You will not find a specification, because there isn't one.
The Pi4 has the same power manager as the Pi3B+ and Pi3A+ so the current limitation would be the same (the PMIC is rated at 1.5A). The Pi3 regulator is rated at 1A and has been tested at 800mA (on 3.3V).
There is no polyfuse or limitation on 5V, so you could in principle draw up to the limit of ...
What happens during a brownout is not "physical damage" in itself, rather, digital devices start to behave erratically when underpowered. This can indeed result in physical damage too: if the SoC accidentally reconfigures an input pin as output, it can create an internal short circuit and fry the pin, the SoC itself, or an external device connected to that ...
The best solution of your problem is using a High discharge Li-po battery cluster(12V) with a 5V-10A BEC. In this way you can get the power to run two pi's efficiently and without any throttle. But you need a powerful battery if you want to use it some more time without charging it now and then.
A single battery doesn't have that much discharge rate.
I presume by context you mean the 3V3 power rail pins (pin 1 and pin 17). They are NOT GPIO.
On the recent Pi models you can draw about an amp from the 3V3 power rail. On the earlier Pi models you can draw about 100 milliamps.
As an aside you can only safely draw about 20 milliamps from a single GPIO and about 50 milliamps in total from the GPIO.
Before using a cable you must first notice these things first:
1. Never use a very long wired USB type-c cable
2. E marked or not you should use a cable that can sustain fast-charge
3. Always go for a good quality cable otherwise there will be losses in cable
4. Use a fresh set of cable and avoid using converters.
Use an adapter with minimum 5V-2A. You must ...
I've successfully powered a Pi 3B+ using a cheap 12V 3A wall wart from aliexpress and a cheap buck converter from aliexpress. The 12V 3A provides for well above 3A when dialed down to 5.1V through the buck converter.
The most difficult part is soldering wire on to a USB plug.
First of all I have to say about battery. Battery store energy as voltage. The term of current comes when we are trying to put a load across it. The voltage reduces in a rechargeable battery after using it for a while. A dead battery has no voltage,neither it can provide any flow of electricity.
If a battery dies, and that battery has some abnormal ...