Prius Prime Battery Life Cycles

The most cost efficient way to drive is: Just DRIVE it......and not worry about all of the minute details.
The HV battery can fail due to a lot of factors not related to the number of charge cycles.
So can other parts of the car.

 

Some Scania APU generators with Lithium battery are over 9 years old and they are used hard still no big signs of high drop on SOCthis are first Generation Lithium battery3 generation is superior in all places and BMS are state of the art nowHow long they will lastHard questionThey are warranted for 8 years 100 000 miles or more


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Welcome to PriusChat! I hope you enjoy your Prius as much as I have mine.

The Prime is new this year, so no real world experience exists.
In CA, Toyota warranties it for 150,000 miles or 10 years. If a significant number failed, they would go broke, so they really expect 10 years.

On a pessimistic note, more owners will have their Prius totaled in a wreck than ever need a second battery, so ebay has lots of used batteries. Be careful out there. Focus on traffic, not your battery.

 

A couple things : Failure of a battery pack means it is holding less residual charge than expected for its life. So the CA warranty doesn't really help much since most of them assume that around 10 year the battery will drop to about 60%. Nissan expects its battery pack to hold 60 to 70% of its original capacity at 10 year mark. They warranty 70% original capacity for 5 years. Toyota has spare capacity in the battery that we can not touch, this means that they could programmatically release this capacity over time to allow the overall usable kwh to stay nearly flat while the battery pack itself is holding less residual charge.

I will gladly take 60% capacity at the 10 year mark and not get too grumpy. That said, you only charge what can be pulled back out. A battery that no longer holds charge above a certain amount, doesn't take the charge. It is true that it may take more power to charge it to what capacity it has versus what it used to take, but it isn't going to stay flat while capacity drops off a cliff.

I haven't seen anything real definitive on lithium packs for cars and how they are holding capacity. Tesla has shown a battery pack go through simulated charge discharge cycles for what would be 500k miles while retaining 80% of its original capacity. Understand that Tesla's formulation for the battery is different from others so you may not see the same performance from a Toyota or other pack, but it certainly is a promising thing to think about. Also an article states that Tesla was seeing a 3 to 5% drop after 50k miles but only a 3 - 5% for the next 100k miles. It seems that drop gets lower and lower because car battery setup is very different from a phone or laptop.

 

You can always source used battery on EBay and some day make even bigger traction pack...That is my next project when my Prime eventually come to this84 MPH EV is good start

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Hi Marinna and welcome to the forum. You have a legitimate question in that the charging cycles of a lithium ion battery is finite.

Toyota came late to the Li game supposedly to see how it would hold up in real life. They introduced Li in the 1st gen PiP and then in their 2016 Prius and have jumped in with both feet with the Prime. The Tesla has been using Li for quite some time and aside from a few QC and defective issues, I have not heard of anyone complaining about the reduced range due to the life cycle of the battery pack. Time will tell.

Toyota warrants the battery for 100,000 miles, granted, I have not read the fine print (and you have inspired me to do so) but this is my 4th Prius and I have never had a single issue with any of them. I hope my track record continues.

 

We don't know what the life cycle of the Prime is and Toyota doesn't tell us. I can tell you on the PiP with lithium ion, I'm at ~2000 charge cycles and around 15% degradation over 4 years.

Battery degradation is more exponential than linear. It starts off sharp and then gradual levels out. Toyota does not allow use of the full capacity of the battery, max SoC is 85% and I don't know what the bottom end is. I used to charge 3 kWh out of a total 4.4 kWh. 4 years later, I expect I'm charging 2.5 kWh based on a 15% degradation. I don't have a kill-a-watt meter.

So just like my iPhone with 50% of capacity, that I use without issue, I expect to use my PiP with shorter and shorter range. On an iPhone, most people replace the battery. Based on your calculations which I see nothing wrong with, it wouldn't make sense to replace the Prime battery at this point. As long as it fits your needs there's no reason to replace the battery. Batteries don't usually quit without warning. I expect in time the PiP will no longer accept charge from the plug, at which point it becomes a regular Prius on the road. What's wrong with driving it as a regular Prius? Of course, this is speculative.

 

That's based on charging to a float voltage of above 4.2V, and draining to zero (100% depth-of-discharge) like is common in cell phones.

The Prime doesn't do that, as mmmodem told you above.

