Long Inclines And Battery Drain

[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!

[patsparks]

Maximum speed limit here is 110km/h or just under 70mph so never had this happen to me even on the longest steepest hills

[Patrick Wong]

This is fascinating. Two red bars is the lowest battery SOC that I have seen.

If you don't have any warning lights on, then there will be no stored DTC and hence your dealer won't take any action.

I wonder if your use of 85 octane is related to the lack of power; this would have caused the engine to run with retarded ignition timing as compared to 87 octane.

[Gadgetdad]

I have had mine go to purple bars climbing steeply in the Sierras and Death Valley. I had all the speed needed for the road considering the steepness and curves. I was more concerned with the long downhills overcharging the battery!

I'm not sure if you have a problem or not. Your car is a bit young yet and may improve with more miles.

Lee

[Ricochet2U]

Originally Posted by Patrick Wong

This is fascinating. Two red bars is the lowest battery SOC that I have seen.

If you don't have any warning lights on, then there will be no stored DTC and hence your dealer won't take any action.

I wonder if your use of 85 octane is related to the lack of power; this would have caused the engine to run with retarded ignition timing as compared to 87 octane.

I did not have any warning lights on. I feel like there is something to do with octane. I have no knowledge of octane ratings and how it works. I just wanted to try 85 octane because someone in this forum talked about getting better mileage with 85 octane. Thank you!

[statultra]

i get my car down to one bar once in a while, and what happens even if you do full throttle acceleration is the engine would charge the battery, once it goes down to 1 bar your car will be so slow.

[archae86]

I think it depends on both the grade and the chosen speed. Some folks here report charge gain on long grades.

My personal commonly used roads include a three-mile uphill stretch on about a 4% grade with a 55 mph limit. If I enter with six bars and travel about 52, I quite quickly go down to two, and sometimes even one. If I hold back to 48 mph, I can preserve three pretty often.

People have reported some pretty significant moding, so these effects may not be monotonic in either speed or grade.

As discharging on a long uphill is energy wasteful (the energy is guaranteed to be replaced from the engine, not from regeneration), I sometimes wish I could hit a hint button marked "long upgrade". We easily notice that trips including a round trip up and down this grade give us much worse mpg than our other trips in town.

[V8Cobrakid]

i have! passing through 80.. i think.. above colorado. just before you have to cut right. there is this really really long pass.

i learned that you shouldn't floor it.. and just mildly gain energy as you climb up.. it will start out slower but in the end you should end up with a higher amount of assist. so.. 3/4 petal or so instead of the full throttle.. and since this petal is complicated (just barely touch the high rpms on the ICE)

but yeah.. i too was stuck at 55-60mph in a 70 zone... slow lane for me! haha.

You still get decent gas mileage in the end. (shrug)

[V8Cobrakid]

85 octane is used in higher climates. it's needed to be that way. if you talk to the dealers, they'll say the the prius needs 85 in your area!

[Ricochet2U]

Originally Posted by V8Cobrakid

85 octane is used in higher climates. it's needed to be that way. if you talk to the dealers, they'll say the the prius needs 85 in your area!

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