Leaving a cooler of ice in the Prius for hot weather.

If the frozen water bottles are water tight, and if the condensation that collects in the cooler does not leak out or completely evaporate, then you are actually drying the air in your car.

 

dry ice!

 

The thing is, we would need data of battery temperature after shut down to see if there was any merit. There may be better approaches such as pulling down state-of-charge (SOC) e.g. by upping A/C before parking. Reportedly the worse thing to do is park in sun at full SOC (battery self-heats).

We have very little data on battery failure rate..we know some go bad, but we don't know how many and why they failed. Especially Gen3 we have very few reports here. Anecdotally the hotter regions are worse. Maybe some of our battery replacement vendors can comment on how many Gen3's they see.

 

Yes you are correct. The way the batteries are packed into the case with 28 other modules, there is no way to cool the battery pack simply lowering the temperature of the cabin by 1 degree with an ice cooler. The center of the battery is so hot and packed so tightly, it's already engineered to be able to withstand that heat.

If you have extra time on your hands.......go do something fun (to the OP)

 

could be that batteries that go bad had a defect from the beginning.

 

A more direct way of cooling the battery would simply run the hv fan on days it's really hot. Tap into the fan wiring and get another car battery to run the fan. Charge the 2nd car battery when you have time, rinse and repeat. At least that gets what you want done.

Someone can easily make this to work. Hybrid automotive makes the fan adapter/bypass

 

Actually, sun shades do not prevent heat build up in the car. Every car, when exposed to the heat for an extended period of time, assumes the temperature of the air around it.

 

Well this may be true but I much rather stand in the shade in a hot day vs standing in the sun. I think the windshield shades work really well

 

But when also exposed to strong sunlight, such greenhouses tend to get much warmer than the ambient air. They don't assume the temperature of the ambient air until well after sunset.

 

So what?
You said you were "worried" about it.
You bought a newer Prius. It has a hybrid battery warranty, no reason to worry until you surpass it.
No real good way of testing for potential failure.

You may easily be able to go 12 years...it may fail .1 second after warranty expiration.
Given this, worrying about it is a waste of time.

 

Your from Menifee and don't believe that a reflective style sun shade keeps the interior of a car cooler? I can't believe that! I used to live in Temecula and it gets hotter n hell and the sun can be brutal, I would much rather get into a car that has a sunshade blocking the windshield during those 110+ deg desert days than not....

With that said I don't even use a sunshade, I have my car Fully tinted out and don't live out there anymore...

 

Very true, and furthermore, a little longer after sunset on a clear night, the temperature of the car (especially upward-facing exterior surfaces) will fall below the temperature of the ambient air. (Otherwise, dew would not form.) The statement that a parked car will always assume the temperature of ambient air is nonsense.

 

I think it's undisputed among experts that high temperatures accelerate the aging of NiMH batteries. See for yourselves: Google

My personal guesstimate would be that one could extend the life of the battery by up to about 5% by taking reasonably convenient measures to keep the battery cool. But that figure is certainly disputable.

I myself, personally, do the following:

• Park in the shade when reasonably convenient
• Use sunshades when parked in the sun and when reasonably convenient
• Park facing the sun when parked in the sun and when reasonably convenient
• Allow the climate control to automatically run on recirculate until it thinks that the cabin air is cool enough to push through the battery, when reasonably comfortable
• Direct part of the cold AC air overhead and towards the battery cooling air intake, when reasonably comfortable

Keeping the cabin cooler while parked has little impact on battery temperature as long as the car is parked. But after the car and AC has started, the cooler cabin materials and cooler cabin air help cool the battery a little quicker and with a little less energy.

 

My Cmax Energi is an air-cooled LiOn design and I monitor its battery and interior temps with a scangauge. I've found parking in the shade during the day is the most effective thing for the battery. 20 minute pre-conditioning with a/c really cools the interior (brrrr) but usually raises the battery temp a couple of degrees.

There are a couple of folks on the Energi forums trying to come up with cooling ideas like the OP here but theirs are much more complex. Me? I just leave for work a little earlier so I get the best parking spots in the shade.

 

The Solar Roof could have maybe have been used to run the hybrid fan when the car's off. Not as sexy as cooling the cabin, and might raise alarm bells with potential buyers. I wonder if an aftermarket solar collector would have enough oomph? Still, only effective if the cars sitting outside in sun.

 

If cooling the battery is a necessity, Toyota probably would have integrated something to do that. We are on Gen4 Prius cars and Toyota has not developed anything to cool the battery while it sits......that to me just means it doesn't need it.

 

I'm thinking that a battery that spends a lot of it's life right at the hot edge of the design limit is going to be impacted. Yes it's within specs, but it's not a good/not good digital thing.

I watched the temp with a Scan Gauge, and we have an uninsulated garage that can really start to cook in summer. I suspect worst case is driving on a hot day, into the hot garage, and there it hot soaks.

 

But when a car is sitting the battery is much cooler than when it's actually used while driving. Those temperatures exceed whatever temperature is when the car is sitting in the sun.

If you trust in the engineering of Toyota and their battery designers, then you would have to trust that whatever heat there is when the car is sitting, it won't affect the battery. But in any manufacturing process, nothing is perfect. That's where you get some failures in the battery prematurely....but that does not mean it's heat related. I've had more batteries fail me during cold winter months than hot summer months.....but that's lead acid stuff