Parallel connect power banks to power Jetson Nano

So what I’m trying to do is to power my Jetson Nano with a mobile power source (e.g. powerbank) through the DC barrel (requires 5V/4A). Since there are no powerbanks that can output that much, I connected two powerbanks (which have 5A/2.1V) USB-output each) in parallel to gain the double amount of ampere with same volt.

Here’s a picture:

Now my problem is that my Jetson does not boot up properly when connecting it. It shows the NVIDIA split screen, but then it powers down and video signal is lost. I can’t say what the reason for this is ot how to fix it. Am I doing something wrong? Is there any other possibility to power the Jetson with mobile power source on DC?

Thanks for your help in advance!

You’d need an oscilloscope to be sure about what is going on. Consider though that the output of those power banks are not batteries. Those are active regulators, and they do not know about each other. Minor differences between them might cause unexpected issues which are quite different than just putting two batteries in parallel.

What you really need is a buck/boost regulator capable of that much output, and separate batteries to put in parallel to feed the buck/boost regulator. Or a single supply capable of the output you want.

The issue with finding higher output current is because you are looking for power packs which natively provide the micro-B USB connector. This in turn ties the charging and power delivery specs to the USB standard. Other 5V supplies which do not natively use USB (with output to terminals instead of going to a micro-USB connector) won’t have that problem. You would need an above average power stability from the regulator, but as long as there is no USB stuck in the middle of the wiring, and you go to the barrel connector, then it should be ok.

Someone else will probably have specific recommendations on either a power pack or a buck/boost regulator which can be added to raw batteries.

You need to use a oscilloscope to check if voltage drop during power on as the power bank may not be suitable to this kind of working mode.