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 on my bikes (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 stopped 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 my routes. 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).
-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 that last year 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.