12 volt battery change and alot of water under it

Well I have been watching my 12 volt battery voltages in the morning before I start my 2006 Prius and I have been noticing the voltage is getting lower ( 11.6) a couple of times. So I decided to replace the 12 Volt battery with a Optima Yellow Top DS46B24R that I purchased from my Local NAPA.
NAPA's Part number for this battery is N9951HEV. Manufactured 1/13 and 12.8 volts. Install went fine and all is well.

But I noticed a lot of water in the cavity under the aux battery. I went through the carwash last week and I suspect the water is getting in through the HV battery air vent to the outside. This is making me very nervous. Any other car I would leave the little rubber plug out of the well under the battery and let it drain out all the time. I am little more cautious of doing this with all the electronics in that area of the Prius.

Anyone else ran into this? Probably should stay away from the under car washes from now on.

 

I didn't see any water other than the water under the battery area. It doesn't look like the door seal is leaking. I may just remove the spare tire cover pan and sit in the rear area and run the car through the car wash and confirm where the water is coming from.

 

OK I didn't go through the car wash since I dried out the water under the aux battery and I looked tonight and there was some more water under the aux battery. I removed the aux battery and dried the area under the battery again and looked at the seams around that area and noticed one area that was not gooped up with the sealant they use. I used some silcone sealant around the suspect area and assembled everything again. I will check it again this weekend. Looks like more rain in the forecast so I can test it. The door seal looks fine. I'll post my findings this weekend if I remember.

 

Well the hunt for the source of the water below the 12 volt battery was interesting to say the least. All I can say is you better have real good eyes or in my case a magnifying glass. I really didn't have much chance to look for the water source this weekend on my 2006 .

My daughters 2004 Prius 12 volt battery was failing so I had her bring it down and I was shocked to find her car had about 2-3 inches of water under her 12 volt battery. I drained it, replaced the battery and bunch of other items.

After searching all the same water issues everyone is having here my son and I did the garden hose on the outside and me on the inside. Leaking like sieve inside between two pieces sheet metal above the battery area. I followed all the advice from everyone else s water source hunt. Checked the hatch seal, removed gas strut on that side, looked at all the seams on the hatch channel and all looked good.

After finding a message here about small cracks under the trim stripe on the sides of the roof I revisited looking at that area my her 2004 ( with a good light and magnifying glass this time) and low and behold a small crack right below the small clip that holds on the trim piece. Well I used some clear silicone on hers and looked at my 2006. Same thing.... So I hope that does it but I am sure it will. So if you are still looking for the source of the leak on your car really clean this area and good with a magnifying glass and good light. I missed this the first time.

 

I wonder if you can buy that in a smaller can? Quart would be over kill for what I need.

 

2006 Prius crack right rear corner

 

2004 Prius right rear corner

 

Neither has leaked yet....after I used some clear silicone. The silicone probably won't last but time will tell.

 

If you look at your car roof there are black plastic strips one on each side. Pop the rear part of the strip off at the rear of the car.( it pops straight up very easy) then clean the area around the little metal clip very good. I used 409 cleaner and a old toothbrush. The 409 cleaner was only used because it was handy. Then I used compressed air to blow the area off. If you don't have compressed air use water in a spray bottle and let it dry. Look very close because I missed the crack the first time.

 

My leak was the cracks I posted in the pictures and they are fine now. I just used clear silicone on the crack after I cleaned them up with an old toothbrush and compressed air. I was back in that area last spring changing another bad module in my HV battery and it was dry.