CATL or EVE?

[Sverige]

What do you mean by 14a discharge current? The test was with a 300w inverter who was on max load, so it’s not even a 0.1C test. Therefore I wonder if a higher C-test could lead to even less capacity

I’m no expert on discharge capacity testing, like I said I don’t do it, but I thought it was meant to be carried out at 0.05C down to a 2.5V/cell cut off for representative testing against spec sheet parameters. 0.05C would be 14A if C is 280Ah.

Pulling a higher current would cause the low voltage cutoff to be reached sooner (as the voltage dip from internal resistance is higher at higher currents) and therefore you’d expect your test result to show a bit lower than spec sheet.

 

[TomC4306]

I’m no expert on discharge capacity testing, like I said I don’t do it, but I thought it was meant to be carried out at 0.05C down to a 2.5V/cell cut off for representative testing against spec sheet parameters. 0.05C would be 14A if C is 280Ah.

Pulling a higher current would cause the low voltage cutoff to be reached sooner (as the voltage dip from internal resistance is higher at higher currents) and therefore you’d expect your test result to show a bit lower than spec sheet.

I think you were confusing charging and discharging specifications.
A typical discharge test per the spec sheets is usually 0.2 C down to low voltage disconnect at 2.5 volts at 25 C degrees.

The 0.05 C tail current that you refer to is on the charge. In constant voltage charging, once the cell reaches that charging voltage, it will take less and less current as it absorbs. Once this current falls to 0.05 C (14A for a 280k), charging can be considered complete.

 

[Sverige]

I think you were confusing charging and discharging specifications.
A typical discharge test per the spec sheets is usually 0.2 C down to low voltage disconnect at 2.5 volts at 25 C degrees.

The 0.05 C tail current that you refer to is on the charge. In constant voltage charging, once the cell reaches that charging voltage, it will take less and less current as it absorbs. Once this current falls to 0.05 C (14A for a 280k), charging can be considered complete.

Ok, that’s right I’m sure. Sorry @Philiptinyhouse for the confusion!

 

[Philiptinyhouse]

Ok, that’s right I’m sure. Sorry @Philiptinyhouse for the confusion!

No problem we are all here to learn

 

[Philiptinyhouse]

I think you were confusing charging and discharging specifications.
A typical discharge test per the spec sheets is usually 0.2 C down to low voltage disconnect at 2.5 volts at 25 C degrees.

The 0.05 C tail current that you refer to is on the charge. In constant voltage charging, once the cell reaches that charging voltage, it will take less and less current as it absorbs. Once this current falls to 0.05 C (14A for a 280k), charging can be considered complete.

I tought it was at least 0.5C, but anyway is there a difference in capacity if it’s 0.1C test or 0.2? A higher C rate is stressing the cell more, right?

 

[TomC4306]

I tought it was at least 0.5C, but anyway is there a difference in capacity if it’s 0.1C test or 0.2? A higher C rate is stressing the cell more, right?

C = Capacity.
0.5C = ½Capacity or 140 amps for a 280 amp hour battery.
Many prismatic cells have a max continuous charge and discharge spec of 0.5C
0.05C = 5% of Capacity. Therefore, 0.05 x 280ah = 14 amps.

The differences in realized capacity based on 0.1 or 0.2 charge rates depend also on the voltage that you charge at.
Watch this.

 

[justgary]

0.05C = 20% of Capacity. Therefore, 0.05 x 280ah = 14 amps.

I don't mean to be "that guy," but 0.05C is 5% of Capacity, which is 1/20. Still 14 Amps for a 280Ah battery.

 

[TomC4306]

I don't mean to be "that guy," but 0.05C is 5% of Capacity, which is 1/20. Still 14 Amps for a 280Ah battery.

Edited to correct.
Thanks 'that guy's ?

 

[Sverige]

@Philiptinyhouse have you obtained any insulating sheets to sit between the cells when you assemble them into a pack? I can’t currently find a supplier here in Sweden for the epoxy sheets which seem popular amongst forum users.

I’ve been searching on Bauhaus, Jula, Jem&Fix, etc but the only epoxy I find is the liquid glue ?‍ maybe I have to use a thin sheet of wood or several layers of paper between my cells.

 

[TomC4306]

@Philiptinyhouse have you obtained any insulating sheets to sit between the cells when you assemble them into a pack? I can’t currently find a supplier here in Sweden for the epoxy sheets which seem popular amongst forum users.

I’ve been searching on Bauhaus, Jula, Jem&Fix, etc but the only epoxy I find is the liquid glue ?‍ maybe I have to use a thin sheet of wood or several layers of paper between my cells.

Or cut pieces of thin poster board from the office supply or arts and crafts store .
I used thin cardstock that usually is the backer for paper tablets. The grey stuff.$1 per sheet and I think I got five or six cell dividers from one sheet.

