There's not much to look out for - like you say, there are fewer moving parts. Do some research into the specific model you're looking at. Is the battery included or will you have to sign up to a battery rental agreement? This isn't always clear in adverts. Some models (like the Nissan Leaf) will have a battery indicator which will give you an idea of the state of the battery. Generally, a battery will lose around 2% of its capacity each year, although this is dependent on factors like how often it's been rapid charged. Look for an example with full service history as this should mean the battery warranty is still valid. A warranty probably isn't as much of an issue on an older EV, although the Consumer Rights Act 2015 will give you some protection on a used car bought from a dealer.