Testing battery health is a bit technical, which is why most mechanics etc don't know how to do it properly. First of all, individual voltages or pack voltage don't tell you anything. I can show you a weak battery with 16+ Volts per module, and a strong battery with <14V per module. The difference will be the load. The best way to test the battery health is under load. If you are charging a battery, and it shows, 16V per module, it doesn't mean the battery health is good. Similarly, at the time of the engine start, if the modules show 14V, that doesn't mean they are bad. Some apps have features to test battery health, you can use those features to test the battery to varying measure. For example, Dr Prius App will show you a percentage health remaining (that sometimes even shows above 100% BTW, so take it with some salt). Similarly, there is this app called Hybrid Assistant, which has a hybrid battery check feature, which has to be used with another app called hybrid reporter. You run that test, and it will give you an approximation of how healthy your battery is. But keep this in mind, that there are several variables that govern battery health, so these are all approximations in the conditions you tested in.
In short, I would say, take care of your battery by not flooring the car often, and driving on the engine as much as possible. You will, surprisingly, get good average, and your battery will not go bad soon.
