I have an 50Wh “Hama Pipe” powerbank with 21W output power (2×2.1A ports OR 2.4A+1.8A), which would equal 4.2A at 5V in total, minus resistance.
But the input power is only 2.5W, which equals 0.5A at 5V. (no typo, see http://www.hama.com/00137422/hama-power-pack-pipe-13000-mah-weiss-grau)
Is that a technical limitation? The powerbank does not produce any heat during charge, so it is probably an *easily bypassable** limitation of the charging IC of the powerbank.
I have a different powerbank with 10W of input power, which produces heat.
Is that 2W limitation technical? Can it be bypassed?
My smartphone supports fast charging (9V 1.7A), but when I connect it using 5V, it does not take 3A (charger has 20W maximum output), not 2A but only 1.2A. I should build a power step-up transformer out if hardware modules.
It is not because of the resistance in the long cable. Short cables aloow 5V 1.3A. The USB multimeter shows 5.26V 1.21A for the long cable.
It is because the charging controller refuses to take all available power.
How can I manually overthrottle the charging IC?