Eve 280ah resting Voltage

[Colonel.lp]

I'm interested in what your per cell resting voltage is at least 12hrs after a full charge to 3.65v?

Edit: the reason I'm interested is I received 4 fully charged cells from Xuba, and after full charge they are settling at 3.3x. currently capacity testing.

 

[Steve_S]

On average without any load or discharge, just sitting idle, once they reach 3.65V and accept no more, they will settle to around 3.55V +/- a bit, depending on pack assembly. This is not unusual behaviour for LFP.

 

[Luthj]

With even a small load, the pack should come down to 3.35V very quickly. From there is the steady drop until you hit the lower knee.

 

[Colonel.lp]

With even a small load, the pack should come down to 3.35V very quickly. From there is the steady drop until you hit the lower knee.

Do you know what you're settle at with no loads?

 

[Luthj]

The cells have a very low self discharge, but if left long enough they will all settle to about 3.3V. Anything around 3.35-3.4V after a 100% charge would be expected.

I would be looking for any outlier cells though.

 

[Colonel.lp]

The cells have a very low self discharge, but if left long enough they will all settle to about 3.3V. Anything around 3.35-3.4V after a 100% charge would be expected.

I would be looking for any outlier cells though.

Mine drop from 3.65 to 3.3 really quickly, that with the cells all arriving 100% charged, one dented and one at 260ah. I'm just trying to make sense of what's normal before a speak to the supplier. Buying this cells is right at the beginning of me taking a sabbatical from work for a year or two. I can't afford for these cells to fail.

 

[Gazoo]

I'm interested in what your per cell resting voltage is at least 12hrs after a full charge to 3.65v?

Edit: the reason I'm interested is I received 4 fully charged cells from Xuba, and after full charge they are settling at 3.3x. currently capacity testing.

All of my cells are as of now are between 3.572 and 3.584 and as you know I took them off the charger Friday morning at 1:00 A.M.

If you did not have any load on the cells and they dropped to 3.3 volts after 12 hours then you should be concerned. Was anything connected to them during the 12 hour period? BMS? Anything?

 

[Colonel.lp]

All of my cells are as of now are between 3.572 and 3.584 and as you know I took them off the charger Friday morning at 1:00 A.M.

If you did not have any load on the cells and they dropped to 3.3 volts after 12 hours then you should be concerned. Was anything connected to them during the 12 hour period? BMS? Anything?

Just an ElectroDacus BMS and that draws 60mA.
Yes I am concerned.

 

[Gazoo]

Then you do have a load connected to it. After you capacity test, charge the cells up fully. Then disconnect the BMS. I bet the cells will hold the voltage above 3.5 volts for a long time. The internal BMS in my Valence batteries draws the voltage down quickly but I am not exactly sure how many ma's the BMS is.

 

[Luthj]

Do you have balancing enabled? That could be drawing a bit. 60 mA is 0.5% per day. That's 60x the self discharge rate.

 

[ArthurEld]

Mine drop from 3.65 to 3.3 really quickly, that with the cells all arriving 100% charged, one dented and one at 260ah. I'm just trying to make sense of what's normal before a speak to the supplier. Buying this cells is right at the beginning of me taking a sabbatical from work for a year or two. I can't afford for these cells to fail.

Did you figure out what is going on with your cells?

 

[Colonel.lp]

Did you figure out what is going on with your cells?

I've just done another series charge then top balance so will check them tomorrow. It might have been the BMS that brought them down last time, but who knows. My gut feeling with these is that they are a batch of seconds, I'm not saying all Xuba cells are as no-one else has mentioned them arriving fully charged. I think they were running out and these are the dregs. I paid on my CC so whether Selina (the new Amy) coughs up or not I want my money back, one dented, one very low capacity, two borderline capacity isn't what I paid for.

How is your testing going?

 

[cwstnsko]

As another data point, my 8 cells have been settling for about 36 hours after charging to 3.65. I left them paralleled for about 12 hours, then took off the bus bars. About 12 hours after removing the buss bars I wired up the Overkill Solar BMS, and now about 12 hours later they are sitting at 3.558-3.560v per cell

 

[Colonel.lp]

Thanks for that.

As another data point, my 8 cells have been settling for about 36 hours after charging to 3.65. I left them paralleled for about 12 hours, then took off the bus bars. About 12 hours after removing the buss bars I wired up the Overkill Solar BMS, and now about 12 hours later they are sitting at 3.558-3.560v per cell
View attachment 27370

 

[ArthurEld]

I've just done another series charge then top balance so will check them tomorrow. It might have been the BMS that brought them down last time, but who knows. My gut feeling with these is that they are a batch of seconds, I'm not saying all Xuba cells are as no-one else has mentioned them arriving fully charged. I think they were running out and these are the dregs. I paid on my CC so whether Selina (the new Amy) coughs up or not I want my money back, one dented, one very low capacity, two borderline capacity isn't what I paid for.

How is your testing going?

My testing is going fine. I am a little disappointed that it seems difficult to squeeze 280Ah out of these cells. But I really don't give a damn about a few Ah. I just want them to play nice together and last a long time.
I am suspicious that the 3.3V resting voltage that these cell typically come is very misleading. I don't think it represents state of charge at all.
I was thinking that might be the case with yours. Were your cells 3.3V when you received them from China?

 

[Gazoo]

I am suspicious that the 3.3V resting voltage that these cell typically come is very misleading. I don't think it represents state of charge at all.

It doesn't represent the state of charge and it's not supposed to. Why is it misleading?

 

[Gazoo]

As another data point, my 8 cells have been settling for about 36 hours after charging to 3.65. I left them paralleled for about 12 hours, then took off the bus bars. About 12 hours after removing the buss bars I wired up the Overkill Solar BMS, and now about 12 hours later they are sitting at 3.558-3.560v per cell

Yes I noticed that too after I hooked up my BMS and it was longer then 12 hours. The BMS is not dragging down the voltage like I thought it would.

 

[Gazoo]

I've just done another series charge then top balance so will check them tomorrow.

If the cells don't maintain a voltage above 3.5 volts when you check them tomorrow then you have another problem.

I paid on my CC so whether Selina (the new Amy) coughs up or not I want my money back, one dented, one very low capacity, two borderline capacity isn't what I paid for.

I would want my money back too. It's very surprising you received cells in that condition. I don't know of anyone who has received cells from any supplier that were fully charged. Good luck.

 

[ArthurEld]

It doesn't represent the state of charge and it's not supposed to. Why is it misleading?

It is done 100% for looks. People think that is better if the cells are all the same voltage.
Most people think their cells are already balanced so they connect them up and have all kind of trouble.
That is worse than misleading. It's stupid.

 

[Colonel.lp]

My testing is going fine. I am a little disappointed that it seems difficult to squeeze 280Ah out of these cells. But I really don't give a damn about a few Ah. I just want them to play nice together and last a long time.
I am suspicious that the 3.3V resting voltage that these cell typically come is very misleading. I don't think it represents state of charge at all.
I was thinking that might be the case with yours. Were your cells 3.3V when you received them from China?

Yes they were at pretty much 3.3V, but as said it indicates quite a wide band of charge. It is a shame not to squeeze out 280ah, I assume you have adjusted load tester for voltage drop?