diy solar

diy solar

Docan 8x EVE 280ah slightly swollen

Hello everyone,

I just received 8x EVE lf280k from Docan Power. The buying process was pleasant and professional. Had contact with Amy Zheng and Beki and both were really helpful and answered all my questions. Shipping was 6 weeks.
Opened up the packages today and all cells seem to be in good shape. Voltages range between 3.302 and 3.303 between all 8 cells. Manufacturing dates are all December 2021. Visually the cells look brand-new, except they are slightly swollen. I'm not sure whether this level of bloating is acceptable for (assumingly) grade A EVE cells. I also noticed that the swelling is visible in the picture I was sent pre shipment (see first photo). Since I was in the middle of preparing to move I didn't take a closer look at the provided picture.
The other photos are cells 5-8 but 1-4 look the same.
I wanted to start compressing and top balancing today. However, since I just noticed the bulging I would appreciate some feedback from the community. Does it seem like an acceptable degree of swelling or does it mean trouble in the future.
Thought about discharging a bit more before compressing. What do you think?
Best regards

Odd, this is the first time I've heard anyone report a problem like this from Docan. The bulge you are seeing is from someone not paying attention when charging or discharging the cells. If you stick between the recommended voltages (2.5v to 3.65v) you will never get this problem. It doesn't appear too bad, but it certainly indicates someone over charged or over discharged these 4 cells. Probably not by a significant amount, and likely the cells are just fine. Probably best to test them and see if they are able to give full capacity, and then decide if it is worth the effort to send them back. These were probably returned to Docan.
 
Still unable to find a good source for class t fuses. However, I read in a German diy solar forum that a lot of people over there use NH type fuses. AIC 120kA. Are those also suitable or are they all on the wrong track?
Example: https://datasheet.eaton.com/datasheet.php?model=200NHG1B&locale=en_GB

The AIC is indeed what you are looking for, provided all the other parameters are within range. Anything above 25 to 50k amps is what you want. This chemistry can produce some really massive currents if shorted and the resistance is low enough.
 
Well you lost me there. I wasn't going to ground the chassis of the battery (will be a standard plywood box anyway). The raceway will be max 3 feet. And different sources say #2 gauge will be good up to 180A. E.g. https://www.powerstream.com/Wire_Size.htm
Could you clarify why you think #2 won't be sufficient?
I've been using the Blue Sea circuit calculator, it seems pretty accurate and the company has a good reputation. So far, not problems.


I've been using 2 gauge for 150 amps with no problems, although except for surges mine stay under 70-80 amps.
If you have an infrared camera, you will find any problems with ease.
 
Just weighing in to say, got 64 cells from Docan and some of them have a slight budge like the OP.

If I pick four batteries at random and stack them together, they measure exactly 290mm. Which is 72.5mm / cell - at the top end of what the EVE battery specification says they should be 72.0mm +/- 0.5mm.

I'm choosing not to worry about it (what other option is there :LOL: )
 
Probably best to test them and see if they are able to give full capacity, and then decide if it is worth the effort to send them back.
I just finished the 2nd capacity test. Wasn't sure the first time if I got it right but the results were consistent:
- Top balanced to 3.6v
- during discharge the cells stay in between 20mv so well balanced I'd say (BMS balancing disabled for the test)
- discharge until 2.5v disconnect from BMS
Both tries were around 265Ah. Measured with a known and tried battery monitor.
One cell starts running noticeably below 3v. It starts at roughly 2.9v, the cells are +/- 20mv apart. At the point of disconnect, cell #2 reaches 2.5v, the other ones sit comfortably at roughly 2.8v.
That's a rather large deviation at the bottom right?
The AIC is indeed what you are looking for, provided all the other parameters are within range. Anything above 25 to 50k amps is what you want. This chemistry can produce some really massive currents if shorted and the resistance is low enough.
I've been using the Blue Sea circuit calculator, it seems pretty accurate and the company has a good reputation. So far, not problems.


