Testing new Fullriver LiFePO4 26650 cells for capacity before building?

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battery_dispenser

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I've been reading around on the forums a bit and I've seen several members mention that it's not worth testing new batteries for capacitybefore building a power wall unlike harvesting used laptop 18650s. Is that only for 'name brand' batteries from LG, Panasonic, etc where quality control, reliability, tolerances, etc is much higher? Fullriver seems to be no-name, and I'm using 1100+ individual cells. I'd prefer not to spend weeks testing them a few at a time, but will do so if it makes for a stronger, more capable battery. I'm not sure what name brand batteries vary by with regards to capacity, but if new no-name cells vary substantially, I'm not opposed to making my pack smaller (it's for a solar powered tiny-house) and using the substantiallydeviating cells for some other projects like a motorcycle or carbattery.
 
I would at least check all new batteries with a volt meter to make sure there's none that stand out from the rest as being low. For Chinese cheapies, off-brand, or new "old-stock" cells that sat for a long time, I would still capacity test each one. If you got them Fullrivers where I think you did, they sat for a couple of years. I think everyone is going to have their own preference on how they manage/test new cells.
 
I just check my tenergy 32650 5.5 ah(looks similar to the fullrivers but bigger) for voltage, if they all had the same voltage I went ahead and used them. I build 2x 4s20p 110ah lifepo4 packs last year and they seem to be working ok except for going out of balance when charging. Since I didnt test the cells, deep down I don't think its actually 110 ah but I never actually drained it all the way, and my balancing problems might be because the parallel groups aren't matched up in mah?

At 5.5 ah, charging and discharging and testing (at 1 amp) each cell will take about 10 hours each. Thats too much time for me and I don't have the equipment to test more than one at a time.

But on the endless sphere forums, someone did test some of the fullrivers 26650 and he said he wasn't getting the 3300 mah rating, he was only getting between 1000-2500 ah on the ones he checked. This is the page "https://endless-sphere.com/forums/viewtopic.php?f=14&t=26383&start=1525". Maybe he got a bad batch of cells. If you got the equipment to test a few, it might be worthwhile just to make sure you got a good batch of cells.
 
Oh man, this is not good. Most of them tested at around 3.20 to 3.23v out of the box on my cheap Harbor Freight Cenntech multimeter. My eBay battery capacitor tester ($3 HW-586 model that seems pretty popular) shows similar (highest so far of 3.28v) voltage when first popped in. They all showed as fully charged after sitting in my Liitokala Lii-202 charger for a brief period of time after blinking at the 75% gradation initially. As soon as the testers were turned on (two 5w resistors in parallel so 2.5w, or roughly .2C of the rated battery) the voltage of the three and a half Ive tested now dropped to 3.09v to 3.15v. The highest one tested at 1131mAh, another at 283mAh, and the first one was at something like 300 (didnt write it down. Looks like this fourth one will test at maybe 600-700mAh. Can they really be rated that poorly for how big they are? I wasnt expecting 3300mAh out of them, but 10-30% isnt acceptable. Hopefully maybe another charge cycle from a depleted state followed by another discharge will drastically change their capacity. Im unsure how the chemical process of battery charging works, and Im also not sure how my inexpensive Asian battery charger works although I did do a bunch of research on the charger and it seemed like it was the best one when it came to LiFePO4 batteries (https://lygte-info.dk/review/Review Charger LiitoKala Lii-202 UK.html)
Ill update this weekend sometime after I draw down a few more and from another 10 pack of batteries (I ordered 1120 of them). Hopefully if theyre all this terrible the seller will refund my money even though Illnlikely be our a hefty return shipping amount. I ordered them back at the beginning of March but didnt have all my testing equipment until earlier this week.
 
You may find they need a few cycles to come back up in capacity?
 
I regret I didnt test my tenergy 5.5 ah lifepo4, I'm sure there are many like you have. But even after a year of daily use, the battery has been performing great better than any lead acid.Someone else here on the the forum did a powerwall with those fullriver 26650 cells and said he is getting good performance out of them. But healso had balancing problems worst than mine.
Cycle them a couple of times to wake them up, I think they been sitting for 3 years in a warehouse and some had mfg dates of 2012.
But the cells testing less than 1000 mah that is very bad, even I wouldnt use cells that low.
 
Hi...I bought some batteries from the same seller and found him to be reliable. My battery packs are big and heavy, but they've tested out at rated capacity and I haven't had any problems so far. The ones I got were already connected in 7p batteries and I just had to put them together in series for a 20s 7p (60v nominal) pack that lasts me a whole week per charge.

turnkey pcb assembly
 
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