 

[justgary]

@Philiptinyhouse have you obtained any insulating sheets to sit between the cells when you assemble them into a pack? I can’t currently find a supplier here in Sweden for the epoxy sheets which seem popular amongst forum users.

I’ve been searching on Bauhaus, Jula, Jem&Fix, etc but the only epoxy I find is the liquid glue ?‍ maybe I have to use a thin sheet of wood or several layers of paper between my cells.

Search for "FR4 sheet" to find the raw PC board sheets like DOCAN is providing. 1.5mm is plenty thick, and seems to be fairly standard.

 

[Zwy]

@Zwy
In reading the thread, did you say you have both EVE LF280k and EVE 304? We purchased EVE LF280k's back in Oct of 2021, and built a rack for them. Side by side with the 16 cells I have about 6 inches of shelf width left. Are the 304s wider (short side) and deeper (long side) than the 280 cells? Not sure my shelf is wide enough.

How wide and deep are the new EVE 304 cells?

Not sure if I responded to this post as I wasn't notified of your response.

The dimensions are almost the same. The 280K are 5/32" taller than the older 280N and the terminals are wider like the 304Ah. I had 8 of each and decided to make one 48V battery from them. I went to the local Menards flooring section and found the pvc plank flooring samples were the right height, attached the free samples after trimming the samples down in the table saw with some thin VHB tape. Have worked perfectly and stay in balance. The busbars sent with the cells were long enough to reach, even though at a slight angle between the middle 280K and 280N.

The 304Ah are the same height as the 280K, 5/32" taller than 280N. Terminals are farther apart like the 280K. I had already made cables and busbars according to the 280N dimensions and had to make up some new busbars to attach to the T fuse and longer negative cable (from long negative busbar in the cabinet) to reach the terminals.

 

[houseofancients]

Not sure if I responded to this post as I wasn't notified of your response.

The dimensions are almost the same. The 280K are 5/32" taller than the older 280N and the terminals are wider like the 304Ah. I had 8 of each and decided to make one 48V battery from them. I went to the local Menards flooring section and found the pvc plank flooring samples were the right height, attached the free samples after trimming the samples down in the table saw with some thin VHB tape. Have worked perfectly and stay in balance. The busbars sent with the cells were long enough to reach, even though at a slight angle between the middle 280K and 280N.

The 304Ah are the same height as the 280K, 5/32" taller than 280N. Terminals are farther apart like the 280K. I had already made cables and busbars according to the 280N dimensions and had to make up some new busbars to attach to the T fuse and longer negative cable (from long negative busbar in the cabinet) to reach the terminals.

280k and 304 are exactly the same dimensions, both in cell size and terminal spread

 

[MrM1]

I got 16 EVE 304s yesterday. Docan. Days shipping from TX. Cosmetically perfect. Not testing yet.

 

[houseofancients]

I got 16 EVE 304s yesterday. Docan. Days shipping from TX. Cosmetically perfect. Not testing yet.

looking forward to you test results and build ( pictures or it didnt happen )

 

[MrM1]

looking forward to you test results and build ( pictures or it didnt happen )

Testing? What is the this testing you speak of?

I probably will produce a video though. I'm Makin some major changes here starting with this battery 304Ah x16 addition to my existing 18kWh 24v battery , then adding 3 of the new EG4 DC powered ACs and probably another 6k of solar for them and then 1+k of solar to my 5.2k array for the new batteries.

 

[Zwy]

280k and 304 are exactly the same dimensions, both in cell size and terminal spread

Yes, that is correct. The 280N however is not.

The 280K are more flat than the 304Ah. I had to adjust compression for the different pack length due to difference in flatness.

 

[Sverige]

Search for "FR4 sheet" to find the raw PC board sheets like DOCAN is providing. 1.5mm is plenty thick, and seems to be fairly standard.

Thanks, I see a few possible suppliers for that, but they’re all kinda pricey (close to $10 per sheet, and I’ll need 7). I’ll no doubt use a cheap substitute like Tom has suggested, because i don’t think I need ultimate hardness. If my isolating sheets compress a bit over time I’ll just tighten the nuts on the compression mount.

 

[houseofancients]

Thanks, I see a few possible suppliers for that, but they’re all kinda pricey (close to $10 per sheet, and I’ll need 7). I’ll no doubt use a cheap substitute like Tom has suggested, because i don’t think I need ultimate hardness. If my isolating sheets compress a bit over time I’ll just tighten the nuts on the compression mount.

i use this

https://a.aliexpress.com/_EzsJzKr

 

[tim0shel]

I'm loving my CATL Cells from Docan so far. The EVE ones I have one of the 4 is weak and is causing low voltage cutoff when high amps are pulled from it. It has been an issue for some time and so I ordered the 4 CATL cells replaced the EVE's in the solar generator. Planned to build another with the 4 EVE cells do top banlace again see if that one cell will come back to life but seems like its not. I want to buy another to replace it but hate to put a new with these used ones.