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Discussion Starter · #1 ·
I travel in Washington state to go hiking. Sometimes I might drive from sea level to 5000 or even 6000 feet. Some would be paved highways with reasonable gradient. Others might be gravel roads with 20% grade, lots of switchbacks, and travelling no more than 5 or 10 mph.

So I figure the battery pack might be exhausted from the climbing. I might park the car at this high elevation, then go backpacking for a week.

What happens to the battery in this situation? Will it be ok to leave it at low charge for so long? Will the car slow down because the batteries are discharged part way up the hill?
 

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Stairman said:
Don't forget to turn off the smart key, so the 12v battery doesn't die.
how is this done?
 

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MFD......that flat tv-looking thing in the middle of the dash......
MULTI-FUNCTION-DISPLAY.....
Must be a Honda guy?

 

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MtnTraveler said:
I travel in Washington state to go hiking. Sometimes I might drive from sea level to 5000 or even 6000 feet. Some would be paved highways with reasonable gradient. Others might be gravel roads with 20% grade, lots of switchbacks, and travelling no more than 5 or 10 mph.

So I figure the battery pack might be exhausted from the climbing. I might park the car at this high elevation, then go backpacking for a week.

What happens to the battery in this situation? Will it be ok to leave it at low charge for so long? Will the car slow down because the batteries are discharged part way up the hill?
The low speed roads should be no problem--20% grade seems awefully steep though--are they really that steep? If they are, and they're gravel I'd be pretty concerned about the Prius' ability to climb that. I'd be concerned about a 4WD's ability to climb that!

The battery on Prius seems to be most likely to drain to the low "pink" level and become unable to assist in providing significant power/torque with prolonged steep climbs at relatively high speeds. Of course this could occur at lower speeds too if the climb is long enough and steep enough. But, it usually takes only brief plateaus for the system to recharge.

And No, I do not think there's any need for concern leaving the prius in a low SOC while you're backpacking. Remember, the trip home is downhill and you'll be seeing a full green charge before you've gone 2 miles!
 

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Discussion Starter · #8 ·
Not Honda -- I have an old Volvo station wagon that just died. So I'm carless in Seattle. I need a car -- anyone willing to donate one?!

efusco said:
20% grade seems awefully steep though--are they really that steep?
Logging roads can get darn steep. Maybe 20% is an exaggeration... but not impossible. The roads typically climb and climb and climb relentlessly. Then I hop out of the car and climb more on foot until reaching the top. It's a grand sport.

Remember, the trip home is downhill and you'll be seeing a full green charge before you've gone 2 miles!
Sounds like the recharging is very quick. Due to entropy, I won't recover all the potential energy at the top of these gravel roads, but it'd be nice to get some back.

I'm still debating if a hybrid meets my general auto needs, or a diesel is more appropriate. I *should* take the bus to work, which means mostly I'd be doing highway driving. But I'm very intrigued with this technology. And unfortunately (for my pocket book), I rented a Prius for a couple days and really enjoyed it.
 

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bshef said:
Stairman said:
Don't forget to turn off the smart key, so the 12v battery doesn't die.
how is this done?
Should be a small black button to push below the steering wheel, just above your feet. No indicator, but it is either in or out. Hope that helps!

Curt.
 

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You have an old Volvo station wagon and need a replacement; I have just the car for you-- 71 Volvo sedan, engine out of car, your's free, come and get it, in VA. Steep gravel logging roads and a Prius--not a good match. The car may not be able to make it if its a long climb at less than say 25mph. I haven't seen any data, but, since the engine sees only high gear, the battery/MG2 provides all or most of power at low speeds. Of course, the engine will be running and charging the battery but, if the discharge rate is greater than the charge rate and the engine is providing very little or zero motive power, the car will stall. If there are level stretches or level pull-overs, then you can stop and allow the engine to recharge the battery. Another concern is the OEM tires which are designed for high mileage and have low rolling resistance (LRR). Many posters have complained about the lack of traction of these tires. I recommend a trail type motorcycle or a Jeep wrangler. Try it with a rental Prius and report back on your experience. Good luck.
 

