25 Miles

A long test drive

Today was a day of test drives.  The first was a speed test.  While cleaning up some wiring I realized that the accelerator cable may not be pulling the controllers sensor fully, so I lowered the effective top of range to 70% of full scale.  Well it made a difference and the motor is now spinning near 4300 rpm in neutral.  Which is very close to the theoretical limit of 50 rpm/V with a 85V battery.  Given, this I wanted to see what Jane would do in 4th gear, so we headed to the one stretch of nearby road with a 45 mph speed-limit which is outside the city limits.  On the level straight-away, Jane hit 53 mph and was humming along.  There may have been a few more mph available, but at about 50 mph, I noticed that the front wheels are out-of-balance and started to shimmy a bit.

Well, after a top-off-charge, we headed out again, this time with a goal of testing range and the fuel gauge.

The image shown above is the screen shot from the GPS Essentials program which shows 25.2 miles covered with a max speed of 35 mph.   The max speed is only captured while the screen is on.  It looks like in 2nd gear, Jane will do about 37 mph, which for city driving is perfect. 

The fuel gauge showed 15% remaining which calculates out to 41 AH consumed (out of the 60 AH available in the battery).   Using the 80% available capacity, this works out to a range of 29.6 miles on a full tank (with a 10% reserve still there to protect the battery).  The batteries were not showing any signs of being depleted.  Only one near the end did the low-voltage alarm trigger during a very steep hill climb.  It cleared as soon as the load was reduced.

The other interesting calculation is 41 AH x 84V / 25.2 miles = 137 WH/mile or 7.2 miles/KWH.  This works out to about 250 miles/gallon (MPGe) using the conversion factor of 1 MPGE = 0.0292 miles/KWH.  This does not take into account the efficiency of the charger which would lower this by about 40%.  You wouldn't think the charger would have to be taken into account....  I have not done the math to see if spending more on an efficient charger would save enough electricity to justify the added cost.

To take this one more step... At $4.00/gallon, Jane with the gas engine hit about 42 mpg or about 9.5 cents per mile for gas.  Based on Oregon electricity prices at 11.5 cents/KWH... the electrical cost comes in at about $0.115/7.2 miles or 1.6 cents/mile.  Even factoring in 60% efficiency 2.25 cents/mile.  The battery pack adds about 4 cents per mile so this brings the total cost of the electric mile to about 6.25 cents (a 30% savings from the gas model of 9.5 cents/mile).