"Grade A (vendor claims)" vs Grade B 280ah cells lab test. EVE Lithium Iron Phosphate LF280.
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- Опубликовано: 22 авг 2024
- Not all cells are created equal relying on voltage is not a good way to test lifepo4 cells.
Please note we are keeping this video up, but we have to clear up something NEITHER CELL IN this video were certified cells, this was when we started our business and were taking our supplier's word about grade A cells. As we clearly state in the video both cells came from the same vendor, it turns out neither was Grade A. But 1 cell was clearly worse.
So at best this should be considered Decent Grade B vs Bad Grade B Cells.
NEITHER CELL was ever sold on our site, in fact all Cells form this vendor we auctioned off on eBay until we found a reliable cell supplier which was Directly from EVE.
It was for this reason we deal directly with EVE, see our true certified grade A cells:
• Certified Automotive G...
Part 2:
• EVE Lithium Iron Phosp...
Updated Video to address concerns: V-sense and 4 cell test vs Certified EV grade cell: ruclips.net/video/KD-av4cTL-Q/видео.html
Why not name the supplier? They obviously can't and shouldn't be trusted.
The Chinese Government introduced new rules for battery manufacturers. They now test for Automotive Grade, everything that fails is Storage Grade. Also in China there were several grades of A. Storage grade is ok for most solar applications. The Off Grid Garage channel on YT is trying to get suppliers to label them properly.
We will see what they do ;)
Good, EXCEPT you simply can’t do a test like this without using the V sense leads. That’s why they have them!
I just found your channel and liked and subscribed
I think the "Res" value from the PARA display is the virtual load resistance, NOT the cell internal resistance.
If we divide the displayed volts and amps, it fits.
Interesting
Legal Reasons, we live in a sue happy world 😒
You are 100% correct - that electronic load is NOT showing the cell's internal resistance. Specific ex. at around the 1:41 mark, V is ~2.737 and "Res:" shows .03 Ω. I = V / R, so 2.737 / .03 = 91.2 which matches the current being displayed on the load.
Thanks for the great info . I've been looking at options for upgrading my Travel Trailers solar systems batteries and your focus on QC bring me a step closer to buying a set of your 260 ah batteries .
I see battery grade "A" tested with 90Ah draw and battery grade "B" tested with 200Ah draw
Watts = amps * volts
Cell 1 Can provide 250 watts at 90 amps * 2.77 volts
Cell 2 required to 212 amps * 1.17 volts to provide the same power.
Cell 2 is defective.
This is a chance you take with grade B cells some are good some are ok and some are just garbage.
You dont need "lab grade" eqipment ...lol to run a load test. Any inverter will do. I like space heaters for the load. But def big thanks for not selling crummy batteries.
Bought $4k dump load, forgot $5 V-sense wires. FAIL.
V-sense wires will not represent real world situations. Your inverter will not have separate wires just for voltage measurements. Our testing is designed to represent what will happen in actual deployments meaning this will result in a low voltage disconnect.
But enough people have requested this so part 3 will be coming out by the end of the month which will include v sense wires.
Btw it was only .3 volts different.
@@sfkenergy Ok, i will try to be clear. You need sense wires because voltage drop from battery cables forces the dump load to increase load current to maintain constant power target of 250W. You are unfairly loading weak cell to over 200A which will add even more voltage drop in the wires which leads to higher load current. It's a closed feedback loop situation. Just try retesting same cells with Vsense wire lugs connected to battery terminals first, then load cables on top of Vsense lugs. It's very important to measure actual voltage as close to battery terminals as possible. You will get significantly different results.
@@antronx7 so as stated earlier we will make part 3 eventually and show the test with v sense wires but the difference you are assuming is way off. At most the difference we measured even with v sense was .3 volts.
The main wires are 2 awg pure copper
The dc load is asking the cell to provide 250 watts of power. It is up to the cell to provide this at the volts x amps that it can. We aren’t bullying the cell and asking for it to provide 200 amps.
At the end of the day inside a battery none of these benefits will be available to the cell if you ask 1000 watts from the battery each cell be under a 250 watt load. This load will trigger low voltage cut off on this weak cell.
