Has anyone purchased/tested the lifepo4 310ah from aliexpress yet ?

smithgeo

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What Voltage did you set your electronics load to cut off low Voltage at? You may have to compensate the low cutoff Voltage due to the tester meter is not showing true Battery Voltage reading because the Volt meter of the tester is not directly connected to the battery terminals. You can check the Voltage drops on the wires between the Battery terminals and the terminals of the tester to see what it is. I get about the same difference Voltage readings on my tester and the meter too.
Voltage cutoff is set to 2.5 right now. I will see how things look in the morning, and if the delta is still the same (around 0.17v) I will drop the cutoff voltage to compensate. I was not expecting that big of a difference (made the cables myself with nice ring terminal) - that being said, it's a cheap load tester..

40AH down - 270 to go! (I hope!)
 

Bud Martin

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That is close enough, that is the same setting for me so basically it will stop discharging at around 2.6 ~ 2.7VDC.
What did you set the discharge current to? I set mine to 15A, I blew mine up when set to 20A dues to the MOSFET used in the tester has low SOA (Safe Operating Area), luckily I have spare MOSFET. The limit of the tester based on which one reached first, the 20A is reached first or the 180W is reached first for my tester.
I cannot wait to see your result.
 
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smithgeo

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That is close enough, that is the same setting for me so basically it will stop discharging at around 2.6 ~ 2.7VDC.
What did you set the discharge current to? I set mine to 15A, I blew mine up when set to 20A dues to the MOSFET used in the tester has low SOA (Safe Operating Area), luckily I have spare MOSFET. The limit of the tester based on which one reached first, the 20A is reached first or the 180W is reached first for my tester.
I cannot wait to see your result.
I hade mine set to 20A but now you’ve got me nervous :). I will drop it down to 17.5A for the night.
 

Bud Martin

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You will notice that the MOSFET and the two diodes right next to the MOSFET all get too hot to touch. Keep close eye on the tester, if the MOSFET shorted out then the battery will be drained down completely since the shutdown signal feeding the shorted out MOSFET will have no effect. I start my test early in the morning so I can keep my eyes on it all day (about 15 ~ 18 Hours)
 
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smithgeo

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745AM.
Tester: 3.02v : 215.81AH
DMM @ Cell terminals: 3.240V

1010AM.
Tester: 2.94v : 262.62AH
DMM @ Cell terminals: 3.179

1020AM.
Tester: 2.870v : 285.45AH
DMM @ Cell terminals: 3.124
 
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smithgeo

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Well - here we are.

12:20PM

2.550 @ the Terminals with DMM...
2.300 @ the Tester...

Andddd 301.36AH

I do have to say, the charge of this cell was not ideal. I discconected a bunch, and initially only charged to 3.60.
So lets see how the next cell works.

And - the next cell is coming off the charger at 3.650 - per @SparkyTMS - will be letting this one rest for 24H before I begin a discharge test.
 

smithgeo

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Here is what we have... (cell 1)
Not sure what to think at this point...

TimeVoltagev Drop
2:423.650
3:423.5950.055
4:423.5640.031
5:423.5450.019
6:423.5310.014
7:423.5230.008

With the "better" charge of the second cell in my batch, I feel like I am getting better numbers all around. Will be curious to see what we end up with after 24H.

I am trying to source a power supply with more then 10A so I can charge all 8 cells I have, and do a 24h self-discharge test.

Cell 2 thus far:

TIMEVoltagevDrop from previous hour
3:353.655
4:353.6160.039
5:353.5970.019
6:353.5840.013
7:353.5760.008
8:353.5700.006
9:353.5640.006
10:353.5600.004
 
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SparkyTMS

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My Understanding (from my own research, I'm no Guru by any means, just a dumb old Electrician) is that it's common/good practice to charge batteries then let them rest/stabilize for 24 hours before taking Voltage readings to assess whether or not they are good, serviceable batteries; also, 3.5V is considered acceptable/normal voltage reading on LiFePO4 cells after charging to 3.65V & resting for 24 hours. That's my 2 cents anyways...
 

