On Three occasions now I have had my HV battery be very low after being parked all night, It had enough power to start it twice and I had to jump it once, It seem to happen after driving through standing water during a rain. Does anybody have an Idea of anything I should look at. I am planning on taking it in for a complete checkup when I hit 30,000 I now have 25000 miles on it. We are trying to make it to summer break so it will be easier to get it worked on as then we won't need 2 cars. Does the break pump run off the HV battery system?

 

The problem is probably the 12v battery, not the HV battery (jumping a battery only works for the 12v). In any case you are still in warranty - take it to the dealer.