Gas engine turning on & off rapidly in rush hour traffic with hot weather and AC running

[local_host]

The other day I was driving home from work- stop & go traffic, about 5/10 miles per hour for about 45 minutes (yeah I know it sucks). It was pretty hot outside (almost 90 degrees) so I had to keep the air conditioner on. I understand that the gas engine has to kick on when the battery starts to run low, but this time it seemed really annoying. Everytime I would accelerate a little, the internal combustion engine would turn on, and then when I hit the brakes to slow down (not stop) it would shut off. There were about 2 bars left in the battery so I assume this is the reason. Perhaps if I shut off the AC, it wouldn't have been as bad, but it was just too hot outside.

What I don't understand is why doesn't the ICE stay on till the battery is recharged more than just one or two bars? Therefore it wouldn't need to power on and off so rapidly, charging a tiny bit at a time. I wouldn't mind all that much but everytime the ICE comes on, the car jerks a little bit and I can actually "feel" it, and it's very annoying when it happens every minute as I'm accelerating and decelerating in the stop & go traffic.

By the way, each time I accelerated in the traffic that day, I wasn't pushing the pedal hard enough to trigger the ICE to come on, I can tell because when I'm driving normally I can sense when it's in electric mode from light acceleration and gas mode in heavier acceleration (under 40 MPH). I just got this car in January so I have yet to have the experience of driving in the heat during rush hour. Is this normal??? Man I would hate to get caught in a hurricane evacuation when everyone has to drive 10 miles an hour for about 10 hours in the extreme heat (like what happened in Houston back during the 2005 hurricane Rita evac) AND have to endure the ICE repeatedly shutting off and on like this every minute........

[efusco]

<div class='quotetop'>QUOTE(local_host @ Apr 28 2007, 02:11 PM) [snapback]431768[/snapback]</div>

What I don't understand is why doesn't the ICE stay on till the battery is recharged more than just one or two bars? Therefore it wouldn't need to power on and off so rapidly, charging a tiny bit at a time. I wouldn't mind all that much but everytime the ICE comes on, the car jerks a little bit and I can actually "feel" it, and it's very annoying when it happens every minute as I'm accelerating and decelerating in the stop & go traffic.
[/b]

The reason is b/c it's very inefficient for the ICE to run and just charge the battery. It's "waiting" for you to start normal driving again where it can take advantage of optimum RPM range. The condition you described is normal and makes the best of the alternatives. Best thing you can do is turn the AC to a lower setting (ie higher temp...I usually use 78-80 degrees) or turn it off and roll down the windows to ventilate.

[local_host]

<div class='quotetop'>QUOTE(efusco @ Apr 28 2007, 02:21 PM) [snapback]431772[/snapback]</div>

The condition you described is normal and makes the best of the alternatives. Best thing you can do is turn the AC to a lower setting (ie higher temp...I usually use 78-80 degrees) or turn it off and roll down the windows to ventilate.
[/b]

Thanks for the suggestion, but that's just not reasonable here in Texas. In my opinion TX is THE hottest state in the US. Even though places like Phoenix and Las Vegas are constistently in the 110s in the summer, here in Texas we consistently get into the 100s BUT with much higher humidity which makes the heat index up in the 115 range. Add the "heat island effect" of a big city and the temperature might be even higher...

I simply cannot have the AC at 78-80 degrees with the windows cracked in the sweltering heat. And it's not even summer yet, so the daytime heat right now is just 'mild'. Not too mention I don't want to have the windows open because when sitting in rush hour, the smell from everyone's exhaust is really nasty (especially from the big commercial trucks). Exhaust fumes seem to smell stronger in heat and humidity.

If this is "normal" for the Prius I might have to consider a trade after this year...

<div class='quotetop'>QUOTE(efusco @ Apr 28 2007, 02:21 PM) [snapback]431772[/snapback]</div>

The reason is b/c it's very inefficient for the ICE to run and just charge the battery.
[/b]

By the way, sometimes I get fast food and then eat it in the parking lot with the AC on. After the battery runs low, the ICE kicks in for about a minute, shuts off, and doesn't come back on for at least another 5 minutes. But when driving in rush hour with the AC on, the ICE kicks in every single time I (lightly) push the accelerator (not every 5 minutes). What's up with that??

[Tideland Prius]

Why about tinting the windows or adding sunshades (if tint isn't your thing)??

Also, the engine won't come on to recharge (stay on that is) unless the battery is almost at the 1 bar / 2 bar threshold. Only then will it idle and charge to 3 bars.

If you're still well within the 2 bar area, then it'll cycle on and off as you've described.

Also, your car is still relatively new. The engine shut down is still rough when it's new so it will smoothen out as the car ages. (I think it took nearly a year for me since I bought it in Oct 04).


The other option is to use the A/C more haha and drain the battery to that 1 bar so that the engine will come on. I think using the front defroster might even help idle the engine.

[local_host]

<div class='quotetop'>QUOTE(Tideland Prius @ Apr 28 2007, 02:46 PM) [snapback]431786[/snapback]</div>

Why about tinting the windows or adding sunshades (if tint isn't your thing)??
[/b]

Yes, tinting is something I plan to add in the near future. However, the effects of cooling down the car will be negligible. I think people underestimate the heat in Texas. It is BRUTAL. Just think of sitting in a sauna with all of your work clothes on. That's what it feels like in a car, in TX, in the summer sun, in rush hour traffic, with no AC (or AC on at a high temp).

