I agree it is a bit mad. I was charging at 20 amps so it would basically put that cell on hold until the others caught up.
Topping off or balancing a set of LiFeP04 batteries?
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At top of knee my charge current is down to a couple of amps. So the bleed works very well to do the same thing.
I have perfect balance until the whole pack gets to about 3.55Vpc, then a couple will start to creep ahead of the others. This tells me it's top of charge - based on the voltage charts.
Interesting though, if you bleed the top ones off, the lower ones finally get pushed up a little more. Just when you think they won't budge anymore they creep up as well. It's a very short jump for one to creep forward to 3.65V and then bms shuts down charging.
I have perfect balance until the whole pack gets to about 3.55Vpc, then a couple will start to creep ahead of the others. This tells me it's top of charge - based on the voltage charts.
Interesting though, if you bleed the top ones off, the lower ones finally get pushed up a little more. Just when you think they won't budge anymore they creep up as well. It's a very short jump for one to creep forward to 3.65V and then bms shuts down charging.
littleharbor2
Solar Addict
Same experience here. The 230 Eve cells I bought from them were all exactly the same voltage down to the thousand's of a volt.
WindWizard
Solar Enthusiast
One of my cells in the Cell pack that I purchased and did not top balance finally started to go to 3.65v and cause the BMS to shut down. I was able to attach my car light setup to the cell and discharge it to the point where it was ok with the other cells. I found this to be relatively easy. It did require a bit of time to monitor the cell and make sure that I did not discharge it to far. If tlhe cells have not been top balanced then it is better to watch the cells closely once they start over 3.5V.
The new Cell pack is performing very well now and both Cell packs do not require further bleeding of the cells. I set the Charge Controllers to charge at as high of a current as possible which is around 80 amps per Cell pack. Once the two Cell packs in parallel reach 55.6 Volts (bulk charge) Then the Charge Controllers both go into absorb mode set at 55.5 volts. This is basically a constant voltage for the Cell packs. so that when the sun is shining the charge controllers do not stop supplying energy. What I was finding was that I would monitor the Charge Controllers and they would say charged and then they would basically just shut down until they decided to start charging again. I wanted to use the solar power during the day and not have the batteries run down during the night. That way when the house draws more power than the charge controllers supply the power to the house and not the Cell packs. Once the Cell packs are full then it is a shame to just waste the solar power.
My whole purpose in this is to reduce the electric bill. CMP just raised the rated to over 22 cents/kw. Some of you may say hey that is a great rate but for us the bill would have pushed $200 per month. Last bill was $71 which my wife was pleased with. I tried to add the hot tub to the Magnum mspae 4448 and it was to much. I just added the hot tub heater to the Solar and left the hot tub pump on CMP. I will see if that trims the bill down further next month.
The new Cell pack is performing very well now and both Cell packs do not require further bleeding of the cells. I set the Charge Controllers to charge at as high of a current as possible which is around 80 amps per Cell pack. Once the two Cell packs in parallel reach 55.6 Volts (bulk charge) Then the Charge Controllers both go into absorb mode set at 55.5 volts. This is basically a constant voltage for the Cell packs. so that when the sun is shining the charge controllers do not stop supplying energy. What I was finding was that I would monitor the Charge Controllers and they would say charged and then they would basically just shut down until they decided to start charging again. I wanted to use the solar power during the day and not have the batteries run down during the night. That way when the house draws more power than the charge controllers supply the power to the house and not the Cell packs. Once the Cell packs are full then it is a shame to just waste the solar power.
My whole purpose in this is to reduce the electric bill. CMP just raised the rated to over 22 cents/kw. Some of you may say hey that is a great rate but for us the bill would have pushed $200 per month. Last bill was $71 which my wife was pleased with. I tried to add the hot tub to the Magnum mspae 4448 and it was to much. I just added the hot tub heater to the Solar and left the hot tub pump on CMP. I will see if that trims the bill down further next month.
Hi. A- can you really drain a battery that's still in the bank/pack? electrically how does that work? I have been un bolting on balance day (quarterly)kHere's the bleeder I made up:
Clip on the cell terminals and it drains that cell. It's pretty slick. And yes, you can do this while the whole battery is charging.
BMS balancing happens after 3.4Vpc, but it's not very strong. This bleeder really helps get them all even. It doesn't take long, and you need to do it at high-knee - watch the cell voltage with your bms app and remove it when it gets down to what the other cells are. You can balance them all to be the same. I have done this several times and they stay very well balanced - mine are not super grade-A cells, and I don't charge past 14.2 volts.
You can also charge one cell the same way, to boost it up to equal the others. Use 3.65 volts on a power supply. I just found the bleeder to be much easier to manage.
BMS balancing happens after 3.4Vpc, but it's not very strong. This bleeder really helps get them all even. It doesn't take long, and you need to do it at high-knee - watch the cell voltage with your bms app and remove it when it gets down to what the other cells are. You can balance them all to be the same. I have done this several times and they stay very well balanced - mine are not super grade-A cells, and I don't charge past 14.2 volts.
You can also charge one cell the same way, to boost it up to equal the others. Use 3.65 volts on a power supply. I just found the bleeder to be much easier to manage.
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