Long Inclines And Battery Drain

[Bob64]

Maybe if you fill it with premium it'll balance the octane out?

[qbee42]

Originally Posted by Bob64

Maybe if you fill it with premium it'll balance the octane out?

You don't want to "balance the octane"; 85 is the correct octane at high altitudes. Switch back to 87 when you get back to lower elevations.

Tom

[Bob64]

Well, since he is now - assumingly - in a "normal" altitude area with a half of a tank of low octane gas... filling the rest of it up with a high octane gas may balance the octane enough to ensure performance and drive-ability.

[Ricochet2U]

Originally Posted by Bob64

Well, since he is now - assumingly - in a "normal" altitude area with a half of a tank of low octane gas... filling the rest of it up with a high octane gas may balance the octane enough to ensure performance and drive-ability.

You are right I am back in Kansas "normal altitude" and 87 octane gas in my prius.
I think cause of my problem was long inclines, 1.5 liter engine, high speed and more.

Do you guys know how battery conditioning works in prius and in average how long it takes prius to condition it's battery or is it required on prius? ThanX!

[Priusaurus110]

Ricochet: I have experienced the exact same situation on one trip through Colorado on I-70 through the Rockies. It happened on two different particularly long and steep climbs. However, I never saw zero battery bars. In my case the battery level dropped to 1 or 2 bars, and cut out the electric motor assist. The ICE and transmission were working hard and did sound louder than normal. Once I reached the summit of those 2 passes, batteries started charging, and everything was back to normal. So, I think what you and I saw was normal Prius operation under very extreme climb conditions.

Originally Posted by Ricochet2U

Past week, I took a long road trip to Yellowstone, and my battery kept draining very low on the way back to Colorado. I think at one point there was no bars on my battery indicator and my engine had no battery assist. It was noisy. I notice this while driving on long inclines. I had to drive 55-61 miles per hour while speed limit was 75 on that road.

Has anyone else had battery drain to very low points on long drives?

I figure elevation had something to do with it, but I was constantly being passed by other Prius cars that seemed to not have a problem with scaling the same inclines.

- Car 08 with 4500 miles
- Gas 85 Octane while in Yellowstone
- MFD avg 48.5
- Elevation 6000ft-8000ft
- Drove 9 hours 500+ miles a day average for 4 days.

Should I take it to toyota? Any thoughts? Thanx!

[richard schumacher]

85 octane is correct for high altitude, above 5000 feet or so. Buy plain old 87 octane when you get back to lower elevation.

The battery dropping and the engine roaring are completely normal when going up long inclines. After all, the battery cannot provide infinite energy, so the engine revs up to provide the necessary power. The computers won't let the engine redline or harm itself, and they take care of the batteries also. Just drive it. Don't be afraid to floor the gas pedal when it seems necessary.

(But *don't* run out of gas. That's one of the few things that are easy to do that can cause a lot of expensive damage.)

[mingoglia]

Here in AZ, I'll pull the 7% 12 mile grade going up North and get down to a single bar. I've ran it twice. Both times with 2 adults and 2 kids and the A/C on. I can maintain my usual 85-90+ while going up it. Not the best for fuel economy but road trips are fair game for me. I drive extremely conservatively during every other time... but once I'm on a road trip all bets are off.... luckly I only go on a couple of road trips a year.

[qbee42]

Originally Posted by Ricochet2U

I just found out that according to 08' owners manual no less then 87 octane for prius. Hum ...

Right, but that assumes sea level pressure altitude. Octane requirements change with pressure altitude, unless you have a supercharged or turbocharged engine. Thin air changes the characteristics.

Tom

[mingoglia]

Originally Posted by qbee42

Right, but that assumes sea level pressure altitude. Octane requirements change with pressure altitude, unless you have a supercharged or turbocharged engine. Thin air changes the characteristics.

Tom

Correct. I'll just add a bit. Octane in very simple terms is how difficult the fuel is to ignite. The higher the number, the more difficult. So visualize this. The air/fuel mixture is injected into the engine, the piston compresses this mixture. If it gets too hot in the cylinder there's a chance for the fuel/air mixture to ignite sending the piston back down. This is not supposed to happen. The piston is supposed to make it's way up and the air/fuel is supposed to be ignited by the spark plug. If this "pre-ignition" happens, you need a higher octane fuel to make sure the mixture doesn't ignite prematurely.

When you're in the mountains you'll notice less power (unless you have a supercharger/turbocharger). This less power is a result of less air. Less air means the potential for pre-ignition is slightly less and therefore you can technically run a lower octane (since pre-ignition is less likely).

On the flip side of all this, this is why most supercharged/turbocharged engine require higher octane fuel (because more air is forced in there). In addition to this higher octane fuel these engines will have a lower compression ration than their normally aspirated versions (to reduce the fuel pre-igniting due to the higher pressure) if the engine is to run on pump gas.

[miaxapa]

I just returned from a east to west coast round trip. I experienced the same thing on rt 70 going thru southern utah. At one point I had no bars and running on engine alone. It would not let me go above 55. Those gradual inclines really make this car work hard. I averaged 36mpg on that stretch from vegas to green river utah. Once I got on the Denver side of the mountains I never had this happen again. On the whole trip according to my notes. I averaged 45.2 mpg. The car was a great road trip car.