High Altitude Battery Life

I think it is behaving just as it was engineered. See also this thread:
http://priuschat.com/forums/gen-iii...m/82455-battery-after-100-000-miles-myth.html
wherein a discussion about running the traction battery down to nothing can be found.

 

That's normal.

Also normal.

That's actually the abnormal part. It's not normal for the battery to charge to full (8 green bars) under normal driving. Six blue bars is the nominal state of charge that it will typically try to maintain.

 

Well - when I lived in south Orange County (CA), my home was at 1,100 ft elevation and my office was at sea level. 25 mile one-way commute. The 2004 would routinely show 7 or 8 green bars on the traction battery SOC gauge, when going downhill.

 

LOL going up hills drains the battery going down hills charges it. Normal

 

Stats: 2007 Gen2, 240,000mi on original battery.

Ok...the older battery does NOT charge well or hold a charge at altitude. I’m talking straight and level. We are on the flip side of a trip from San Luis Obispo, CA to Angel Fire, NM. I am caravaning with my son who is driving a 2007 Gen2 with 180,000mi. I was on one magenta bar from Flagstaff almost all the way to Angel Fire. Pretty much all on the ICE. Both cars loaded about the same with 4 passengers plus gear. The shortest climb even at slow speeds immediately drained all reserve (I usually didn’t have any...passed by just about everyone). My sons car maintained a 3-bar level and rarely (once?) hit two bars. We were chatting back and forth on two-way radios comparing notes. I could not use cruise control since the ICE would hit max rpm trying to maintain speed. I was just waiting for the red triangle of death. Never happened...but a few short steep climbs at altitude were 20mph max. Now that we are headed home west of Flagstaff at 2300 feet, we can maintain max speed limit and 4 blue bars. Above 7k feet, eastbound on straight and level it was one bar and we could not get up to the speed limit of 75mph. However, my son’s Prius was doing fine. My conclusion is that altitude DOES affect charge capacity, and it seems to be much more apparent in higher mileage cars (assuming a lot more traction battery charge cycles). This was about as close to a real world A-B test you could get. Note: mpg was still decent at 42mpg for my car and 47mpg with my son’s car. Not home yet to give you the flip side mpg. I am rethinking my plans to rebuild this battery until it really dies...it seems to be back to normal at the lower altitudes. Apologies for the lengthy post.

 

troopers!

 

Wow that sounds super rough on a engine, especially a high mileage engine. I hope you're checking the oil leavel, mine always used more oil when loaded down on the highway.

 

That’s what I was thinking Aaron’s. Tough on the engine and really tough on the trans. Only thing that saved them is it’s old outside or they would have ended up sitting on the side of the road. Seen so many of those on this site.

Altitude is not the problem it’s the huge power demand on an overloaded car going up big long hills.
Power in the g2 comes from healthy charged up hybrid battery. Without that battery charged and happy the car is basically a go kart with a screaming anemic engine.

Low state of hybrid battery charge + huge load + super power demand (thats you flooring it) equals low voltage & power to MG2 equals extremely high current through motor winding's equals trans death.
Want to kill a electric motor low volt it and stall it under load. Bet you smelled something burning.

Smart play with that kind of big load is while going up a big hill and battery flags pull over and stop and force charge the hybrid battery and then take it easy up the hill. Turn off all power demands. When battery flags repeat. If not your giving the cars powertrain the beating of its life. The engine's screaming and the Inverter is really screaming. If the car survives that event it will not forget it though lol.

I would immediately replace the trans fluid and engine oil after that beating.

 

You both assume too much. You overlooked the part in the post where I described going slower and NOT using cruise control to specifically protect both the engine and the transmission. I used the throttle to keep the rpm below 3500 most of the drive and we checked fluids at each stop. I always check the oil since this engine will consume almost a quart of oil over 5000 miles (by design).