I've been using 2 gauge for 150 amps with no problems, although except for surges mine stay under 70-80 amps.
If you have an infrared camera, you will find any problems with ease.
Thanks for your insights!
Just weighing in to say, got 64 cells from Docan and some of them have a slight budge like the OP.

If I pick four batteries at random and stack them together, they measure exactly 290mm. Which is 72.5mm / cell - at the top end of what the EVE battery specification says they should be 72.0mm +/- 0.5mm.

I'm choosing not to worry about it (what other option is there :LOL: )
Good decision! However, roughly 15Ah missing because one cell drifts heavily annoys me.
However, I'm in contact with Amy from Docan and she seems motivated to find a solution.
I'm really impressed with Docan, great communication, fast replies to my questions and overall very professional. So I would recommend them since I got the impression my case is rather the exception.
But let's see what happens.
 
Well you paid half the price of grade A so you get what you pay for.

By now People should realize Docan, Basen, QSO, and the rest of the overseas sellers with the exception of Luyuan (partially as looks like Luyuan has also started to sell grade B cells, but you can still get grade A cells).

There are grade A sellers but price is 2x, so the debate is it worth the extra? No one can really say, because we have not had grade B in service for long this question will answer it self in about 3-4 years.
 
Yeah those look deformed, but this is typical basen, docan, qso random quality, but on the same token they are cheaper than grade A cells. Perform a test and just hope for the best.
again, this is a crap message..

a lot of people have gotten Docan cells, and had no such issue at all.
This means that either this was a mix up, or these cell were wrongly charged.

Docan Tech, QSO, Basen are different companies..

I suggest you keep to your own company ( Sun Fun Kits) and work on that , and stop bashing competitors
 
again, this is a crap message..

a lot of people have gotten Docan cells, and had no such issue at all.
This means that either this was a mix up, or these cell were wrongly charged.

Docan Tech, QSO, Basen are different companies..

I suggest you keep to your own company ( Sun Fun Kits) and work on that , and stop bashing competitors
Thanks, I had a similar impression but as a newbie in this forum I didn't want to call BS regarding other users. Like I said, the whole buying process was flawless and professional so I don't have any quarrel with Docan. And they seem motivated to straighten things out.

However, another situation evolved: I noticed a weird behavior on one of my scc's:

You can set constant charge and recovery charge voltages. Constant charge is set to 27.9 (~3.5v/cell). Recovery is set to 26.8 (3.35v/cell). So expected behaviour would be:
SCC charges until 27.9 and then cuts charging. The cells settle at roughly 3.35v/cell. Once I start using energy the voltage drops below 26.8v and the SCC should start recharging. As I understand it, this is somewhat similar to floating lead acid.
However, once the battery reaches the recovery voltage the SCC stops charging and the battery stays at 26.8v instead of fully charging to 27.9v.
Anyone having a clue what's happening here?
Please see the attached excerpt of the SCC manual.
 

Attachments

  • IMG_20220530_164815.jpg
    IMG_20220530_164815.jpg
    92 KB · Views: 12
Thanks, I had a similar impression but as a newbie in this forum I didn't want to call BS regarding other users. Like I said, the whole buying process was flawless and professional so I don't have any quarrel with Docan. And they seem motivated to straighten things out.

However, another situation evolved: I noticed a weird behavior on one of my scc's:

You can set constant charge and recovery charge voltages. Constant charge is set to 27.9 (~3.5v/cell). Recovery is set to 26.8 (3.35v/cell). So expected behaviour would be:
SCC charges until 27.9 and then cuts charging. The cells settle at roughly 3.35v/cell. Once I start using energy the voltage drops below 26.8v and the SCC should start recharging. As I understand it, this is somewhat similar to floating lead acid.
However, once the battery reaches the recovery voltage the SCC stops charging and the battery stays at 26.8v instead of fully charging to 27.9v.
Anyone having a clue what's happening here?
Please see the attached excerpt of the SCC manual.
what scc is this ?
looking at the icons a mpp / voltronics ?
if so, in the settings there should be a lithium setting, provided it isnt older than about 3 years.

did you preform a topbalance ?
this looks like a saturation issue, but cant be completely sure
 
again, this is a crap message..

a lot of people have gotten Docan cells, and had no such issue at all.
This means that either this was a mix up, or these cell were wrongly charged.

