Friday, October 3, 2014

Mt Washington

The ALT Energy Summit (http://altenergysummit.org/) alternative vehicle climb at Mt Washington was held on September 13/14.  The mountain road starts at 1565' elevation, runs 7.847 miles up to about 6200' at the parking lot (the summit is 6288'), and has historically been used as a test of vehicles- the first motor vehicle to go up was a steam powered Stanley Locomobile in 1899.  After a lapse of the event for several years, Ted Dillard, (President of the Boston Chapter of the  Electric Auto Association), wanted an excuse to run his electric motorcycle up the road and revived it.  He secured sponsorship from the local utility- NH Electric Coop- and organized a Summit last year.  I had debated whether to attend, and later regretted not going because Michael Corbin brought his Sparrow electric auto.  Michael had lived two houses up from me when I was a teenager in 1970's Connecticut, and made Corbin Gentry motorcycle saddles in the old mill in town.  He also had an orange fiberglass bodied Phaeton with a VW motor, and at the time I had just started to put Porsche 356 motors into a VW bug and a Karmann Ghia, so it would have been nice to finally connect.  Unfortunately he didn't attend this year, but it's interesting that we have both moved towards electric.

Since Ted had graciously taken part in the Upper Valley Electric Vehicle Forum and Demo last May, it gave me a push to attend the Summit this year.  I also wanted to display Sierra Club information because of their sponsorship (along with Plug in America and the Electric Auto Association) of National EV Week (https://driveelectricweek.org/).  Although I would be out riding the Longtail up the mountain, Dolores Rebolledo of the NH Department of Environmental Services had a table next to mine, and was able to answer questions.
Mt Washington is known for it's bad weather, and there were
clouds around the summit when I arrived...

I had designed the solar electric cargo bikes to cover ground between towns, so I knew that hill climbing was not their strength.  The Longtail also has a direct drive hub motor, which really isn't the best for hills.  My game plan was to get off for the very steep parts, and walk along with the bike turned on low.  (My bikes have a speed control on the grips, not pedelec control.)  Based on hills around my house the climb seemed very possible but slow, and a major goal was to not burn out the motor or it's controller and get too expensive.  It was also encouraging that another (highly modified) direct drive bike had not only climbed Pike's Peak but had third fastest time, an article with some details is at:    http://www.electricbike.com/pikes-peak/

Inside the base tent- my Upper Valley Sierra Club display was on the far table.
Directly behind me was Chargepoint EV charging stations, and
Dolores Rebolledo of the NH Dept of Environmental Services,
Other displays were from sponsor NH Electric Coop,
Dragonfly Aerials, National Electric Drag Racing Association,
and Mohawk electric mowers.  When it started  raining later
the vehicles were moved inside around the edges of the tent.

In addition to several Teslas, there were two race cars from Entropy Racing,
an electric Cobra, a Fiskar Karma, and a Mercedes converted to a grease wagon.

Dartmouth brought their Formula race car up, and there were
EV team members from Olin and MIT.  Photo credit: Benswing Rich

A cute little kart with an ETEK motor.  Nicely done layout, with huge fins on the
motor controller.  I'm not sure why a main contactor is mounted on the steering though.

Dr Bass of the Endless Sphere forum rode his Zero to the event.  Notice the
panniers on both his and Benswing Rich's bikes that are packed with extra batteries,
and also upgraded chargers to make long distance travel more feasible.
To make a long trip like this, Dr Bass showed me a route map he creates
with software that lists the details of charging stations along the way.

The RooPod with both hatches open, and in behind it is a Dirigocar,
and then a Ford Fusion Energi.  These are internal combustion engine cars.

Bikes included two Outriders, as well as eVelos, and a RANS recumbent.

