My Fogstar cells have arrived
- Thread starter Smudgey
- Start date
LiFePO4 Prismatic Cells | Fogstar Batteries
We offer a wide range of LiFePO4 Prismatic Cells purchased directly from the manufacturers. Legitimate cells that come with a QC certifications to state that the voltages, capacity and sizes are all matched.
www.fogstar.co.uk
Scroll down after the Lifepo4 cells, both battery cases (105ah and 280ah) are there. It is a pretty good deal especially if you get a 15% off offer, plus I see post is free, maybe I made a mistake not buying these! lol
LiFePO4 Prismatic Cells | Fogstar Batteries
We offer a wide range of LiFePO4 Prismatic Cells purchased directly from the manufacturers. Legitimate cells that come with a QC certifications to state that the voltages, capacity and sizes are all matched.
Scroll down after the Lifepo4 cells, both battery cases (105ah and 280ah) are there. It is a pretty good deal especially if you get a 15% off offer, plus I see post is free, maybe I made a mistake not buying these! lol
Thanks both - unfortunately 4S, I have 16*280Ah cells on backorder with them at the moment. Might change my mind but at the moment I am planning on making a
MisterB1959
Solar Enthusiast
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280ah ABS Empty DIY Cell Case
280ah LiFePO4 empty (ABS) cell case, holds four 280ah cells and a BMS, for DIY lithium battery builds. Next day delivery. Low prices - Fogstar UK.
www.fogstar.co.uk
MisterB1959
Solar Enthusiast
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In the same position - just waiting for them to arrive
MisterB1959
Solar Enthusiast
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ive just had a text from Becs at Fogstar - the cells have arrived so fill your boots !!
I only ordered the other day so expecting December
MisterB1959
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Just get in touch with her? You might get lucky?I only ordered the other day so expecting December
My first basic test of my grade B cells, using a known load of 400watts and calculating by time came in at around 273ah.
A bit disappointing, but I’ve been waiting for a capacity tester to come from China, which arrived yesterday.
Unfortunately this confirmed I’m only getting 270ah out of my first pack of 4 cells.
It seems cell 2 hit 2.5v ahead of the other three cells.
I did a full charge and top balance to 3.65v per cell before doing the test. The tester is only 300watt, so I set it to pull a steady 20a which is well under .2c, if anything it should make the result more accurate.
Tomorrow I’ll test the second set of 4 batteries and hope all four cells are good.
Then I’ll check cell 2 from the first battery pack on its own and see how it goes.
A bit disappointing, but I’ve been waiting for a capacity tester to come from China, which arrived yesterday.
Unfortunately this confirmed I’m only getting 270ah out of my first pack of 4 cells.
It seems cell 2 hit 2.5v ahead of the other three cells.
I did a full charge and top balance to 3.65v per cell before doing the test. The tester is only 300watt, so I set it to pull a steady 20a which is well under .2c, if anything it should make the result more accurate.
Tomorrow I’ll test the second set of 4 batteries and hope all four cells are good.
Then I’ll check cell 2 from the first battery pack on its own and see how it goes.
That’s a fair point, the pack was at 13c, but it’s looking more likely, cell 2 was sub par and brought the whole down.
I’ll know more when I’ve checked each cell individually.
It’s going to take quite a while! Lol.
Will test my second pack in the morning, hopefully it’ll do better.
I’ll check also, that it isn’t a connection issue on cell 2.
A mini torque wrench is on my Christmas list!
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Further to your message, reading up on it your most likely right that temperature is at play here. Thanks for pointing that out, I'll try again at the correct temp
Being prone to attacks of RLS, which destroys any chance of sleep, I found myself dressed with nothing to do at 2am this morning.
It was even colder at 10c, but I pressed on with the test of my second battery anyway.
Just finished now, almost identical result 270.80ah, 3407.6wh.
Battery one was 270.40ah, 3409.5wh
I think I can safely say both batteries should make to spec at the correct temperature.
I’ll recharge, top balance again and get them into service asap.
It’s easy to get worried with the ‘relatively’ high costs involved, thank goodness there’s resources like this forum to have a whinge…er! I mean chat! ? and get good advice.
It was even colder at 10c, but I pressed on with the test of my second battery anyway.
Just finished now, almost identical result 270.80ah, 3407.6wh.
Battery one was 270.40ah, 3409.5wh
I think I can safely say both batteries should make to spec at the correct temperature.
I’ll recharge, top balance again and get them into service asap.
It’s easy to get worried with the ‘relatively’ high costs involved, thank goodness there’s resources like this forum to have a whinge…er! I mean chat! ? and get good advice.
I think grade A would be similar in capacity at the temperature I tested at.
The difference would be in horse power on very very heavy loads, that might buckle B grade cells.
I’ll probably try a 200ah test( highest safe test my JK’s can handle) just out of interest, hopefully no cell weaknesses will be raised.
If all good, yes the price paid is great. Could have had grade A for the same price with Black Friday though…..grrrr! ?
Yes, all top balanced in parallel with a bench psu to 3.65v, then reassembled in series, left for an hour or so before testing.
I didn’t think about the temp in my garage, beginner mistake.
Alkaline
Solar Wizard
What was your Watt-hour rating, this is very important, don't just look at the AH you need to also read the WH rating.
basically if your cells do not average 3.2v the AH rating you are seeing is misleading.
A 280 should test to 896WH.
basically if your cells do not average 3.2v the AH rating you are seeing is misleading.
A 280 should test to 896WH.
Alkaline
Solar Wizard
Hrm.... 4x 896WH = 3584 WH
so 3408 / 3584 = 95.13% rated capacity
I would say you did pretty decent. Probably had 1-2% loss form the BMS itself which would mean you are in reality about 96-97% of what its supposed to be.
Yes, I agree.
It's all been a learning curve for me, I've done a lot more reading up and now armed with a bit more knowledge, I get that the bms wasn't accounted for, nor did I consider the cables that came with my DL24 tester. Those might have added some resistance at 20a, plus of course the tester is hardly state of the art, though I've read it's supposed to be reasonably accurate.
I'm happy enough not to start the whole process again just now, I've only a small 5a bench psu, which takes days to charge these cells.
Not much solar in N.Ireland at the minute, heavy cloud from the next few days
30a charger on the way from China and two more modules for the DL24 which will give me up to 600w to play with. I'll make decent cables for it and do another test, just out of nerdy interest!
So much to learn, but it's fun and interesting, such as AH vs WH and nominal voltages.
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