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EVE 280AH 12V Battery - Shenzhen Luyuan - Parallel Top Balance Timeline

Sillyputty

Solar Enthusiast
Joined
Jul 21, 2020
Messages
188
This is the timeline I recorded when top balance my EVE 280AH cells I purchased from @Amy Wan (Luyuan) at Shenzhen Luyuan.

Tools:
  • Cheap 10A - 30V Power Supply (w/new 10 gauge leads and larger clips)
  • Two tested multimeters - to confirm accuracy
  • Patience
Timeline:
  • Paralleled cells and set PS to 10A and 3.65V
  • 6/9/21 - All cells at 3.26V
  • Charged for 9 hrs - Cells now at 3.29V - Turned off charger
  • 6/10/21 - Cells at 3.29V
  • Charged for 15 hours - Cells now at 3.31V - Turned off charger
  • 6/13/21 - Cells at 3.3V
  • Charged for 4 hours - Cells now at 3.33V - Turned off charger
  • 6/14/21 - Cells at 3.315V
  • Charged for 17 hours - Cells now at 3.336V - Turned off charger
  • 6/15/21 - Cells at 3.330V (?)
  • Charged for 14 hours - Cells now at 3.349V - Turned off charger
  • 6/16/21 - Cells at 3.300V (??) What the hell.
  • Charged for 15 hours - Cells now at 3.35V - Turned off charger
  • Re-calibrated/reset power supply and moved clips to busbars
  • 6/17/21 - Cells at 3.33V at 9AM
  • Amps began dropping at power supply at 2PM
  • PS switched from constant current to constant voltage at 2:30PM
  • Voltage at battery w/power supply on = 3.44V
  • Voltage began rising ~ 1mv every 10 seconds
  • Amps decreased to 4.5A after 30 minutes
  • Voltage at PS and batteries reached 3.63V at 4PM
  • Voltage at PS and batteries reached 3.649 at 5PM
  • Amps at PS = 0.66A
  • DONE after 82 hours
  • 6/18/21 - All cells at 3.545V after resting 16 hours.
Notes:
  • Approximate time at constant current (CC) of 10A: 79 hours
  • Approximate time at constant voltage (CV): 3 hours
  • Going from ~90% charged to ~100% is FAST!
  • Despite power supply showing 3.74V under load while charging, repeated tests under no load showed it at 3.65V
  • Both meters were used and watched carefully during CV phase - one on batteries and one on PS output. Neither reached more than 3.65V
No idea why charging/balancing stalled at around 3.3V - most likely the cheap power supply was the culprit.

I hope this helps someone else that’s freaking out during parallel balancing of their EVE cells.
1624034072542.png1624034103686.png1624034337420.png
 
This is the timeline I recorded when top balance my EVE 280AH cells I purchased from @Amy Wan (Luyuan) at Shenzhen Luyuan.

Tools:
  • Cheap 10A - 30V Power Supply (w/new 10 gauge leads and larger clips)
  • Two tested multimeters - to confirm accuracy
  • Patience
Timeline:
  • Paralleled cells and set PS to 10A and 3.65V
  • 6/9/21 - All cells at 3.26V
  • Charged for 9 hrs - Cells now at 3.29V - Turned off charger
  • 6/10/21 - Cells at 3.29V
  • Charged for 15 hours - Cells now at 3.31V - Turned off charger
  • 6/13/21 - Cells at 3.3V
  • Charged for 4 hours - Cells now at 3.33V - Turned off charger
  • 6/14/21 - Cells at 3.315V
  • Charged for 17 hours - Cells now at 3.336V - Turned off charger
  • 6/15/21 - Cells at 3.330V (?)
  • Charged for 14 hours - Cells now at 3.349V - Turned off charger
  • 6/16/21 - Cells at 3.300V (??) What the hell.

Not that nuts. Not-fully-charged LFP seems to settle very unpredictably.

  • Charged for 15 hours - Cells now at 3.35V - Turned off charger
  • Re-calibrated/reset power supply and moved clips to busbars
  • 6/17/21 - Cells at 3.33V at 9AM
  • Amps began dropping at power supply at 2PM
  • PS switched from constant current to constant voltage at 2:30PM
  • Voltage at battery w/power supply on = 3.44V
  • Voltage began rising ~ 1mv every 10 seconds
  • Amps decreased to 4.5A after 30 minutes
  • Voltage at PS and batteries reached 3.63V at 4PM
  • Voltage at PS and batteries reached 3.649 at 5PM
  • Amps at PS = 0.66A
  • DONE after 82 hours
  • 6/18/21 - All cells at 3.545V after resting 16 hours.
Notes:
  • Approximate time at constant current (CC) of 10A: 79 hours
  • Approximate time at constant voltage (CV): 3 hours
  • Going from ~90% charged to ~100% is FAST!
  • Despite power supply showing 3.74V under load while charging, repeated tests under no load showed it at 3.65V

This is pretty typical of the voltage drop trying to push 10A @ 3.65V with the cheap power supplies.

  • Both meters were used and watched carefully during CV phase - one on batteries and one on PS output. Neither reached more than 3.65V
No idea why charging/balancing stalled at around 3.3V - most likely the cheap power supply was the culprit.

