Why is the Prius traction battery so incredibly inefficient?

Since it has to be warrantied for 10 years and 150,000 miles, I doubt there are any AGM batteries that will consistently go the distance. (and time)

In fact, Toyota strives to not tax the traction battery in an effort to make them last for the CARB mandated warranty. If a part has over a 5% failure in the warranty, the manufacturer will lose money on the product.You may wish to check how many of those 'better' batteries have a non prorated 10 year 150,000 mile warranty.

 

The battery does not weigh 200 lbs., it's much lighter. How many batteries do you know of that can go 10 years or more without replacement? Will five group 31 diesel truck batteries go the distance or need replacement? Toyota advertises these cars with batteries that should last the lifetime of the car. Although the car's been so reliable, it seems the car's outlasting the batteries.

 

Obviously the OP statement is wrong, as it pertains to Prii, the NiMH hybrid batt is apparently very efficient: relatively low weight, small size, able to handle the required current flow, and reliable vs. a heavy lead-acid (AGM) battery. Any more than that we'd have to be electrical engineers to explain the advantages. But why should we have to defend it? we got a car that goes 50+ MPG and it's so roomy most people could not even tell you where the battery is hiding.

 

Over 200lbs? Most of the numbers I'm finding put it in the 100-120lb range. One of your group 31 batteries weighs 60lbs. Lead acid isn't very efficient with high loads. As stated before, they also wouldn't last as long, even the 12v battery in most hybrids only lasts 5 or 6 years living a relatively relaxed life.

 

what id this 'other hybrid' you speak of?

 

In addition to lifespan, there some other issues I can think of to not use lead acid. Since the traction pack is in the cabin, lead acid batteries would have to be vented to the outside. Then there is the issue of how much energy they could absorb while braking.

 

I wonder if he is counting all of the weight of the protective casing/cabling of the traction battery, but ignoring the amount of protection/cabling AGM batteries would need?

 

OP: Google 'energy density by battery chemistry.'
Then spend some time learning about the differences between battery chemistries as they differ in regard to

1. Specific Power
2. Energy Density
3. Recharge cycle life and shelf life
4. Thermal runaway risks

 

My 2006 traction battery is on it's way out, I'm seeing full green SOC on city driving now and that has never happened in the past. Oh how I wish it would be inefficient and crap out before my warranty ends.......

 

Asked and answered.

Toyota actually spent a little bit of money.....actually.....a butt-ton of money on battery development.
They still are.

This isn't a new problem.
The Germans and Rooskies have been tinkering with battery technologies since the 40's and 50's (respectively) and there is an entire industry struggling furiously to allow devotees of Gorilla Glass to endanger the driving public for longer periods of time between charging their batteries.

Engineering is compromise.
Marine batteries won't last, are less energy dense, require maintenance, and they're too heavy and would be loads more dangerous if you scale them up for use as a traction battery.
I'm pretty sure that the pointy-heads in Aichi, JA considered using them........



......very briefly.

 

I saw the same change in battery behavior in our Gen2 Prius -- the first time a couple of years ago, yet the Prius is still going strong.

The capacity loss appears to me to be a log function; or perhaps a geometric series if your math skillz tend in that direction.

 

Ask the yacht owner who relies on AGM marine batteries to power the accessories on his yacht how often he has to replace the batteries. Or look in the yachts for sale listings and see how often "replaced batteries on bla bla date" is used as a selling point. And most of those don't have to function every day and the yachts aren't used in the winter.

Ask the golf car (cart) owner how often he has to replace his deep discharge batteries. Mine lasted 5 years and need replacement.

 

200lbs? Wow just a little off! The PiPs LiIon battery is only 168lbs, the 2010 Prius NiMH Battery weighs 68lbs. And as the next generation is worked on the battery is improved and weight goes down. Even the Gen I Prius battery weighed only 53.3 kg including the protective shell.

 

First the prius only uses about 40% of the SOC of the battery, so we need 0.5 kwh with power of 27 kw. The number I found when I googled was 53 kg for the battery pack or 117lbs. A 110 amp hour marine agm battery is 75 lbs, but that is just the battery not a whole pack, and it only can be charghed at 40 amps making it less than 0.6 kw charge. You need a heavier agm battery to handle the charge discharge of the prius hybrid cycle. Unless I am missing something you need a heavier battery to do what the nimh prius battery does with any lead acid chemistry.

You can use a smaller lighter battery. A 1 kwh lithium polymer battery would weigh less, and be able to provide that 27kw of power and 0.5kwh of usable energy.

 

After reading this thread, I just had a CAPITAL idea!!

Of course, you wouldnt want to use diesel truck or AGM marine batteries in place of your HV traction battery. Buuuut what about using a Prius HV battery in a boat in place of the AGM marine batteries!!

Right now in my 27' Four Winns, I have two group size 31 AGM batteries. They dont last all that long when Im out on the hook (read: anchored out overnight) and they are very heavy. BUT a Prius traction battery, converted down to the proper voltage, would probably power my electric demands on the boat for days....

I might just be a genius after all

 

Just take the DC-DC converter that's attached to the battery along with you. You'll have 100 Amps of 12V power at your disposal.

 

Hi there, prius121212 ... and welcome !!

That the Prius traction pack is efficient - is not news - but rather a question. The search tool can sometimes be your friend. Other times, it sucks big time. What kind of hybrid do you have?
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