Normal swelling of aluminium cased cells?

[Gazoo]

Maybe I'm missing something but...why would I top balance 4 cells individually? Shouldn't I be top balancing all 4 cells in parallel then when 0 amps, build the pack in series?

I am certain he meant parallel top balancing.

 

[rickst29]

Yes, that would work OK. But you want to stop when they are all at the desired balance Voltage, NOT waiting until they have all reached the full Voltage of the Charger.

 

[Draconius]

Yes, that would work OK. But you want to stop when they are all at the desired balance Voltage, NOT waiting until they have all reached the full Voltage of the Charger.

Yes...will be following Prowse's video of using a bench power source and when amp gets to 0.1 then the pack is fully top balanced, then compress with my BMS (https://www.lithiumbatterypcb.com/) and hook it up for real!

 

[Gazoo]

Yes...will be following Prowse's video of using a bench power source and when amp gets to 0.1 then the pack is fully top balanced, then compress with my BMS (https://www.lithiumbatterypcb.com/) and hook it up for real!

Make sure you set the voltage of the power supply before you connect to the cells.

 

[Draconius]

Make sure you set the voltage of the power supply before you connect to the cells.

Will do, thanks! I will be at 3.65 (bought mine to have 2 decimal points). I am trying to recall...and actually I think you're the one that calls it out a lot...Do I want CCurrent or CVoltage setting?

 

[Gazoo]

Will do, thanks! I will be at 3.65 (bought mine to have 2 decimal points). I am trying to recall...and actually I think you're the one that calls it out a lot...Do I want CCurrent or CVoltage setting?

There is no setting for CC/CV. The PS should default to constant current mode when you hook it up. Good cables and connections will help greatly. Most of the cables that come with the PS's are crappy.

Once the voltage gets close to 3.65, the PS will go into CV mode and the current will begin to drop. It best to also monitor the cells voltages and compare with a DMM. Not only for accuracy but to see the difference of the reading of your power supply and the reading of a DMM right at the cells terminals.

You will notice the voltage readings at the cells terminals will be less that the voltage displayed on the PS due to voltage drop. Once the PS reaches 3.65 volts and the amps drop to zero, the voltage of your DMM and PS should be the same.

 

[Draconius]

There is no setting for CC/CV. The PS should default to constant current mode when you hook it up. Good cables and connections will help greatly. Most of the cables that come with the PS's are crappy.

Once the voltage gets close to 3.65, the PS will go into CV mode and the current will begin to drop. It best to also monitor the cells voltages and compare with a DMM. Not only for accuracy but to see the difference of the reading of your power supply and the reading of a DMM right at the cells terminals.

You will notice the voltage readings at the cells terminals will be less that the voltage displayed on the PS due to voltage drop. Once the PS reaches 3.65 volts and the amps drop to zero, the voltage of your DMM and PS should be the same.

Thanks good sir! Here we go! I have plastic cutting boards between each cell, the plywood and on the table. The clamps are barely finger tight, the cells can be moved, but with moderate force required. This way I knowI'mnot wrenched hard on the cells. Once I make my permanent setup then will have more specific torquing.

Voltage set to 3.65. all cells still at 3.293 (.001 variance)

 

[Gazoo]

Looks good to me. How much current is the PS putting out?

 

[Draconius]

Looks good to me. How much current is the PS putting out?

Weirdly only 5.95. It's supposed to be a 10amp. I had it set to 3.65, clipped it on and was at 8amps but then my voltage spiked to 3.75ish. Guessing that was play in the dial so teased it back to 3.65. I have my current dial cranked to the right.

Weird question...can I unconnect and turn OFF my power supply overnight so I can continue to monitor the current and stop the PS once I reach 0.1amp? I feel a little iffy about letting it run overnight. I don't see why not since basically you're just starting a new cycle at a higher SOC, right?

 

[HRTKD]

Sure, you can stop/start the process any time you want. The cells will settle some, so the next time you start it will have to make that up.

 

[Gazoo]

Weirdly only 5.95. It's supposed to be a 10amp. I had it set to 3.65, clipped it on and was at 8amps but then my voltage spiked to 3.75ish. Guessing that was play in the dial so teased it back to 3.65. I have my current dial cranked to the right.

The reason it's not putting out the full amps with the voltage set to 3.65 is because of the cheap cables that come with the PS. Is it in CC mode?

 

[Draconius]

The reason it's not putting out the full amps with the voltage set to 3.65 is because of the cheap cables that come with the PS. Is it in CC mode?

The light is next to voltage dial, so guessing CV. I did everything Prowse said. Set voltage, crank current to max, attach clips to leads, set it and forget it.

Based on the manual CC doesn't allow you to change voltage, which I can. CV doesn't allow you yo change voltage.

Not the end of the world having to only push 5.88amps....

Been at it for about 5 hours and went from 3.293 to 3.320 at the battery terminals...

