I’m currently doing a top balance on 16 280ah cells. I have the cells in parallel and before I started the cell voltage was 3.27. The power supply is set to 3.6 and the amps haven’t gone down in 2 days, 48 hours. The amps are sitting at 5.6 exactly and the test started around 6.34 amps. Am I doing something wrong?
Top balance
- Thread starter Mikep876
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Nope, you're doing it right. It's going to take a while. Don't get in a hurry. Do check the voltage at each terminal. Not the bus bar, the terminal. If the connection isn't quite right, the bus bar will report a voltage the same as all the other cells. But the voltage at the terminal will be different. If you have welded on studs, just check it at the stud.
Yea I did add studs to the terminals due to them being so weak.
It will take a long time (days) , also move one of the charger leads to the far end of the battery , so the charge goes through all the batteries. You may have to extend the lead but you will get better results with the positive lead on one end of the battery and the negative lead on the other end.
Ampster
Renewable Energy Hobbyist
Also, ditch the battery clips and banana connectors for ring terminals and bigger wire. The resistance of that connection may be why you saw a drop of current.
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Bob B
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That's a lot of cells for doing a low current balance.
If you assume they were at 50% to start that would be 140 ah x 16 = 2240 ah needed for full charge .... if you divide by a 6 amp average, that is 373 hours.
It would be good to try to try to beef up the leads and ditch the alligator clips and put ring terminals on both ends and that may give you more current.
Just don't get impatient and bump up the voltage.
If you assume they were at 50% to start that would be 140 ah x 16 = 2240 ah needed for full charge .... if you divide by a 6 amp average, that is 373 hours.
It would be good to try to try to beef up the leads and ditch the alligator clips and put ring terminals on both ends and that may give you more current.
Just don't get impatient and bump up the voltage.
Ampster
Renewable Energy Hobbyist
Or 16 days.
On the positive side, it is more than 16 days of power at 6 Amps per hour
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Consider a PSU with higher voltage and current, like 14.6V at 30A, bulk charging four cells at a time to get them close, followed later by top balancing as you are doing now.
https://www.amazon.com/MENZO-Universal-Regulated-Switching-Computer/dp/B06VWV5YCH/ref=sr_1_4
https://www.amazon.com/MENZO-Universal-Regulated-Switching-Computer/dp/B06VWV5YCH/ref=sr_1_4
Ampster
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Ampster
Renewable Energy Hobbyist
Bob B
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It might not matter much but your busbars should be staggered like the ones in my photo so they are all laying flat against the terminal and making full contact.
Also note the 12AWG cables I made for my power supply. If you are using a 10 amp power supply it should be putting out 10 amps or very close to it, and the power supply should be in CC mode. It's also important to be very clear the voltage of the power supply must be set to 3.65 volts before connecting to the cells.
Note in my photo my 12 amp power supply is only putting out 5.84 amps, and is in CV mode and is not in CC mode. This is because I was trying to be careful so I set the voltage to 3.40 volts to start and that did not work out well.
Once I set the power supply to 3.65 volts, it went into CC mode, put out very close to 12 amps, and did its thing. This also happens when using the crappy cables that come with the cheap power supplies due to voltage drop. Some of the power supplies come with 18AWG cables and if you use a voltage drop calculator everything becomes clear comparing at least a 12AWG cable vs. an 18AWG cable.
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Oh my. I didn't notice how he had arranged his bus bars. Not a good layout.
Mike, a bus bar on the bottom of one terminal needs to be on the bottom of the next terminal. Similarly, a bus bar on the top of one terminal needs to be on the top of the next terminal. Your bus bars aren't making optimal contact.
Getting off topic here, but it's not just what someone knows; relevance and presentation count for a lot.
You also think outside the box; when I thought that air compression was an original idea, I later discovered that you had broached the topic a week earlier.
Okay, back to topic.
You also think outside the box; when I thought that air compression was an original idea, I later discovered that you had broached the topic a week earlier.
Okay, back to topic.
Yea you guys have a good point on that. I didn’t even think of the bus bar layout