smithgeo

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My Understanding (from my own research, I'm no Guru by any means, just a dumb old Electrician) is that it's common/good practice to charge batteries then let them rest/stabilize for 24 hours before taking Voltage readings to assess whether or not they are good, serviceable batteries; also, 3.5V is considered acceptable/normal voltage reading on LiFePO4 cells after charging to 3.65V & resting for 24 hours. That's my 2 cents anyways...
Makes sense. After 24h we were at around 3.532.... 0.001 voltage drop over 3 hours. I'm going to throw it on the tester shortly and see how we make out. Again, this time with no inturruptions or changes. Hoping I can pull 310!
 

smithgeo

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Well. Cell number 2 only pulled 299AH. Looks like they are closer to 300AH cells then 310AH.
Anyone know what I should expect when going back to the supplier?

I am assuming a few cycles really wont make a difference?
 

BretS

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Seems there was another thread of 310s coming in closer to 300... I know I will be happy if mine are in good shape and end up around 300. To me, most important at this price is they all stay above 3.5V after the 24 hr relaxation period.
 

SparkyTMS

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Well. Cell number 2 only pulled 299AH. Looks like they are closer to 300AH cells then 310AH.
Anyone know what I should expect when going back to the supplier?

I am assuming a few cycles really wont make a difference?
Yup, they're B-Grade... 🤷🏻‍♂️ If you do file a complaint with the seller, keep us posted on how it goes...
 

smithgeo

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Seems there was another thread of 310s coming in closer to 300... I know I will be happy if mine are in good shape and end up around 300. To me, most important at this price is they all stay above 3.5V after the 24 hr relaxation period.
From a physical POV - mine are all in really good shape. A lot better then what most seem to look like throughout the forum. No buldging, dents, or scratches at all. Also - it was nice to receive them in 30 days instead of the 90+ we see sometimes too.

The 4 cells I have tested so far, all seem to settle around 3.535 volts +/- 0.005. I will keep updating as I keep testing. The tester consistantly shows 00.15-00.16 ohms while the tests are running.

I've ordered a 60a 3.3v power supply so I can run thru tests quicker. I have 8 cells, so my sigle 10A PS has been limiting. I don't feel like building my pack and then tearing it apart again.
 

Denis

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From a physical POV - mine are all in really good shape. A lot better then what most seem to look like throughout the forum. No buldging, dents, or scratches at all. Also - it was nice to receive them in 30 days instead of the 90+ we see sometimes too.

The 4 cells I have tested so far, all seem to settle around 3.535 volts +/- 0.005. I will keep updating as I keep testing. The tester consistantly shows 00.15-00.16 ohms while the tests are running.

I've ordered a 60a 3.3v power supply so I can run thru tests quicker. I have 8 cells, so my sigle 10A PS has been limiting. I don't feel like building my pack and then tearing it apart again.
Hey nice to here good results, to me these cells are as much grade A cells than any others found here on the forum. In the posting or site that you purchased these, in the specs they are advertised as nominal capacity of 300ah - 310ah.
Just saying these looks great, no complaints here.
 

Denis

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Yup, they're B-Grade... 🤷🏻‍♂️ If you do file a complaint with the seller, keep us posted on how it goes...
You say grade B and there pictures of the cells shows the true qr code at the right place,????

Just saying unless pictures are not accurate.
 

Gazoo

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Anyone know what I should expect when going back to the supplier?
As I recall the supplier you ordered from is showing cells with QR codes displayed in the proper place. And the cells you received have fake QR codes? You could pull the black cover off to see if there is the original QR code scratched off. Someone else already verified this.

That's really the only ammunition you have if you are looking for a discount from the supplier and I would call them out on that. I hate false advertising and it happens too much. It's up to you.

On the other hand, as Denis pointed out, the supplier is is advertising them at 300 to 310ah's of capacity. As long as all your cells test close to 300ah's you did very well. And if they all test at close to the same capacity that's even better. The fact they are holding voltage at +3.5 volts after resting for 24 hours is very good. Looking forward to more tests. :)
 

bgflyguy

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btw, at 301ah you are around -3%. If you don't know your tools and testing procedure well, that could be all within the error of your environment.

I would be surprised if you get much from the supplier. Use high quality wires and connectors to limit losses in other places, and feel confident that you have a solid 300ah battery.
 
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