lifepo4 chemistry(s)

like the normal lithium batteries there are multiple chemistries does lifepo4 have multiple chemistry variants?

while watching a video https://www.youtube.com/watch?v=8-Lwy42mbsw

Bluetti EB3A Portable UPS Powerstation Teardown and Demo

i noticed that it uses supposedly 7s2p of lifepo4

the termination voltage of a 7s lifepo4 based on 3.65 volt per cell should be 25.55 the video measured 27.25 volts that would be 3.89 almost 3.9 volts.

that does not seem right so.

1. lifepo4 does not have just 1 formula there are multiple formulas making it possible to manufacture lifepo4 cells without violating a123 and the patent of the original mit version.

2. fresh new cells will come off the charger slightly higher but as they break in the voltage will go down to 3.65 while the capacity comes up.

3. the unit is using standard lead acid based ups board or charger with lifepo slapped on it so the floating voltage will push the cells into the danger zone.

4. today's lifepo4 is not your father's lifepo4 and can tolerate slightly more similar to LIHV.

5. back when lifepo4 was first developed long term overcharging effects was not known and now they are finding out it is safe to charge at 3.89 volts.

6. they are not lifepo4 but normal lithium 4.2 volt maybe NMC or something witch makes it more stable so it wont catch fire.

hopefully someone knows why the higher voltage.

Marketing BS. The internal voltage often is irrelevant, power conversions going on input and output.

YT is not a good primary source to educate yourself.

LFP is one chemistry. There are HUGE variations in the build quality of different cell manufacturers, purity of their slurry, QA processes in binning Grade A vs the rest.

There may be little tweaks in formulation, but the effects of that will be far less than the above.

Drop-in sealed units and powerbanks are very poor value compared to just buying good quality cells and adding those components **you** need for your use case.

3.45Vpc is the highest anyone should go if you care about longevity which isolated at rest will go down to 3.32-3.34Vpc, anything higher is just useless and stressful surface charge.

Allowing any cell to go near maxV (3.6V) is stupid, accomplishes nothing but reducing lifespan.

If you insist on paying lots of money for a small crappy battery, then just follow the mfg guidance for its care, and do not expect more than a few years' longevity

i am looking for a ups that will run on lithium so i can replace the lead acid and some of them solar generator units have ups mode where they will run the inverter if the power goes out.

i would replace the battery with a bigger one that will give longer runtime since batteries are getting very cheap especially on http://batteryhookup.com since their sources are ev makers who cant just re drill new holes if the mounting holes mis align or cant machine custom bus bars if they dont align or are from crashed cars like teslas where people get too confident in the self driving feature.

so many of the batteries have low milage or no milage in the case of mis drilled holes.

so my intent would be to buy a lifepo4 based solar generator with ups so i can keep my computer up longer.

the ups i have i used a car battery (optima spiral wound cells) but hear the end of it's life it was squirting acid out around the side terminals and ate a partial hole in the particle board base of the computer desk (i have to replace a section of the bottom board.

so now i am using original ups batteries until i can get a solar generator.

i have seen that lifepo4 is a suitable replacement for lead acid but i am worried about the floating voltage (lead acid can handle being left on floating voltage for ever since they are a very safe chemistry but will just wear out sooner)

but i am worried that if the bms while it will stop the charging ok it may not be able to stay on when the inverter is called upon.

that is why i am thinking solar generators use very specialized bms.

fortunately i found a pair of lifepo4 batteries on amazon https://www.amazon.com/Lithium-Rechargeable-Maintenance-Free-Scooters-Lighting/dp/B09H3FG1D5/?_encoding=UTF8&pd_rd_w=p9Iyl&content-id=amzn1.sym.8cf3b8ef-6a74-45dc-9f0d-6409eb523603&pf_rd_p=8cf3b8ef-6a74-45dc-9f0d-6409eb523603&pf_rd_r=TZ6NRPJYGCAMBTSH4R73&pd_rd_wg=kc7Nb&pd_rd_r=882c9a43-d740-465d-8f9e-600e7997c677&ref_=pd_gw_ci_mcx_mi&th=1

that if lifepo4 would work these would be a suitable guinea pig.