12v battery runs down while driving

2007 Prius 5. 187k miles. One year old new hybrid battery. Just had inverter water pump replaced. Right after that the car started to have random dash lights. Brake light wood come on then turn off. Checked brakes and fluid, looked good. Then a steady alarm beep would come on (like when you get out when the key fob is inserted.) Again it would be intermittent. Come on, then turn off and not come on for a day or more. Then the AC would stop blowing cold air. Again, briefly, then it would stay again.

Finally, while driving home the brake light and the alarm came on and the anti lock brake light came on. Shortly after, the ac stopped the blowing cold. Then the red triangle came on and the car lost power. I pulled over off the road and then the dash went dark and the car died and would not start at all. And the windows wouldn't roll up, radio wouldn't play. When AAA got to me, the driver mentioned seemed like the 12v battery was dead. But towed to the house and sure enough the 12v was dead. But it charged over night and was showing 13v in the morning.

Since then, the car appears to run fine in the mornings before the heat of the day. But when driving home, of I drive more than about 30 minutes I start to get the same symptoms but it hasn't died since. But I notice the fully charged battery is putting out 13v and it seems to drop about 0.5 volts each day of driving and when it starts to have the intermittent symptoms, it is going to show a bit under 12v. So I can drive the car 2 or three days then have to put a charger on the battery to top it off.

What could be causing this?

Thanks for any ideas.
Michael