Purchasing 32- Eve 304 ah cells or 32- CATL 302 ah cells which one is best advice needed

Stepandwolf

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What would you base that assertion on?
The two with the lower values were on one tester, the two with the higher values were on another tester. I can't compare the testers like HR can, but it is easy to make an assumption based on the results. In either case, the numbers are all over the place.
 

Just John

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The two with the lower values were on one tester, the two with the higher values were on another tester. I can't compare the testers like HR can, but it is easy to make an assumption based on the results. In either case, the numbers are all over the place.
I meant the assertion that the X8 is the more accurate. Certainly they appear to give different results, but I didn't find those cheap testers to be off by much when compared to a calibrated load. I don't have an X8 to compare, but I did check multiple versions of those cheap testers. All 4 models were within 2 amp hours.
 

Gul-Dukat

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I meant the assertion that the X8 is the more accurate. Certainly they appear to give different results, but I didn't find those cheap testers to be off by much when compared to a calibrated load. I don't have an X8 to compare, but I did check multiple versions of those cheap testers. All 4 models were within 2 amp hours.
I will test the cells again with the correspondingly opposite tester to see how the results vary and will update you all.

I think the x8 also has its accuracy challenges, but if i had to make any assertion or commentary around perceived accuracy I would be thinking the x8 is better/slightly more accurate - mostly based off the multimeter measurements performed when both the 180w tester and the (I have two) x8 have been connected and what is being reported.
 

Just John

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I will test the cells again with the correspondingly opposite tester to see how the results vary and will update you all.

I think the x8 also has its accuracy challenges, but if i had to make any assertion or commentary around perceived accuracy I would be thinking the x8 is better/slightly more accurate - mostly based off the multimeter measurements performed when both the 180w tester and the (I have two) x8 have been connected and what is being reported.
Thanks! I'd be interested. I did check mine compared to the Kunkin (calibrated in January this year). Like I said, about 1-2% off. I will also note that temperature changes can affect actual cell capacity. If you get too far away from 75 degrees Fahrenheit, the cells themselves are affected.

I know the cheap tester has challenges with voltage accuracy, the 4 wire version (DL24P with a color screen) at about twice the price has no voltage measurement problems.

I documented how hot the cheap testers run, but will also point out that I haven't had one fail yet. Other people have, but (knock on wood) not me.

 
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hotrod

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Little update on my Eve cells , it looks Like the ship has unloaded and left the port of Los Angeles now in route to Oakland Hopefully my cells were unloaded in Los Angeles. I know its still probably gonna be a while before Ups has them headed my way I know they still have to be unloaded from the containers and then make it though customs. But hopefully they will be headed my way on the UPS truck within the next couple of weeks. I have also went ahead and ordered the EBC-A40L Charger and discharger from Ali express a few days ago. Everything should get here around the same time. Fingers crossed. Now I need to get the Batrium BMS ordered and a shunt trip breaker. Any recommendations on a good shunt trip breaker that want break the bank. I'm looking at a couple used EBB- S5N breakers but they are a little pricey
 

Yurtdweller

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Just gonna pop in here real quick. My cells are on the way, and I plan to build some 12v packs. I ordered more than I need, and hope to sell off any excess as built packs. So, I'm going to want to capacity test the packs. I may or may not cap test individual cells. But my question is, not owning any testers yet, I do own a Victron bmv-700. Does anyone have any opinions If the bmv-700 is accurate enough to use for a capacity test? So far, it always has agreed with my bms readings for ah used. I currently have a 100ah pack from lynx batteries, with a Daly smart bms, and, as I say, the ah used readings on the bms and the bmv always agree. At least when drawing down. My bmv-700 sometimes gets confused as to soc, especially if I have several days without a full top-up due to poor solar, but I think this is just because of the low voltage curve, and because I have not reprogrammed the bmv since I switched from AGMs. I rarely read the bmv-700 anymore, due to having the smart bms.
 

hotrod

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I just received my zketech ebc-a40l charge/discharge battery testers that I ordered a couple weeks ago on AliExpress and it did not come with any software for the computer . Where can I find and download the software for my computer and also the driver software for it. I have found a place online to download the software and have downloaded it but it will not recognize my com port it is always blank. I have the usb cable that came with the charger plugged directly up to my laptop, am I supposed to have another cable to connect to my laptop. I have downloaded it removed it twice and it still will not connect to my computer. Can you tell me the link where I can download the software for this charger. Thanks
 