Not sure what you mean by this, if you mean a huge chunk of the charging occurred in the 3.3XV range, than that's normal. The chemical reactions responsible for the bulk of the charging occur in the 3.3-3.4V range, and it's even more pronounced when using such a small current compared to the massive capacity.


I hope this helps someone else that’s freaking out during parallel balancing of their EVE cells.
View attachment 53316View attachment 53317View attachment 53318

Nice work!
 
Not sure what you mean by this, if you mean a huge chunk of the charging occurred in the 3.3XV range, than that's normal.
Thanks for the feedback! Other than the alleged PS error, I'd thought that might be the case, but had no experience or confirmed information (as in someone else's specific timeline to reference) otherwise.
 
I use a Tekpower 15V/40A Desktop Bench charger. Dialed in at 3.65V and starting with Full on CC @ Max amps, from 3.29 to 3.65 full saturation (taking <2A CV) take 12 hours for a batch of 4. It is VERY SLOW between 3.200-3.400 and then picks up quickly as it nears the end. Within an hour of charge end the cells settle to 3.500-3.55 which is normal. After I do sets of 4, then I link them in parallel as a set of 8 and re-top them (quite quick actually) then they are ready for 8S config.
 
I use a Tekpower 15V/40A Desktop Bench charger. Dialed in at 3.65V and starting with Full on CC @ Max amps, from 3.29 to 3.65 full saturation (taking <2A CV) take 12 hours for a batch of 4. It is VERY SLOW between 3.200-3.400 and then picks up quickly as it nears the end. Within an hour of charge end the cells settle to 3.500-3.55 which is normal. After I do sets of 4, then I link them in parallel as a set of 8 and re-top them (quite quick actually) then they are ready for 8S config.
That is almost exactly what I do as well using the same supply. I bought it based on your recommendation. If you can afford a 12v BMS, you can speed up doing groups of 4 considerably. Your numbers match mine as well. Good advice.

Doing groups of 4 can help the impatient, along with the 40 amp supply. I like toys, so I am waiting on a 30v at 40A Wanptek to arrive. They also sell a 20A at 60v supply for those doing a 48v system. I will report on reliability and build quality after I receive it and have a chance to test it. Other reviewers have all been favorable.
 
I think most people know it, but it is worth pointing out: People should completely ignore the voltage displayed on these cheap power supplies.

Adjust the voltage with nothing connected to the power supply. Use a good, well calibrated multimeter when setting the voltage. I use a Fluke 175, but most less expensive meters are probably OK. (Flukes are going to be more accurate, generally) I have 4 relatively cheap power supplies, and when I set them all to the same voltage using the Fluke, the displays on the power supply can vary as much as 0.2V. DON'T BELIEVE THE DISPLAY.

It worries me when so many people sound like they just go with what the PS displays and assume it is correct. It almost never is.
 
Update: I was going to wait until I built a compete battery box w/compression to place the battery cells into a series configuration with a BMS in order to finish charging, but decided to go ahead with just the cells clamped temporarily.
  • After parallel charging @ 3.65V for 82 hours and resting (still parallel connected) for 10 days the cells were at 3.46V
  • Connected in series w/Overkill Solar BMS - 13.84V at battery terminals & 13.47V after BMS (.37V drop)
  • Set PS to 10A and 14.6V - PS went from CC to CV in ~2 minutes
  • BMS went into "protect locking" when all cells were around ~3.62V - no over-voltage at cell or battery pack level (?)
  • BMS "discharge" button was turned off. (?) Turned it back on and it resumed charging for ~10 minutes
BMS ended charging when one cell reached 3.65V cut-off. Lowest cell was 3.637V (.013V difference)

Surprised that it didn't take long at all to finish, and happy there were no "runner" cells during charging. I doubt I'll do a capacity test while the heatwave is pounding the west coast (it's 102F right now) but if I do I'll update with results.

Thanks for everyone's help on this site! - I (probably) could have done it without you, but I'm sure much more "magic smoke" would have occurred. :)?⚡
 
Update: I was going to wait until I built a compete battery box w/compression to place the battery cells into a series configuration with a BMS in order to finish charging, but decided to go ahead with just the cells clamped temporarily.
  • After parallel charging @ 3.65V for 82 hours and resting (still parallel connected) for 10 days the cells were at 3.46V
  • Connected in series w/Overkill Solar BMS - 13.84V at battery terminals & 13.47V after BMS (.37V drop)
  • Set PS to 10A and 14.6V - PS went from CC to CV in ~2 minutes
  • BMS went into "protect locking" when all cells were around ~3.62V - no over-voltage at cell or battery pack level (?)
  • BMS "discharge" button was turned off. (?) Turned it back on and it resumed charging for ~10 minutes
BMS ended charging when one cell reached 3.65V cut-off. Lowest cell was 3.637V (.013V difference)

Surprised that it didn't take long at all to finish, and happy there were no "runner" cells during charging. I doubt I'll do a capacity test while the heatwave is pounding the west coast (it's 102F right now) but if I do I'll update with results.

Thanks for everyone's help on this site! - I (probably) could have done it without you, but I'm sure much more "magic smoke" would have occurred. :)?⚡
Just as an FYI, 3.65v is to do a top balance. You should not aim for 3.65v during a "standard" charge (which will drop to 3.4v range within an hour).

Don't charge to 3.65v and leave them. A few days, no problem. A few weeks in high temperatures, you will shorten cell life. 108 here, much nicer than last week.
 
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