I just bought a MPPT charging controller for $38.00 for experimental purposes to learn how they work

[sam_sam_sam]

It looks like an ordinary PWM controller to me.

U6 and L3 appear to be associated with the USB ports.

U1, L1 and U4 appear to power the ICs on the PCB.

This appears to be the user guide:

https://ia804609.us.archive.org/2/it...8100A_text.pdf

I see nothing that would be consistent with an MPPT controller.

This appears to be the design registration for the box (SY48100A):

https://qxb-img-osscache.qixin.com/p...194f0dbe56.pdf

I don't know how to search for the patent(s) here:

https://english.cnipa.gov.cn/

Display controller (HT1621A):

https://www.holtek.com/webapi/116711/HT1621_21Gv340.pdf

The chip is marked "HOLETK" (sic), so it looks like a fake.

H6215L is a "12-200V input, 2A, buck constant voltage chip (high power - line loss compensation)".

https://taoic.oss-cn-hangzhou.aliyuncs.com/6511/product/HHBDT_1663134630000.pdf

https://www.hxc-power.com/h-col-113.html

So what is the verdict is a MPPT charging controller or is it PWM charging controller or something else

[truclacicr]

It's PWM.

MPPT controllers have large coils:

https://www.google.com/search?q=MPPT+controller+pcb&udm=2&sclient=img

https://hilelectronic.com/mppt-controller/ (includes circuit diagram)

https://makingcircuits.com/blog/mppt...arger-circuit/ (DIY project)