Heat management is an important consideration when pushing design limits.  I did a dozen runs up a 12% slope, 1.25 mile long hill near my house with an infrared thermometer in hand to prepare for the Summit.  On one sunny day the controller peaked out around 119 degrees F- hotter than I like but within limits. (I use the "too hot to touch is too hot" rule for electronics.)  I then modified the Longtail by adding a sheet metal bracket that moved the controller out into the air flow.  One of the Outriders pictured above had it's motor overheat at mile 3, and unlike my Longtail they didn't have the option of getting off and walking alongside, so rather than burn it out the owner decided to coast back down.  (The trikes that climbed Pike's Peak had custom cooling fans.)  I'm trying to decide how to cool the mid motor on the third bike, because long before the electrical insulation catches on fire the permanent magnets start to degrade.  At the moment I'm thinking of a small fan on the outboard end of the shaft (away from the drive sprockets), with small holes in the motor casing for air flow.  If moisture turns out to be a problem, the holes could be sealed, and then the motor would become a regular TEFC (Totally Enclosed Fan Cooled) frame style.  An advantage of a hub motor over an RC (Radio Controlled) type motor is the larger surface area, (most of the time only the frequency of magnetic transitions is considered).

This is what a mid motor kit looks like on a recumbent.  John Anderson 
(see Yahoo groups: power assist) added a Cyclone RC type motor with
planetary first stage speed reduction to his RANS, and fed the power
into a large fourth front sprocket riding on a crank freewheel.
This was the fastest bike of the day, however I would have some
reservations about building this and selling it to the general public,
as an unskilled mechanic could easily mess this up.

Randy Bryan had his Prius generator conversion display, and the 
next display over was about weatherization and energy efficiency.

The climb turned out to be reasonable, not as steep as I had imagined, just much longer than the climbs on my errand runs.  There are actually two 500' long sections of my town road that are steeper.  Of the 7.8 miles, I ended up walking the Longtail for about 2.  My original plan was to stop every mile and measure the temperature of the motor and controller, but they never got above lukewarm (~80F) so I didn't bother after the first few times.  Part of the reason they stayed cool was the weather- the top third of the ride was 30 degrees F, with a 36 mph headwind (gusting to 42), and no solar heating (i.e. in the clouds).  Another reason was that I was favoring the motor to prevent burning it out, but a large third reason they stayed cool was that the motor controller cut back on the energy it was delivering.  I'll write a blog post about electric motor voltage (Kv), efficiency, rpm, and work, but for here the short explanation is that electric motors are sensitive to rpm just like a gas engine, and neither likes being lugged at a slow speed.  It's true that at stall an electric motor develops it's greatest torque, but because the shaft isn't spinning all the energy going into the motor is coming out as heat, not as work.  At low motor rpm's, there is a large amount of slip in a motor's field between the magnets and coils as it approaches the stalling condition, and the motor controller (Infineon EB3xx series chip) reduces the current.  (I have not studied the algorithms yet, only a program that allows me to reset some of the controller parameters.)  I had noticed this effect occasionally for a few seconds during regular errand runs:  At speed (20 mph) going up a slope the motor would be running around 700 to 750 watts with peaks around 800 w, but as the bike slowed down (on the same slope) the wattage would drop (due to amps, not battery voltage sag).  During the sustained climb up Mt Washington at 3 to 9 mph much of the ride was around 480 watts, sometimes dipping to 340.  I could try to remedy this by resetting the controller amp limits, but the motor would still be running at a less efficient slow speed.  I've noticed a Chinese company that is now building a two speed geared hub bike motor, and a few companies that have also started offering gearboxes (often having only 2 speeds) for electric vehicles that need a wider speed range.  For an EV under average use a gearbox is just added weight, expense, and something else to break down.  As an example the first Tesla model had a two speed gearbox, which was discontinued.  However under extreme situations the lack of low rpm performance can be noticed:

Luke Live for Physics's Death Bike racing a Tesla S
Neither of these vehicles has a gearbox, but the extra mass of the Tesla accentuates the low rpm problem.  For the third bike I'm planning on using the derailleur system to allow the motor to be shifted, and the question isn't so much the benefits of shifting down, but more of how long a shifting mechanism and chain will last at 700 watts.

