Monday, June 23, 2014

Sunday ride data and Zen video

Yesterday I took a Sunday ride on the bakfiets, up to a regional Upper Valley/New Hampshire/Vermont Sierra Club meeting in Hanover.  It was sunny with cool air and fair weather clouds, and the meeting was from 1-5 pm, so the meeting was a great excuse for my first longer ride of this year.  I thought the trip stats from the Cycle Analyst data logger would be interesting to others:

Distance:                 40.75 miles
Elapsed time:           2 hours, 30 min, 5 sec
Average speed:        16.2 mph
Maximum speed:      42.7 mph
Volts, start:              41.6  (this is a 36 volt system)
Volts, end:               39.4
Volts, min:               35.9
Amps, min:              -0.02
Amps, max:              17.08
Energy used:           509.58 Watt hours (13.63 Amp hours)
Watt hours per mile:  12.5  (equivalent to 2640 mpg)

A few notes to help interpret the numbers:
-The Cycle Analyst measures any time the wheels are turning.
-The route was mostly two main roads (Rte 5 and Rte 10), with 6 notable hills that are about 0.6 to 0.75 mile long.  I haven't measured the grade on them like I did for my road, but they could roughly be considered "San Francisco" hills.  My speed is 12-14 mph up the hills, and the maximum speed of 42.7 mph is coasting down one of the hills.
-The CA also lists Amp hours forward (13.646), and Amp hours regen (0.0105).  This bike has a gear drive motor with a slip clutch and cannot do regen, the small amount of back current is from the collapsing magnetic fields in the motor coils when the throttle is turned off.  The longtail being built right now has a direct drive motor and can do regen, and I'm looking forward to comparing the numbers.
-I use the EPA standard of 33 kWh per gallon of gas for conversion to mpg.
-13.64 Amp hours is 68% of battery capacity (20 Ah), so the range works out to 59.8 miles, not counting the solar generation.

Solar contribution:
This is not directly measured yet, and has to be calculated.  I have some shunts to put in the solar wiring, but haven't had the time to install them and go through the process of checking the calibration and then the scaling.  However from testing I know that the plug in battery charger is about 85% efficient, and thus the 509.58 Watt hours recorded by the CA should have taken 599.5 Watt hours to recharge.  But when I plugged in the battery after the trip my Kill A Watt meter recorded only 470 Watt hours during charging.  The difference of 129.5 Watt hours would have been provided by the solar panels, which is 25.4% of propulsion energy, or 21.6% of total energy counting battery charger efficiency losses.

The regen is measured by the CA because it feeds back to the battery through the motor wiring, but the solar generation is a separate set of wires and not measured.  The solar 129.5 Watt hours would have been good for another 10.4 miles of range, but since I didn't travel the extra distance it shows up as a fuller battery at the end of the trip.

All in all it was a fun ride, traffic was very nice, the weather was great.  I've been riding only short 15 mile trips to the center of town once in a while, so the electric assist was a big help.  I wore regular street clothes for the meeting, and my legs are 99% normal after the longer ride.  I'd do it again.


Unrelated to the statistics from the trip, here is an interesting video.  Jack Kerouac (author of On the Road) wrote a letter to his first wife, Edie Parker, about 10 years after their marriage had been annulled, while he was discovering Buddhism.  Film director Sergi Castella and film maker Hector Ferreno made the letter into a short video for Dosnoventa Bikes- We were never born:

WE WERE NEVER BORN from Dosnoventa on Vimeo.

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