8mo ago

If I have a USB powered device, could I leave it plugged into a portable power bank (like the kind you charge your phone with) as a power outage backup?

Basically as the title says. We have semi frequent power outages where I live. The noise machine in my daughter's room goes out and wakes her up. If I were to buy a USB powered one, plug it into a power bank like one of those 10000ma ones you get for charging cell phones, would it have continuous power. Basically like a cheap UPS

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DO NOT leave a lithium battery both charging and discharging indefinitely in your daughter's room. The suggestion below of a small UPS device intended for routers and they like is the way to go.
- Since you didn't explain why... Using a normal power bank as an UPS is a bad idea because lithium batteries have a limited amount cycles it can charge and discharge. With a power bank the power has to flow from the charger into the battery then out to the load which eats up those cycles. An UPS is a little more clever as the power goes straight to the load via a capacitor bank and a mosfet bypassing the battery. When the source power is cut the UPS runs off of the capacitors for the milliseconds it takes for the mosfet to switch the load over to the battery. This vastly extends the life of the battery and reduces the risks of fire and toxic fumes from being released.
  
  Any recommendations of a modem/router UPS that would keep one up and running for a few hours? I've been needing to get one for WFH.

Both of my USBc power banks have passthrough charging and would work for this. That's the feature you need to look for.
However, keeping a battery bank charged to 100% isn't good for longevity, make sure you get a good name brand one so it doesn't catch fire.
Edit to add: the ecoflow & jackery power banks can also charge their batteries while running something. They can do 120v/240v and run the current nose machine, but they're more expensive

They make and sell mini UPS devices. Usually marketed for modems and routers. I use one of those and they have several hours of autonomy for low power consumption devices, and they don't beep uncontrollably like regular PC UPSs.
- Yea I think this is the way to go. I've got some Cyberpower UPSs around the house for tech equipment but even with the beeping muted they're still pretty noisy (like a buzzing). Looks like these mini ones might be the way to go.

Most power banks can either provide power, or be charged, not both.
They actually make what you want however, you can get usb UPS modules. They are intended for raspberry pi power, but just present a usb socket. They hot switch between external usb and internal batteries, as required.
- That's old power banks from decade ago. Majority if not all reputable powerbank brands now have charge passthrough.
  Some will charge your device to full first, then disconnect the device and charge itself second.
  Some will slowly charge both the device and the powerbank itself (I emphasize the Slowly part, probably at 5V 0.5A).
  For OP, look for something on the packaging that indicates it have the mentioned above function.
  HOWEVER! No good powerbanks will work as a UPS. Because they have built-in protection that will disconnect the power when fully charged or turn itself off when the plugged in devices is full.
  I said "good powerbanks" because cheap, no-name one doesn't have those protections and will keep on trickle charging both itself and the devices, which is really bad.
  Also, as a rule of thumb, you DO NOT want to plugged in your lithium battery at all times and keep it at 100%. That's the recipe for disaster waiting to happen.
  A cheap or 2nd-hand acid-battery UPS can be bought for as little as $30-$50 on Ebay, even the smallest one will be capable of powering the noise machine for days.
  
  That is definitely still a premium power bank feature. I've got a few newer ones that have full pd capability etc and they still don't do both.
  Lithium ion are fine in a UPS capability, they just need to be treated right. What most do is pass through to a boost buck converter. The external power passes through via a diode. When the external drops, the battery takes over instantly. Critically, when powered, the li ion is effectively disconnected.
  Raspberry Pis often require this capability, so most usb UPS units mention raspberry pi, making it a useful search finder.

Yes Absolutely. Not all of them will charge while plugged in, but I have a couple that do.

Most power banks won't output power and charge at the same time.
There are USB "UPS"s that will do that, though. They're typically used to run Raspberry Pi projects and are quite a bit pricier than regular power banks.
Maybe something like this?
https://www.amazon.com/ENOFLO-Portable-Charging-Compatible-Smartphones/dp/B0BX8R392P
- General UPS are great of medical/server devices too. You can get a generic one and then use software to disable the beep. It's what they are used for. The batteries are even replaceable.
  Example: https://www.amazon.com/CyberPower-ST425-Standby-Outlets-Compact/dp/B07GZR981Y/ref=mp_s_a_1_7?crid=1PC2DTQZZGWJ&dib=eyJ2IjoiMSJ9.v54x2i99M6VkWYl8gYCyJpx_BxQQpzTtNeQLrP6mQ8w6Bd7gyUlav6Ql5nFE2tDT-6Y70Tkhaxyn8oMbgDJiQ0WbIHHj5k5MTHHuj_BxBm4vtCPBf6VGTihuuwLshniqvcn-vX-Vr_cA1RmD2EJc-V5stqY3k90oS4SypMAMaDitV3z18DsDiaPNoAReGrAxqheb_lzXsycwkP7YezbPyg.3EVAEzPdF5nTb1n50l9Rad4cNGBW-g6gBCUscRvrVkM&dib_tag=se&keywords=ups&qid=1718411844&sprefix=ups%2Caps%2C303&sr=8-7
  
  I was gonna suggest a regular UPS (some have USB ports), but OP said it was for a noise machine/sleeping, so didn't want to recommend something that would start beeping randomly lol.
  
  How do you disable the beep?
  I have six of these in my house and that would be a life saver.

Depends if it is able to power while being charged.
None of my battery banks do that.
- My battery bank also functioned like SatansMaggotyCumFart
  
  Something something, RimjobSteve

I got my son a noise maker that has a built in battery for this same reason. It doesn't seamlessly switch to battery I'm sure there is one that does.
- This one does: https://www.techradar.com/reviews/lectrofan-micro2
- We use the Hatch Rest. Same idea, uses battery if unplugged, no disruption in sound. Only lasts ~8 hours on battery alone tho.

Yes, battery banks with at least two ports and pass through charging will handle it like this. The Anker bank I have (Anker 737) does this.
For long term use the battery cells may degrade in capacity and max current after a couple years of sitting at 100% charge, but that's probably not too big of a deal for you since the noise machine is probably fairly low power.
- Connect it to a smart plug that you set to turn off for several hours periodically. When it shuts off, the Anker will have to start using its own power for a while, and since this will occurr regulary, it won't be sitting at 100% nearly as often.

Check out the power bank reviews from the channel "Allthingsoneplace". He does excellent reviews, pretty much exclusively focused in the technical side, testing efficiency, protections, etc. He also tests if it would work as an UPS. Most dont work and turn off after a while.

As long as the battery bank supplies sufficient power continuously, it would certainly power it! If it doesn't, you'd have to look at a battery bank to power the device but I'd bet your daughter's noise machine is likely going to work fine on anything.
However, skatrek47 brings up a good point: The battery would need to just be powering the machine (unless you had an automatic cutover, but that seems like overkill for this application).
For your use case, I'd say just run it off the battery all the time and charge it once the battery gets around 20%.
There's USB batteries that'll do passthrough charging too, but keeping a battery charged all the time will kill it, so you might as well just use the battery.
If you wanted to go nuts, you could get an APC or something but that would be pretty silly for this.

Would a home battery backup be overkill? If you have frequent outages it might be worth looking at something from EcoFlow ($) or Tesla ($$) to provide power when the grid fails. Other vendors exist besides those two of course.
- Yea I've looked at this stuff before. Usually the outages aren't that long, more of an annoyance than a problem. I've got some UPSs around the house to keep the tech gear going, just looking for a cheap solution to the noise machine shutting off

I don’t think the ones I have would since you have to push the power button to tell it to start charging a plugged in device.

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