18650 4s battery build

[jrobb911]

I built my first 18650 battery pack and have a few questions because it's not working right. Was going to use it for 12v items,110v inverter, and some USB devices like cameras around the cameras. I tested the battery on my inverter but the voltage was too high for the inverter input. My 4s battery pack at 16.8 volts so I plugged it into a group of fans to use up some power. I got it down to 15v but now it won't send any power to the inverter. When connected to the inverter it shows like 2v. I'm thinking the BMS is turning off the power due to low voltage. Any ideas? Do I need a boost controller to bring down the voltage? The plan was to charge it only to 14.8 using my solar controller.
This is the BMS I bought Protection Board 4S 30A 14.8V PCB BMS 18650 Li-ion Lithium Battery Protection Board with Balance

I'm kinda thinking of taking it apart and building two 3s batteries instead but was thinking the 4s would be better at running an inverter.

 

[schmism]

Used cells are problematic in terms of there capacity.
What kind of charger are you using. What is your pack configuration 1p4s? 4p4s?
I think most 18650 cells are like 3.0-4.2v (3.6 nominal)
Per the BMS you listed
Over charging voltage: 4.095-4.195V
Over discharge voltage: 2.55±0.08

so a 4S pack is going to run 10-16v
16V is going to be to high for most 12v inverters that I've seen so your going to stuggle with that unless you can specify an upper charge voltage on your charger.

 

[jrobb911]

The charger was going to be a solar controller with settings as high as 14.8v for lithium. The pack is a 4s 12p at 43AH. I had previously charged them individually and balanced the legs using repackr. The initial idea was to build a 4s so I had plenty of power but mainly using it as a 12v battery. Do you think it would be better to redo them as 3s and charge them to 12.6 or get a boost controller?

I removed the BMS and it does produce power at 15v which is still too high for my 1000w inverter.

 

[Thorsonic]

Who sells solar charge controllers that can recharge 4P 18650 cells...? CC/CV

Just answered my owned quest - found:

https://www.amazon.com/Lithium-Battery-Charging-Controller-Protection/dp/B082939ZXX?ref_=ast_sto_dp