Powering AGX Xavier with DC-DC Converter

Hello

We have 12V batteries available and they cannot power the AGX Xavier despite having enough voltage to do so, the documentation specifies voltages in the 9-19 range, I suspect it’s due to current spikes in the booting process leading to a sudden drop of voltage (dV/dt >= 0.5 V/s leads to a shutdown of the Xavier), so I got a DC-DC Converter with a suitable input and voltage range. I can output 1-12V from the DC DC converter but the problem remains, a sudden drop in voltage nullifies the boot process.

Has anyone had a similar issue? My next step will be using a capacitor with a suitable voltage rating (~15V) but I was interested in listening to the community’s thoughts.

Has anyone had similar issue?

Hi, it could be the voltage drop by current spike during boot. A big capacitor or stronger power supply is necessary if so. Have you captured the voltage drop with scope?

The Jetson AGX is very, VERY sensitive to input voltage. The lower the voltage is, the more sensitive it is.

I have a 2200 35V uF capacitor straight across the 19V input, and I power it with a 16 V LiPo battery with XT60 connectors, and it works mostly OK. Note that, for capacitor voltage rating, you want much higher voltage than your expected voltage if you have the choice, because this will make the capacitor last much longer. Each 10V of additional voltage rating above what you actually supply, and each 10 degrees C of additional temperature rating above actual ambient, will up to double the lifetime of the part. (These are rules of thumb, check the actual supplier data sheets and support literature for more exact numbers.)

You need to make sure that your battery is capable of high current delivery, and that your wires are as short as possible, and ideally that you are in the upper range of the input voltage, for a battery powered system to work well.

Also, the barrel connector itself seems fairly sensitive; when my system is jostled, it will sometimes reset. I have been meaning to solder a real XT-60 connector to the devkit board, but haven’t gotten around to it, so I don’t know if this would actually fix it or not.

I’ve confirmed voltage drops with an oscilloscope and I’m trying to find out what capacitance I need to power it. Right now, a 25V 47mF capacitor with 12V of input almost does the trick when the Xavier is isolated, but connecting the Xavier to an HDMI monitor + USB peripherals caused even more voltage drops and I ended up corrupting the OS.

Next step is to connect a plastic dielectric capacitor in parallel with the electrolytic to try to phase out high frequency noise.

I’m very much limited to the power source, it’s 12V @ 2.5A and it’s a few years old. I’m certain that were I allowed to use a dedicated battery, this issue would be half as difficult.

Just as a ballpark estimate I’d say the capacitor should be at least 1000uF.

Hello, after exhausting the possibilities of powering the Xavier with a Pb acid 12V battery, I’m looking for other batteries. After reading through some other posts on this issue, I read you use a Turnigy 4S 5000 mAh LiPo battery, but that seems to be out of stock everywhere. I’m looking around for other LiPo batteries, as 24V Pb batteries are out of my budget.

So far I’ve found a few 4S LiPo batteries with around 4000mAh (a Goldbat https://www.amazon.es/-/pt/dp/B08BZM21T4/ref=psdc_1642149031_t3_B07LCJPGT5?th=1 and a Team Orion 14.8V 2700mAh 4S LiPo 50C - Deans Plug) . I’ve never worked with LiPo batteries, from what I see I’d also need to get a dedicated charger for them and a XT60 connector as you mentioned. Is there a particular LiPo model in stock you could recommend?

Also, could you please be more explicit with how you connect the battery to the Xavier? Did you solder the wires from the batteries output to a XT60 connector’s input, and then soldered the connector’s output to a barrel jack connector?

Most LiPo batteries will work fine, unless they really are bargain basement. LiPo has much higher C rating than lead-acid, in general. The main difference in the mAh rating is how long the battery will last when not on wall parallel. And, yes, you need a LiPo capable charger, although in a pinch, a desktop power supply can do pretty well, set at a reasonable current limit, and a voltage limit just below the max voltage of the battery (i e, 4.1V per cell for a LiPo battery that nominally goes up to 4.2V per cell.)

Another option is to simply parallel the lead-acid batteries. If you have a 12V 2.5A battery, get two of them, and connect them in parallel (+ to + and - to -) and you will have a 12V 5A battery! Also make sure you use reasonable gauge cabling – 18 gauge is about right for these loads (or, of course, anything coarser, like 16 gauge lamp cord or 12 gauge US roamex wall wiring, which would be overkill.)

Deans plugs are perfectly fine too. I actually prefer them over XT60 because they are slightly slimmer, and because you need to make your own pigtail to go to the Xavier anyway, pick whatever suits your fancy. But Deans seems to be “old tech” and everything recent seems to be XT. Also, XT30 could work too – the Xavier doesn’t draw more than 5A.

First of all, thank you so much for your reply.

I had already tried two parallel lead-acid batteries, but that didn’t resolve the issue, the voltage drops were still too much. What I ended up doing as a temporary solution is to put the 2 lead acid batteries in series, and then modulating that 24V down to 18V with a DC-DC converter. It works (kinda) with the Xavier at the 15W power mode and whenever I try to use the GPU at 30W, it immediately crashes. So for this assignment, I’ll probably have to do with the two series lead acid batteries and write down my recommendation to use a LiPo battery (easier to implement in the mobile platform itself, we only have one lead acid battery meaning five total batteries for one charger, among other issues).

Again, thank you so much for your help.

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