Has anyone actually used a LiFePO4 battery to the end of its lifetime? If so, how long did it last?

[AntronX]

Can you elaborate on the 15 till 20 ºC for maximizing LFP cell calendar life?

Lower temps slows down parasitic reactions inside the battery which supposed to make it last longer. You don't want to go too low or you risk doing damage via lithium plating at higher charge rates. There is no clear experimental research confirming this.

 

[sunsurfer]

The Micronova will be here before your packs die. Battery life will be the least of your worries.

 

[45North]

As I understand it lithium batteries don't really "die" so much as just fade away. They gradually hold less charge.
At some point you may decide to replace them but you'll have lots of notice. And if you're patient, tolerant or poor you can keep using them until they get so annoying you can't stand it anymore.

 

[MattiFin]

Yeah, 300 amp-hour cells charged then dumped at 200 amps will complete a full cycle in about three hours. So, eight cycles are nominally possible in a 24-hour day. 1.71 years for 5000 cycles. I guess someone could have done that, but I don't know. I am guessing that the actual manufacturers have done. EVE has published charts showing cycles (past 10,000 if I remember right) at various pressures. The charts look like actual data, so maybe they cycled the cells that hard.

The more I write here, the more certain I am that the makers have done this, but I don't have any links to share right now.

Australian government renevables lab has tested some batteries to nearly 4000 cycles

https://arena.gov.au/assets/2018/05/lithium-ion-battery-testing-public-report-12.pdf

Two thing to learn from that: Lifepo4 seem to well with cycling and software is crap in half of the products

 

[upnorthandpersonal]

I guess someone could have done that,

We're actually doing that in the lab here. As soon as we have results, we will publish them. It's just that in the past this data has been under NDA (done for a customer), but now we're also running tests that will be public, including at different temperatures, both LFP and Sodium, etc.

 

[sunsurfer]

As I understand it lithium batteries don't really "die" so much as just fade away. They gradually hold less charge.
At some point you may decide to replace them but you'll have lots of notice. And if you're patient, tolerant or poor you can keep using them until they get so annoying you can't stand it anymore.

Interesting. How about after the cells are down to 10%, break down the packs and hook them up to a small LED and solar panel? Those 280ah cells still making 28ah could run a bright LED for a month.

 

[timselectric]

I don't plan to ever need to replace my batteries.
In 20 years, they will have 20% less capacity. But all of the appliances will probably be 20% more efficient. So, it should be a wash.

 

[SouthernSolar]

I'm 85. If I am alive in 10 years I will be happy to buy new batteries

 

[timselectric]

"Are we there yet? "
The answer is still, no.

 

[Giggs]

Please delete my post. I had no input here.

 

[TomC4306]

Pack 1 deployed Dec 2021. Pack 2 deployed Mar 2022. When not making heat or cooling, overnight usage is generally 45/50%

 

[cj0]

Lower temps slows down parasitic reactions inside the battery which supposed to make it last longer. You don't want to go too low or you risk doing damage via lithium plating at higher charge rates. There is no clear experimental research confirming this.

The (#2 LFP cell manufacturer) BYD, its battery box LVL15.4 warranty gives an indication. The warranty duration is depending on (average?) "Ambient temperature":

• 0~20ºC: 10 years
• 20~30ºC: 7 years
• 30~45ºC: 5 years

And of course in the 0 till 20ºC operate at reduced rates. For example for discharge, correct:

• 0~10ºC: -25% C-rate
• 10~20ºC: -12.5% C-rate

And even reduce the rate further below 20% SoC.

 

[wpns]

The (#2 LFP cell manufacturer) BYD, its battery box LVL15.4 warranty gives an indication. The warranty duration is depending on (average?) "Ambient temperature":

• 0~20ºC: 10 years
• 20~30ºC: 7 years
• 30~45ºC: 5 years

And of course in the 0 till 20ºC operate at reduced rates. For example for discharge, correct:

• 0~10ºC: -25% C-rate
• 10~20ºC: -12.5% C-rate

And even reduce the rate further below 20% SoC.

Well, I'm screwed, except (silver lining) EG4 doesn't warrant their batteries for anything but calendar time.

MariaDB [Monitoring]> select min(EG4$Alpha$MaxCellTemp_BMS), max(EG4$Alpha$MaxCellTemp_BMS), avg(EG4$Alpha$MaxCellTemp_BMS) from EG4 where EG4$Alpha$MaxCellTemp_BMS > 15;
+--------------------------------+--------------------------------+--------------------------------+
| min(EG4$Alpha$MaxCellTemp_BMS) | max(EG4$Alpha$MaxCellTemp_BMS) | avg(EG4$Alpha$MaxCellTemp_BMS) |
+--------------------------------+--------------------------------+--------------------------------+
|                       27.00000 |                       41.00000 |                   33.929197123 |
+--------------------------------+--------------------------------+--------------------------------+
1 row in set (3.032 sec)

MariaDB [Monitoring]> select min(EG4$Alpha$MinCellTemp_BMS), max(EG4$Alpha$MinCellTemp_BMS), avg(EG4$Alpha$MinCellTemp_BMS) from EG4 where EG4$Alpha$MinCellTemp_BMS > 15;
+--------------------------------+--------------------------------+--------------------------------+
| min(EG4$Alpha$MinCellTemp_BMS) | max(EG4$Alpha$MinCellTemp_BMS) | avg(EG4$Alpha$MinCellTemp_BMS) |
+--------------------------------+--------------------------------+--------------------------------+
|                       25.00000 |                       39.00000 |                   32.001762793 |
+--------------------------------+--------------------------------+--------------------------------+
1 row in set (3.121 sec)

I sure wish Tbat worked!

No, I'm not putting in AC for the batteries.

Maybe low C rates help? I'm pretty much always below C/10 on my 280AH batteries:

 

[akitawpo]

I think the consensus on multiple forums is that the electronics side (BMS) will die much sooner than any perceivable degradation. If you have a DIY battery or able to change the BMS on a pre-made battery,10+ years of service at the rated capacity should be achievable. I have been with my EG4 LLs for two years, no problems. Ten years from now I'm hoping EG4 still carries BMS replacements that will fit the case. If not.....I'll improvise. Also, by the time they are dead new chemistries should be available. Maybe Musk will cheapen their house reactor ;-).

 

[Brucey]

Well, I'm screwed, except (silver lining) EG4 doesn't warrant their batteries for anything but calendar time.

Are we sure about that? There's certainly the possibility that they will consider the warranty "satisfied" once the battery has delivered what they've claimed, 82.6 MWh:

If they only used 10 calender years as the deciding factor you could put one to work running three full cycles per day doing time of use arbitrage etc.

The ones installed outside in hot ambient temperatures will certainly have an earlier death than ones installed in cool all year round basements etc. Not sure if eg4 will ever add temperature of use limits in the future.

 

[Brucey]

The (#2 LFP cell manufacturer) BYD, its battery box LVL15.4 warranty gives an indication. The warranty duration is depending on (average?) "Ambient temperature":

• 0~20ºC: 10 years
• 20~30ºC: 7 years
• 30~45ºC: 5 years

And of course in the 0 till 20ºC operate at reduced rates. For example for discharge, correct:

• 0~10ºC: -25% C-rate
• 10~20ºC: -12.5% C-rate

And even reduce the rate further below 20% SoC.

That is interesting info, thanks. So the bms is tracking ambient temps for warranty purposes. Makes sense to me, given what we know about high ambient temps causing very significant battery lifecycle degradation.