I'll order a benchtop power supply and get them top balanced. They were balanced from the manufacturer when they arrived but I know LiFePo4 voltage may not indicate the cells are truly balanced.I'd try to get it top balanced ..... I don't think that Daly BMS has much balance current. Do a search on here for balancing with a resistor .... but you probably don't have one. Maybe connect them in parallel and let them sit a while.
Update: got the cells top balanced and they're charging up to the full 14.4V which is good.I'll order a benchtop power supply and get them top balanced. They were balanced from the manufacturer when they arrived but I know LiFePo4 voltage may not indicate the cells are truly balanced.
How would I test this? I did double up the bus bars but they are pretty thin.Are your bus bars dropping lots of voltage.
If you are getting a considerable voltage drop your bus bars will be very warm to the touch. All the loss is in the form of heat so VERY easy to check.How would I test this? I did double up the bus bars but they are pretty thin.
Wow I just confirmed the bus bars are warm to the touch when pulling ~400W. Battery dropped from 13.2V under no load to 12.3V with load.If you are getting a considerable voltage drop your bus bars will be very warm to the touch. All the loss is in the form of heat so VERY easy to check.
Thanks so much for your help! I think I will build my own bus bars out of copper tube since it seems there aren't good quality bus bars available. I am still seeing voltage drop under small loads like 40 watts. Even though the bus bars aren't warm at that wattage can I be sure the bus bars are the issue?I don't know if it's been discussed, but some bolts provided are too long, and they don't provide good contact with the bus bars.
If your bus bars are getting warm it's because they're too thin, or they are only lightly held in place. If it's because they are too thin, replace with thicker or add more thin ones. If it's because the bolts are too long, add washers to the bolts.
1) battery is not fully charged.
2) you have a loose connection somewhere.
3) you have high resistance in a cell or component (fuse/breaker)
4) you have bad cells.
Thanks snoobler for your patience as I am just a novice. I will fill out the above info when it's dark and the panels aren't producing any output.From my original response:
This thread was getting tedious, so I haven't hung in there for every post. I still don't see any evidence that you've narrowed it down beyond minimizing #1.
You need to stop looking at total voltage.
What are the cell voltages before and during the load? Fill out the following information:
At rest, record:
Cell 1 volts:
Cell 2 volts:
Cell 3 volts:
Cell 4 volts:
Apply load
Load, W:
Approximately 15 seconds into the load, without removing the load, record:
Cell 1 volts:
Cell 2 volts:
Cell 3 volts:
Cell 4 volts:
Remove load
wait 5 minutes
At rest, record:
Cell 1 volts:
Cell 2 volts:
Cell 3 volts:
Cell 4 volts: