Will I blow up this portable charger (battery)?

I have a couple of those external batteries you can use to charge up cell phones and other portable devices. I got this one, and we have others that are pretty much the same.

Both of mine, and all of the others I have seen, have a standard size USB jack for the output side and a micro USB on the input side for recharging. They generally come with a short cable with plugs of those types at each end.

Ever since I got the first one a couple of years ago, I have wondered what would happen if I plugged the output into the input. It’s like that urge to jump that some people have when standing at the edge of a cliff, or like this.

To anyone with even a slight knowledge of electricity it’s clearly a terrible idea. But there’s nothing physically to stop you from doing it, and there are plenty of total idiots out there (obviously!). So shortly after I realized it *could *be done, I tried to reassure myself that there must be some sort of built-in circuitry that would prevent a disaster if someone actually did it.

But I haven’t tested it to see if I’m right. Does anyone know?

If it were $5.00 I might test it but at $31.00 I would ask the SDMB first.

I would think something inside would overheat and it would shut down.
Upon looking around online (it seems you’re not the first person to ask this), some/all newer power banks can actually detect that you’ve shorted the input and output and will shut down. Whether or not that’s just based on an internal temp raising or something smarter than that, I don’t know.

If you check out the youtube channel BigClivedocCom [spelled out just like that], he’d be the guy to ask, he’d probably even do it as part of explaining it and he seems to have an abundance of power banks, cheap knock offs on ebay an actual good ones.

I’d have no problem plugging one in and letting sit out side for a while, my bigger issue would be if nothing happened and I had to go back and ‘disarm’ it. I’d rather see a fuse pop or the battery catch fire.

Will I blow up this portable charger (battery)?
Probably not. Both the output and input are at 5V, so you are not going to fry any of the electronics due to over-voltage.
I can’t think of any obvious problem that might kill the device, but…no guarantees.

Take a regular battery, D, AA, whatever. Run a wire from the positive to the positive and another wire from the negative to the negative. What happens?


(As opposed to running a wire from one end to the other. Very bad idea.)

So what might be different with a pack like in the OP? There’s extra circuitry for current limitation, voltage regulation, etc. All of which would help prevent problems rather than make them worse.

Some waste of charge might happen but that’s probably it.

Now the “but”'s:

Does the manual say anything about not using the batter pack while charging? Did some offshore manufacturer cut corners somewhere thinking "No one would be stupid enough … " so they bridged something to save a half cent? Etc.

Why would it even overheat? The output is current limited. At most it would be outputting the maximum amount of current it’s designed to output. And the battery won’t get hot because it’s not actually being charged.

I have tried this on the new one I got for black Friday. (Anker brand 10k for $20). If the charge port is connected to power the output shuts down. So you cannot loop them even if you have 2 of then.

I suspect you’d be arrested for violating the Law of Entropy.

A guy received a small first degree burn carrying a 9v battery in his pocket, where it shorted out touching a coin.

Why isn’t connecting the input of my charger to the output the same as connecting “one end to the other”? I knew that was a bad idea and assumed it was the same with my charger.

You were trying to charge it while it was charging another device?

I’ll theorize the existence of two switched-mode power supplies connected to the battery:

-One SMPS is supplied by the battery, and delivers regulated voltage/current from the battery to the output jack, not to exceed 5 volts and some number of amps (see USB specs here; could be up to 3A, depending on standard used).

-Another SMPS is supplied with power from the input jack and delivers regulated voltage/current to the battery, not to exceed whatever voltage/current limits were deemed prudent by the manufacturer of the device.

Bottom line, there’s no reason this thing should overheat if you plugged the output to the input. At worst, you’d just be powering a couple of SMPSs, and incurring the losses from doing so; the energy of the battery would be slowly dissipated as heat due to the inefficiencies of those SMPSs (and any ohmic losses in the wiring along the way).

The particular product linked to by the OP (here) indicates that it does not allow “pass-through charging”. So it doesn’t know that you’ve connected it to itself, it only knows that it’s connected to a supply in the input and a drain on the output, and it shuts itself down.

I hadn’t thought to test it by trying to charge the battery while it is charging another device. If it shuts down (which users say this one does), then it can’t try to charge itself. So I was right in assuming it had a failsafe.

But what about others that allow pass-through charging? Could they be damaged or overheat the cable if plugged into themselves?

I curious as to your background that you say “ohmic” instead of “resistive”.

My background is obviously not in English grammar.

:confused: Not sure how to answer that. White, middle-aged, American, middle-class, male, engineer, English is my native language…Did one of those descriptors hit on something you were thinking about?

Yes, what kind of engineer? I’d expect an electrical or electronic to say, “resistive”.

Mechanical. :stuck_out_tongue:

I looked at several Anker manuals and they have warning of use, but don’t mention this problem at all. Predicting the idiocy of your customers is an important QA procedure.

The port used for recharging devices is USB-A. The charge port(s) are either USB-C or MicroUSB.


I suppose it’s possible that the device would do this, then realize it’s no longer connected to a supply and turn on the output, then realize it is connected to a supply… and something breaks from this rapid back and forth. Seems unlikely though, there should be some time delay before switching modes.