External battery power supply

Hello,
I’m looking for a solid external battery supply which worked for you for powering the Jetson Nano.
If that helps, I’ll be connecting WiFi nano USB Adapter, RPI Camera V2, keyboard, mouse to the JNano.

The one I’ve found is 3.7V one that is used in Jetbot project (Iniu external battery), but in the notes it’s written 2X external battery. Which makes me wonder, why would I need two of them? And also, if I purchase one, how one will work with only 3.7V?

The INUI power bank from JetBot is 5V⎓3A (dual output), so it works with Nano no problem. In the JetBot bill of materials, it lists quantity 1 of them, so only 1 is needed. What the JetBot notes are referring to regarding 2x is that it has 2 outputs, not that you need 2 of them. I’ve used this 10000mAh INUI battery quite a bit with Nano and not had problems with it.

If you want something bigger and with more capacity, check out this 25000mAh power bank, which has the added benefit of being able to power the Nano’s DC barrel jack in addition to USB.

Does this mean that if a battery pack has two 2A or 3A USB outputs each, would I be able to run the Nano in 10w mode by plugging in both the mini USB and barrel at the same time (using a USB to barrel adapter for the second USB port).

That’s possible if the two outputs can work at same time.

I dont think you can. I read online that if you use the jumper to use the barrel Jack, it no longer powers from micro USB. If you want more power, I think theres a way to power from the gpio pins to provide 5v 3a to two separate pins, providing 30 w total.

That won’t work, but you may be able to adapt a barrel jack (or the 40-pin GPIO header) to a USB connection using an adapter like these:
https://amzn.to/2JgvsId
The USB-A connector on the lower-right could plug into the battery bank, and you’d solder a wire to the board and use a barrel screw terminal adapter like this:
https://amzn.to/30arVRa

Note that going through USB is not a great long-term strategy, as it’s not designed or rated for 3A, so there will be power loss and heating.
A proper LiPo battery pack (either from the RC hobby, or from power tools, or from high-power flashlights) with a 4A or better rated DC DC converter to take it to 5.2V would be better.

So does that mean that the microusb or barrel Jack does not have any kind of current regulator? I’ve seen posts and from other sources that if supplied a higher current source, the micro USB would limit it to only 2 amps so it is recommended to get a slightly higher power source such as a 5V 2.4A in order to account for any kind of power loss.

I think you’re confused about the role of “current” and “voltage.” Ohm’s Law is your friend!

A load may attempt to “draw” some current (perhaps at a certain voltage.) It will attempt to draw all the current it needs, and no more. The current source (battery) will have some ability to supply current at its given voltage, before the voltage drops too much, this is generally modeled as “source impedance.” (e g, a 5V battery with source impedance of 0.1 Ohm will provide 4.9V when you draw 1A from it.)

For switching voltage converters, which is pretty much everything that will generate 5V (and not 3.7V, or 120V AC, or whatever the “raw” input is) the function is not linear – the DC DC converter effectively has zero or even negative impedance. However, nothing is infinite, so the DC DC converters will hit some “limit point” after which they will either:

  1. Reduce voltage (CC/CV models)
  2. Cut off current entirely (hiccup models)
    or
  3. Burn up (cheap Chinese converter boards from ali express)

What does all of this mean? It means that if you provide a 5V 10A power supply to a simple LED that only draws 20 mA, the power supply won’t “push” 10A into the LED. The LED will draw 20 mA, the power supply will supply 20 mA, and all will be well. Same thing for a Jetson, as long as the Jetson draws less current than the ability of the power supply to supply while keeping voltage stable, everything will be fine.

It doesn’t make a lot of sense to talk about “current regulator” in the sense of a computer module like the Jetson, although for certain applications such as LED lighting, you will use a current limiter to avoid overheating of the LEDs. Instead, for the Jetson, you need a voltage regulator, that’s ready to provide whatever current the Jetson demands, which is something that changes very quickly depending on what the CPU and GPU is up to.

The Micro USB connector or cable won’t “limit” anything, but it has a built-in resistance, which will drop the voltage more the more current is drawn through it. Additionally, this voltage drop will turn into heat, so at some point you burn off the insulation of the cable or melt the connector off the board – although you’re likely to see the voltage drop to an unacceptably low level before that actually happens.

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Ok thank you for the explanation but doesn’t that contradict what you just said about 3A power supply to the 2A USB as bad since it will only draw 2A? I get the idea of having a higher voltage to make up for the voltage drop from the internal resistance, but I’m specifically asking about using a higher current power source. Every single source for power supply including the nvidia officially linked start up guide has said to get a power supply with a higher than 2A current rating so I just want to make sure I’m not missing anything.

A higher current rating is good for at least two reasons:

  1. it’s more likely to deliver a solid voltage at the current you actually draw
  2. the Jetson may perhaps instantaneously draw more than 2A for a very short while at times, which won’t be enough to heat up the cables/connectors, but would be a problem if the power supply was limited

Given the amount of trouble people seem to be having with this, it might have been better for them to not allow power over USB and just do the barrel jack or 5V rail inputs. And they probably would have done better squeezing a DC DC converter on the barrel jack input, so a 19V 1A adapter would have worked.
(I also still don’t quite get how this product came about – it’s … half an X1. At the X1 level of technology. Maybe they have tons of chips that didn’t test/bin for the Switch, so they now need to sell them somehow?)

But, it is what it is!

I have power bank with 5V and 2.5A but when I using this power source, my Jetson Nano can’t start. Can Anyone met this issue help me?