Desert heat testing

*looking out the window at the rain falling... and it's 60 degrees out there*
Um, mine is doing fine so far...

 

<div class='quotetop'>QUOTE(jstack @ Jul 20 2007, 02:05 PM) [snapback]482375[/snapback]</div>

I'm in an even hotter part of Arizona than you, and I have noticed a lack of power after the car sits in a hot parking lot (I'm talking 120 plus) for a couple hours. A few times the fan by the rear back seat has come on and is much noisier than in cooler weather. My MPG is also about 1 to 2 MPG less than in the winter time temps of 65 to 75. But my only complaint is a slight rattle in the dash board (maybe that's where it is) that also started when the temp went up. Hope that will go away when it cools down !!!!!

 

I haven't noticed any major problems. MPG seems to have dropped a bit. Battery seems to be low when I leave work after leaving the car parked outdoors all day, so the engine needs to run more than during the winter. The A/C can keep up with the heat, but that is also a drain on the battery. I keep the A/C on Auto, with the temp set around 74, except when I get a phone call and can't hear the phone over the sound of the fan.

The biggest challenge I have in the desert is trying to keep my white car from turning brown in the dust/rain storms of the monsoon.

The only things I changed when I moved to the desert are:
1. Tinted windows
2. Always use windshield shade when parked in the sun
3. Installed Prius Hood over the MFD screen

 

It was a blistering 105 yesterday and my 2005 Prius was parked outside.

When I started it, the car showed 6 bars on the battery meter. This dropped down to one purple bar within a minute, and it started running erratically and sluggishly. Mileage took a serious dive.

I took it in to the dealer first thing this morning, and the mechanic said that they couldn't find anything wrong with it. He stated that they've started seeing this kind of problem everywhere (he mentioned AZ and Las Vegas) lately. He said that when it gets really hot, the battery protects itself by discharging to dissipate heat, and sometimes the car shuts down altogether. I'm not sure he knows what he's talking about since several here claim that everything's fine in the heat. Any similar experiences?

 

I did lots of 'hot driving' in a 2001 Prius with no problems at all. Patrick Wong (posting at the Yahoo groups) has reported some minor issues, so perhaps the jury is still out on this one. All I can say is run the A/C when it's hot, because that will help keep the HV battery cool. When better aftermarket instrumentation becomes available for the current-model Prius, one could monitor MG1 temperatures and do a precautionary 'stop and cool off' when that value exceeds 120 oC.

Lhazzard, the HV battery will make heat both while charging and discharging, so your mechanic may not be on firm ground there

If anybody is seeing performance issues in the heat, it would be important to confirm that the inverter coolant system is performing correctly.

 

I've driven through the dreaded Mojave Desert full tilt during the day and had no problems.

 

The only time I have experienced the problem with dropping to one bar and the engine/motor behaving somewhat erratically was when I was leaving the Weiss Guys carwash on Elliot in Tempe. I won't go there again because I don't know what they did to drain the battery.

I think there is a problem with the car in that the power does work erratically when the battery is drained that low.

 

From my observation this doesn't really have as much to do with the battery being low then the car being hot.

If I leave my car parked in the Sun for a couple hours over 110 degrees I have the issues discussed here but the erratic power is regardless of my battery having 6 bars or 1 bar. I have only had this happen when my MFD reads 113 and higher outside temperature.

Once the AC cools the inside of the car off the car drives with no issues.

I believe what the one person was saying is true.

The car seems to discharge the battery to help cool it off and discontinues the use of the battery for propulsion this is why it seems that we have no power because we are depending on our torqueless motor to propel us from a standing stop.

Once I drive with the AC on for 5 or 10 mins all is back to normal.

 

That makes absolutely no sense at all. Batteries have internal resistance, so discharging them creates heat inside of them. Just touch the NiMH battery pack of of an R/C car after it's been driven hard a few minutes and you'll find the pack is very hot.

 

I know you are correct that batteries get hot when charged and discharged.

Maybe it doesn't actually discharge to cool but maybe it doesn't allow the battery to charge and that is why it appears to discharge.