Docan Tech, QSO, Basen are different companies..

I suggest you keep to your own company ( Sun Fun Kits) and work on that , and stop bashing competitors
I work for a data center company in Dallas Texas in the Carrier 1 Data Center on Round Table Drive, I have personally been to the Docan Warehouse in Houston Texas on Goar Road which they run as Lithicore, (there is no Docan Tech) as well as Sun Fun Kits which is run inside a home remodeling warehouse in Baton Rouge.

The only affiliation you could say if that is even considered is that they are hosting there site at our DC.

I have met with Both The young Asian lady that ran lithicore (not sure her name, maybe heather?), and Tommy & Dwayne at Sun Fun Kits and looked at what they had for sale, Docan was selling LF280 original cells in a 4 pack that were made in 2019 (Date code was J96) and Sun Fun Kits was out of stock. This was in January 2022.

Maybe you are affiliated with Docan or one of there agents that work there, who are you? The old dude that worked in the ware house at lithicore?
 
I bought EVE cells two years ago and a few were slightly bulged but they worked fine. The thin aluminum cases are likely to bulge under the least amount of pressure, unlike the ribbed prismatics I used to buy for an EV conversion that were two and a half times as expensive.
 
I work for a data center company in Dallas Texas in the Carrier 1 Data Center on Round Table Drive, I have personally been to the Docan Warehouse in Houston Texas on Goar Road which they run as Lithicore, (there is no Docan Tech) as well as Sun Fun Kits which is run inside a home remodeling warehouse in Baton Rouge.

The only affiliation you could say if that is even considered is that they are hosting there site at our DC.
nice anacdote

I have met with Both The young Asian lady that ran lithicore (not sure her name, maybe heather?), and Tommy & Dwayne at Sun Fun Kits and looked at what they had for sale, Docan was selling LF280 original cells in a 4 pack that were made in 2019 (Date code was J96) and Sun Fun Kits was out of stock. This was in January 2022.

Maybe you are affiliated with Docan or one of there agents that work there, who are you? The old dude that worked in the ware house at lithicore?
since i live half way around the world that would be pretty impressive...
Again not affiliated with any supplier nor manufacturer
 
Nothing he said is untrue, though. Docan do not sell grade A batteries, if they did they could provide test reports, which they do not. It's pretty open and shut here.

did you ask for the test reports ?

I bought 64 LF280K from Docan so I'm not saying they're a terrible supplier, but you get exactly what you pay for.

i was responding to his FUDD , that this is part of a bigger ( or as someone else suggested Hydra-like company
 
By now People should realize Docan, Basen, QSO, and the rest of the overseas sellers with the exception of Luyuan (partially as looks like Luyuan has also started to sell grade B cells, but you can still get grade A cells).

Amy (Luyuan) rarely has any of the grade B cells in stock. Apparently, it is difficult to find any sort of reputable and reliable source for them.

There are grade A sellers but price is 2x, so the debate is it worth the extra? No one can really say, because we have not had grade B in service for long this question will answer it self in about 3-4 years.

I've had a set of 16 grade B cells since 10/31/2020. Other than the fact that they are indeed grade B, they were a bargain for storage purposes. I paid approximately $1600 for them including everything, shipping, taxes, credit card fees, etc. Two of them measured 265 AH, the rest all between 270 and 281 AH (mostly 274 AH). I have multiple grade A matched sets to compare them to, and can say you generally get what you pay for. The real grade A cells all perform exactly as you would expect, you get full capacity, single digit millivolt spread through the entire charge/discharge cycle. The grade B cells are not for anyone who gets concerned about voltage deviation, your packs are limited to the lowest cell capacity, and don't even think about trying to draw more than 0.25C rates from them. The biggest advantage of buying grade A cells is that you know exactly what you are getting. Grade B, be sure to order a couple of extra cells, and plan for not drawing high C rates (i.e. parallel to keep current low).

