No, your PC won’t explode if you plug a coffee warmer into its USB port

I don’t know about you, but I’ve received a few gifts like this over the years: a plug-in USB coffee warmer.

It’s not always a plug-in USB coffee warmer, but it’s a similar USB tool meant to be a lovely little addition to your desk, yet it makes you shudder to think about actually connecting it to your PC. Your lovely, hand-built, precious PC that you use for work and gaming—that one.

I’m not going to lie: I’d actually love something like this. I’m forever moaning about cold tea in the MakeUseOf Slack channel, and I get through about eight cups a day. It’s a painful moment when my tea is cold.

But the main point is that despite what you may feel about the horrors a plug-in USB coffee warming plate may inflict on your PC, those terrors are likely unfounded, for a few reasons.

USB isn’t that powerful

It’s actually difficult to make it do anything dangerous

Credit: Gavin Phillips/MakeUseOf

So, we all love USB. It’s crazy useful, works basically everywhere, and with USB-C, has become the universal connector long dreamed of. But despite its incredible usefulness, it’s not particularly powerful. At least, it wasn’t until USB-PD (USB power delivery) became one of the most useful updates to USB in years, but more on that in a moment.

A USB port has a basic power output level depending on its generation and type. Now, it can be a little confusing at times because of the overlap between USB as a standard and USB Type-C as a connector type that also comes with some enforceable standards depending on the USB generation. Not to mention all the different colored USB ports there are. Still with me? Let’s take a closer look.

• USB 2.0: 5V at 0.5A → 2.5W
• USB 3.0/3.1: 5V at 0.9A → 4.5W
• USB-C (non-PD): 5V at 1.5A or 3A → 7.5–15W

Now, most of the plug-in USB coffee warmers I’ve seen during my research have been around the 7.5-15W mark. That’s basically the bare-minimum level required to actually keep your coffee vaguely warm, and even then, it’s going to be a struggle depending on the coffee mug material.

But what about USB-PD?

So, USB power delivery got me thinking. USB-C with power delivery can, in theory, deliver up to 240W using the latest USB4 standard. That would be more than plenty to power a plug-in USB coffee warmer, and you know, actually keep it warm.

But I actually couldn’t find one that took more power than around 15W. So, while some motherboards absolutely support USB-PD to deliver much higher wattage, that’s actually also not a problem you’ll necessarily encounter anyway, as the USB coffee warmers aren’t drawing sufficient power.

In short, that USB-powered coffee warmer isn’t configured to use what USB-PD offers.

Okay, but what about USB4?

USB4 doesn’t have a power level of its own — it just uses a USB-C port. If the port supports USB Power Delivery, it can deliver 30W, 60W, 100W, or even 240W. But without PD negotiation (which a cheap coffee warmer can’t do), a USB4 port still falls back to the same 5V, 1.5–3A as a regular USB-C port.

Related

What does it mean when a USB port is red?

A red USB port means business – make the most of it.

Your motherboard is also quite good at managing power

It’ll cut off devices that could cause problems

So, you plug the USB coffee warmer into the USB port on your motherboard. What happens if the USB coffee warmer is faulty and tries to pull more power than it should? Or more power than your USB port is designed to provide?

Thankfully, your motherboard is pretty smart and has some integrated tech to stop exactly this scenario from taking place.

Your PC has multiple layers of safety between a novelty heating pad and anything important.

The actual risks of using a USB coffee warmer on your PC

Because there are problems, just not the ones you may have considered

That five-dollar USB coffee warmer isn’t completely without risk, mind. There are two significant issues that could arise from using something like this with your PC.

1. The cheapo USB coffee warmer shorts out. At absolute worst, it could technically cause some damage to your motherboard, but the aforementioned built-in polyfuses should offer some protection.
2. Poor insulation causes the cheaply made USB coffee warmer to deform, melt, or otherwise, and causes damage to your desk. Or if you truly have a warped sense of adventure, you were keeping your coffee warmer on your PC’s top fans, and it melts into your PC directly.

Both scenarios are unlikely in general, but definitely something worth considering.

How you should really keep your coffee warm

These options are so much better than a USB coffee warmer

When it comes down to it, there are just better ways to keep your coffee warm than using a USB coffee warmer.

For example, plug-in coffee warmers do exist, and there are loads of options to choose from, with smart functions, timers, and so on. There are countless people out there who want consistently warm coffee, and who can blame them?

The big difference is that a corded electric coffee warmer will do the job much better than the USB model, as it can draw more power. This 36W Coffee Mug Warmer has a 2-12 hour auto-timer, temperature display, and a 5.2-inch heating plate, and will keep your coffee at 176℉/150℉/130℉.

It’s just so much better in every way and doesn’t compromise your computer in any way.

You could also go a whole step further, too, and buy a smart mug. Yes, you read that right: you can buy a smart mug that keeps your coffee at your perfect temperature, never wavering from that ideal supping temp. The Ember Smart Mug 2 is highly rated, and while I’ve never used one, there are multiple writers and editors at MakeUseOf who swear by them.

You don’t need to muck around with potentially dangerous tech to keep your cup of joe warm!

Brand

Ember

Connectivity

Bluetooth

Color

Black

Material

Ceramic