Torque My Console
I’m having lots of fun driving the little electric 914 around town – to work, to the store, to meetings, to visit friends, to movies and to restaurants. I always daydreamed about converting a gas vehicle to electric, but I never thought it would actually come to pass. I’m growing accustomed to the novelty, but every so often it dawns on me all over again: “Holy Crap! I’m driving an electric car!”
The picture above is a shot of my new little friend, the Torque app. I mentioned it in an earlier post, but since then I’ve realized how indispensable it is, and I don’t drive anywhere without Torque open on my Android device. The console shown above is my preferred arrangement of gauges, which are graphic representations of Parameter IDs, or PIDs. There is a large selection included with the Torque app for regular gas-burning vehicles, but the electric vehicle PIDs shown above were created by Ewert for their Orion BMS. The complete set can be downloaded from Orion’s website, transferred to the MicroSD storage of the Android device, and then selected from the setup menu to display on the main console. The various gauges I’m using above are as follows:
- SOC (state-of-charge): Displays the percentage of charge left on the pack, similar to a fuel gauge. The SOC meter above reads about 75%, which is equivalent to about 60 miles.
- Amphours: Shows the amount of amphours remaining on the pack. The cells I am using are rated at 180Ah per full charge, and the gauge above shows 136Ah remaining. Like SOC, this display also acts like a fuel gauge. Although somewhat redundant, it’s very instructive and interesting to watch how the amphours get used.
- Pack Voltage: After a full charge of about 3.6 volts maximum, all cells quickly come to rest somewhere around 3.4 volts. Multiply by 36 for a total of 122 volts when the pack is fully charged. Pack voltage is just one of the variables used to calculate amphours and state-of-charge, although it is not an indication of state-of-charge.
- High and Low Cell voltage: Crucial data, because cell voltages must remain balanced within a narrow range relative to each other. Any cell that strays too far from the pack is either overcharging or over-discharging, and should be given immediate attention before it affects the health of the others. Think of it as your oil pressure light.
- Amps: This is the actual current being drawn by the motor and controller to propel the car at any given instant. At the moment the above Torque screenshot was taken, the motor was drawing about 60 amps. When the car is in regenerative braking, juice flows back into the pack and this gauge displays negative numbers.
- DCL (discharge current limit): The amount of amps that can safely be drawn from the battery pack at any moment without overstressing the lithium cells. This figure is based on the “C” rating of the cells, and is manually programmed into the Orion using the BMS Utility. Using this number as a baseline, the Orion then continuously calculates the appropriate DCL for the pack’s present state-of-charge. The above DCL gauge is reporting 450 amps as the discharge current limit that the pack can sustain over an extended period without harm. However, the pack can handle momentary bursts of 500 to 1000 amps for several seconds without harm. That’s the fun midrange muscle on the freeway.
- Safe Amps: Torque allows the user to build custom gauges by running calculations on any combination of existing PIDs. Safe Amps is an example that I built by subtracting Amps from the DCL, revealing the amount of instantaneous free amps that are safe to draw before the batteries enter stressland. It’s the display I watch while I am accelerating, similar to watching the redline of a tachometer. Torque also allows the creation of audible alarms that trigger according to user-defined criteria. In this case, the alarm sounds when Safe Amps reaches zero, suggesting I let up on the pedal.
Torque has many other cool features, like recording error codes and performing realtime graphing on multiple selected parameters, but one of the coolest functions is trip logging. It uses Google maps and GPS to give an incredibly detailed record of your travels, complete with imbedded data from your selected parameters. The default data used above is MPH, displayed in colors. The distance travelled figure is also very handy when tracking EV range per charge. The Porsche’s maximum range of 80 miles is still speculative, but Torque has given me the confidence to begin planning a test drive that will nail the range figure down once and for all.