Traction Battery Questiion

<div class='quotetop'>QUOTE(Perk @ Jan 21 2007, 12:26 PM) [snapback]378757[/snapback]</div>

Here is a cutaway view of the battery cooling system.

 

Note especially that the traction battery is cooled by cabin air. If you avoid using air conditioning in very hot weather in an attempt to improve your fuel economy you may actually reduce fuel economy and risk damaging the traction battery, because it may be running too hot.

 

Following on Richard's point, a few Prius drivers have added equipment that allows monitoring HV battery temperatures with the sensors already installed. In my 2001 Prius I make a point to use A/C whenever the max battery temp reaches 45 oC. Summer driving is a necessary but not sufficient condition for this. What really gets it hot is up and down mountainous terrain. The highest I have yet noted is 51 oC and I went to full blast A/C at that time. The coolling rate is about 1 oC per 5 minutes, and very much slower of the ventilation system is set to 'recirc'. I would not claim that 45 oC is a 'danger level', but certainly there is one, and it may not be very much higher.

DAS

 

If the battery's getting hot, you'll know about it because the battery fan in the back will come on full blast... If you can't hear that fan running, then there's definitely nothing to worry about.

And on top of that, if the battery is too hot for safety, lots of warning lights will come on...

Don't worry.

 

<div class='quotetop'>QUOTE(KMO @ Jan 24 2007, 08:26 PM) [snapback]380369[/snapback]</div>

Agreed, I overstated the case: the traction battery won't allow itself to be damaged. But if it's too hot (or too cold) it will operate less efficiently. Rule of thumb: if you're comfortable then so is the battery.

 

Hi Tideland, in 2001-2003 Prius the HV battery air inlets are on rear shelf, and the outlet is external. Cabin air flows through, especially when not set to 'recirc', and heated or cooled according to heat/A/C settings. On the new model it is similar.

I am not trying to sound alarms here about HV battery temperature control. Just to note what I have seen, my criteria for action, and the observed results. I would agree completely that under many driving conditions, no operator intervention whatever should be required.

In general NiMH battery lifespan is reduced by excessive temperatures, but it may also be that my decisions to intervene are on the conservative side.

 

I think the same is true for low temperatures. For some time I tried not using the heater for cool days. The result where that the engine shut off more but I wasn't getting much help from the battery. The result seemed to better or actually slightly worse then keeping the heater to 65F (for temperatures under 32F)

 

<div class='quotetop'>QUOTE(tochatihu @ Jan 24 2007, 03:15 PM) [snapback]380336[/snapback]</div>

on of the advantages of the Classic is when you use the A/C to cool the battery your actually cooling it, the G2 uses the HV battery to run the A/C compressor and that conversion of chemical to electricity makes the HV battery get even hotter.

 

Not really... it CAN use the battery for A/C (like while waiting at a light), but it will simply use the ICE if the battery and motor to generate the current for the A/C if the battery is getting hot. It will not heat up the battery in order to run A/C so it can cool the battery--that would of course not work.

 

<div class='quotetop'>QUOTE(KTPhil @ Jan 27 2007, 01:15 PM) [snapback]381742[/snapback]</div>

sitting in low speed or stopped traffic with the A/C on it'll pull the battery down to 2 pink bars before the ICE will cut in that chemical reaction to produce electricity to run the A/C causes heating of the battery. This summer I'll pay attention to the voltage and amperage draw on the HV battery just to see what temps it'll get the battery to. The G2 A/C pump should have been hybrid like the HAH any time the ICE is running it powers the compressor and when it's off the battery does. That first 5 minute run of the ICE should be driving the compressor.

 

My battery drops to two pink bars and the cooling fan comes on full blast every day on the way home from work during the summer. I've tried everything.

My office recently trimmed the tree I used to park under so it no longer provides shade.

It really sucks because when I first get on the highway, I have a hill to climb, and the battery drops to one pink bar. After that, the car kind of comes back to normal.

Nate

 

In the winter, the engine runs to make heat, so the battery is nearly full when I get on the highway.

Nate

 

<div class='quotetop'>QUOTE(Tideland Prius @ Jan 28 2007, 05:37 PM) [snapback]382099[/snapback]</div>

Take a look at the link I provided above.

 

<div class='quotetop'>QUOTE(Tideland Prius @ Jan 28 2007, 10:49 PM) [snapback]382194[/snapback]</div>

yes it vents out behind the plastic rear bumper corner behind the rear wheel opening.