I’ve rebuilt several engines in my life and treated the powertrain the best way possible given the circumstances. We weren’t about to abandon our vacation because of the batteries inability to hold a charge. My post was meant to provide an interesting performance note for other owners. Your assumption that I merely “floored it” is about as far from the mark as you can get. I even started this trek with a fresh oil change.

With that said, I would take what was shared as a precaution to other higher mileage Gen2 owners. The battery pack does not do well at higher altitudes...flat & level...compared to a lower mileage or newer vehicle. If you DO find yourself in this situation, control the engine RPM and get used to going slower...don’t push your car or as implied earlier, you very well could burn up your tranny as the replies to my story thought I had done.

Also, a zero charge battery doesn’t mean immediate failure...this is an ICE vehicle with battery assist. With a poorly performing charge/energy system, use caution and don’t push the car’s ICE. Once you are at a lower altitude your vehicle’s performance may fully recover...mine did, even with extended climbing back up through Tehachapi.

I am now looking at ways to rebuild my battery with new cells (not recovered cells).

Merry Christmas and safe travels!

 

It’s not the battery that preformed poorly at high altitude, it was the engine. The higher the altitude the thinner the air the less horsepower you have available. It had less power available from the engine to run the car and change the battery, that’s what you were seeing.

 

I might agree to ‘some’ extent. However, my son’s car...nearly the same month of manufacture...did not experience the same problems. So...he was kind of a “control group”. What makes this experience unusual was the fact that we had two cars...loaded the same...filling up with the same fuel at the same stations...with the only difference being the more heavily used vehicle having a difficult time with the battery charge. I might chalk this up to the higher mileage and an engine that was more “worn” than my son’s car. However, once we were at the lower altitudes (heading west...and on the extended climb through Tehachapi)...my car performed the same as my son’s...and it held up the charge and had similar mileage.

Of course there are a LOT of other variables here...but the electrical performance was dramatically different at higher altitudes.

I am sure that many of you may have your own opinion...but I am going to stick with altitude affecting the battery depth...

Now all I need to do is rebuild the battery with new cells...and repeat the trip. That would either corroborate or put to bed the “thinner air” or “tired engine” theories.

 

Someone correct me if I'm wrong, but I don't believe the traction battery cells are vented. As such, it cannot know what the outside air pressure is, even if pressure was somehow a factor in battery performance. My bet is that the amp-hour capacity of the battery is diminished from age and this is not accurately represented by the SOC indicator. The engine is less able to charge the battery at high altitude and the battery has less power to deliver when charged.

When I had the pre-purchase inspection done on my '07, they told me the HV battery was at 92%, indicating that it was able to deliver 8% fewer amp-hours than the rated capacity of a new battery.

Anyone who has spent any time with rechargeable batteries has noticed that they lose charge capacity gradually over their useful life. I believe that's what the OP experienced here, combined with the reduced power output of the ICE.

 

You’re wrong.

There are vent tubes for each module on top. In the Gen2 there was an issue with smell.

 

Sorry but your conclusion is WRONG.

Changes in altitude (ambient pressure) does NOT affect the capacity of the battery itself.
It does somewhat decrease the power produced by the engine, thus trying to make up for more of that with the battery.
That is quite different from a reduction in battery capacity.

 

Again, I could be wrong, but I thought that was the vent for the 12v battery.

 

Nope. Each individual module has a vent and there is a common vent tube header for routing the vents on the hv battery.

The 12 volt also has a vent tube.

 

Pre purchase inspection?...you actually believed what they told you at the dealer? 92% of what? The hybrid battery charging level is always changing second by second. Its not like a flashlight battery. 92% is a completely nebulous number. It will be different by the time you get to the end of the block.

The fact is if you own a 2007 G2 your staring down the barrel at a new hybrid battery no matter what smoke the dealer blew up your you know what.

 

Tellin’ it like it is.

But all valid points.

Add in a brake system repair or an AC system and you’ve got the trifecta .

But I bet the pre-purchase inspection covered all those points.

 

The inspection was not done at a dealer, it was done at an independent shop that specializes in Toyotas and hybrids. I would barely trust the dealer to change my oil.