I just ran this app (Dr. Prius for Android) and it's very useful for monitoring the HV battery's health in realtime. There should be 28 modules total for the V (3rd Gen), but looks like they are displayed in pairs showing 14. You can get an idea which module may be out of balance. I'm using it to also monitor max and min pack voltage that I have seen and under what conditions they show up. You'll need an ODB2 reader with bluetooth.
Max regen voltage generated was 260V. Was in the red but for very short period. You can get to explore what driving habits generate the best regen in realtime. I seem to get good regen when I am in PWR mode and EV mode at the same time when hitting the brake. The key is to drop to below 25mph before hitting the EV Mode button. But I need to check with this app some more to confirm. Great app to see what's happening to your HV battery when going up or down a mountain. When going down a mountain I will test to see if blasting the AC will save the brakes. As long as regen is running, I assume the brakes are being saved.
So I notice packs in the middle are low voltage. It's apparently well known by some PC members that packs in the middle get the hottest and are usually the first to stress out or fail. So this is for the very advanced DIY. Like how we are recommended to rotate our tires every so many miles. It may be wise to rotate the batteries modules every so many miles as well. Where the inner ones are rotated toward the outer. Another thing I notice is that some owners are charging their entire hv pack as one parallel pack. From a battery charging perspective, this is a VERY GOOD thing for the batteries. It allows them to nearly perfectly charge in balance without "hoping" that they will get into balance by discharging heat while waiting for the weak ones continue charging. In parallel, they go through a form of "self balancing". But this is for the very advanced DIY.