The road up Mt Washington is a medium width tar road for the first 5.5 miles, switching to dirt for one mile, and then back to tar at the top.  I didn't take pictures on the way up, and am going to use a video from Entropy Racing to show you what it looks like, (notice the first 15 seconds as the motor speed gradually increases to a more efficient rpm range):

The EVSR car reaches the top in 7 minutes, 28 seconds, or around 60 mph. My time was 1hr 31min 31sec, which is OK- faster than walking, but since the record time for a bike is 49 minutes, there is definitely room for improvement.  In all fairness it should be noted that that I was able to get off the bike at the top and walk around looking at the views like a normal tourist and then ride down, whereas I've been told by a person who has been a pit crew for a bike racer that their job was basically to scrape the racer up off the pavement at the end and ferry them back down.

The summit building with a cog railway train approaching.

The four eBikes that made it to the top during the ALT Energy Summit (l to r):
-John Anderson, riding a RANS recumbent with Cyclone mid motor kit
-Larry Gilbert and coworker of Zoombikes riding eVelos
-Me with the solar electric longtail cargo bike

A closeup of the Longtail at the top.  I need to get the rear panniers finished,
they would have looked nicer for a photo than a shopping bag.  If you click
on the photo you can see the infrared thermometer in the front basket.

The cairn at the very top of the mountain (6288'), with people having their picture taken.

There were at least 200 people hanging out in the summit lodge.  This photo
is blurry because of the high indoor humidity condensing on my cold camera lens.
The building is built for severe weather and has an extremely tight envelope.

Looking down from the summit area to the parking lots, with the Longtail
at the base of the stairs.  It was neat watching the clouds move by,
very much like ocean waves rolling over and around nearby mountains.

Gazing down into the deep blue depths of the ocean.

After looking around for awhile, it was time to head back down,
especially since Ted had asked us to be back for an exhibition period.
It was just as well, because shortly after the weather turned to freezing rain.

3/4's of the way down I had to take a picture of a row of knobs with a very deep
valley between me and them.  However the wind was probably around 45 mph,
and I had a hard time standing on the edge and holding the camera steady.

There were some fantastic rock formations,

About half way down I realized that I was looking down
at a ski area  under the clouds.

The Longtail used 670.97 Wh of electricity on the way up, giving 86.4 Wh per mile, at an average speed of 5.14 mph.  This is one of the worst fuel mileages I've seen, similar to the other end of my road.  Coasting back down I turned on regeneration and had a pleasant, leisurely ride looking at the scenery.  Regen put 151 Wh, or 22.5% of the energy back into the battery, reducing trip energy use to 35.2 Wh/m, however a second glitch in the electronics showed up.  After a few minutes of regen around 320 watts (15-16 mph), it turned off, and after I slowed down it turned back on again.  The controller was cold, so my best guess was that the battery voltage rose above the upper limit, and the Battery Management System (BMS) shut off.  I rode the rest of the way down using the brakes occasionally to hold the speed down to 200 watts (10-12 mph), (and also pedaling on the more moderate declines to keep the regen up), and the regen stayed on,  At this point I don't think regen is all that helpful on a bike.  During the last summer it has usually returned only 0.5 to 4% on my longer trips, and the only large regeneration happens for short time periods down one or two hills on the route.  It's best use seems to be a substitute for braking, but even then I haven't used it much- if I am coasting 15-25 mph down a hill I prefer to stay at that speed and cover ground, I've mostly turned it on above 25 mph for only brief periods of time.  The solar panels are usually several times more productive (20-40% generation of load).

