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Car phone charger works in a 12v car port but explodes from a 12v DC adapter? Answered

I've got a lighting project that is powered by a 12v power supply and is driven by a 5v arduino. I want to minimize the amount of wiring I run to the project and power the arduino from the 12v power supply. One of the instructables recommended to use a simple car phone charger. 12-24v to 5v. Well I did and the thing exploded. I checked the polarity (bought a few of them) and it's correct, there's also an onboard LED for indicating power on. Thing lights up, works for a second and smoke starts coming from the IC.

What is so different between the car 12v and DC adapter 12v?

the onbaord IC is ADB85063


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Jack A Lopez
Jack A Lopez

2 years ago

I think I have seen that power converter board before, and I can guess where you got it from.


So certainly these little boards are cheap, but that by itself does not explain why they would be so explodey, or why they would fail when connected to 12 VDC that comes from an AC adapter, but not fail when connected to 12 VDC that comes from a car battery.

ThirdEarthDesign's comment, I think, gives us some good advice, that is to be suspicious of your 12 VDC power supply. Is it really supplying 12 volts DC? Perhaps it is AC, or is DC with large amplitude ripple,


Also he is asking for details of how you hooked it up, probably because, like me, he is thinking you just did something dumb, like getting the polarity backwards, or somehow wiring a short across the 5 VDC output of this board.

Regarding the IC, at the heart of your module, the ADB85063, the data sheet for that is out there,


It might be similar to MC34063


By the way, I seem to recall, a few years ago, taking some pictures of a previous version of this USB cigarette-lighter-socket gizmo, here:



That one really did have a MC34063 in it.


2 years ago

Just to be clear, you hook everything up via the USB phone charger in a car socket and it all works perfectly fine, but when you use the same USB phone charger with a 12v DC adapter, it all ends in smoke and tears?

First thing I would suggest is to put a multi-meter on the DC adapter and check it is definitely outputting 12v. I would also try a different 12v DC adapter (if you have are using a cheap chinese DC adapter the voltages can be poorly regulated, often they don't output the correct voltage).

Another thing to check is how much current can the DC adapter and the car adapter handle, make sure everything is within the required tolerances (but I guess your current draw is low, so probably not the issue).

It might help if you can post a photo of how you have everything hooked up, in case that offers some additional clues.