Electric vehicles have finally started seeing commercial success over the last decade or so, and they’re now at the point where their only really downside is the limited range and time it takes to recharge. Even so, the per-mile cost of operating an electric car is so much cheaper than an equivalent gas-powered car that those inconveniences are worth it for a lot of people. That’s particularly true if you charge your car at an optimal time, which is why Ryan Walmsley used a Particle Photon to upgrade his EV charger.
Walmsley’s power company is Octopus Energy, which operates in the UK. Their prices are roughly on par with other companies during the day, but the prices drop down to a mere 30 percent of that for a four hour period during the night. That’s because the grid usage is lowest during that time period. Walmsley wanted to take advantage of that and only charge his electric car during the low-price window, which can save a significant amount of money in the long run.
While many electric cars and charger models have built-in timer functions intended specifically for that situation, Walmsley’s setup didn’t have a satisfactory way of doing that. So, he cracked open his EV charger and eventually found two functions that could be used to achieve his goal. The first is a lock-out, which is intended to disable the charger so other people don’t steal your electricity. The second is a control pilot signal, which is used for communication between the car and charger so they know each other’s status.
He couldn’t just trigger the lock-out, because the charger doesn’t automatically turn back on after the lock-out has been disengaged. He also couldn’t disconnect the control pilot signal during charging without throwing errors. The solution was to do both: first lock the charger, then disconnect the control pilot. That was done with a simple relay controlled by a Particle Photon, which is triggered by an IFTTT timer. Walmsley reports that the setup works well, and can be improved upon in the future for even more specific cost-savings measures.