My system is about 1 week old and since day one I have a problem with a voltage drop in one of my batteries (check photo) and a second follows really close. My battery bank is an 8s with 280ah each battery is Any solution that you suggest? I need to mention that I balanced my batteries and that I'm using a Daly BMS. Thanks
Issue with voltage drop in 2 of my 8S battery pack. Any solution?
- Thread starter ale5ole
- Start date
More details are needed for advice. Here is a "short" list:
1) Is this a DIY battery?
2) What are the cells inside (brand)?
3) Where they were ordered from?
4) Did you measure capacity before assembling the bank? If yes - what were the numbers?
5) What capacity is being pulled out of the battery when you see these numbers?
6) Did you top balance the cells? If so - how was it done?
1) Is this a DIY battery?
2) What are the cells inside (brand)?
3) Where they were ordered from?
4) Did you measure capacity before assembling the bank? If yes - what were the numbers?
5) What capacity is being pulled out of the battery when you see these numbers?
6) Did you top balance the cells? If so - how was it done?
1)Yes, my first one actually.
2)Ogreen battery. https://a.aliexpress.com/_EwBnEfR
3)from AliExpress.
4)No this is something I never did. I saw instructions from different YouTube channels and no one mentioned something like this.
5) 2500W or more when it is 100% full or just 300W when it is 50% full are enough to drop the voltage under 2,75 that my BMS settings cut off the battery (low voltage protect settings)
6) I top balanced them yes by charging all cells up to 3,65 volts each.
P.s. Someone told me that I need to totally discharge these two batteries and short them for the internal resistance to become the same with the others...
Thanks
Do not ever discharge below 2.5V and never short your cells! You'll destroy them.
Charging the cells to 3.65 should have properly top-balanced the pack. But please, be more specific here. Provide step by step process on how you did that.
Check your busbar connections. If a busbar is heating up you need to redo it by cleaning the cell terminals and the busbar and reassembling it with the proper torque. Post a few pictures of your battery to see if there is something obvious that should be corrected.
And let's not rush into that, but based on the fact that you've taken cells from Aliexpress I assume that these are of bad quality. They are likely to be with higher IR and lower than the advertised capacity. And are very unlikely to be matched, so there will be a pretty high difference in the capacity among them. There are topics for recommended suppliers in the forum. It would be better if you have looked at them before purchasing the cells.
To sum it up - start by verifying that the busbars are properly installed and by providing details on how you did the top balancing.
Charging the cells to 3.65 should have properly top-balanced the pack. But please, be more specific here. Provide step by step process on how you did that.
Check your busbar connections. If a busbar is heating up you need to redo it by cleaning the cell terminals and the busbar and reassembling it with the proper torque. Post a few pictures of your battery to see if there is something obvious that should be corrected.
And let's not rush into that, but based on the fact that you've taken cells from Aliexpress I assume that these are of bad quality. They are likely to be with higher IR and lower than the advertised capacity. And are very unlikely to be matched, so there will be a pretty high difference in the capacity among them. There are topics for recommended suppliers in the forum. It would be better if you have looked at them before purchasing the cells.
To sum it up - start by verifying that the busbars are properly installed and by providing details on how you did the top balancing.
labeeman
Solar Enthusiast
You NEVER fully discharge ANY lithium battery it will ruin them. You have two cells that are not even close in capacity to the other cells. You need to do a capacity test on all cells and see what you have to get your money back.
Pete@SolarBatteryBarn
New Member
After you charged the cells to 3.65V, did you verify they were balanced at the resting voltage?
DALY BMS requires a good top balance before you build the pack.
DALY BMS requires a good top balance before you build the pack.
