If someone would be willing to EL5 this for me, I’d be deeply appreciative.
° Power is almost always stored on DC batteries.
° Converting (DC to AC, or/and AC to DC) makes you lose about 20-30% of your capacity
= Use as much DC as possible!
if you want to charge a phone from a power station. Use the USB or DC ports that is has. This can save you 20%+20% (battery DC to AC and back to phones DC)
Don’t charge a power bank, to charge a phone. Every converting step takes a bite out of your capacity
But basically all big or motor/compressor appliances run on AC and changing them to DC requires skill and time and money. Although doable for me, I would not recommend this to anyone without them having an Electrical Engineering degree
Almost everything is powered by AC. The things that actually work on DC like electronics, have power adapters to convert AC into DC for the device, like the little brick that comes with your laptop or phone charger.
There are rare exceptions, but EILI5 doesn’t care about those.
If you have examples, we could clarify.
Even at ELI5, I’d nuance this. Big things like fridges and washing machines use AC, most small things like phones and laptops use DC, and have to have the AC that comes out of our wall sockets converted to DC before they can use it. This wastes a bit of energy. If you can, run small appliances straight from DC to avoid those conversion losses
This is going to sound exceedingly lame, but the foremost example is a box fan. I sleep with a fan at night and if there’s ever an outage I just want to be able to plug it in and go back to sleep.
The other use case for me would just be consumer electronics: tablet, laptop, phone.
All AC plugs.
Anything that you plug into a household power outlet is designed for ac. If it plugs in directly to usb it’s dc
if you’re like me and just need the noise from the fan, and not the air circulation, there are other, more efficient ways to get white noise… some of which would have battery power available.
for instance, i use an old laptop (with an internal battery for ‘backup’) and usb powered speakers (the ones built in aren’t loud enough when the lid is closed (it runs that way). if the power goes out, the laptop runs for several hours (even with the old battery) before it hibernates due to a low battery.
Thank you for the suggestion, but I definitely need the air circulation. For whatever reason my body runs hot.
Are you looking for suggestions for a battery backup? How much are you willing to spend?
You can use DC for electronics like a phone. You just remove the wall plug portion and use the cable by itself. This should help conserve power since you aren’t converting AC into DC, but if thats not a concern, you can use either.
I have never seen a consumer product that has a 2 or 3 prong plug that expects DC on that plug.
aka
Anything with a 2 or 3 prong plug, as in, anything that plugs into your wall of your house, that will want AC. If the device is powered by like, a USB cable, that’s going to be DC.
Based on the fact that you’re asking this question, it’s safe to assume pretty much everything you use is AC powered.
The “charger bricks” for some of your electronics convert AC to DC for you, but trying to bypass them “for efficiency” has a high probability of ending poorly.
Get/use AC on your backup system
The “charger bricks” for some of your electronics convert AC to DC for you, but trying to bypass them “for efficiency” has a high probability of ending poorly.
Like plugging your charging cable into a USB port instead of a wall outlet? There’s no danger there.
OP mentioned a 600W charger. Sure there’s no danger in plugging into a USB port but 600W of USB ports would look dumb and are probably not what I’l OP is referring to when they mention “DC plugs” on their “emergency power supply”. They also mentioned a box fan in the comments.
USB ports are fine for USB things and those provided by the charger may be slightly more efficient than using one of the AC plugs and a separate phone charger but were taking marginal gains on a tiny load that runs for a small amount of time. On a large AC battery system, the USB ports are just as likely to use an off-the-shelf AC/DC converter like most chargers as they are to use a DC/DC converter built for their operating voltage. They’re also limited in power output to whatever the battery manufacturer decided, which is probably not a lot.
A hypothetical person with infinite time, knowledge, and money, could create a whole DC ecosystem yes, but someone like OP posting for a vague ELI5 on the difference between AC and DC needs an AC system 99.99997% of the time. If it comes with extra USB ports, whatever, they’re fine I guess and have a chance of giving you a 0.2% efficiency gain on the whole system. But don’t try and run a large box fan on them.
There is still a charger brick there…now cut a USB cable plug off and connect the power wires in to a wall outlet directly…
Plugging into a USB port on your computer? Your power supply is already converting 120/240 vac(depending on location) to 12 vdc. That’s fine. Bypass that power supply and connect your phone to wall power directly and expect flames…
USB’s 5 volts, ain’t it? Not 12. Feed it 12 and you’ll break stuff.
(At least without USB-C PD negotiation.)
– Frost
Oh shit you’re right. I shouldn’t respond with a technical answer late at night…
if you’re running off a battery bank, then run as much DC as you can. if a generator, AC.
It’s a little 600W emergency power supply, not a generator.
use as much DC as you can
if you’d plug a device into a regular wall outlet for power, it’s ac. if your power bank has an internal inverter and provides an ac outlet, you should be able to just plug it in–provided its power demands fit within the output specs of the power bank. a normal box fan using 20-75w (approximately what ours here are, depending on age. newer models are more efficient) should be ok.
Changing power types is inefficient.
Batteries (which is what your emergency power supply uses) and solar panels are DC. They will be most efficient powering other DC devices directly.
Rotating generators (powered by engines, turbines, wind, anything that creates movement through motion pretty much) are AC. They will be most efficient at powering AC devices directly.
As soon as you’re changing DC into AC, or AC into DC, you’re losing power (usually a quite significant amount) in the conversion process. DC->AC requires an inverter. AC->DC requires a rectifier. Both are inefficient.
The direct answer to your question is that your DC power bank will be most efficient powering DC devices, and less efficient powering AC devices.
It’s going to depend on each individual’s power requirements. Some things use straight AC power (lamps, refrigerators), others DC (computers, most electronics, bare batteries). Those examples are not definitive. You need to check every item you want to put power to and go from there.
For most people the short answer is, mains power is so reliable that it’s not worth your bother to worry about the emergency situations. As long as things work, even a significant amount of inefficiency doesn’t add up. So stop worrying, just get things working.
If, on the off chance, you actually are using emergency power a lot, for whatever reason, then yes, this is a worrying about. In that case, you no longer want a short answer. You need a long, complex answer that covers all the different possibilities. So you need to start studying. Be prepared to spend months working at all the details for your specific situation.