For comparison:
-John Anderson used 750 Wh on his RANS recumbent, at an average speed of 7.1 mph, (showing the advantage of using gearing to keep the motor rpm higher).
-Dr Bass commented that his 2012 Zero S, modified with a 2013 motor and ZF15 equivalent battery (13 kWh usable), with of total weight of 500 pounds, took 2071 Wh from start to the summit and got 800 Wh of regen on return.
-Ted Dillard had estimated about 2 kWh usage for his homebuilt electric motorcycle.
-Tim Letourneau commented that the Ford Fusion Energi regenerated about 6.92 kWh on the way back down from the summit, giving him a 91% charge on the battery.
-I heard anecdotally last year that a Tesla had regenerated about 60-65% of the energy used during the climb.

At the end of the climb after the group photo.  In behind my bike is
one of the Outrider trikes, the MIT 914 electric car conversion, and the
MIT trike with an Agnelli axial motor (see Cedric Lynch) and battery trailer,

Besides getting a better feel for designing a cargo bike for both distance and hill climbing, there were two other rewards for the day.  The first was that a picture of the Longtail got posted on the Tesla Motors Club forum: (http://www.teslamotorsclub.com/showthread.php/30898-2014-Mt-Washington-Trip/page4).  The second was that after pushing some limits climbing Mt Washington, the upper Connecticut river valley forests and hills were an indescribably beautiful trip home.

Monday, September 8, 2014

Cedar Circle Strawberry Festival 2014

On June 29, Cedar Circle organic farm held it's annual Strawberry Festival.  The farm is managed by Will Allen, (author of The War on Bugs) and Kate Duesterberg, who had put in a large roof top solar array on one of their barns several years ago, and are now arranging a community array along the Ag fields on the northern border in a buffer zone that cannot be farmed organically.

The strawberry fields along the Connecticut river.  Most of the displays,
tents, music, and food were behind me in the farm buildings up the hill.

I had taken part in the festival a couple times before, with a solar education display for Solar Hartland, and also with the Transition Town bicycle blender:

Farm Education Coordinator Cat playing music with the band at a previous
Berry Brunch in the Fields event while making a bicycle smoothie.

My display was on the border of the fields and buildings,
between the farm's electric tractor and Sun Common's booth.

Cedar Circle converted an old Allis Chalmers model G to electricity by replacing the gas engine with an electric motor.  It's turned out much nicer for the field crew planting and working alongside the tractor.  A problem has been the lead acid batteries.  I've read several times that lead acid batteries do not work well in an electric bike, simply because if they are discharged below half full the plates become sulfated quickly and ruin the battery.  Most people cannot stop using an eBike assist during a ride as long as the batteries have any charge left, with the result that generally lead acid batteries do not last a year.  After the festival we talked for awhile about the benefits of using lithium batteries (which can be drained almost to empty), and adding a few solar panels to the battery box cover.

I brought up the Bakfiets, along with the new glassless, frameless solar panel and some pictures of the Longtail.  It turned out to be a very cosmopolitan crowd, with 2 separate people telling me they had owned a Bakfiets (one in California, one in Amsterdam), and another young family who said that their Bakfiets was in storage in Chicago at the moment, awaiting shipment to Hanover.   They had been using it in Portland, Oregon on relatively flat terrain, and we talked about the process of adding an electric drive to make it more usable in this area.  Unfortunately there were no test rides, as there were too many people (1400) and little kids were running everywhere,  I also had my picture taken with 3 high school students from NYC!  They were looking for environmental projects to write about for a science class report.

There were 3 teams of draft horses giving alternative transportation
hay wagon rides, this team is Jim Fitch's from Cornish, NH,

A local theater group also had horses that the kids could get close to.

The bike parking area.  Cedar Circle offered free admission to the 
Festival for anyone arriving by bike or walking.  Hopefully this
will grow greatly in the next few years.


