Have a question - EV vs ESS batteries

[GFruge]

The wire transfer hadn’t gone through just yet. I canceled it. People are claiming the EVE EV cells are the best option.

 

[GFruge]

Here’s a response I received while asking awhile back:

the normal ESS grade cells not grade A , they are just grade B cells(but new, no used, good performance for 3-5 years, after that then will have some unstable performance)

the true ev grade A cells cycles around 10-15years

 

[Hedges]

How about modules (presumably made with passing cells) instead of reject cells?

https://batteryhookup.com/products/new-4s-sunwoda-14-8v-150ah-2-2kwh-lithium-ion-51-kwh

16 of these to make 16s4p battery for 32 kWh, $1760
You would need 4 BMS, one per 16s.
I'm using JK PB for a different module.

 

[Alkaline]

Here’s a response I received while asking awhile back:

the normal ESS grade cells not grade A , they are just grade B cells(but new, no used, good performance for 3-5 years, after that then will have some unstable performance)

the true ev grade A cells cycles around 10-15years

You can read this thread:

F

Thread 'Are we all getting GRADE B cells??'

Apr 28, 2022

I have a facebook group in Danish where we build LFP batteries for our boats and since I opened the group I have recommended Basen Tech as being a reliabel supplier of GRADE A cells...

Now my frinds have bought 16 x 304AH CATL and they do not seem to be GRADE A. QR code seems to be scratched away and a few cells has minor dents in the casing.

I looked at this video yesterday saying that if we do not get certificates and Excel spreadsheets with test results for each cell then we are dealing with GRADE B...

Is this correct? Are we all getting rejected cells that cannot be used for fx...

• flemmingdjensen
• Replies: 269
• Forum: DIY LiFePO4 Battery Banks

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B mark:

Thread 'EVE identifies Grade B cells using new marking Method'

May 20, 2022

Yesterday I got a new information from my supplier. I was supposed to order EVE LF230 (230Ah) cells from them. But it seems there has been a change on how EVE is sending out rejected cells (Tested to be lower than Automotive Grade) for auction to the Chinese market (grey). According to the new information EVE has started marking the letter "B" on the QR code of LF230 and LF280K cells that were being auctioned. I have attached the pictures below.







It looks like they have also scratched off the serial number part. However the production date code is...

• DSmartLife
• Replies: 7
• Forum: DIY Solar General Discussion

• 

Docan will take the B cells, remove the B and then try to resell them as Grade A or call it ESS cells but they will hide the B on the qr code:

W

Post in thread 'Docan Power bad experience, beware.'

May 2, 2023

Finally I decided to look what's under the black cover of the cells.
The outcome was predictable. QR code area looks sanded and I have no doubts the new QR code was printed on top of the old one to hide the "B" mark or to change the product code.
It's up to you to decide whether it is a normal business practice to remove original manufacturer's labels and print your own.

• wepower

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• 

Understand many alibaba sellers do the samething it is not unique to Docan, QSO, Basen, Yiaxing, everyone except Luyuan does this scam. Luyuan is the only seller that tells the truth if you want grade B they will see you grade B and it will have the B letter on it, if you want grade A with test report you will get it with test report.

But you will be paying a higher price so decide what is more important to you, price or quality.

 

[Brucey]

The wire transfer hadn’t gone through just yet. I canceled it. People are claiming the EVE EV cells are the best option.

Here's the cell types that their website shows as options, I'd go with the grade A mb31 and their 5A active balancer upgrade

 

[GFruge]

Just got with Amy at Docan. I had already upgraded to Grade A 280ah cells from the canceled transaction this morning. I just requested the Grade A MB31 cells upgrade. These are 314ah and date stamped July 2024. There was a cost difference, but nothing astronomical. Before shipping out, I requested QR codes and test reports.

Thanks for the help and guidance

 

[GFruge]

So, she explained the difference between the 2 batteries are the capacity and the c-rate. The 280ah battery is .5 and the 314 MB31 is .25.

I’m not well versed on this, but understand it’s the discharge rate. Am I still good with my 48v system? The 2 batteries will be 314ah / 16kwh each, so somewhere around 32kwh. My inverter is only 6,000 watts. The most I’ve seen pulled on the system was about 3,500 watts.

Will this .25 vs .5 affect me?

 

[Hedges]

32kWh x 0.25C = 8kW, should be OK.

I thought most cells were continuous 1.0C discharge and 0.5C charge.
There is actually a table or curve showing high rates at some SoC and temperature, tapering off lower under some conditions.

 

[GFruge]

Thanks

 

[Brucey]

So, she explained the difference between the 2 batteries are the capacity and the c-rate. The 280ah battery is .5 and the 314 MB31 is .25.

I’m not well versed on this, but understand it’s the discharge rate. Am I still good with my 48v system? The 2 batteries will be 314ah / 16kwh each, so somewhere around 32kwh. My inverter is only 6,000 watts. The most I’ve seen pulled on the system was about 3,500 watts.

Will this .25 vs .5 affect me?

I would expect the C rate to higher on the ev grade mb31, i.e. .5C for the ev grade cell and then maybe 0.25C for the random 280Ah ess grade cell they would use by default (prob rept 280ah if their cell pricing is anything to go by). Maybe moreso for charging?

Either way with two batteries and a 6kW inverter you'll be fine even with some occasional surge.

 

[Henderson]

Thanks for the advice on the BMS and cell grade. I have 1 estimate with Docan at the moment and waiting on one more quote from a company named Avepower. Both claim A grade cells.

Which direction did you end up going? I recently came across Avepower as well.

 

[GFruge]

Ended up buying batteries from Docan. Had them upgraded with new MB31 cells.

 

[Henderson]

Ended up buying batteries from Docan. Had them upgraded with new MB31 cells.

The few persons I had interactions with at Docan seem to be decent folks.