Kaya won't boot under battery power (but will with wall power)

My Kaya Jetson Nano works fine with the wall power adapter, but will only get halfway through the boot sequence under the recommended battery power with recommended Pololu 5V voltage regulator before powering down. I’ve even put in the recommended resistor to bring the voltage up to 5.1v – no joy

Is anyone else having trouble powering the Nano from a battery like this?

Hi Chris,

Sorry to hear you’re having issues. It’s strange that you’d see this during boot up, as the Nano shouldn’t be putting much load on the regulator yet. I’ve only seen this happen with bad connections or faulty components.

  • Check all wiring for bad connections, and ensure that the battery is fully charged. Pay close attention to any crimped connectors. Can you tug on the connector without pulling it off?
  • Test the voltage from your 5V regulator output and compare this against the wall adapter output to make sure you are delivering an acceptable voltage to the Nano. (Should be ~5V, and can never fall below 4.75V)

You can try to isolate the issue by disconnecting the 12V regulator for the dynamixels, as well as any USB peripherals from the Nano. It may be helpful to check voltage at each point along the path to ensure everything is as expected. Try without a monitor as well. Does it remain powered then?

You could try adding a capacity at the 5V regulator output or putting the Nano in 5W mode using “NVPModel,” but I don’t think that will fix whatever your underlying issue is.

I checked all that, including the voltage, and it does indeed fall below 4.7v at the exact time the Nano browns out. Same with or without a monitor attached. All other connections test fine.

Maybe a bad 5V power regulator?

Hi Chris,

It may be that the regulator is bad, yes. It should be able to provide enough power for the Nano to run without issue, especially since you aren’t even loading it yet. It’s also possible that there is a weak connection somewhere and something isn’t making good contact. Silly as it may sound, sometimes these problems can be solved simply by taking it apart and reassembling it, since this requires you to go through every connection over again.

You could put a capacitor across the output of the regulator as well, but this is probably more of a patch-over than an actual resolution to your issue.

Check the inner diameter of your barrel jack as well – there are both 2.5 and 2.1 mm ID jacks available which share the same 5.5 mm outer diameter. The Nano connection is 2.1 mm ID, so a 2.5 mm barrel jack will fit, but not make a good connection.

Unfortunately I’m not sure I’m able to provide much more help than this without being able to look at your Kaya in person.

I had this exact same problem. The voltage at the barrel plug on the Jetson dipped below 4.7V during boot. However, measured from the regulator terminals it was a solid 5V.

I think the recommended power cables in the docs are just kind of crappy. I bought these 18AWG cables and it totally fixed my power issues: https://www.amazon.com/gp/product/B072BXB2Y8/ref=ppx_yo_dt_b_asin_title_o00_s00?ie=UTF8&psc=1

Thanks Heathkit! I’ll try those

Thanks, heathkit. Chris, please let us know if this solves your problem. It’s possible that we should change the BOM item so that others don’t experience the same frustrating issue.

Yep, that was it. The cable Heathkit recommended totally resolved the problem. The one in the BOM is too thin gauge and quickly heats up (increasing resistance) under power, dropping voltage

Thanks, Chris. I’ll see to getting the BOM changed to prevent this in the future.

Enjoy your Kaya robot!

Also this tip from the Nvidia Jetracer build keeps the Nano from drawing too much power:

To prevent the Jetson Nano from drawing more power than the battery can supply, we set it to 5W mode

Open a terminal and call the following to set 5W mode

sudo nvpmodel -m1