USB-C Decoy Triggers

I’m back on the hunt for battery products for my photography slider project, Raspberry Pi Zero DSLR Camera control System

What I want to do is to power the Pi Zero and associated bits and bobs from a USB-C Battery bank, however I need 9-12v out of it.
No issues, I got a 12v decoy trigger to tell the USB power bank to give me 12v, and that works swimmingly.

I am not trying to use the same technology for a solar project and want the reverse of a decoy trigger. ie I want a board that I can give a set voltage, say 12v, and it can the output USB-C to charge a phone or USB-C power bank.

Does anyone have any ideas as to such a device?
Similarly, a solar controller that can take 5-55v (or similar) input and output USB-C that would be even better.


Hi Andrew,

EDIT: whoops, totally misread your post! Looks like you just want a PD (or at least beefy 5V) power supply.

I reckon searching for a USB-PD car charger would be the go. If you needed to connect that into your project, maybe something like this would be helpful?

Hope this sorts you out!


Hey James no worries at all!

Let me give you the full story in case it changes anything.
I am a Scout Leader and we have 10 kids (and two leaders) going to the World Jamboree in South Korea next year.
It’s going to be epic, but three weeks without access to mains power is going to be a challenge.
I have one Leader going with me that needs a CPAP machine.
The Australian organisers are telling us that we are on our own with access to power, even for medical devices.

We have successfully used a 20Ah USB C power bank to power his CPAP gear and that worked very very well, using a USB-C cable and 12v Decoy Trigger, so we think that that will be the solution, however, we still need to charge the powerbank.
We can charge the powerbank with a folding solar panel, however I havent found any reasonable options that have PD high power output that the powerbank needs to charge in a reasonable time.

The other limitation is size and weight, and of course what you are allowed to take on a plane.
12v gel or lipo batteries is what he uses for CPAP when we are hiking, however that is iffy to take on the plane due to Watt limits and weight, and we still have the charging issue.

I just noticed a solar charing project by @James46717 so I’ll take a look at that too.


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However, I like your solution.
I could use a buck converter to smooth out the solar output to 12v and just run a PD charger from a car.
That would actually work without much fuss.


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Hi Andrew,

For some reason I forgot the obvious commercial option. Less exciting, but if you run out of time to make this happen, could be worth a look

Bluetti have solar/LiFePo batteries that output 12V, 240V, or USB PD, and MPPT charging for solar panels. They even have kits with appropriately sized panels too:

That’s a small one, they get huuuuge, the kinda thing you could power a house with if you were careful.

While LiFePo batteries are generally safer than Li-Ion, they might not get on a plane without trouble :confused:

Keen to see where you go with this one!


Hi @James84823 thanks for the response.
Yeah I have looked at the Bluetti stuff before, it does look good, if expensive, however there’s no possibility to get that on a plane.
Unfortunately, not only do I have to comply with the airlines Watt Hour restrictions on batteries, and I dont know what airline we are travelling on yet, but there is also a hard restriction on 35kg and single bag. I need to get everything for 16 days in that restriction, as well as whatever solar gear Im taking and batteries.

I can split it over a few people so that is OK, but I did want to take multiple solar panels to boost daily output.

I will update this thread when I get any more worked out.


Hi Andrew.
Reading your problem with interest. You do have a dilemma re batteries on planes.
Suggestion. Do you have time to put something suitable together and send it on ahead with surface transport (sea etc). This would bypass the airline restrictions which I am grateful for when a passenger.
Cheers Bob


I’ve already gone down that avenue Bob, and been emphatically told no, unfortunately.

I do have 3 days prior in Seoul that would give me no restrictions other than what I can carry, so if I was able to work out somewhere to buy a good system there, then I might be able to get away with it, but then I would have to do something with it after the camp.
We are told that there is no way to do something like post gear back home, either, but I will be looking into that too.


Hi Andrew
Your last post has highlighted another idea.
As I believe the batteries are the main concern with Airlines and postage could you put a suitable set up together here and purchase batteries locally in Korea (or wherever you finish with Airlines) and just leave the batteries behind when you return. This might be added expense but may be the only way out.

I don’t quite believe that. You may have to look into the customs angle but. Like you might be taking or sending equipment out of the country and bringing or posting the same back and there could be some paper work or declarations to happen before you go. Makes it easier when you return, believe me.

I made that mistake a lot of years ago when I went to Irian Jaya (Indonesia part of New Guinea) to do a job. Just loaded everything onto a private aircraft in Cairns and off we go. Not much problem at the destination (Timika) but my troubles started when I got back. Not only did I have all this test equipment and some spare bits but they belonged to someone else (AWA) and by then I was not an employee (contractor). Got away with it with a bit of swift talking and a plea of ignorance.
Cheers Bob


Thanks Bob.

The posting home comments are not postage or customs related, but because we are going on an International scouting event that starts when we leave Sydney, and ends when we get back, we’ve been told, rightly or wrongly, that we are not allowed to leave the group, or the main campsite, at any time.
There’s wiggle room getting to Seoul as we have three days to ‘explore’ before being bussed to the camp, so if I could find batteries locally that would be easier, but I’d need to ditch them on the way back.

If I can get away with using <100Wh USB-C powerbanks then I will as it is the simplest option, just need a fast charger from 18v to be able to get them topped off daily.


Hi Andrew
Lots of brands from Korea like Samsung, Kia, Hyundai etc so would be very surprised if yo could not get batteries.
Cheers Bob


Hi Andrew,

I just wanted to clarify and make sure I understood what you were hunting for.

The fastest battery charging for consumer devices that is widely available will be the USB Power Delivery standard. Which will ramp up the voltage to compatible end devices. Non-compatible devices usually can’t draw more than 5V at 2Amps. What’s the maximum charge rate your end devices will accept? Perhaps this will be sufficient.

Most solar regulators I’ve seen will either output 12 or 24 V as they are intended to be connected to a SLAB or alternatively they will have batteries built in and only output 5V at a maximum of ~2Amps.

I haven’t been able to locate anything with USB PD output that doesn’t have a mains input. So locating a solar input USB PD output consumer device seems to be a bit of a unicorn hunt. The only options that are close are fully integrated systems like the Bluetti ones but the cost is ramped up by integrating the batteries onboard.

EDIT: one other left field option might be to try and repurpose a battery drill USB charger.


Thanks Trent.
So the powerbanks that I am hoping to run, have an input at 9v @2A as the fastest charging option. This is what I was hoping to be able to provide it, however, that is over USB-C and will need to be tricked into outputting that amount.
There’s an aliexpress box that does this:

that can output 100W over USB-C but I was hoping for something more compact and more affordable.
(I know that it cant output 100w if the input isnt sufficient)

So Ideally, yes, a USB PD device is what I want, but not a decoy trigger, they turn USB-C into a specific voltage, I want to turn a specific voltage INTO USB-PD.

I might have the solution though, a 12v Car USB-C adapter with PD. I can then wire up a few of them and use that.

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Not an exact solution to your issue, but may help:

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