Just John

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I just received my zketech ebc-a40l charge/discharge battery testers that I ordered a couple weeks ago on AliExpress and it did not come with any software for the computer . Where can I find and download the software for my computer and also the driver software for it. I have found a place online to download the software and have downloaded it but it will not recognize my com port it is always blank. I have the usb cable that came with the charger plugged directly up to my laptop, am I supposed to have another cable to connect to my laptop. I have downloaded it removed it twice and it still will not connect to my computer. Can you tell me the link where I can download the software for this charger. Thanks
I uploaded it to the resources section here.


Note that the included driver is an older version, from before when Prolific patched the latest to reject clone chips by other manufacturers.
 

hotrod

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I have finally received my 32 new Eve 304 AH cells I purchased and payed for these cells back on 7/19/2021 from Mrs. Amy at Shenzhen Luyuan Technology Co., Ltd she has been awesome to work with and has answered every question I have ask of her during this long wait. The Cells arrived at my door on 10/18/2021 so it took a total of 91 days from the time I payed for the cells till they were delivered at my door. It took a little less than 20 days for Mrs. Amy to order the cells from Eve and get them in then weld the studs and get them shipped out headed this way. The boat ride and then getting unloaded and clearing customs is what has taken so long. There here now so its time to start unboxing to check there condition and then start testing. I've opened 1 box so far and both cells in that box looks perfect, and the outside of the other 15 boxes look very good as well. Top notch packing is all I can say. I will post some pictures in the next couple of days.
 
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hotrod

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I finally got my test bench built for my new batteries and I have now opened all 16 boxes of my cells that came in over a week ago. I have inspected all 32 cells and they are in perfect shape not a blemish anywhere, no dents gauges or scrapes on any of the cells and all cells have very flat sides no bulging. I'll have to give Mrs. Amy and her company 2 Thumbs up. She has sent me some very nice cells. Now its time to get them under compression and connected for top balance and then start capacity testing each cell. 30 cells tested 3.292 volts and the other 2 tested 3.293 volts.
 

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hotrod

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Hi guys if I compress my cells then charge each of my 16 cells to around 3.5 volts and then parallel all the cells and top balance the cells to 3.65 volts, after I let them sit for a couple hours remove the bus bars and start capacity testing each cell. After I finish capacity testing the cells and reinstall the bus bars to top balance the cells again, if I let my cells sit for 24 hours and remove the bus bars and remove the compression from the cells to re arrange the cells in series for my 48 volt battery will the cells be ok or are they likely going to swell. My cells are all very flat right now and I don't want to take a chance of them swelling what is the best way to do this without damaging my cells.
 

Steve_S

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While you're doing all the tests etc keep the binding as is. When you want to do final assembly, the simplest thing, is to do it with the cells sitting around 3.2V (nominal voltage)as that's the midground. I like to set cells in 4-cell blocks because if ever I need to take it apart, don't want to undo & redo everything, so each "block" also get's a Pull String. People thought that was nuts, until they had to pull some cells from a large pack... Saved me a lot of stressed when doing reconfigs & tests but that's just me.... I don't like extra work when it's just not nescessary.

Everyone freaking over swelling.... LFP expands & contracts when in a Prismatic format like these, usually no more than 1.5mm sideways @ nominal temps (25C/72F). Temps DO affect the amount of expansion/contraction. this is expected as well (even in many of the docs too). The Higher the Amperage Pushed or Pulled also affects the rate of expansion (due to heat generated by the process). IF you charge at 0.5C you will see more expansion than if charging at 0.25C. (Charging is the Usual Cause for the swelling process).

