I have a battery pack comprised of 2 6S 8000mAh LiPo batteries (link) with each one connected to an individual BMS module (link). I'm trying to charge the pack using a 25.5V dc power source as specified by the BMS manufacturer, using a 500W power supply I had which is fairly similar to this one. The BMS are connected parallel to each other.
Technically, the system works. However, the charge rate is very, very slow - to the tune of plugging it in at 22.2V, and 12 hours later it is only at 22.8V. What I am wondering is if there is something I am doing wrong, or perhaps something I need to add to my system to make it charge properly.
A few things that may be relevant:
- I have added a few 220uf caps parallel to the output voltage of the power supply to reduce ripple
- The power supply's output voltage sags down to the voltage of the pack while charging it.
- While testing, I added a small-value resistor in series with the BMS in order to measure the current across it (my meter only goes up to 10A) - the pack was drawing about 16A, however this also caused the voltage supplied to the BMS to no longer sag (is this a good thing? Should I be charging with such a resistor installed?)
Any assistance getting this pack charging at more reasonable rates is much appreciated.