 

[Gazoo]

I did everything Prowse said.

Except get beefier cables and use ring terminals. It's the only way you can take full advantage of the PS especially at the lower voltage. I think your PS came with 16 or 18awg cable. The more voltage drop you have at a set voltage the less current will be able to flow. The cables are acting like a resistor. Try plugging some numbers into this voltage drop calculator and you will understand better.

Voltage Drop Calculator

This free voltage drop calculator estimates the voltage drop of an electrical circuit based on the wire size, distance, and anticipated load current.

www.calculator.net

Not the end of the world having to only push 5.88amps....

Been at it for about 5 hours and went from 3.293 to 3.320 at the battery terminals...

No it's not the end of the world. And you should be ok. It took me 4+ days to parallel top balance my 8 280ah cells. I believe they came with around a 50% SOC. I used a 12 amp power supply and made my own 12awg cables with ring terminals.

Anyways please keep us updated

 

[Draconius]

Except get beefier cables and use ring terminals. It's the only way you can take full advantage of the PS especially at the lower voltage. I think your PS came with 16 or 18awg cable. The more voltage drop you have at a set voltage the less current will be able to flow. The cables are acting like a resistor. Try plugging some numbers into this voltage drop calculator and you will understand better.

Voltage Drop Calculator

This free voltage drop calculator estimates the voltage drop of an electrical circuit based on the wire size, distance, and anticipated load current.

www.calculator.net

No it's not the end of the world. And you should be ok. It took me 4+ days to parallel top balance my 8 280ah cells. I believe they came with around a 50% SOC. I used a 12 amp power supply and made my own 12awg cables with ring terminals.

Anyways please keep us updated

Thanks for all the info! I have some 12 awg cable for when I wire my van. With the ring terminal, fo you connect the wires, THEN turn on your PS that previously was set to 3.65 or turn it on and then drop the ring terminals on it?

 

[elvis_asaftei]

While waiting to purchase my BMS, I put my 8 272ah Lishen from the group buy in parallel. To top balance--starting at 3.28 I slowly and finally got them up to 3.55. I, too, have the symptoms described above, with slightly "puffed" cells. I can't tell from the discussion how much "swelling" is too much, so would you look at my pictures? Thanks!
View attachment 42045View attachment 42046

I received 144 batteries all like this ! They are from PWOD seller from AliExpress and received after 115 days from the payment day. Be very careful:

 

[Draconius]

Except get beefier cables and use ring terminals. It's the only way you can take full advantage of the PS especially at the lower voltage. I think your PS came with 16 or 18awg cable. The more voltage drop you have at a set voltage the less current will be able to flow. The cables are acting like a resistor. Try plugging some numbers into this voltage drop calculator and you will understand better.

Voltage Drop Calculator

This free voltage drop calculator estimates the voltage drop of an electrical circuit based on the wire size, distance, and anticipated load current.

www.calculator.net

No it's not the end of the world. And you should be ok. It took me 4+ days to parallel top balance my 8 280ah cells. I believe they came with around a 50% SOC. I used a 12 amp power supply and made my own 12awg cables with ring terminals.

Anyways please keep us updated

So I unplugged the pack at around 6pm last night (was about 3.320v across all four sets). This morning right before reconnecting the PS they were at 3.306. Is this 0.014 within ok range? I'm guessing since I had them all hooked up in parallel that they were balancing themselves and settled?

 

[HRTKD]

So I unplugged the pack at around 6pm last night (was about 3.320v across all four sets). This morning right before reconnecting the PS they were at 3.306. Is this 0.014 within ok range? I'm guessing since I had them all hooked up in parallel that they were balancing themselves and settled?

There isn't much passive balancing that takes place. It's just settling down to a resting voltage.

 

[Gazoo]

So I unplugged the pack at around 6pm last night (was about 3.320v across all four sets). This morning right before reconnecting the PS they were at 3.306. Is this 0.014 within ok range? I'm guessing since I had them all hooked up in parallel that they were balancing themselves and settled?

That's normal self discharge. Keep going... Just because all cells have the same voltage that does not mean they all have the same SOC. That's why parallel top balancing is recommended...to initially get all the cells to the same SOC, or as close to it as possible because these commodity cells do not come capacity matched.

 

[Draconius]

That's normal self discharge. Keep going... Just because all cells have the same voltage that does not mean they all have the same SOC. That's why parallel top balancing is recommended...to initially get all the cells to the same SOC, or as close to it as possible because these commodity cells do not come capacity matched.

Ok...here is a weird readout. Put my DMM onto the metal banana plugs for the alligator clips and the readout is NOT the same as my PS. Should I trust the PS or dial in the PS to have my DMM read 3.65?

 

[HRTKD]

That reading is why it is frequently recommended to replace the cables and clip that comes with the power supply.

The voltage drop on cheap cables is not a good thing.