So close and yet so hot

[TonyPSchaefer]

After the 120-mile, 57MPG drive home from Hybridfest, I have been working to get this tank back up to at least 66MPG where it belongs. I've been seeing jumps of up to 0.5MPG per day on average and felt that it was in the bag yesterday on my evening commute because in the morning I got it up to 65.6.

All was going well for the first few miles. Oh sure it dropped the obligatory 0.2 from the first segment, but with the second segment starting a string of ~75MPG I was feeling confident.

Then it all went horribly horribly wrong. There was nothing I could do to stealth. It just wasn't happening. Gliding was pretty much out of the question also. It was as if Priapus had forgotten that there was a big-ole battery in the back with 6 bars of charge. Press the pedal and the ICE kicked in; let up and the regen began. There was no middle ground.

That's when it hit me: the battery is too hot. The ambient temperature was 89ºF and with the A/C off and the windows up, the internal temp was definately in the 90s. When I'm sitting still I roll the windows down to cycle out the hot air. But when you're timing the stop lights, you don't stop much. So I did what seemed counter-intuative to someone trying to improve their mileage: I turned on the A/C. Set to 85 at first, then lowered to 80 and finally 75. I've got to admit it did feel good. Sure enough, after only a few minutes, I was stealthing again.

Now I'm not going to claim to be a wise man. You see, after things went well for several miles I figured it was all okay. So, of course, I turned the A/C off again. You've got to undersand, even when I was gliding I could see the battery draining which made stealthing harder and the engine run more to regen. Yes, with the A/C off I reached the point of no-stealth/no-glide again and ended up turning the A/C back on.

End result: I made it home with a running tank average of 65.8MPG.

This morning the temp is a very nice 70ºF and my current running tank average is 66.2MPG. I'm pretty sure I'm going to be running the A/C on the way home.

[paulccullen]

<div class='quotetop'>QUOTE(TonyPSchaefer @ Aug 3 2007, 06:33 AM) [snapback]489898[/snapback]</div>

That's when it hit me: the battery is too hot. The ambient temperature was 89ºF and with the A/C off and the windows up, the internal temp was definately in the 90s.[/b]

No disrespect Tony, but are you crazy? Is the few pennies you save in FE by not using A/C worth the sweaty discomfort of sitting in a 90ºF car?

OK, I admit, I play that "how high can I get the MPH" game too, but I like my creature comforts too.

[Danny Hamilton]

<div class='quotetop'>QUOTE(paulccullen @ Aug 3 2007, 09:58 AM) [snapback]489916[/snapback]</div>

OK, I admit, I play that "how high can I get the MPH" game too, but I like my creature comforts too.
[/b]

You're fuel efficiency must be pretty poor.

I used to play the "how high can I get the MPH" game all the time, then I bought a Prius, and fell under the spell of the Prius Affect. Now I am one of those drivers I used to complain about, tailgate, swerve around, etc.

Yes, I realize it was a typo and you meant to say MPG, but I just couldn't resist the joke.

[Danny Hamilton]

<div class='quotetop'>QUOTE(TonyPSchaefer @ Aug 3 2007, 08:33 AM) [snapback]489898[/snapback]</div>

I'm pretty sure I'm going to be running the A/C on the way home.
[/b]

Ok, so:

Some people have moved some of their acceleration off of gasoline and on to "the grid" (Plug-In Prius)
Some people have moved some of their ICE warm up off of gasoline and on to "the grid" (EBH)

In both instances people are finding that "the grid" is a more efficient and cheaper source for the energy.

What I've been wondering in these past few days here in northeast IL, is if it would be cheaper and more efficient to move some of the passenger and battery cooling to "the grid", and what would be the best method to do so.

I haven't taken any of my thoughts too seriously, but excessive heat and sleep deprivation can lead the mind down odd paths sometimes.

For example, there are these "cooler packs" some sort of fluid with a low melting temperature encased in plastic. You pre-freeze them at home, then toss them in a cooler with food or beverages instead of ice. They make less mess as they melt since all the fluid is inside the plastic casing.

Ok, so my thought was, if I could find a way to tie, mount, or otherwise attach one of these next to, or just above the intake vent in the back seat area, then the air flowing into the battery compartment would be significantly cooler than the passenger compartment, thereby moving some of the battery cooling to "the grid"

[TonyPSchaefer]

<div class='quotetop'>QUOTE(paulccullen @ Aug 3 2007, 09:58 AM) [snapback]489916[/snapback]</div>

No disrespect Tony, but are you crazy? Is the few pennies you save in FE by not using A/C worth the sweaty discomfort of sitting in a 90ºF car?

OK, I admit, I play that "how high can I get the MPH" game too, but I like my creature comforts too. [/b]

No disrespect taken, Paul, because in fact, yes I am crazy. When I think of all the quarters I spent in the dark, cramped video arcades trying to get a high score on a stupid meaningless arcade game I go crazy. Nowadays, I save those quarters playing my own game.

And you know as well has I that the highest concern gets the most consideration. That's just how people work. I've already admitted to driving in a hot car so you know where I stand. The same would have applied had I said that running my A/C at [MAX COLD] consistently affects my mileage but I don't care. It's just the way I roll; it's the game I play.

[richard schumacher]

<div class='quotetop'>QUOTE(paulccullen @ Aug 3 2007, 09:58 AM) [snapback]489916[/snapback]</div>

No disrespect Tony, but are you crazy? Is the few pennies you save in FE by not using A/C worth the sweaty discomfort of sitting in a 90ºF car?
[/b]

I also would choose to run the A/C on a hot day at the cost of a small reduction in MPGs, but no such tradeoff is needed in the Prius. The point here is that he *reduced* fuel economy by *not* using the A/C, because the traction battery and associated electronics got too hot. The cabin A/C cools the traction battery system along with the driver. People who drive around with the A/C off and the windows down on hot days thinking that they are improving the fuel economy of their Prius are in sweaty error.

[narf]

I wonder if at some point the added effeciency of the battery at room temperature makes up for the small load by running the AC?

[slair]

No offense, but this quote:

<div class='quotetop'>QUOTE(TonyPSchaefer @ Aug 3 2007, 11:43 AM) [snapback]489941[/snapback]</div>

No disrespect taken, Paul, because in fact, yes I am crazy. When I think of all the quarters I spent in the dark, cramped video arcades trying to get a high score on a stupid meaningless arcade game I go crazy. Nowadays, I save those quarters playing my own game.

And you know as well has I that the highest concern gets the most consideration. That's just how people work. I've already admitted to driving in a hot car so you know where I stand. The same would have applied had I said that running my A/C at [MAX COLD] consistently affects my mileage but I don't care. It's just the way I roll; it's the game I play.
[/b]

makes it sound like you value money more than yourself.

Horde money to live well
Live horrible to horde money

Sometimes some things just done make sense.

Sorry, now that I review my post it almost looks like I'm bashing you. I promise I am not, I'm just curious.

[FireEngineer]

The AC will cool the battery about 1 degree F every 5 minutes when starting from hot, documented by some other folks at the Yahoo PTS group. What helped more was doing something to drain the HV battery down a little from the 60% point. When you know the battery is warmer than normal, try driving with 4-5 bars of SOC, easier to put current in/out of a partial empty battery than one at 6 bars-so sayeth the BCM.

Wayne

[priussoris]

Tony the heats getting to ya, turn on the AC
another tip : don't move to the Southwest in the summer :P