Our NEW GO-TO LiFePO4 vendor...09.20.21

[Gazoo]

There are several references to CATL's 12000 cycle life cells if one does a google I would really love to see a spec sheet for these cells as well as the price. As far as I can tell CATL made the announcement in 2019.

It might be Evlithium can get them. I personally have no interest in buying these but perhaps someone who may be interested can contact Evlithium and see if they will supply a spec sheet as well as pricing.

CATL New LiFePO4 Battery 280Ah Prismatic Cell

CATL 3.2V 280Ah Lithium iron phosphate battery cell with more than 10000times super long cycle life

www.evlithium.com

 

[robby]

CATL 280Ah Battery cell performance​

The cell has a maximum cycle life of 12000times = 32.8 years of service if treated right. WOW !

They should last for 32 years yet they only warranty them for 3 ?

 

[magic8192]

I know that a while back CATL claimed to have a million mile LIFEPO4 battery for electric vehicles. Tesla is currently using the "million mile" CATL LIFEPO4 battery in some of their electric vehicles in China.

 

[Sback]

They should last for 32 years yet they only warranty them for 3 ?

I laughe at people who convert cycle life to calendar life. Cycle life has nothing to do with calendar life, its strictly cycles. All lfp holds the same Callender life. Regardless of cycles.

 

[robby]

I laughe at people who convert cycle life to calendar life. Cycle life has nothing to do with calendar life, its strictly cycles. All lfp holds the same Callender life. Regardless of cycles.

Cycle life and calendar life are two different things but for our application which is what they are selling those batteries for they will typically get one full cycle per day. You are wrong about all LFPs having the same calander life. That is very dependent on the quality of construction. We have already seen cheaply made LFP batteries leak within the first few months after being sold (see Will's Video) while other have gone way past 10 years.

 

[robby]

I know that a while back CATL claimed to have a million mile LIFEPO4 battery for electric vehicles. Tesla is currently using the "million mile" CATL LIFEPO4 battery in some of their electric vehicles in China.

Have you noticed that in the last 6 months the Trend on cells being sold on Alibaba has been pretty consistent?
6 months ago most said 2000-3000 cycles. Then about 4 months ago 6000 became common. Then 3 Months ago it was 7000 cycles and now it's 12,000 cycles. I suspect that in another two months they will be telling us 20,000 cycles.
It's all about making you spend money with them and not their competitor.

 

[Dzl]

Have you noticed that in the last 6 months the Trend on cells being sold on Alibaba has been pretty consistent?
6 months ago most said 2000-3000 cycles. Then about 4 months ago 6000 became common. Then 3 Months ago it was 7000 cycles and now it's 12,000 cycles. I suspect that in another two months they will be telling us 20,000 cycles.
It's all about making you spend money with them and not their competitor.

This is one reason its important to always ask for a manufacturer datasheet and basically take with a grain of salt all technical claims made by the seller if they cannot be verified.

 

[Sback]

Cycle life and calendar life are two different things but for our application which is what they are selling those batteries for they will typically get one full cycle per day. You are wrong about all LFPs having the same calander life. That is very dependent on the quality of construction. We have already seen cheaply made LFP batteries leak within the first few months after being sold (see Will's Video) while other have gone way past 10 years.

I agree with what your saying. I was just stating that cycle life has nothing to do with calender life. The average Callender life of lfp is 10 years. Yes there are the cases of just a bad cell that prematurely fails.

 

[Horsefly]

I was just stating that cycle life has nothing to do with calender life.

I think this statement can be very misleading. I believe that cycle life - as described by cell manufacturers - is the number of full charge / recharge cycles until the usable capacity has dropped to 80% of its original capacity. For the purposes of discussions here, I think people refer to "calender life" as that same measure, in time. That is, people only care about that same measure translated to calendar months / years. So if I have an application where I cycle the batteries literally every day, if the cycle life is 2,000 cycles, then the useful calendar life of those cells is 2,000 / 365 = about 5.5 years.

If I may ask, where does your 10 years calendar life come from?

 

[robby]

If I may ask, where does your 10 years calendar life come from?

I think he is using the average warranty period as many of the battery pack makers offer a 10 year warranty. Who knows what the reality is, these battery packs may last 15 years or more.

 

[Dzl]

For the purposes of discussions here, I think people refer to "calender life" as that same measure, in time. That is, people only care about that same measure translated to calendar months / years.

But that is not what Calendar Aging means at all.
I don't know how most people here interpret the term, but if they assume it means cycle life in years, they are fundamentally misunderstanding the meaning.

