While my wife and I could hardly be considered early adopters of the technology, we did purchase our first battery electric vehicle (BEV) earlier this year. It has become our primary form of transportation around town and around the metro area. However, I thought our recent experience might be worth sharing.
On a Thursday in the past month or so, a storm resulted in widespread power outages all around lower Michigan. Estimates for when the power would be restored ranged from several hours to several days, so we really didn’t know how long we would be off the grid. We had been using the BEV rather extensively that day, and when the power went off, we were down to 60 miles (97 km) of range left.
Fortunately, we had prepared our home (to some degree) by installing solar panels on the roof and adding a back-up battery in the garage. Both were expensive, to be sure, but we intend to stay in this location for a very long time, and the savings on utility costs will pay back the investment within a decade or so. Also, the battery provides a degree of emergency power sufficient for some (but not all, as I will explain in a moment) of our electricity needs.
Before we do some basic arithmetic, a few numbers and constraints are in order. The solar panels produce anywhere from zero (when the sun is not shining) to about 4 kW at noon on a sunny day, with an average output of about 20 kWh per day in the summer. The battery will hold 10 kWh and can discharge at 3 kW maximum. Our electric vehicle has a 65 kWh battery. The Level 2 charger we have installed in our garage requires 12 kW of power, while the Level 1 charger requires 1.1 kW.
We quickly discovered that the total output of the solar panels and the battery was insufficient to run the Level 2 charger (and if it did work, would have depleted the home battery to zero in a few minutes, leaving us with no power for the home). While the Level 1 would work, it took 1.1 kW and added less than 5 miles (8 km) of range per hour. Even so, we tried to only use the Level 1 charger while the solar panels were generating over 1 kW, to avoid depleting the home battery.
To charge the BEV from a fully depleted to fully charged state with the Level 1 charger would have required about 60 hours (about 2.5 days), while the Level 2 charger would accomplish the same task in about five hours. By carefully managing the Level 1 charger, and limiting our travel to only a few miles from home, we were able to live fairly normal lives while the power was out, in spite of having to limit the use of high wattage appliances. The outage lasted two days, and we were even fairly popular with the neighbors, who came over to charge their tablets and cell phones during the day!
Also, our second car is a gasoline-fueled vehicle, so we could have traveled further if necessary. Bottom line, we are still very happy with our BEV, but only because we are fortunate enough to have a second (gasoline-fueled) car, a home with a place to have a Level 2 charger and a back-up electrical system for when the grid fails. So, although BEVs are becoming more popular, they are still not for everyone, particularly those without access to a Level 2 charger at home or a back-up source of electricity during power failures!
Ed Becker is a Fellow and Past President of STLE. He is currently president of Friction & Wear Solutions, LLC and can be reached through his website at www.frictionandwearsolutions.com.