Can I connect a 5w 5w solar panel directly into a 10k mAh portable battery bank safely via USB 2.0, or does it need some sort of protection in-between like a solar charge controller or a schottky diode?
Example of battery bank (except one with usb 2.0 input): https://www.anker.com/ca/products/a1229
Example of solar panel: https://www.aliexpress.com/item/1005006012344670.html
That is a cheap shitty knock off scam panel, just looking at the specs. it claims:
Power: 5W
Working voltage: 5v
Working current: 0-380mA
but of course, you won’t get 5w from 5v * 380mA, only 1.9w based on the specs.
the square area via the specs is 125cm^2 (assuming that’s the panel, not the package!)
and the realistic maximum power possible is 200w / m^2, so 125 / 10000 * 200 = 2.5w for that dinky panel.
get yourself a decent version of this if you really need a portable version.
something more like this, or catch a better version on sale:
https://amzn.to/3VqsztI
Then there are these kick ass USB monitors that will tell you exactly what’s going on during charging:
https://amzn.to/4ao74xU
This is very helpful. I actually have two of those panels so I can try wiring them up in parallel.
I also have that exact USB monitor which is super handy.
Excellent. What does the monitor show for volts with full sun and no load?
To parallel them, you might get away with using an (very) old USB v1 hub. Or solder something up from the junk drawer or parts from an old junk pc