LifePO4 Lifespan (not cycle life)

Batteries, Chargers, and Battery Management Systems.
redilast   1 kW

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Re: LifePO4 Lifespan (not cycle life)

Post by redilast » Dec 04 2016 6:26am

Really depends on the brand and type. I have seen entire batches of LifePo4 cells go dead to 0v after 2-3 years of storage. In my experience LiFePo4 cells are the easiest cell chemistry to screw up from the manufacturing sides of things.

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Boekel   1 mW

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Re: LifePO4 Lifespan (not cycle life)

Post by Boekel » Dec 02 2019 2:06am

Interesting old thread!

I've tested hundreds of Winston LiFeYPO4 cells lately, mostly from 2011-2012, after a working life in electric buses with multiple charges per day!

about 80% of cells were still very good, capacity between 150-165 Ah (a new cell from those years would have had 175-180 Ah?)
Some were very bad (130-140 Ah) some swollen, some dead. and some that were already replaced (so only 2-3 year old) tested 170-180 Ah

Of the cells above 155 Ah, almost none had a high internal resistance

about 2-3% had some or a lot of self discharge (fully charged, rest for at least two months, than charge again to see how much was lost)

I'd say the Winston cells are -very- good. (don't know if the ones with Yttrium are better than the ones without)

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Matador   10 kW

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Re: LifePO4 Lifespan (not cycle life)

Post by Matador » Dec 05 2019 10:29pm

I think you can find the answer in that post I started on Calendar Aging of lithium cells:
viewtopic.php?f=14&t=86777&p=1269133&hi ... r#p1269133

Look at the graph of LFP chemistry.

Calendar aging is dependant on storage state of charge (SOC) and storage temperature. Both have an effect on residual recoverable capacity, and on internal resistance (which will increase slightly relative to brand new manufactured cell's internal resistance). Interestingely, IR doesn't seem much affected for LFP chemisties as compared to other chemistries like NCA and NMC, as you can judge from the graphs.

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fechter   100 GW

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Re: LifePO4 Lifespan (not cycle life)

Post by fechter » Dec 06 2019 11:37am

It's hard to find good information on calendar aging. I have some A123 cells that are nearly 10 years old that still perform reasonably well but I haven't done an actual capacity measurement.
"One test is worth a thousand opinions"

cooking monkey   100 mW

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Re: LifePO4 Lifespan (not cycle life)

Post by cooking monkey » Dec 06 2019 12:05pm

I am interested in this topic. I am in the process of switching over my house batteries to lifep04. I currently have 4 Battle Born lifep04 batteries bought for over 5000.00 and will be buying 4 more soon. I am wanting these to be the last batteries I have to buy. Once I have a full bank of 8 (10.2 kwhrs), cycling them roughly amounts to 2kwhrs a day spring, summer and fall, Nov, Dec, and Jan roughly 3.5 kwhrs a day. I will be changing my charge controller setting twice a year, In Feb I will set my bulk charge to 13.9 or 14 volts, then come oct, I will bump the bulk charge up to 14.4.

If anyone has experience with these type batteries I would love to hear about it.

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