If you're fine using a cheap Amazon board, then get one with current limiting:
https://www.amazon.com/dp/B01EQT63SS/
I actually don't know how well it works. There is a XL4015 buck converter on there and I suspect that the current limiting is handled by having the LM358 adjust the feedback.
Not a very good one for low voltage and low current. They oscillate so bad you can make a strobe light with a 12V power LED.
Hello
I am looking for a simple -yet efficient way to limit the current consumption/output for an XL-6009 based DC-DC buck boost converter:
https://www.amazon.com/Adjustable-Converter-Automatic-Voltage-Regulator/dp/B07NTXSJHB
This won't be elegant but it could be done one of two ways. Power BJT in series on the positive output. Collector on the converter side and emitter as the output positive. A 1K resistor from collector to a 10K to 20K potentiometer set up as a rheostat. Between wiper and base add another 1K resistor. This will limit current but will also change the output voltage some. You will probably have to experiment with the resistor values.
Second way is with a Mosfet with drain at the converter side positive and source as output. Add an adjustable voltage divider before the Mosfet between positive and negative rails. Resistor values will be in the range of 1M from negative to a 100K potentiometer then a 100K to positive rail. From wiper add 10 ohm to the gate. Depending on the mosfet used, you'll have to experiment with resistor values. A change in output voltage will occur with current adjustment.
Not a great way to current limit but it does work.
Very few of those cheap buck converters have very good current control a low power.. Most just have current limit, which is to say when the amount of current drawn reaches set limit the voltage drops out.
Battery charging can be even more problematic because the Battery will want to draw as much as it can. Sometimes just a power resistor in series works the best.