Limiting the full-charge float voltage to something like 4.1V-4.15V and limiting the depth-of-discharge to around 15%-20% enormously enhances the longevity of Lithium batteries, up to a factor of 10-20 by some estimates, though a factor of something like 4 is more conservative.



From: How to Prolong Lithium-based Batteries - Battery University

Looking at it, I suspect the green curve is closest to the way a Prime full Ev charge cycle looks (85% - 25%). So, that means you'll loose 10% in 2,000 cycles (one cycle a day for 5 1/2 years) and 15% in 4,500 cycles (one cycle a day for over 12 years). Of course, all this is dependent on chemistry, temperature, duration held at full charge, and so forth.

 

And does not have thermal management

 

The remaining ~3kWh unused by the Prime in Ev mode is mostly that top-of-charge and bottom-of-charge reserved area so that the batteries last a long time.

We don't know the actual numbers yet, but it's something like this:

0% - 17% - reserved for battery longevity
17% - 27% - Hv mode
27% - 82% - Ev mode
82% - 100% - reserved for battery longevity

So, 17% at the bottom and 18% at the top (35% of the total) is never used at all, and 45% (35% reserved and 10% for Hv mode) is not used for Ev mode.

 

This result is based on a standardized test that bears little resemblance to how the battery is charged and used in a car. The test is probably useful in comparing two competing Li-X chemistries but it tells you very little about longevity in a car.

 

welcome!
actually, the pip is the first prius where a full charge can be used everyday. all we can tell you is 5 years and no known failures yet.

there are too many outside variables to connect all the dots. most prime batteries will fail due to those variables before they reach their ivory tower finite cycles.

as for the best way to drive it for longevity, probably ev auto.

all the best!

 

First most of the raw life cycle test data on Lithium Ion batteries are based on 100% Depth of Discharge (DoD). Toyota only allows about 60 to 65% DoD of the available battery storage. Also their new battery is extremely heat resistant versus the older PiP battery like mine so it should be even better for life cycle usage. That being said, I've noticed no appreciable degradation on my battery after plugging it in just about every day for the last 5 years or roughly 1,600 to 1,800 times. I have some considerable data from OBD-II that shows voltages and resistance have not changed in my PiP's battery over this same period of time and I still have the same EV estimation for this time of year.

If you want an analogy, Lithium batteries are like people. They need to be exercised daily. Lithium batteries will lose life if they are full all the time. Batteries also don't like excessive heat. A full charge, plus no usage, plus heat is a guaranteed killer.

If you think you need to "rest" your battery, then like people try a fast. Leave it discharged over the weekend if you won't be using it.

So here are couple of my rule of thumbs for keeping your LiIon battery young:

If you charge it, use it. ASAP. Use the timer functions.

There is no shame in driving on a partially charged battery. If the battery has enough charge left to get you to where you need to go without a full charge, even better.

If it gets really hot out, use the A/C.


Unsupervised!

 

This is why laptop batteries don't last long. Having a battery fully-charged inside a hot computer all the time is a horrible use condition.

And that's why I keep my home laptop charged to 60% instead of 100%. I use it mostly on AC power, but 60% still gives me an hour or so of heavy use before dropping below 20%. At almost 6 years old, it still behaves like brand new. Same with my work laptop - I have it set to charge no more than 75% (I use it off-AC more than my home machine) and I only fully-charge it on those rare occasions where I'm going to be in a plane or a long meeting without power available or something.

Reducing charge level while the battery is hot saves a huge amount of battery lifetime that has nothing to do with cycle count.

 

If you think of a laptop as an example, the charger has MUCH less intelligence than Toyota invests in the Prime. The owner is much more likely to run it to 0% charged, then charge it to 100% than a Prime.

The makers of EV cars seem to use lower safety factors, so they can advertise longer distances. That is less important on a PHEV as they can fall back to gas, so Toyota can leave a larger safety factor.

It is an interesting (frustrating) anomaly that if you charge a PHEV fully, then drive downhill, it turns the engine to avoid over filling the battery. You will find multiple threads with angry owners.
Full Battery & going downhill - Engine coming on? | PriusChat
Living at the top of a hill... Disabling engine braking? | PriusChat

 

is this true of apple? my battery is lasting way longer than dell.

 

I don't own or use any Apple products, so I have no idea. But the two machines I described are Dell's.

 

at least the dells were replaceable, but something close to $100.!