Here is one succinct definition of Calendar Aging:

Calendar aging comprises all aging processes that lead to a degradation of a battery cell independent of charge-discharge cycling. (SOURCE)

In other words calendar aging is the aging that occurs at rest and independent from cycle life aging. My understanding is that Cycle and Calendar aging are separate and parallel concepts, which are both in turn affected by a number of different variables.

Two of the main factors leading to accelerated calendar aging are storage at high SOC and storage at high temperature.

What you are referring to (Cycle aging expressed in years) is something different than Calendar Aging, its just a different (and probably very rough) way to express cycle life in units of time rather than number of cycles.

 

[Horsefly]

But that is not what Calendar Aging means at all.
I don't know how most people here interpret the term, but if they assume it means cycle life in years, they are fundamentally misunderstanding the meaning.

Here is one succinct definition of Calendar Aging:

In other words Calendar aging is the aging that occurs independent from cycle life aging. My understanding is that Cycle and Calendar aging are separate and parallel concepts, which are both in turn affected by a number of different variables.

Two of the main factors leading to accelerated calendar aging are storage at high SOC and storage at high temperature.

What you are referring to (Cycle aging expressed in years) is something different than Calendar Aging, its just a different (and probably very rough) way to express cycle life in units of time rather than number of cycles.

That's fine, but abusing the cells in terms of storage at high temperature or high SoC will reduce the number of cycles too.

I stand by my statement, that most people care about how long their cells will last in their situation if they take care of them. That is, how many times they cycle them in a given time, projected over time. I don't see any meaningful reason to discuss calendar life unless it is in terms of how long the cells will last for them.

Besides, the original statement was that the calendar life of LiFePO4 is 10 years, period. Clearly that doesn't fit your definition either.

 

[kid744]

Received my battery shipment from Docan Tech today.
Pictures here: Eve304 Shipment
Kid

 

[Ampster]

I stand by my statement,

You and @Dzl are now talking about different issues. His statement clarifies the definitions and your statement is what people care about. There is nothing incorrect about either statement.

 

[Horsefly]

You and @Dzl are now talking about different issues. His statement clarifies the definitions and your statement is what people care about. There is nothing incorrect about either statement.

That made me laugh to read what you wrote, but I guess you are right.

 

[Sback]

I think this statement can be very misleading. I believe that cycle life - as described by cell manufacturers - is the number of full charge / recharge cycles until the usable capacity has dropped to 80% of its original capacity. For the purposes of discussions here, I think people refer to "calender life" as that same measure, in time. That is, people only care about that same measure translated to calendar months / years. So if I have an application where I cycle the batteries literally every day, if the cycle life is 2,000 cycles, then the useful calendar life of those cells is 2,000 / 365 = about 5.5 years.

If I may ask, where does your 10 years calendar life come from?

The internet and the internet does not lie it knows everything ? I read a report on lfp and it mentioned average calendar life is 10 years. But to be honest I don't think anyone knows the real world life expectations on either cycle or capacity with the way most of use them.

 

[Dzl]

As @Ampster alluded to, my last comment is simply meant to clarify a misuse/misunderstanding of a term. Not to make or disagree with any broader point in whatever broader thing is being debated (I haven't followed this discussion closely enough to know, or have an opinion on that).

That's fine, but abusing the cells in terms of storage at high temperature or high SoC will reduce the number of cycles too

Precisely. Both cycle and calendar aging are factors impacting overall cell life, and both are dependent on a number of variables like SOC and temperature and in the case of cycle life C-rate. But to be clear, calendar aging is not only the result of abuse, it is just accelerated the further from optimal you get, but its a factor no matter what.

I stand by my statement, that most people care about how long their cells will last in their situation if they take care of them.

I'm not arguing with that statement, I agree with it for the most part.
What you would like to focus on (how long cells can be expected to last in real world conditions) is what matters to most of us most in a practical sense, its just not what calendar aging means.

Calendar aging + cycle aging together will determine how long your cells last, and both will depend on a number of variables that are not always aligned (for example, low temperatures are more optimal for calendar aging, but mild or warm temperatures are better for cycle life).

Point being its important to understand the difference between cycle and calendar aging, and understand that real world life of your cells is the product of both. Simply dividing the cycle life figure from the datasheet by 365 will not give you an accurate estimate. Both calendar and cycle aging will affect the real world life of your cells and specifically how and in what conditions you use your system will determine to what degree each factor matters.

 

[sunshine_eggo]

As @Ampster alluded to, my last comment is simply meant to clarify a misuse/misunderstanding of a term. Not to make or disagree with any broader point in whatever broader thing is being debated (I haven't followed this discussion closely enough to know, or have an opinion on that).