Saturday, August 23, 2014

Longtail construction (2/3) Rear rack

In the first post about building the Longtail frame, I covered extending the chain stays and putting in a platform for the battery box to sit on.  The next step was adding on the rear rack and then tying the top and bottom horizontal tubes together to form a truss structure.
After installing the wheels, the frame was propped up along a line drawn on a flat and level floor.  (You can do this work at any angle if you are willing to do a lot of measuring and calculating offsets, but it's much easier and more foolproof to just hold up a level.)  I used an oxy acetylene torch to heat the tubing while bending human friendly curved ends on the rack, as the radius was too tight for any cold bending forms I had available.  It was then rested on top of the battery box with 3/8" thick spacers to create space for a tie down rope to fit through, leveled, propped in place at the rear, and then notched to fit to the seat tube.  There are wedges centering the front of the tire in the chain stays so that the tire tracks straight, and the boards clamped on each side of the tire are the right width to hold the rear of the rack centered.  At this point the old seat stays are not connected to anything at the top.

The sequence for connecting the chain stays to the rack was based on working from the fixed point at the seat tube towards the tail end, and fixing any errors from welding heat warping as I went along:
1.  Tack weld the front of the rack to the seat tube to stop things from moving around.
2.  Cut and tack on uprights that just clear the back of the battery box.
3.  Readjust the rack to be square and level, and add diagonals from the drop outs to support the back of the rack.  The upper ends are notched as usual with a grinder to fit, but the lower ends were slit for an inch and squeezed in to make a taper on the tubing, and then hammered square to fit over the existing luggage rack mounts on the drop outs.
4.  At this point the assembly is starting to be self supporting, and cutting tools can now be used on the top of the old seat stays to fit them to a new cross stay inside the rack tubes.
5.  A diagonal is then run from the cross stay to the main chain stay junction.

All of the fitting work had to be done inside on the flat floor, which is OK for one project, but if I were going to build several bikes I'd make a table or jig in a better space or outside.  Each diagonal was briefly tack welded in place with many plywood shields around it to contain sparks, and when enough triangles had been formed to stabilize the structure it was moved outside for more complete welding.  Tack welding an assembly first also helps control warping from welding.

The cross stay that connects the top of the old seat stays to the rack tubes.
It also links to the diagonals running down to the chain stay extension junction,
and holds the rack tubes at the right width.

After making several mock ups, I decided that the board on top of the rack should be about 5" to 6" wide.  If it was wider the corners cut into the insides of a passenger's thighs, and if it was narrower it wasn't as useful for supporting a load.  Since standard 1"x 6" lumber is 5.5" wide, I used that width so it could be an option even though I planned on using thin plywood, as 5.5" would also allow strips to be cut from a sheet of plywood with a margin for a kerf but not too much waste.  The rack tubes are 5 5/8" wide, so that the tubes stick out 1/16" further than the plywood on each side to act as a rounded bumper.

With diagonals welded in to form triangles, the rear section of the frame was pretty stable, and I went back to finish up the front of the rack.  (Although some parts look yellow in this photo, there was no brazing, only welding.)  I added two strips for attaching the top of the battery box, and finished the seat tube welds.  Unfortunately the rack landed on the original seat tube exactly at the top, so I removed the old seat clamp lugs, and then welded a few inches from the top of another tube on top.  

I try to work as cold as I can to avoid changing the properties of the steel, while still achieving a good weld penetration.   But even though I also used a piece of aluminum tubing (it doesn't stick to a weld) inside the seat post to align the top extension, all the welding in this area deformed the seat tube enough that a seat post would not go in.  I don't have the proper size reamer to fit this bore, so I taped a 1" wide strip of coarse grit belt sander cloth on a 3/8" rod, wound it around to build up the width until it just fit inside the tube, and spun it with a drill for about 20 minutes inside the problem section to open it back up.

Looking at the rack attached to the lower chain stay assembly from the rear.

