I bought a prius 3rd Gen

If the battery is full on the gauge, i press EV mode it only lasted 10 seconds. I did some Googling and a post said its normal, i was skeptic and got an obd2 reader, did a life expectancy battery test on dr prius, but 3/4 of the way it stopped said bad obd2 but i still got results, but is that normal it says that? I use a obd2 viecar