Charging LFP battery from AC-DC unit
Tried to charge LFP from Meanwell se-200-15. Lynac Lithium 120AH battery marketed as 100AH, you discharge to 80% DOD and get 100AH. Was partially charged already, resting 13.1V. Battery manual sugg...
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Almot wrote:There is current flowing through your cables between the power supply and the battery creating a 0.05V drop across the cables. The higher the current the higher this voltage across the cables will be. This is known as IR. Your Meanwell doesn't have sense lines so you will have to accept this.
Set Meanwell to 14.2V, connected LFP. Voltage went up quickly to 14.1, then slowly climbed to 14.15 and refused to go any higher for a couple of hours.
Meanie got hot, I stopped the charging, disconnected LFP, set Meanie to 14.23, connected LFP. In a couple of hours voltage went up to 14.19 and didn't go any higher. Disconnected again.You need to put a fan on it.
My guess is it's going into thermal protection. It overheated, turned the output off, battery voltage dropped to 13.8V, it cooled down, turned output back on and battery voltage climbed back to 14.05V. If you were measuring the current you would have seen it go to 0A then back to 14+A with the voltage changes.You really need to put a fan on the power supply.
Set Meanie to 14.22, connected LFP.
Voltage immediately jumped to 13.8 and was going 13.8-14.05 for half an hour (this up and down didn't look normal to me),then settled at 13.95. Meanie got really, really hot, was giving off a smell and making a quiet high-pitched buzz - not an alarm buzzer, but I got the message and disconnected it.
This is limiting the power supply current output, creating a very slow charge profile. Your power supply is happy with this, but is your battery?
Connected Meanie to solar controller input and LFP to controller output. Voltage under charging 13.1, controller output 11A. After a few hours voltage climbed to 13.4, current dropped to 10A. Now everything goes as it should.
Your 14A Meanie is a little underrated for the task. Are you getting the proper charge profile to protect your $800 investment?
Wire a 120V fan or 2 on the power supply input and use them to cool the power supply. I wouldn't wire 12VDC fans on the output because you need every mA you can get to charge the battery.
