY (rear wheel), YYY (battery box)
reach (roughly, depending on terrain): almost twice to work and back


       


Basically I didn't have that much of an eye on beauty but only tried to make it sturdy enough to ride around with it and that it allows me to transport more-or-less heavy items that I couldn't haul with a regular bike. That means:

• the battery is in a box to protect it from rain - I used a simple plastic container that had roughly the measures as the batteries from the "Jumbo" store, jammed the batteries inside and "glued" the top on the container by melting plastic using a soldering iron(!). The only external connections are the cables to the controller and the wheel, the fuse and the on/off switch. For this I "soldered" holes into the box and used silicone to close the remaining gaps to make sure it is waterproof. All very ugly but it fullfills its purpose. The battery box is what takes most of the work and time.
• a fuse has to be installed accessibly between battery and motor to protect the battery from overcurrent/shorted connections.
• the controller has to sit outside the battery box because it produces heat. This is not a problem as controllers usually come in a box and are easy to install.
  

 

• the wheel already came ready to install with spokes etc.

• the battery box has to be tightly connected to the frame to prevent the heavy battery from wiggling or falling out. That's why we welded all connections using a YYY. Two U-shaped steel strips are welded with their ends on the bottom frame pipe. An aluminum strip that wraps around the box is then connected with hex-screws to those steel pieces. (We used aluminum for the wrapping strip for weight reasons and steel for the other pieces to actually be able to weld it on the steel frame.) Another two U-shaped steel strips are welded closer to the bottom of the frame to mount a rectangular piece on it to prevent the box from sliding down.

   

• we had to weld a little bit for the luggage rack as well so that we could screw it easily on the frame

• I always had a bag with me with various items like alarm boxes that I wanted to mount on the bike but never did, spare fuses, etc. In the second photo you can see the charger box with cable.

   

Low Pressure to Full Pressure Turbo Conversion of a Saab 900 Turbo '93

Early this year, when the Geneva fog cover created inversion weather (awful in Geneva, sunny a few hundred meters up) and destroyed any illusions that spring would be coming any time soon... anyway, that was the time when I finally bought a car, but not just any car ;) . A Saab 900 Turbo, 1993. I bought it from Magnus, the president of the CERN Saab club. He is basically a walking Saab encyclopedia. It was one of his around ~20 Saabs that were scattered on his property over garage and backyard some of which did not come into question for purchase :-) . Here a few photos:

           

When I got the car, it was in an (almost) flawless state. There were a few little things that needed substituting, like the blinker lever, central locking unit... all more or less common issues for that a Saab that age. There were various reasons why I bought this car; it seemed to me that it is a symbol of its time, made to last with lots of unusual features, not to forget the engine sound... unconspicuous but very powerful.

There was only one thing that bugged me. The turbo ran at "default" low pressure which means less power at the same fuel consumption. So I invested a bit more and got the turbo setup from Magnus's wrecked Saab model. The catch is though that it has a modified/tuned APC box and bigger air flow (BFIC) pipes so it will be stronger than regular turbos. We both dissembled all the necessary turbo parts from his old car. For the conversion I basically followed Louis Sautelle's instructions, another member of the CERN Saab club. It took me 2 full (rainy) days from turbo-installed-in-Magnus's-car to turbo-installed-in-my-car. The biggest pain was to get the knock sensor screwed into the engine block into a rusty, uncovered hole located at the probably least reachable position under the hood:



Here some more impressions:

             


Here the author after some mechanics work...

 


Big thanks go to Magnus and the CERN car club who allowed me to besiege one of their garages the full weekend.

The only thing that's missing now, according to the saab-forum page, is the new gearwheels in the gearbox. The full turbos run at a higher ratio. However, since a gearbox is one of the weaker parts on a Saab, I decided to hold off with this one. Maybe some day my gearbox will break and then I could buy a complete gearbox... not sure.


To do:

Repair the headlining
Repair the clutch bearing

Installing Debian Lenny on an IBM T61 with NVIDIA graphics card

I followed largely the instructions at www.thinkwiki.org/wiki/Installing_Debian_Lenny_on_a_ThinkPad_T61
Good instructions also at carrot.hep.upenn.edu/wiki/doku.php?id=thinkpad:start


NVIDIA:
- install the proprietory driver from the NVIDIA homepage
see the T61 & NVIDIA report at en.opensue.org/NVidia_Suspend_HOWTO:
- check that intel_agp module is blacklisted in /etc/modprobe.conf with "lsmod | grep intel_agp"
- add option "NvAGP" "3" in /etc/X11/xorg.conf (check with cat /proc/driver/nvidia/registry)
- in grub add acpi_sleep=s3_mode agp=off <-- note that there are many other reports that say "acpi_sleep=s3_bios" however those are the settings for a VESA graphics driver while mine is an NVIDIA driver!!
- add to  /usr/share/hal/fdi/information/10freedesktop/20-video-quirk-pm-lenovo.fdi the following lines:
      <!-- T61 with NVIDIA -->
<!--      <match key="system.hardware.product" prefix_outof="7665;6460">-->
      <match key="system.hardware.version" suffix="T61">
        <merge key="power_management.quirk.s3_mode" type="bool">true</merge>
<!--    <merge key="power_management.quirk.save_pci" type="bool">true</merge>-->
    <merge key="power_management.quirk.vbemode_restore" type="bool">true</merge>
      </match>
This is because, aside from the grub settings, the power-manager (wrapper around s2ram to deal with all the hardware differences - the suspend and wake-up procedure seems to depend very much on the hardware/graphics driver combination, see /usr/src/linux-source-2.6.22/Documentation/power/video.txt). Not actually sure if the acpi_sleep in the kernel option or the corresponding pm-option determines what's done.

Modifications to power-manager (pm):
- add to /etc/pm/config.d/defaults the lines
S2RAM_OPTS="-f" <-- not sure if you need that but just to make sure it works
SUSPEND_MODULES="ehci_hcd uhci_hcd" <-- if the usb modules are not unloaded then the computer wakes up again right after going into suspend
- modify /usr/lib/pm-utils/sleep.d/90clock so that this script executes OK (there was an error in /var/log/pm-suspend.log):
substitute "/sbin/hwclock" with "/sbin/hwclock --directisa"