We have seen this enough times to never mess with grade B cells.
ruclips.net/video/22zMfe-jYwM/видео.html Go on and keep posting BS on the DIYSOLARFORUM I'm sure your Fake Gucci Gang will provide you with re-enforcements.
This is the problem im having under a 200 to 300w load on a lifepo4 200ah battery WITH 100A BMS I bought use and the seller without hesitation refunded me in full ... so now I have the task of getting rid of this battery....
Thanks for sharing, makes sense
i don't have lab grade eq. now what do i do to test my cells?
Can you say just by testing the IR with a decent 1kHz Tester (like YR1035+) if a cell is good (grade A) or bad (grade B-) or is it more complicated? Do you need a DC-load test with 100+ Amps and measure the voltage breakdown?
i been putting off buying some i didn't trust them other on line stores in china
Thanks sir!
Subscribed! ...looking to build a 24v lifepo4 pack for my van.
use sensing wires and measure again
ruclips.net/video/22zMfe-jYwM/видео.html V-sense only measures the resistance of the wires.
@@sfkenergy Not the resistance per say it eliminates the voltage drop of the wires under load. First you probably need to enable it in the electronic load, just plugging it in doesn't mean you are using it, what it does is measure the voltage at the battery, and eliminates the voltage drop over the wires during load.
Creo que te refieres a la resistencia interna de la bateria , es asi ?
Wrong test you should definitely use voltage sense from the terminals
Hi
This was a watt load test this simulates what is happening during a battery that is under a 1000 watt load (250 x4 on a 12v battery) .
@@sfkenergy i used watt test on a and b grade cells too, and with voltage compensation wires and good connection to battery with conductive paste under 400w load, current was arround 120-130a, fully charged cell from 3.32v goes to 3.12-3.15v under load
@@sfkenergy You have no clue what you are doing. V-sense wires are required to eliminate voltage drop of battery to load cables. At such low battery voltages they add their resistance to battery internal impedance and distort your readings. You also using incorrect measuring method. You have to use constant current and not constant power.
@@antronx7 You are an mis-informed Sir. V-sense measures he resistance of the wires going to the cell. You can view this: ruclips.net/video/22zMfe-jYwM/видео.html
Liked and subscribed! Q: does the inability of the Grade B cell to discharge at a higher amp rate also mean that it won't be able to charge at a high(er) rate? Would that limit the overall charge acceptance rate if you used it in a 4s1p pack?
This vid has tremendously valuable information, as I'm planning on buying LiFePo4 cells to make a house battery bank for my life-aboard sailboat. Thanks and greetings from Key West.
Capt. Blackheart Charlie
Hi.. I see this is an older video, and you only sell certified cells on your site currently. In this video you mention rejecting 15-20% of your orders.. at the time of this video were you buying what we now know are traction rejected cells? (Not accusing you of anything bad, just trying to understand the timeline as knowledge has increased over time)
I can't find you website, how do I contact you?
Thx.
Very useful information👍
Wish we knew what suppliers to avoid though. No diy-er has this type of equipment. Would've been nice to get something out of this video :/
You can easily improvise, put a load on a battery and check voltage of each individual cell or better test each cell individually, no need for fansy equipment just find a load that fits your requirement
95% is crap.
RESPONSE to V-SENSE: ruclips.net/video/22zMfe-jYwM/видео.html as you can see this makes virtually no difference because we use sufficient wires for testing.
What should Grade A 280ah cells cost on Alibaba? I know some listings say they are Grade A..... would be nice to find a supplier that sells them. Do you sell them?
The one place I know for sure. szluyuan.en.alibaba.com/
If you order the bulk cells, order extra. The grade A, order what you need, they get tested and matched by the factory in batches of 16.
The cells we will sell will be labeled as bulk cells. They are what all alibaba sellers call a++ in our tests real world capacity is between 270-290 with many averaging about 278ah. These are direct from the manufacturer and had a data sheet showing 291 ah for all.
We have also seen batches of cells that are just 263 ah.
Mind you that our tests are at .25c discharge.