The best time to stop a battery fire? Before it starts.

The reignition is yet another reminder of how difficult fires in lithium-ion batteries can be to deal with. They burn hotter than other fires—and even when it looks as if the danger has passed, they can reignite.

As these batteries become more prevalent, first responders are learning a whole new playbook for what to do when they catch fire, as a new story from our latest print magazine points out. Let’s talk about what makes battery fires a new challenge, and what it means for the devices, vehicles, and grid storage facilities that rely on them.

“Fires in batteries are pretty nasty,” says Nadim Maluf, CEO and cofounder of Qnovo, a company that develops battery management systems and analytics.

While first responders might be able to quickly douse a fire in a gas-powered vehicle with a hose, fighting an EV fire can require much more water. Often, it’s better to just let battery fires burn out on their own, as Maya Kapoor outlines in her story for MIT Technology Review. And as one expert pointed out in that story, until a battery is dismantled and recycled, “it’s always going to be a hazard.”

One very clear example of that is last week’s reignition at Moss Landing, the world’s biggest battery storage project. In mid-January, a battery fire destroyed a significant part of a 300-megawatt grid storage array.

The site has been quiet for weeks, but residents in the area got an alert last Tuesday night urging them to stay indoors and close windows. Vistra, the owner of Moss Landing Power Plant, didn’t respond to written questions for this story but said in a public statement that flames were spotted at the facility on Tuesday and the fire had burned itself out by Wednesday morning.

Even after a battery burns, some of the cells can still hold charge, Maluf says, and in a large storage installation on the grid, there can be a whole lot of stored energy that can spark new blazes or pose a danger to cleanup crews long after the initial fire.

Vistra is currently in the process of de-linking batteries at Moss Landing, according to a website the company set up to share information about the fire and aftermath. The process involves unhooking the electrical connections between batteries, which reduces the risk of future problems. De-linking work began on February 22 and should take a couple of weeks to complete.