Toyota Prius - Depleted Battery Power in Mountains

I have not experience this but have a friend that has. He didn't get to the bottom of it by the time I last spoke to him, but I await an answer on here. My hunch is that it could be to do with the electric engine having to work harder to regulate the temperature, if it was either very hot or cold.

The temperature was in the 30s when we went through on one occasion and in the 40s on another. Did it twice and both times, we watched that graph on the dash just go to nothing. Then, we crawled up the summit around 25 miles per hour, not a secure feeling at all. That little engine was working pretty hard. Did not overheat, but, seemed to strain. Not doing that again, we're done taking it up that road again. My Subaru Outback would have been better going up that mountain pass! Even so, it's hard for a lot of cars. We saw people even struggling more than our Prius, but, they were in some much older vehicles.

Yes, I would definitely be interested to know about your friends experience.

just a thought, but when in the mountains it suggests putting the drive in B mode which is like gearing the car down which will make the motor turn over faster and might help keep the battery charged!

Gassipiper - interesting theory, I'm impressed that you thought of that! Did you find this in the owners manual? All I can say is that you might expect the car to do this automatically on a steep grade, that's what automatic transmissions are supposed to do, correct? The Toyota Prius is marketed as a "CVT transmission ", but, it's technically a "power sharing transmission ", which uses CVT like technology, but, not like a conventional CVT. Their "hybrid synergy drive" as its called, should have made adjustments automatically. Tell me, am I missing something here? Anyway, I have to say that either way, the 1.5 litre Four just worked so hard on this climb to just over 11,0000 feet, I don't think I'm going to do that again. It did make it, but, we slowed down to about 25 miles per hour near the top. I guess my point is that it's just too much for this car, two people and luggage. First time we went through it was normal temperaturea, I really don't think that makes a big difference.

Gassipiper, found this interesting, see http://geekswithblogs.net/gaijin42/archive/2006/10/12/toyota_hyb rid_camry_prius_b_mode_braking_brake_fade_downgrade_failure_.a spx

Here's the most salient point of the Web link I sent you just now, "So essentially, you should ignore B mode, unless you are driving down a mountain. It is not used for towing, snow, up hills, or any other time when you would use the low gear in a normal car."

Had a very similar experience with my 2009 last week in 60+ degree weather on I5 in Washington and later just driving a few miles. I finally noticed the HV battery was depleted to one purple bar on screen when the engine would rev exceedingly fast with declining power and speed. I still haven't figured out why it now can discharge in just a minute or two and then without warning charge to all but one green bars in two to three minutes. No codes or check engine light

Cheznelson; question....is your car registered and purchased in Washington state?? Don't know about Washington state.. but, here in California.the hybrid battery is warranted for 10 years and 150,000 miles.... It almost sounds like your hybrid battery is failing?? If you can get it replaced for free..do it.. good luck.

I'm in the mountains in Arizona on the way to Colorado and I am bypassing I-70 for the same reasons as you mentioned. I was on it last year and experienced the same thing as you. This car just can't handle a steep climb without caution and care. At the time I was in a 2005 but had a new battery installed prior to the trip. This didn't seem to matter and I found myself stopping every so many feet until the battery would charge itself back up to the 45% range. I'm using the torque app for android and I saw the percentage dipping to 38, 37, 36, and 35% state of charge. It freaked me out so I would pull over to keep it safe. Now I'm in a 2004 with the original battery and just experienced the battery dropping to about 28% soc and the engine started revving high. Toyota has a flawed algorithm for this car and I believe it's why they updated the 3rd Gen with a bigger engine. I think they assumed you would mostly be puttering around the city where it's safe and not trying to be a pioneer! Just wanted to chime in and see I feel your pain. Cheers!

Zulumask, thanks for validating what I've been trying to tell people....the Toyota Prius is a great city car...and even on mostly flat area with some smaller climbing... but, it's not a long distance runner especially going through the Rockies.... just can't handle it...

Markw1952 - Yes but I'm not the original owner and have a salvage title. It must be failing. I had a recondition/refurbish/replace shop tell me my battery should be able to be reconditioned to the tune of $450 by three cycles of deep discharge/recharge and then balance of the battery modules but alas nothing changed and I cannot maintain freeway speeds even on relatively short hills. I used to travel at speeds around 70 mph uphill through the mountains of Oregon on I5. I'm concerned a new battery will not remedy the problem so am currently slo-poking up hills watching the battery level indicator closely. The slower driving has improved slightly my mpg but that is no consolation.

Had the exact same experience with my 2007 going over Eisenhower pass a few years ago. I've driven coast-to-coast 9 times but that was my first on that route. It does much better going I-80 through Wyoming. Just too much of an uphill haul for the beast, I guess.

Cheznelson; oh boy.... that's bad....... can't maintain speed??? I would suggest that you look into a brand new hybrid battery replacement...it will cost $3,000 ....if you think that's expensive.... consider this... you would probably pay more in sales tax on a brand new car!

Inclines will kill your batt and leave u running on a 65hp gas engine without the help. Might as well be driving a 70's vw Beatle... That weighs twice as much. No bueno. If your batteries are out of warranty try refurbished. Instead of 3k for 1.5k Green bean battery came to my house and installed it with a lifetime warranty. The frame will rust out before I have to pay another cent on batteries.

If the car is putting all the energy into climbing the hill the tiny little hybrid battery will be depleted in short order.

My sister's Prius had to get a new battery after trip Provo to Phoenix w full passenger and baggage load. Her son driving it hard. I smelled burning but we made it home not slowing down.

Yes. It was terrifying and it happened in the Rockies. Sometimes it was okay, but it was definitely a dangerous driving situation. High temperatures and humidity made it worse. The Gen2 engine was not providing enough power to perform properly.

If the battery failed under warranty, it's possible that you could file a claim ? I really don't know how they would handle this situation. We drove across the USA twice with the Toyota Prius and for the comfort and savings of maybe 10 mpg, I would never to that again. It's just not a great road car. It's a terrific city car or for short to middle range distances within 250 miles. There's no worries about running out of fuel because it's a hybrid, but, it's just not as smooth as I would like it to be on the highway Long sustained mountain grades are just not this car's strong point.

You don't worry about running out of gas? You do know the battery only range is only a mile or so? The WHOLE POINT of a hybrid is to harvest the energy otherwise wasted when braking or going down hill. Sustained grades will always deplete the battery. If the engine had to power the car up the hill AND charge the battery you would be crawling up those mountains (and getting really poor fuel economy). People simply don't understand the whole concept of a hybrid. They are not some magic mileage machine. There are ALWAYS trade offs with any mechanical system.

This same thing happened to me last year on my drive from Denver to Frisco. I couldn't get above 30 mph as of about halfway up that climb to the tunnel. And I had to get off multiple times and let the battery charge up, but it would only help for about 10 minutes or so. Now my Prius is also going down to 1 battery bar just driving interstate speeds for less than 10 minutes. I can't even make an 8 mile jet on I-76, with no altitude change, without the battery going down to 1 bar. I'm guessing it's time for a new hybrid battery, but I haven't had it checked out. Ours is a 2009 model with 190k miles. Just replaced the 12V battery last year when the car kept dying just from sitting in our garage for a few days without being driven.