used Prius C has 57% battery for 30k miles

welcome!
no, it is not normal. is it from a toyota dealer? any warranty?

 

In very slow "stop and go" traffic, the car actually uses the HV battery to propel the car and to run the AC.
This is about the only situation where the C uses battery only to move the car.
What you are seeing likely is "normal".

 

My Prius C uses the battery a lot in city driving, not just to propel the car forward and power the AC.

50-60% (or more) of my city miles are EV miles.

 

Maybe test was not done right?

 

The app is useless garbage. It uses a few metrics but it is not a real test.

As for a 2016 Prius C, the pack is smaller to begin with and then you now have 6 years on it (2016 is made in 2015). A Prius can drive with little change until a very low capacity. Just drive it and be happy.

 

The odometer tells you how beat up the interior should be. The calendar tells you what shape the battery is in. In other words, ignore the mileage when evaluating the battery; age tells you more.

You've probably got 3ish years before it needs a replacement hybrid battery. It could last longer, but they are notoriously difficult to predict.

 

Keep the battery fan clean and use plenty of air conditioning. The battery breathes cabin air to keep itself cool, and the cooler you keep it the longer it will last overall.

Welcome & good luck!

 

For the second time the test is meaningless.

As you should have just clearly proved to yourself. Unless you believe your battery self healed

 

That seems much closer to the condition of a 2016 Toyota battery in a car with only 30k miles.

I personally think the data the Dr. Prius app provides can be useful if you need to investigate a potential battery issue, or maybe you have an older battery showing its age and are about to take a road trip - it wouldn’t hurt to connect and test. My 2014 scored 88% at 45,000 miles when I bought it in April 2020. I haven’t tested it since, but I’m curious how much the percentage has dropped with another 25k under its belt, so I’ll get around to it soon.

 

Toyota has a "hybrid health check", utilizes Techstream. I believe in UK having it done allows you to extend the battery warranty? It's big in UK, but nobody seems to have heard about it in North America.

Toyota Hybrid Health Check - Toyota UK Magazine