I got the Cycle Analyst working!
It seems that the problem is that I never bothered to program in the sensitivity of the shunt resistor.
All of the ammeters that I have worked with in the past were simple analog ones. I would have a meter and a matching shunt. It just worked – nothing fancy, no programming. However, the Cycle Analyst is designed to work with a wide range of vehicles, anywhere from a small electric bike up to a pretty decent electric motorcycle.
The other part of it is that I forgot to mark down what the rating was of the shunt. Usually, it’s marked right on the side. However, my shunt is now bolted to the back of the battery pack, near the motor controller on the Vectrix, and under the battery box cover and all the scooter trim. Since I had the battery cover off, it was time to stick my head and a flashlight down there to look.
Sure enough, it’s a 0.5Mohm shunt.
The Cycle Analyst menu isn’t that intuitive. There’s only two buttons on the device. Either cycles through the menu, you then hold the button to get into an item, then hold it again to change the item. It’s very easy to miss, and then have to cycle through the whole menu again. After d0ing that several times, I finally properly set the two items I needed.
The first was setting the range. That’s basically “Are you doing a LOW-power vehicle, or a HIGH-power vehicle?”. It allows you to read hundreds of amps in the high mode.
Next, was setting the RShunt value. That’s a number to match what’s stamped on the side of the ammeter shunt. I set it to .5000mOhm. After exiting the menu, I did a short ride on the Vectrix and then also plugged it in for a charge.
The ammeter values looked like they were correct now. (While I don’t know the exact values to expect on a Vectrix, I do know what my electric Kawasaki pulls, and with a 125-amp fuse the Vectrix should be pulling somewhere around 30-40 amps while just cruising around.)
I also happen to know that I have a 10-amp charger. When I plugged in the charger, the Cycle Analyst showed that I was using -9.7 amps (negative use indicating charging.) Pretty close to a 10 amp rating on the charger. The Amp-Hour meter (AH) also counts DOWN when charging. It counted UP while riding the cycle, and then counted DOWN while charging. At the end of the charge, it was pretty darn close to zero. That seems to indicate that I have a fairly consistent battery use and charging. Now that IS counting the DC power into the battery only, NOT the AC power to the charger. By tracking that with a Kill-a-Watt, I can track my total energy use, which is what I use to calculate watt-hours-per-mile, the electric version of MPG or fuel economy. For those who are more used to gasoline cars and Miles per Gallon, a little bit of applied math can create MPGe, or miles per gallon equivalent.
Last night, I played around with a spreadsheet. I have very little experience with those, but it wasn’t that hard to figure out how to make the spreadsheet automatically do a few calculations for me. For example, by entering miles traveled and kilowatt-hours of energy used to recharge, the spreadsheet can calculate watt-hours used, watt-hours per mile, MPGe, and then also average those figures for me.
Tracking my use for the first 200 miles, I’m averaging 336 MPGe at a cost of a penny a mile.
One thing that I’m still not sure about is that the voltmeter on the display of the Vectrix is always 2 volts HIGHER than that shown on the Cycle Analyst. For example, when the Vectrix display shows 147v, the Analyst will show 145-point-something. I have no idea why that happens. Perhaps a diode somewhere dropping the voltage a bit? If you have ideas, let me know.
Stay charged up!
-Ben