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hyperion said:
Button pictured and location indicated in owners manual.
Thanks for the tip Hyp....but finman went the extra mile and described the location in his post......
 

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Discussion Starter · #13 ·
jtmhog said:
The car may not be able to make it if its a long climb at less than say 25mph. I haven't seen any data, but, since the engine sees only high gear, the battery/MG2 provides all or most of power at low speeds.
Is this based on experience or theory? I've gotten reports on a hiking site that it works fine up 5000' gain on pavement. So far nothing reported for gravel roads.

25mph is awfully fast for gravel. Steep gravel roads are often 10 mph (lots of potholes).
 

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You forget this is a parallel-series hybrid. It is not solely one or the other.
For efficiency in MPG, it is best if the system works as a combination of both. However, if the battery is depleted, then the ICE will simply rev higher to provide the needed power to MG2 through MG1, as well as supply some of the power directly, if indeed low speed high torque is needed. In this way, it will act more of a series hybrid much as a freight train does.

Now you might have problem with traction, but traction has nothing to do with inadequate sustained torque. The car has plenty of torque, which is why you can often beat most cars off the line while they try and get out of first gear. Traction has to do more with having the right tires.
 

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I haven't seen any data, but, since the engine sees only high gear, the battery/MG2 provides all or most of power at low speeds.
You don't have a very good idea how the transmission works. The continuously variable arrangement allows the ICE to deliver more power by reving up, just as in any other car. The percentage of torque which goes to the wheels is fixed, but the electric motors can provide more torque. There is an excellent explanation of how the transmission works here: http://home.earthlink.net/~graham1/MyTo ... Device.htm

I agree that the low ground clearance makes the car lousy for roads that aren't at least well graded.
 

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The Prius engine can supply sufficient power to drive your car up mountain roads just fine if you're not trying to sustain 65+ MPH. So even if you do end up with a "low" battery (down to 40 % charge), you can continue to climb the mountain with just the engine.

Ignore anything you've heard about the engine only being in top gear. That's only true for the mechanical path and is wholly irrelevant for discussions of Prius propulsion at low speeds. That phrase was originally used by someone trying to explain one small piece of the whole working of the Prius. Unfortunately, several people have grabbed onto that phrase out of context as if it explained all there is to know about the Prius transmission. It doesn't come close.

You're Prius can safely be parked for a week with NO precautions, even after a long climb.

However, as others have mentioned, the Prius ground clearance is entirely inadequate for logging roads. The stock tires aren't particularly good for gravel or other loose surfaces either.
 

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I travel in Washington state to go hiking. Sometimes I might drive from sea level to 5000 or even 6000 feet. Some would be paved highways with reasonable gradient. Others might be gravel roads with 20% grade, lots of switchbacks.
******************************************
In the driving conditions you describe; I would worry less about the batteries and more about ground clearance and other semi-off-road stuff. The front end fiberglass chin scrapes the ground easily on dippy surfaces. The Prius is a great car and I like mine a lot but I don't see it as being designed for "extreme" conditions as was, for example, the old VW Bug. ~JD~
 

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RSnyder said:
However, as others have mentioned, the Prius ground clearance is entirely inadequate for logging roads. The stock tires aren't particularly good for gravel or other loose surfaces either.
Tell me about it. I mistakenly took Ladybug's advice on getting to a friend's house from my best friend's house with my best friend and his family. The neighborhood of whose house we were going to is notorius for having badly kept limerock roads. My car bottomed out often, and my best friend's wife cried out in empathy for Ladybug.
The roads Ladybug chose was a shorter route but not the safest or most comfortable.
 

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Discussion Starter · #20 ·
Thanks for everyone's comments. Looks like a Prius would be fine for my needs. I was concerned that the battery pack would deplete too much and thus get damaged. Sounds like the car ain't that dumb.

As for the gravel roads -- these roads are rough but passable by a "family car". There are plenty of other roads where high clearance and 4WD helps. But I'm not going to buy a car for the small 0.5% of the miles when 99.5% of them are on good pavement. Folks pay for their 4WD every single mile to the grocery store and work and most of the way to trailheads. I'd rather walk! But them I'm pretty dumb.
 
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