To me, the grade B cells are too much of a crapshoot, and you really need to order extras to make sure you can get a good set, either that or be prepared to wait a while and argue a lot with vendors.

In summary, as long as you order extra cells and design your system accordingly, grade B are a lot more bang for your buck. If you want something that just works the way you want it to, order grade A.
 
i was responding to his FUDD , that this is part of a bigger ( or as someone else suggested Hydra-like company
Thats not what he said at all just that they have lumped together a bunch of non-grade A suppliers, he's not suggesting they are the same company like that other poster was.
 
- during discharge the cells stay in between 20mv so well balanced I'd say (BMS balancing disabled for the test)

Well, more like a real indicator of grade B cells. Matched cells will stay within a single digit millivolt difference (I have grade B and matched grade A to compare). Generally speaking, mine stay within 4 to 8 millivolts apart through 99.9% of the charge/discharge cycle for the grade A (depends on the C rate, and also the connections). Grade B cells are a good value.

Both tries were around 265Ah. Measured with a known and tried battery monitor.

Your pack will measure the capacity of the weakest or lowest capacity cell.

One cell starts running noticeably below 3v. It starts at roughly 2.9v, the cells are +/- 20mv apart. At the point of disconnect, cell #2 reaches 2.5v, the other ones sit comfortably at roughly 2.8v.
That's a rather large deviation at the bottom right?

It's just an indicator that cell has less capacity than the rest.

Good decision! However, roughly 15Ah missing because one cell drifts heavily annoys me.
However, I'm in contact with Amy from Docan and she seems motivated to find a solution.
I'm really impressed with Docan, great communication, fast replies to my questions and overall very professional. So I would recommend them since I got the impression my case is rather the exception.
But let's see what happens.

I've heard very little bad about Doncan, so it will be interesting what the results are. Even slightly bloated cells are an indicator that something happened. Over charged, over discharged, one or the other. My grade B cells still look (external appearances) just as good as the factory matched sets I have. They do not come from the factory bloated, and only get that way if they were abused. I suspect you got a "previously returned" set. A lot of cheap BMS come set with less than ideal voltage limits, and if they aren't "smart" and allow you to change the values, you can wind up with slightly bloated cells. I have no bloated cells to test, so all I can say is that most people report they work fine with slightly less capacity, I have no clue what it does to longevity or safety.
 
I ordered 32 of these cells from Docan and they arrived this week. I have only unpacked 8 cells (2 boxes) so far and they are all swollen like in the pictures jay_jay posted.

I have contacted Docan to see what their view is but I did not expect this amount of swelling. They do advertise them as Grade A.

The ordering process and the contact I had was very good and provided updates all the way from start to arriving.
 
I only see an AC amp rating. DC is more difficult to extinguish any arc or flame that may jump the gap as the fuse opens. Check with EATON.
Right you are on the AC rating. However, these are "current limiting" fuses (when current is high enough) which means they open in a couple of milliseconds or less. As such they "chop" the rising current quickly and usually well before it hits full or peak level. If you compare the current rise of a short-circuited LiFePO4 battery and an AC source (short-circuit applied at the peak of the AC voltage wave) you will find not much difference. Hence in both cases the Class T fuse will see a rapid current rise over a millisecond or so and do it's "current limiting" thing. Further, an AC short-circuit can contain a considerable DC component (total current at the peak of the first half cycle can reach about 1.6 times what it would be if the short-circuit was timed to have no DC component) and that current is limited along with the AC component by the Class T fuse. This said, yes, there are DC rated Class T fuses. I'd guess they are internally the same but have been tested and assigned a DC rating. For instance: https://amazon.com/Fuse-Voltage-225...4406116&sprefix=class+t+fuse,aps,137&sr=8-105
 
Last edited:
Back
Top