Owning an electric car can be harder if you live in an apartment than a house, since most apartment building garages only have enough power to charge a few cars; if you don’t park at the right time, you won’t be able to plug in. One startup is trying to solve the problem with smarter charging stations: By sending data between the stations, it’s possible to retrofit old buildings to support many more cars at once.

“Most parking garages are designed with enough power for the lights and maybe the gate and an elevator but not a whole lot more,” says Joseph Nagle, director of marketing for EverCharge, the Bay Area startup. “It’s because of that that it gets really expensive to get additional power into most buildings.”

Depending on the building, adding more power might mean drilling through seven feet of concrete, trenching through an entire parking lot, or building a new electrical room, and getting all of the permits to make that possible. “We’ve seen quotes from PG&E that are well over a million dollars for additional electrical infrastructure,” says Nagle. Even on the low end, adding more power can cost tens of thousands of dollars.

By using software, smart chargers can quickly upgrade a garage without major changes. When a charger isn’t in use, it can divert power to other stations that need it. If the battery in a car is almost full–so it’s pulling power in more slowly–the charger can send extra, unused power to another car. Over time, the system can also start to learn when drivers plug in their cars and how much power they’ll need, which also helps the network run more efficiently.

“What we find is that people are creatures of habit, so you’ll see someone doing the same charging routine over and over,” he says. “Doing things like that allow us to predict with a fairly high level of accuracy when a charging station is going to be in use.” If the system knows that a particular car is likely to stay parked for the next eight hours, and the battery is already 70% full, it can send power to other cars that might need it more quickly.

In a garage that could charge two or three cars in the past, the system can support as many as 15 charging stations. In new garages that were built for electric cars, it can help even more. In a recently constructed building in San Francisco, designed with power for 25 charging stations, the company was able to use its system to support around 160 chargers–one for every parking space.

As electric cars become more common, so are the garage retrofits. “With major cities, it’s already becoming something that we see as a must-have, especially in places with high concentrations of electric vehicles,” says Nagle. “Here in San Francisco, it’s already a necessity for buildings.”