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I've been playing around with this project for awhile and finally have a good compact solution.

This charger supports 6v-30v DC input and as long as it's installed correctly, works with both negative and positive ground cars.

-Have a Packard with 6v Postive Ground? This works.
-Have a Packard with 12v Negative Ground? This works.
-Have a 1955 Packard with 12V Postive Ground? This works.
-Have some weird application that is anywhere between 6v and 30v (DC) and is either positive or negative ground? This works like a Dickinson Orphan!

Input: 6-35V DC
Output: USB-C OR USB-A, 60W 3-20V DC (adjusts automatically according to the fast charge protocol)

Supports all major fast charge protocols:

USB PD 3.0 (PPS)
QC4+ thru QC2.0
Apple 2.4A
Samsung AFC

Output voltage is limited to 1v below input voltage.

So what this means is that you can use this to quick charge supported devices on 6v (which is usually 7.2v while running) and fast charge supported devices on 12v (which is usually 13.4+v while running). If you have a device that doesn't support quick/fast charging then it will still charge at 5v up to 3amps.
The chipset on this IC automatically adjusts based on the supported device charging protocol.

This uses a buck-style converter, so it doesn't not get hot like other styles of "dumb" voltage convertors and which also don't support the various phone charging protocols.

You can use the older USB-A or the newer USB-C port. One or the other at a time. Some of the newer fast charge protocols only work with USB-C.

I'm still playing with case design a little bit, which I will 3D print. I'll more than likely add a couple of mounting ears to it so that it can be screwed into the bottom edge of the dash, glovebox, etc. Or mounted with double-sided tape.

But I been charging everything I can find with it to torture test it. I have an adjustable bench top power supply, so I've been simulating 6v thru 15v on it and validating the charging outputs. So far it's been a trooper.

I hope to have these available soon. They with come with the module which has an inline fuse holder, and installation instructions. Only two wires to hook up, so dead simple.

If anyone is interested, please let me know. As soon as I get the case design they way I want it, they will be ready to go. Probably shortly after Thanksgiving. To make them worth my time, I will be asking $29 for them plus shipping.

I like bench power supplies as they are steady and you can creep up on thresholds nicely; have you done a bona fide vehicle run-in test for a couple hours with an inline "low blow" fuse on a pigtail?

Might be smart to validate that you don't have oscillations from the old style 6V voltage regulators that may not show up on the bench configuration...I don't expect trouble, but I'm an aerospace nerd and testing as you fly always shows up something I didnt predict. Old 6V systems use the frame as the positive common ground plane and ALL signals/noise run all over the place, so there may be some unanticipated noise that modern power supplies (in the device that is charging) are sensitive to. Maybe you already have a filter in that buck regulator, but EMI filters often are accompanied by large turn-on initial transient spikes...just food for thought.

Nicely done and innovative...cool once you've validated it in the "flight like" environment and I'll be on your list. I presume you'll have a hookup schematic for the various configurations.

Nice job Kev. For a sandwich case, ideally you want the case to clamp the board between the halves. So for each screw, one side is a cbore thru hole, the board is a thru hole, and the other side gets threads formed by the screw. The tolerance is in the edge of the case. I will make a diagram.

I would also move the ports forward a bit so the board is not exposed. Mostly for cleaner looks. If it's not too late on the PCB design.

Good effort, there is a lot that's hard to design smoothly when it's your first go.

Very cool, I'm definitely interested in one when they come available.

Wow…that looks great! I’m interested in a couple when you have them available.

Very cool! I had been looking for something like this for my cars. Count me in for one or two when you get into series production.

Have you considered the cigarette lighter form factor?

Kevin,

Here is my suggestion for how to do the case which will hold the PCB firmly with no distortion of any component. This has been a successful formula for me in the past for this application. The emphasis is on the spacing between the edges of the cases such that they will firmly sandwich the PCB without case interference but also not leaving a gap.

Obviously since the PCB components take up space, you just need to use a longer screw and a boss.

Attach file:

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  tolerance stack up 3d print PCB case.jpg (1,003.89 KB)

Quote:

Yes, but there are variants to how to some of the prewar cigarette lighter sockets are. Contact locations, diameter, etc.

Also some of the sockets are wired always hot. While the "idle" power usage of then circuit only a couple of milli-amps, if someone left a device plugged in it would continue to pull power.

Someone could buy one of those socket adapters that you connect the wires to if they wanted. But that beyond the scope of this project.

I want something that is small, and discreet that would be attached under the dash or installed in the glovebox.

Only two wires to hook up. Red to postive, black to negative. One wire would be connect to ground (body/chassis metal), the other wire to a switched "On" source. Like the "on/run" terminal on the Ignition swtich.

So wiring would be as follows:

-> 12v negative ground car: Red (+) to Ignition switch, Black (-) to ground.
-> 12v positive ground car: Red (+) to ground, Black (-) to Ignition switch.
-> 6v postive ground car: Red (+) to ground, Black (-) to Ignition swtich.

It's really that simple.

I don't access to 6v prewar car at my immediate disposal, so may look for a volunteer that is actively driving their car over the next weeks that is interested in field testing it.

A disclaimer, I didn't design the IC board. I found an overseas supplier that makes that part, and I've adapted it and repackaged as solution to work in a variety of automotive applications. Designing and producing one of these boards gets very expensive unless volume is involved. So ive been searching for something that could be adapted for awhile.

Kev, sign me up for one once you go into production, and I'm hap to test drive one on my Packard if you need it.