There's a lot that buyers should consider before purchasing a secondhand electric vehicle after Congress passed a bill that will make used electric cars cheaper.

A brand-new $4,000 incentive for used cars is added to the inflation reduction act. The program will go into effect in 2024 for vehicles that cost less than $25,000. The income cap is $112,500 for a head of household.

From how to judge a car's battery health to the models to avoid, here's what you need to know about buying a used EV.

EV batteries lose capacity over time, but they rarely die completely

You can experience battery degradation if you own a laptop or phone for a long time. The same thing happens to the batteries that power electric cars.

If an electric car is rated for 250 miles of range when it's new, don't expect it to travel a long time. According to a study, EV batteries lose 2.5% of their capacity annually.

Some models tend to have faster degradation than others because of factors like a hot climate.

It's not important that the EV's battery dies on you.

The battery packs should be looked at like an engine. "Obviously, a car's engine can fail, but for most of the time, it's an outlier," said BenjaminPreston, an automotive reporter at Consumer Reports.

You can minimize the risk of a bad battery

Chris Harto is a policy analyst at Consumer Reports. He said that he wouldn't buy a used electric vehicle unless he knew the current state of the battery.

Harto said that shoppers can order a state-of-health check on a vehicle. He said that taking an extended test drive could shed light on a vehicle's remaining range.

It's a good idea to check to see if the vehicle's battery is still under warranty, what the manufacturer's policy is, and if the warranty transfers to subsequent owners. Some companies don't bother with battery degradation.

Buying a used car is going to have some risks. Consumer Reports' reliability rankings can be used by shoppers to guide their purchases.

Electric cars need less maintenance and there's less that can go wrong

Electric cars have less moving parts and need less maintenance. You don't have to worry about the previous owner changing their oil or transmission issues.

Used EVs often have outdated tech and less range

Older EV's often don't offer the same driving range as their modern equivalents. The current model of the Model S has a range of between 200 and 300 miles. The first Nissan Leaf had a rating of 73 miles of range.

EV's can charge more quickly.

It could make a great second car

The editor-in-chief of the vehicle marketplace Cars.com said that an older EV can still work great for commuters or as a second car, even though it has a diminished range and DC fast-charging capability. She said that a used electric car could work well for short errand.

Consumer Reports' Harto concurs. He said that a used Nissan Leaf with 80 miles of range would be a perfect car for a teenager to drive. If you have more than one vehicle, not every vehicle needs to do everything.

There aren't a lot of options right now

Since electric cars are only hitting the mainstream, buyers shouldn't expect a lot of secondhand EV options.

Compliance cars were built in small amounts to meet environmental regulations. Harto said that shoppers might consider avoiding those models because of the difficulty in finding parts.

The same considerations about buying a new EV also apply

How much range you need and where you'll charge are other things you'll want to think about. There is a guide for first-time EV buyers.