2008 Prius Traction Battery Replacement (planning ahead just in case)

[S Keith]

Originally Posted by JSH

Sorry, I missed your earlier post.

This is interesting. I wonder if this is heat related (The paper I linked shows high temperature as an issue for Ni-MH).

It also could a "Snow Bird" effect. People that leave their cars for long periods of time at their winter homes and let the battery sit in a discharged rate.

The 40K miles and 2 years early failure condition is presumably heat related.

If you are looking at a 10 year old car with 160K miles, you're not talking about any "snow bird" effect (160K is my average across the ~250 batteries). The failures I would attribute to "snow bird" effect can be counted on one hand.

[JSH]

Originally Posted by S Keith

The 40K miles and 2 years early failure condition is presumably heat related.

If you are looking at a 10 year old car with 160K miles, you're not talking about any "snow bird" effect (160K is my average across the ~250 batteries). The failures I would attribute to "snow bird" effect can be counted on one hand.

Interesting. I would not think a battery that lives inside an air conditioned cabin would be effected much by heat.

Lots of questions:
If 10 years / 160k miles is the average in Arizona what is the average nationally? How does Arizona compare to other hot locations like Texas or Florida?
What do you do to have all this cool data?

[redpoint5]

He did say PHX cuts 40k and 2 years off the average. That would make the average 200k and 12 years. That means we should be seeing 2007 Prii with failing packs right about now.

[S Keith]

Originally Posted by JSH

Interesting. I would not think a battery that lives inside an air conditioned cabin would be effected much by heat.

Lots of questions:
If 10 years / 160k miles is the average in Arizona what is the average nationally? How does Arizona compare to other hot locations like Texas or Florida?
What do you do to have all this cool data?

Perhaps it's just a matter of perspective, but most of the country isn't under clouds most of the time, and even on a comfortable 70°F day, full sunlight exposure can drive interior temperatures North of 100°F. In Phoenix, summer interior temperatures often exceed 140°F.

Do you see how a battery inside an air conditioned cabin could be affected by heat? I've seen battery temperatures as high as 145°F in the middle of summer following a bunch of short trips while sitting in the sun after each trip. Battery temperatures in excess of 120°F are very common in summer.

It's further complicated by the fact that the ENTIRE INTERIOR has to be cooled for the battery to benefit from an "air conditioned cabin." Most folks aim a vent at their face and often close off the other vents... or at least the far right one... that can cool the battery...

TX and FL are about 20K better than PHX. TX is 10-15° cooler than PHX and FL isn't so bad because the peak temperatures aren't that high... the humidity is horrible for humans, but the battery is about temperature - not heat index.

Originally Posted by redpoint5

He did say PHX cuts 40k and 2 years off the average. That would make the average 200k and 12 years. That means we should be seeing 2007 Prii with failing packs right about now.

Important to point out that the data set doesn't include cars with batteries that haven't failed, so it's an average failure of failing batteries... not Prius batteries. It just illustrates that they do fail, and one should not expect them to last indefinitely.

Additionally, I frequently visit one of the local dealerships... at any given time, they have 5-10 cores queued for return to Toyota. They have about 10-20 failures per month across all models.

Lastly, never ever ever buy a 2010-2015 Prius from a hot climate... I'm talking anywhere from the bottom 1/3rd of the country. I've encountered several, and their batteries are destroyed. They rarely drop a cell, but their battery capacity just deteriorates to the point that the car has nothing with which to work. The damage can't be repaired through reconditioning. They are dead.

Why? IMHO, Gen3 cooling system is worse than the Gen2, and they use the batteries more aggressively.

[redpoint5]

I've also heard it's easier to block the air intake in a gen III. Taxis regularly taking rear seated passengers are more likely to have the vent blocked... then there's the problem of dust/lint building up.



Keith, what's your experience with Li-ion battery replacement?

[S Keith]

Originally Posted by redpoint5

I've also heard it's easier to block the air intake in a gen III. Taxis regularly taking rear seated passengers are more likely to have the vent blocked... then there's the problem of dust/lint building up.



Keith, what's your experience with Li-ion battery replacement?

Yep. That lint screen doesn't help anything.

I have only encountered 1 Hyundai Sonata Hybrid with a failed battery. Fortunately, the dealer had their head up their butt, and the owner was still under warranty.

I have encountered a BMW ActiveHybrid7 Series with a failed battery. There were less than 1000 of those produced, and there is no aftermarket. BMW wanted $15K for the battery.

Generally speaking Lithium is more reliable than NiMH provided it is properly cooled. The chemistry essentially demands it. An example of a crap Lithium pack is the Leaf. AZ owners saw 30-40% reduction in range in 1-2 years due to their poor cooling system.

[Piotrsko]

You need to be more specific when you mention lithium batteries. Lipomn as used in gm products seems to be more forgiving or they designed more conservatively than other variations.

[redpoint5]

My interest is in the chemistry used in my PiP, and in regards to the cooling system, which is just a fan that draws in cabin air.

[S Keith]

Originally Posted by Piotrsko

You need to be more specific when you mention lithium batteries. Lipomn as used in gm products seems to be more forgiving or they designed more conservatively than other variations.

Not really. The variants of lithium have their own peculiarities. If one considers those limitations in the design, then they are very reliable - more so than NiMH.

A perfect example is the Tesla Roadster and Model S batteries... poked full of something like 7700 18650 LiPo cells - laptop grade. Absolutely nothing special and NEVER intended to be used for an EV application. Tesla designed a battery around the limitations of the cell. Seems like they got it right.

[JSH]

Originally Posted by S Keith

Perhaps it's just a matter of perspective, but most of the country isn't under clouds most of the time, and even on a comfortable 70°F day, full sunlight exposure can drive interior temperatures North of 100°F. In Phoenix, summer interior temperatures often exceed 140°F.

Do you see how a battery inside an air conditioned cabin could be affected by heat? I've seen battery temperatures as high as 145°F in the middle of summer following a bunch of short trips while sitting in the sun after each trip. Battery temperatures in excess of 120°F are very common in summer.

It's further complicated by the fact that the ENTIRE INTERIOR has to be cooled for the battery to benefit from an "air conditioned cabin." Most folks aim a vent at their face and often close off the other vents... or at least the far right one... that can cool the battery...

I can see it. Lots of short trips doesn't compute with my lifestyle but it does for lots of people. I knew people in Alabama that drove their kids 1/4 mile to school and drove between stores in a strip mall.

I drive about 1 hour to work. The car sits for 9 hours or so. I drive 1 hour home. (In the summer I drive for the first mile or so with the windows down and A/C on to cool down the car faster.) The weekends we drive someplace fun. According to OReGO our VW logged 15 trips last week. (OReGo is Oregon's fee per mile program. It records a trip any time the car starts)