Battery heat condensation?

Gee I don't know anything about it but I don't like the sound of it.
In this new age of electronic vehicles (hybrids and EV's) we need to be mindful to minimize corrosion etc.
I don't like it when my wife stores orange peels and apple cores in the small waste basket we have.
I try to keep windows open a crack in the garage to give moisture a chance to escape.

 

I have a 2007 Prius and have the same issue. At first, I saw water near the rubber weatherstrip and thought water got in. Clean it up and forgot about it. Then by chance I flipped the trunk mat over and there was condensation there. I cleaned it up, put it back, then checked on it a few days later. There was condensation again. There is no water inside, no rain lately, no water in the spare wheel well, back seats are not wet, etc... I don't know what to do or should be worry about this.

 

do you run the a/c consistently? i can't see condensation with a/c drying things out.

 

I do. I run my A/C basically all the time since I got the car. Personally, I don't think it's condensation due to humidity in the air alone since none of the windows or back windshield fog up. It just condenses above the battery. This makes me think it's probably the battery is heating up enough to condense the humid air under the mat, but not hot enough to throw an error (yet).

After some more research, I think it's possible that the HV cooling fan might not be working optimally. It's possible that it's very dirty, filter (is there one for the cool fan?) dirty, something got in the duct and reduced the air flow, etc... I got to open it all up at some point and report back once done.

 

or it could be a body gasket/seam/hinge leak.

 

I was thinking, if anything: AC promotes condensation. Yeah when the car's running the cabin air is dryer, but it's accomplishing this by condensing water vapour outa the air, onto the chiller thingy in the ventilation system. Then when you park with windows rolled up, the chiller thingy temperature comes back up to ambient and the condensate evaporates back into the air.

Now why there's extra dampness under the hatch area mat I do not know. There is a fan drawing air in at the back seat back, running it across top of hybrid battery.

Take the mat out for a while, see what happens. Maybe just throw a blanket in there in the interim, for protection.

 

Condensation doesn't form when something heats up, it forms when something cools down. The battery is thoroughly ventilated so condensation isn't really possible.
Have you removed or modified the foam trays that sit in the rear well? Those are part of the ventilation and form a sort of "duct" under the deck directing air out the back.

 

I looked for cracked seams, etc., but found none. There is no water in the spare wheel well or the backseat. Well, knock on wood and hoping it stays that way.

The heated air next to the battery chassis cools down as it escapes pass the liner and gather onto the rubber mat. I'm thinking that the ventilation of the battery is compromised slightly some how. At least that's my theory. I didn't know about the foam trays. I'll have to look them up and keep an eye out for them when I have some time to open up the rear. Thanks for the extra information.

 

i wonder what happened to camp ooze?

 

If you're running re-circ, this is not the case as all the condensate is coming from humidity in the cabin. Every drop from the evaporator drain to the exterior of the vehicle is less total humidity (dew point) in the cabin.

Even running A/C w/o recirc should lower the dew point in the cabin.

 

I have a new 2015 MY Prius V 4 and there was water pooled under the spare tire and under the 12V battery just after delivery from the dealer. After a little experimentation I found that water sprayed under the vehicle (car wash or garden hose) will enter the above mention area via the traction battery exhaust vent on the passenger side of the car. The exhaust air vent is covered by 5 thin rubber flaps mounted on the vertical wall next to the 12 volt battery. Water sprayed for the outside will easily knock the vents open and allow water to enter. There are a matching set of vent flaps on the driver side of the floor pan, but the clearance between the flaps and the outside body panels is tighter. It does not appear that water is likely to enter on that side. Obviously, water pooled on the floor pan will evaporate and condense on an added rubber floor mat. I suggest that after a car wash, shine a flashlight down at the base of the 12 volt battery and check for water.

 

Thanks dick_larimore for that insightful info. I'll keep an eye on that.

So far I haven't open up the area yet (have been busy working on my Corolla for the last month doing overall maintenance).

 

I finally had some time to clean the battery cooling fan today. It's a nice 60 F sunny day Sorry, no pic.

The fan is definitely dirty. There's a build up of roughly 0.4 mm of gunk on each of fan blade. I took the fan out, scraped it with a bamboo skewer, then sprayed it with brake cleaner. After that I sprayed some dry liquid lubricant on the center pin, hoping it will help lubricate the spindle. Put everything back and now I'll wait to see if that helped with the condensation or not.. Although it's winter weather where I am and the air is dry so I'm not sure if I'll notice anything.

A note: I disconnected the 12v battery before doing this and that resets lots of things. It was disconnected for over 30 minutes. The main thing that it resets that you might have to look out for is the fuel gauge. When I reconnected the battery, the fuel gauge was flashing 1 bar. I did a fuel tank calibration (search on here) and that put it back to where it was before. Also, I noticed 3 relay clicks upon start up and 2 relay clicks on shutdown. Not sure if they ever were there before, but the car runs fine and no error code is shown.

cheer.

 

the air was very moist today.

 

double checked and you were right... 85% humidity. Still no work so no long drive to check. I'll keep an eye out for it though.