[efusco]

<div class='quotetop'>QUOTE(local_host @ Apr 28 2007, 02:39 PM) [snapback]431780[/snapback]</div>

Thanks for the suggestion, but that's just not reasonable here in Texas. In my opinion TX is THE hottest state in the US. Even though places like Phoenix and Las Vegas are constistently in the 110s in the summer, here in Texas we consistently get into the 100s BUT with much higher humidity which makes the heat index up in the 115 range. Add the "heat island" effect of a big city- which bumps up the tempurature even more..

I simply cannot have the AC at 78-80 degrees with the windows cracked in the sweltering heat. And it's not even summer yet, so the daytime heat right now is just 'mild'. Not too mention I don't want to have the windows cracked because when sitting in rush hour, the smell from everyone's exhaust is just nasty (especially from the big commercial trucks). Exhaust fumes seem to smell stronger in heat and humidity.

If this is "normal" for the Prius I might have to consider a trade after this year... [/b]

I just can't imagine trading in just b/c the ICE cycles on and off...try driving the car for a few more months, this is something you'll become accustom to. Worst case you can set the AC to "max cold" and the fan on high and that'll pretty much keep the ICE on almost all the time so you don't have to deal with the cycling.



And, 78 is a fairly comfortable temperture...if the sun is shining right on you cooler may be necessary to feel comfortable, but it's a reasonable temp, IMO...and I wasn't suggesting using 78 AND opening the windows...it was an either or. Option. It gets into the 90s and 100s where I live (with 100% humidity) too, so I can relate to the circumstances and find I do just fine at 78-80 and my family doesn't complain at 78 either.



Like I said though, give yourself a little time to adjust.

[local_host]

<div class='quotetop'>QUOTE(Tideland Prius @ Apr 28 2007, 02:46 PM) [snapback]431786[/snapback]</div>

Also, your car is still relatively new. The engine shut down is still rough when it's new so it will smoothen out as the car ages. (I think it took nearly a year for me since I bought it in Oct 04).
The other option is to use the A/C more haha and drain the battery to that 1 bar so that the engine will come on. I think using the front defroster might even help idle the engine.
[/b]

That's good to know the roughness of the ICE turning on will decrease as the car gets older. I certainly HOPE that's true. Before I bought this car the only other hybrid I drove was the Honda Civic, which apparently is not the same kind of 'hybrid' as the Prius, as the Civic's gas engine didn't seem to shut off everytime you took your foot off the accelerator like the Prius does. The only time the Civic's engine shut off was when idle, so I never really 'felt' it come on and off the same way ..

Not sure what you mean about using the AC more to drain the battery to one bar? The other day in traffic I had the AC on during the entire 45 minute low speed commute home.

[local_host]

<div class='quotetop'>QUOTE(efusco @ Apr 28 2007, 03:01 PM) [snapback]431791[/snapback]</div>

I just can't imagine trading in just b/c the ICE cycles on and off...try driving the car for a few more months, this is something you'll become accustom to. Worst case you can set the AC to "max cold" and the fan on high and that'll pretty much keep the ICE on almost all the time so you don't have to deal with the cycling.

And, 78 is a fairly comfortable temperture...if the sun is shining right on you cooler may be necessary to feel comfortable, but it's a reasonable temp, IMO...and I wasn't suggesting using 78 AND opening the windows...it was an either or. Option. It gets into the 90s and 100s where I live (with 100% humidity) too, so I can relate to the circumstances and find I do just fine at 78-80 and my family doesn't complain at 78 either.

Like I said though, give yourself a little time to adjust.
[/b]

Again, 78 is NOT comfortable for me. It might be for you, but it's not for me. Why should I have to sacrifice my comfort level for a car that I just paid $27,000 for?? Where do you live? Missouri? Are you familar with Texas heat??? It comes early and stays late. "Summer" here is April through November. Also keep in mind that big cities are hotter.

Btw, I did have the AC set to max. Not initially, but after this on/off cycling issue I tried the maximum and it didn't change anything. Maybe there's like a software error in the computer. It just doesn't seem normal for the engine to turn on and off so much. I mean every single time I stepped on the accelerator it came on, and every single time I let go, it turned off, all under 10 MPH or so.. Ever been in horrible rush hour traffic where you have to do this every few seconds?

[alexstarfire]

You should try it with the defroster setting, like windshield defroster only. That thing always makes my car run, even when the battery is fully charged. I do have a 2002 model though, so it could be different for you.

BTW, I'm from Texas and know what you are talking about. Been during the summer and winter months. Summer isn't even that bad. I don't believe I've been there in 100+ degree weather though, as I haven't been during the summer in many years. I do however live in Georgia now, and the summer here is just as long. Started in early March this year and except for like 1 week where it went back to winter it's been over 70 degrees everyday so far. I've already seen 90+ according to my Prius, but it was probably closer to 85 and it's not even the peak season yet.

I just roll two windows down about an inch or two and I'm usually just fine, even when I'm stopped at a light. I've noticed how having two windows open gives you more of a draft, presumably because the air flows between them.

My $.02.

[onlynark]

I think someone mentioned in another thread about how to charge the battery. As far as I remember, you press the brake, then press the gas pedal to the half way point. That should turn on the engine and charge the battery.