I prefer priming the work after I've finished a section, mainly because it splits hours of sanding and cleaning for paint preparation into smaller sessions, but also because it immediately protects the newly worked metal from oils and salt from my hands and dirt, so there is less prep needed.  With this method the primer needs only a light cleaning with a degreaser, a scuff sanding, and then a quick tack wipe when I'm ready to paint.  I've always preferred a self etching primer for automotive work as it adheres a bit better, but I found out on the Bakfiets that the chemicals in it do not work well with an acrylic latex top coat.  The water based paint reacted through the primer and rust spots bled through.  For this Longtail I used a regular plain lacquer style primer and had no problems.

A side view of the rack assembly.

The weak spot in this design is the hole for the battery box, as it has only a short height diagonal brace under it that lands in the center of a seat tube section.  However overall this design is overkill, as the loads in a truss are carried mainly in the top and bottom chords, which in this frame are well braced straight tubing spaced 17" tall.  To give you a rough idea of the strength, compare this to a 10" or 12" high floor joist in your house- the load carrying capacity of a beam increases proportionally to the square of the height.  Without considering the effect of width, a 17" high beam is 2.9 times stronger than a 10" high beam.  A stiffer frame will also give better handling (more precise steering).

Wednesday, August 6, 2014

The Strolling of the Heifers

The Strolling of the Heifers was founded in 2001 to benefit local food, farmers, and healthy agriculture.  It has grown over the years, and now has a Slow Living Summit to go with it.  Brattleboro cargo bike advocate Dave Cohen put out a call for cargo bikes for the parade, and I took the Bakfiets down to it.  A full range of bikes showed up, which included panniers, racks, trailers, trikes, longtails and bakfiets.  I tried to take some pictures while riding, but there is a more complete video of the parade on their website (the bikes are at minute 41). My overwhelming impression was amazement that so many people wanted to watch cows walk up main street.  Bikes are much faster.  But in keeping with the spirit of things, we rode at a heifer's pace, (which I think is just a little faster than the pace set by the preschoolers in my town's 4th of July parade).
I parked on the south side of town and rode in to the parade.  On the way I had to stop at the offices of Building Green, the energy efficiency building journal, next to the Estey organ museum, for a Green Photo.  The row of old mill buildings along the street all have slate siding.

This was our staging area, the hill in the background is across the river in NH.
(Click on pictures to enlarge.)

Among the bikes were Kathleen's trailer/canoe,

a local newspaper bike delivery service,

the frame of a new vendors cart bike being built by Hannah,

 and a nice cargo bike with a front box built by Jesse of Seneca Bicycle Works.

This is Todd's custom ebike with a 2 speed front hub, pulling a trailer.

The drive system of an Outrider trike in the parade.  Note there are only 3 large wires coming out of the motor, so there is no rotor position feedback.  This makes the motor harder to control and not as efficient, I'm in the middle of planning the motor and gearing for the third bike right now, and plan to cover this more in a future post.

Peter explaining his motor upgrade in his very dairy (decorated with cow spots) ELF.

Two Yuba el Mundos with a Stoke Monkey and a Bionx, and a passenger who is ready to ride.

Heading up Main Street.

Looking back down Main Street, (with 1/4 mile of people already).

Rolling UnThunder.  Quiet saves lives?

Stephan and Eliah in their Quadracycle.  Each rider was connected to one rear wheel,
with no link connecting the two sides.  Photo courtesy of Dave Cohen

My Bakfiets. The person riding the bakfiets next to me is Dave Cohen.
His passenger (sitting backwards) is reading the book "Life is a Wheel".
Photo courtesy of Dave Cohen.

About 2/3's way along the route.

Sometimes you don't want Dad's help, you just want to peddle yourself.
She actually rode the whole parade!

My word, the people!  It's heartening to think that most of them are in favor
of local food and agriculture, and so were probably very interested in biking too.

Our line up of bikes during the afternoon after the parade at the Bike Petting Zoo.  We answered all sorts of questions about our bikes.  I took a picture for a mountain biker from Virginia while he sat on the Bakfiets, and I had a great conversation with a couple from New Jersey about urban versus rural biking.

Yes, the LED flag staff lights up!