I see that Fogstar offer tested and matched Grade B Eve 280ah cells for £119.99. 12 month warranty. Has anyone built a battery pack using these and how are they performing?
Cheers,
Sean
Cheers,
Sean
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They say that they guarantee that the capacity will be at least 277ah.I have no idea about the B grade. I did seen a review left from buyer of B grade, stating they are as expected 10% down on capacity. My opinion is if you build a bank and don’t expect to pull big rates, they are worth it. But, if you expect to pull 0.3Cand above, better to go for the grade A. The grade A double terminal it’s miles better compared to the single stud found on grade B.
There abouts, not bad for the price, looks good value.They say that they guarantee that the capacity will be at least 277ah.
This was my thinking on risk also. Probably a lot less risky than buying so called Grade A cells from AliBaba. I've discussed with a lot of AB suppliers over the last few days and 4 x 280ah Eve LF280Ks are costing in the region of $540 to $560 delivered direct duty paid to the UK. This is £450 - £460 and of course you are not sure whether what is going to turn up will really be Grade A anyway. So these matched and guaranteed Grade B for £479 (free delivery) for 4 compare wellThere abouts, not bad for the price, looks good value.
I don’t think it’s any risk Lenny, if they match them from the same batch, and have equal or close resistance, and no bulges, then they as good as new 277ah cells. These cells are not cycled at all, they are just graded by manufacturer at first test, then the seller can grade them again if he/she wishes to weed out the week ones.
How do you know the grade B cells are actually what they say if the grade A aren't?This was my thinking on risk also. Probably a lot less risky than buying so called Grade A cells from AliBaba. I've discussed with a lot of AB suppliers over the last few days and 4 x 280ah Eve LF280Ks are costing in the region of $540 to $560 delivered direct duty paid to the UK. This is £450 - £460 and of course you are not sure whether what is going to turn up will really be Grade A anyway. So these matched and guaranteed Grade B for £479 (free delivery) for 4 compare well
Only because Fogstar is a reputable UK company who purchase direct from Eve and guarantee that the cells are what they say and they test, match, and give a 12 month UK warranty.How do you know the grade B cells are actually what they say if the grade A aren't?
It's a bit of a minefield to be honest you just need to do your homework and stick with good feedback and recommendations and keep your fingers crossed good luck but I would go for A grade and if they were B grade it wouldn't really bother me at that price.
Interesting comparison on grade of cells here.
Hi David,Out of interest did you compress the batteries or decided it was not required? I spent hours of research, did compress mine but I am still not sure if I needed to?
Thanks.Neat solution.
Again, clever. Maybe I overthought mineIn my case I built the ply box very tight, allowing a space for 1.5mm fibre board separator for each cell. Two fibre boards on the ends, so it has 3mm ish compression on a stack of 8 cells. At first full charge, I will take note if the plywood box will bulge out on the ends. At the moment they are not charged and quite snug, cells will not move if I tip the box on its side. I tend to agree that a restrain it’s better than compression, unless you can apply a even 12psi pressure. I have seen the way seplos build theirs, and they do not compress but restrain. Similar results are achieved with fibre tape.
I do not compress the cells in my battery packs as certainly the manufacturer of my cells does not indicate or state that the cells need to be compressed.
SeanF1 on what basis did you compress your cells, did the manufacturer of your cells advise this or was it because of those that promote the practice of doing so on Youtube?
I like Raul restain mine by binding the battery pack together, but I use Kapton tape as does Will Prowse.
I am using eve cells and they recommend using 300kgf compression in their datasheet. I followed the Fibre Tape method used by Offgrid Power Solutions on YouTube as their approach made sense to me
I haven’t run my bms long enough to notice any accuracy as yet. But 100mv for the hole pack it’s nothing that concerns me. I always dial in conservative figures, then keep all charging sources below that at the top, and keep load alarm above the bms limits. I have oversized for my needs, so I won’t cycle the top and bottom ends at all. Unless it’s a emergency.I can see you are using the same BMS as me (the JK). One issue I have is the voltage reported is incorrect. I get the same reading on my two multimeter’s and the victron which was different to the JK. I used that reading to calibrate the JK but it does not hold the calibration across the whole voltage range. In the end I set it when the batteries where at 50% but it is incorrect when fully charged by about 100mv. Have you encountered this?
Haven't run it long enough yet to notice anything like this. I put it together in 4s with the bms to charge it up to 14.3v then disconnected to put the cells in parallel to top balance. Left the cells in parallel after top balance completed and haven't put back to 4s yet.I can see you are using the same BMS as me (the JK). One issue I have is the voltage reported is incorrect. I get the same reading on my two multimeter’s and the victron which was different to the JK. I used that reading to calibrate the JK but it does not hold the calibration across the whole voltage range. In the end I set it when the batteries where at 50% but it is incorrect when fully charged by about 100mv. Have you encountered this?
I could not quit bring myself to buy a proper tester as to be honest it’s pretty irrelevant. I charged that battery to the max cell voltage, reset the victron, set the bms to cut off at minimum and switched enough on the camper to create a 10a load. Left it till the bms shut down, then recharged to full at 10a. Took the measurements from the victron and the bms. In my case the BMS showed 286 and the victron 281.Haven't run it long enough yet to notice anything like this. I put it together in 4s with the bms to charge it up to 14.3v then disconnected to put the cells in parallel to top balance. Left the cells in parallel after top balance completed and haven't put back to 4s yet.
How are you all capacity testing ?