Precisely. Both cycle and calendar aging are factors impacting overall cell life, and both are dependent on a number of variables like SOC and temperature and in the case of cycle life C-rate. But to be clear, calendar aging is not only the result of abuse, it is just accelerated the further from optimal you get, but its a factor no matter what.


I'm not arguing with that statement, I agree with it for the most part.
What you would like to focus on (how long cells can be expected to last in real world conditions) is what matters to most of us most in a practical sense, its just not what calendar aging means.

Calendar aging + cycle aging together will determine how long your cells last, and both will depend on a number of variables that are not always aligned (for example, low temperatures are more optimal for calendar aging, but mild or warm temperatures are better for cycle life).

Point being its important to understand the difference between cycle and calendar aging, and understand that real world life of your cells is the product of both. Simply dividing the cycle life figure from the datasheet by 365 will not give you an accurate estimate. Both calendar and cycle aging will affect the real world life of your cells and specifically how and in what conditions you use your system will determine to what degree each factor matters.

Trying to say the same thing in smaller paragraphs and using numbers:

Battery life = cycle life minus aging factors (calendar life).

Example:
4000 cycle LFP. Cycled daily.

4000/365 = 10.96 years, degrades 1.83%/year

Based on cycle life, the battery should last almost 11 years before capacity drops to 80% of rated.

In reality, the 80% level will be hit BEFORE 11 years because cells deteriorate over time whether used or not. Assuming a calendar degradation of 0.5%/year:

Year	Cycle Loss	Age loss	Cap
1​	-1.83%​	-0.50%​	-2.33%​
2​	-4.15%​	-0.50%​	-4.65%​
3​	-6.48%​	-0.50%​	-6.98%​
4​	-8.80%​	-0.50%​	-9.30%​
5​	-11.13%​	-0.50%​	-11.63%​
6​	-13.45%​	-0.50%​	-13.95%​
7​	-15.78%​	-0.50%​	-16.28%​
8​	-18.10%​	-0.50%​	-18.60%​
9​	-20.43%​	-0.50%​	-20.93%​
10​	-22.75%​	-0.50%​	-23.25%​
11​	-25.08%​	-0.50%​	-25.58%​

80% level would occur in the 9th year.

 

[Dzl]

Trying to say the same thing in smaller paragraphs and using numbers:

If I could pay someone just to follow me around and do this all the time I would ? conciseness is not my strong suit

 

[Gazoo]

It's nice to know under ideal conditions cells will last a long time

 

[nhhiker]

Broke out the new power supply last night, installed all of the grub-screw terminals, hooked the cells up parallel, and put the charge on them, initially to 3.4V. They've been on for over 18 hours and have only gained about 2 tenths of a volt. LOL They started out drawing about 9A, now down to 5.

I'm doing the step method - to 3.4V and rest, then 3.5 and rest, then 3.6, call them balanced. I'm guessing the second and third steps will go quicker.

So far so good...

Did the cells expand at all when top balancing without compression? I'm about to start top balancing a set of the same cells and would like to avoid using a fixture during this step.

 

[Horsefly]

Did the cells expand at all when top balancing without compression? I'm about to start top balancing a set of the same cells and would like to avoid using a fixture during this step.

On the two sets of 8 cells I've gotten (8 x 280Ah and 8 x 230Ah) my charging current was 30A for 8 cells, which works out to be less than 4A per cell. I didn't have a compression fixture and didn't see any swelling. I think if you don't go above 3.65V and go with a reasonable current (per cell) they won't swell. That's my experience anyway.

 

[Browneye]

Did the cells expand at all when top balancing without compression? I'm about to start top balancing a set of the same cells and would like to avoid using a fixture during this step.

Zero zilch flat as a pancake.
And they stay balanced within 4mAh.

After top-balancing I did assemble them into a compression jig:

 

[svsagres]

Another happy customer here. Purchased 8x 230AHr w/ welded studs from Docan. They arrived at my package delivery place in Point Roberts within just a few days of my order, from the Houston warehouse. Packaging was great, and using a calibrated Fluke multimeter I was able to verify that all cells were 3.2930V +/- 0.0015V or so. Next step is to get them into a fixture that I can mount securely in my 27' sailboat, and integrate with the rest of the system I'm building.

 

[Alloy]

Another happy customer here. Purchased 8x 230AHr w/ welded studs from Docan. They arrived at my package delivery place in Point Roberts within just a few days of my order, from the Houston warehouse. Packaging was great, and using a calibrated Fluke multimeter I was able to verify that all cells were 3.2930V +/- 0.0015V or so. Next step is to get them into a fixture that I can mount securely in my 27' sailboat, and integrate with the rest of the system I'm building.View attachment 80612

What freight company in Point Roberts did you use?

No issue driving down there to get them?