There are a lot of ways to bind cells, one of the best is the Nylon Pallet Straps (without buckle) so if you have a buddy that works in a warehouse maybe you can borrow a binder & but the strapping. Alternately, Packing Fibretape also works quite well (1" wide ok, 1.5" better). I clamp the "blocks of cells" lightly with Quick-Grip Clamps with wood to spread the pressure evenly (very light hand squeeze tight) and then bind around the upper & bottom, then remove the clamp and another around the middle. This hasn't failed me yet. DO NOTE, that I built my battery boxes with 3/4" Ply to a tight spec, so the cells are "snug" within anyways. and I mean "snug" as in, takes two people to pull a bundle out because someone has to hold the box down, "snug" (ok borderline Tight LOL). Lesson Learned, DISCHARGE the cells BEFORE pulling them out !
 

Just John

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Hi guys if I compress my cells then charge each of my 16 cells to around 3.5 volts and then parallel all the cells and top balance the cells to 3.65 volts, after I let them sit for a couple hours remove the bus bars and start capacity testing each cell. After I finish capacity testing the cells and reinstall the bus bars to top balance the cells again, if I let my cells sit for 24 hours and remove the bus bars and remove the compression from the cells to re arrange the cells in series for my 48 volt battery will the cells be ok or are they likely going to swell. My cells are all very flat right now and I don't want to take a chance of them swelling what is the best way to do this without damaging my cells.
I've not had any problems with cells bloating, just keep them at 3.65v or below. Discharge them before placing them in a pack, they do expand, but not bloat.
 

hotrod

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Ok I was thinking about going ahead and putting them in their correct orientation for series connection to make my 48 v battery and using no.8 copper wire with ring terminals on each end to connect all the negatives together in parallel and do the same for the positive side in parallel . But after I laid it out on paper I decided that's way to many wires running from 1 battery to another across the top of each other while trying to do a top balance. Ok so after I parallel my cells when I'm done capacity testing and then top balance the pack together to 3.65 volts , then I need to discharge all the cells together back down to around 3.2 volts before I de compress the cells to re arrange the cells for the series connection.
 
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hotrod

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May 12, 2020
Messages
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While you're doing all the tests etc keep the binding as is. When you want to do final assembly, the simplest thing, is to do it with the cells sitting around 3.2V (nominal voltage)as that's the midground. I like to set cells in 4-cell blocks because if ever I need to take it apart, don't want to undo & redo everything, so each "block" also get's a Pull String. People thought that was nuts, until they had to pull some cells from a large pack... Saved me a lot of stressed when doing reconfigs & tests but that's just me.... I don't like extra work when it's just not nescessary.

Everyone freaking over swelling.... LFP expands & contracts when in a Prismatic format like these, usually no more than 1.5mm sideways @ nominal temps (25C/72F). Temps DO affect the amount of expansion/contraction. this is expected as well (even in many of the docs too). The Higher the Amperage Pushed or Pulled also affects the rate of expansion (due to heat generated by the process). IF you charge at 0.5C you will see more expansion than if charging at 0.25C. (Charging is the Usual Cause for the swelling process).

There are a lot of ways to bind cells, one of the best is the Nylon Pallet Straps (without buckle) so if you have a buddy that works in a warehouse maybe you can borrow a binder & but the strapping. Alternately, Packing Fibretape also works quite well (1" wide ok, 1.5" better). I clamp the "blocks of cells" lightly with Quick-Grip Clamps with wood to spread the pressure evenly (very light hand squeeze tight) and then bind around the upper & bottom, then remove the clamp and another around the middle. This hasn't failed me yet. DO NOTE, that I built my battery boxes with 3/4" Ply to a tight spec, so the cells are "snug" within anyways. and I mean "snug" as in, takes two people to pull a bundle out because someone has to hold the box down, "snug" (ok borderline Tight LOL). Lesson Learned, DISCHARGE the cells BEFORE pulling them out !
Thanks for your reply How are you connecting your 4 cell blocks to each other are you still able to use your standard bus bars that come with your cells. I am planning on using 3/4 pvc cutting boards on each end with 1 1/2" aluminum angle close to the top and close to the bottom with 1/4" all thread on each side and down the middle of the 2 rows of 8 cells. If I break them up into 4 cell blocks I will have to use proper sized jumper wires with copper lugs instead of bus bars. Or I guess I could make my own copper bus bars.
 

Steve_S

Offgrid Cabineer, N.E. Ontario, Canada
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The busbars fit no problem, I don't put anything between the cells, being a fixed non-mobile system & quite snuggly bound.
 
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