⚡Quinergy⚡The truth behind B-grade LFP cells

There's been a lot of talk about B-grade LFP cells and why they are B-grade. I have my own opinion about what it means to buy B-grade cells which differs a bit from the general consensus floating around on the internet, let's dive in and find out why I believe B-grade cells are perfectly suited for Home Energy Storage solutions but does mean you need to do a bit more work.
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░▒▓[Associated blog post & Mentioned in the video]▓▒░
Linked files:
Quinergy 70 Luyuan B-Grade cell test excel: blog.quindoria...
Quinergy 70 Luyuan B-Grade cell test no sort: blog.quindoria...
Quinergy 70 Luyuan B-Grade cell test high sort: blog.quindoria...
Quinergy 70 Luyuan B-Grade cell test low sort: blog.quindoria...
░▒▓[Music]▓▒░
Intro&Outro
TheFatRat - Xenogenesis
( • TheFatRat - Xenogenesi... )
During Video
None!

[@robstarkasm]

Thanks for taking the time to walk us through all of this! It's really well presented and educational.

[@IntermitTech]

Thnx, appreciate that!

[@DaveBoxBG]

Exactly what I did as well. I bought used laptop batteries for $1 per battery which has 6 inside and managed to retest and save 77% of the cells and build my battery.

[@wildekek]

Such a nice project. Can't wait till you build them and see your BMS choices.

[@PersonXes]

Wederom een super heldere uitleg!

[@AndrewFroude]

Thank you.

[@andiegli5893]

intersting comparison, tnx for sharing your findings. I believe time plays an important role as well when comparing a and b grade cells. I wonder how your b grades will perfom after 1 or 2 years operation. The experiences I made is that there are big differences in longlifity between a and b grade.

[@IntermitTech]

Interesting, in theory these are still sold as being able to do 6000 cycles, but we're certainly going to see, it's in part also why I measured all of them individually

[@-vermin-]

The average of you pack configurations (270+270+280+285)/4 = 276Ah. Slightly less than the A grade guarantee but considering the cost savings well worth it.

[@t.d.5804]

1 year later, B grade cells are 56€/kWh today. Why are people building 16S1P packs and parallel them ? Each needs a BMS and case. Why not 16S4P ?

[@SpencerHHO]

If you're not pushing high currents in and out of them and limiting their state of charge to say 20%-85% a chunks active balancer with the BMS mitigates the capacity difference between cells. I know guys who buy hundreds of 18650s and only loosly balance the blocks of parallel cells and rely on active balancing to keep the whole thing from catching fire lol.

[@PhG1961]

Schitterend!

[@LackofFaithify]

I would say google Luyuan and Solar Forums. I absolutely believe buying B grade is the best move. The grading and certification they like to go on about...well...certainly they (the actual battery manufacturers) bin and send the best ones off to the automotive world, beyond that, there is zero ability to confirm any of the grading or quality rating claims that are made with regard to home energy storage sales and customers (ie by the middlemen companies like Luyuan, Docan, etc...). You can test the capacity yeah, IR changes (do you really know what the starting IR was to know what the value you measure now means, can you measure the same IR more than once? twice in a row?) , etc... but no one is testing them through all X,000 cycles that are promised and even if one guy does, it is him and his tiny sample as you say. It is important to not lose sight of these facts when making claims in videos and as customers who will be making purchases. Remember, these are not the people making anything. They are just able to buy from the actual manufacturers, then mark up, value add, whatever, and sell to you. That's it. If you have any actual on the record information from EVE or CALB, that would be a very different situation.