sunshine_eggo
Happy Breffast!
This.
Liitokala strikes again
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This.
sunshine_eggo
Happy Breffast!
No they're not. Balance refers to state of charge. Even imbalanced cells in the working range 3.1-3.4V, will show nearly identical voltages.
Voltage is only indicative of balance OUTSIDE the 3.1-3.4V range.
sunshine_eggo
Happy Breffast!
Much closer. with all above 3.40, they are likely at very high states of charge and likely very comparable levels.
3.45 is my "magic" number. if they're all balanced there, they're close enough.
Zwy
Solar Wizard
You are much closer than before. Increase the pack voltage 0.5V and see where the cells are at.
To think you thought these cells were no good.
Quattrohead
Solar Wizard
No those voltages are great, looking good to me.
Zwy
Solar Wizard
Charge them up over 3.4V and let the balancer do it's job. You have about 0.025V delta, the cells will be fine.
sunshine_eggo
Happy Breffast!
You displayed a screenshot showing a 0.025V difference between high and low cells. The data presented do not support your conclusion.
sunshine_eggo
Happy Breffast!
that's a lusciously balanced battery.
That's the first time I've heard the word lusciously used with a battery...but I agree. I'm happy with anything under .06
sunshine_eggo
Happy Breffast!
I have to admit I had to look in the dictionary (non-native English speaker here).
Anyway, thank you all for the feedback. I had almost given up hope that the battery will be of any use.
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LakeHouse
Solar Enthusiast
Coming in late to this conversation... But this is the source of the original balance problem. I've seen the recommendation elsewhere on the forum occasionally to leave cells attached after reaching 3.65V (or whatever) during top balance, and it's a bad idea.
Top balance to your desired voltage, then disconnect the cells.
Here is why: Your cells don't all have identical characteristics in terms of charge and discharge curves or resting voltages. So let's say you top balanced to 3.65V and got all cells to 100% SOC. Now if you leave them connected and remove the charge current, all the cells want to 'settle' to their resting voltage, but if that's not the same voltage (and it isn't!) then there will be some current flow. For example, if cell 1 wants to settle to 3.43, and cell 2 wants to settle to 3.41, one of them can't do that if they remain connected in parallel because you're forcing them to the same voltage. So cell 1 will bleed some current in to cell 2 until they're both at the same 'resting' voltage, but then they're no longer at the same SOC. With very well-matched cells this might be a small difference, but many (most?) of us don't have such perfect cells.
@FilterGuy's tutorial covers this:
Anyway, happy to see that you've got those cells back in balance and your battery seems to be working well!
