I am trying to build a battery power pack for an off the shelf bluetooth speaker board. The goal is to power it at 12 volts with 2 amps available using one lithium ion battery cell, however there doesn't seem to be an easy way to do this with readily available components.
What I've come up with so far is to use a stack of six of these 3.7v to 12v regulated power supplies: https://www.amazon.com/dp/B09D3G96KZ?psc=1&ref=ppx_yo2_dt_b_product_details since the output voltage won't drop over time like the other boards I've used. They output 12v 0.3a, which is 4 watts, so 6 of them in parallel should give me the 24 watts I'm going for. However, after soldering everything together, I'm struggling to even get 10 watts out of the stack. I have a little 12v dust blower to use as a test load and a bespoke power meter, and the output tops out at about 9v 1.2a, which I assume is the voltage drop from overloading the power supply. But I should have enough of them in parallel to output close to 24 watts. What gives?