AlexanderKristiansen
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- Joined
- Mar 18, 2020
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- 96
Cell 8 has the highest voltage because I charged it the longestThat is a big disparity. But cell 8 wasn't the highest cell when you first posted. Cell 4 had the highest voltage.
Cell 8 has the highest voltage because I charged it the longestThat is a big disparity. But cell 8 wasn't the highest cell when you first posted. Cell 4 had the highest voltage.
Too late @Ampster, Im back home with the cell. How do I discharge with a light bulb?The issue is the voltage of that cell when charging in the pack. Everything is relative. Taking the cell with you will not help you solve the problem. Leave it there. By your next visit it will probably settle close to the others. Have a nice drive home.
I think @smoothJoey and I are almost in complete agreement that the problem is not major.
That process only works effectively if the cell is in the pack. You have to do it in increments and charge the pack to see how close the the other cells are. That cell will settle at 3.35 volts if you put a load on it or maybe over time. What is it now?Too late @Ampster, Im back home with the cell. How do I discharge with a light bulb?
I'm think there are misunderstanding afoots here.Cell 8 has the highest voltage because I charged it the longest
Doesn't sound to me you charged all cells equally per the guidance given to you.Cell 8 has the highest voltage because I charged it the longest
Doesn't sound to me you charged all cells equally per the guidance given to you.
It is starting to settle. By the time you get back to the other cells it may settle at 3.35 volts. I realize it must be confusing with three people giving you their own version of how big the problem is and how to fix it.The 8th cell is now 3,51V.
Congratulations. It may take a few iterrations with charging cycles to get it closer. There is still the option of just reducing your charging voltage if that runner is persistant.
No, a serial connection will not bring the voltage down. Lowering the charge voltage of the pack might keep that cell from being a runner.Someone mentioned to keep the cell connected in series with the others, would that bring the voltage down to a level approximately close to the other cells?
That might be a faster way to get them near the top with existing equipment but you would need to watch them carefully so one group of 4 does not get overcharged. I assumed you meant 4P4S? is that correct? I am not sure there is any value in trying to organize in like voltage groups since the voltage curve is pretty flat until you get near 3.4 volts per cell.Slightly different question, with 16cells, can I group in like voltage groups of 4 and charge with a 12v charger?
It would not be any faster since Amps over time to fill Amphours would be the same time. . You would loose the advantage of putting them in parallel which is that 1/4 of the cells would be balanced to each other. To me that would reduce the odds of one cell being a runner. There is no perfect solution. Most advocates of parallel top balancing believe it is worth the time, expense and effort. It eliminates variations in balance more effectively than anything except taking each cell to 3.65 volts individually.Yes, but I was thinking to charge initially as separate groups of 4s as my charger is 3x10amps
Yes, but I was thinking to charge initially as separate groups of 4s as my charger is 3x10amps
and thank you
@Ampster , I am waiting on my cells now, and learning this whole process while waiting. I am getting 12 cells to put in a 3P4S configuration with a REC active BMS. I have read that you should put the cells under compression from the start. Could I put the cells in my box, under compression, in the configuration that I need them with no busbars, and use the power supply to take them one at a time up to 3.64V? Then put my busbars and BMS leads on and good to go? I am guessing this may take longer? My thinking is to not have to remove them and reconfigure after top balancing...It would not be any faster since Amps over time to fill Amphours would be the same time. . You would loose the advantage of putting them in parallel which is that 1/4 of the cells would be balanced to each other. To me that would reduce the odds of one cell being a runner. There is no perfect solution. Most advocates of parallel top balancing believe it is worth the time, expense and effort. It eliminates variations in balance more effectively than anything except taking each cell to 3.65 volts individually.