How many devices do you carry everyday? A smartphone? Apple Watch? AirPods, too? If you’re an on-the-go professional or digital nomad, you want flexibility for your power solutions. And that probably means that you need a power bank with pass-through charging.

When the number of available power outlets doesn’t quite match the number of devices that you need to charge, pass-through power banks can provide a smart workaround. Though this isn’t an everyday problem for most people, in these situations, a power bank up to snuff comes in handy.

Let’s take a closer look at this feature. We’ll first explain what pass-through charging is. We’ll also address some crucial points about battery health and safety. Finally, we’ll examine a few ways that the Power Bar, Einova’s award-winning power bank for all things Apple, simplifies both work and play with its three practical pass-through wireless charging spots.

What is pass-through charging?

Power flows like a river when your power bank is connected to mains electricity: from the wall, to your adapter, to your power bank’s input port, and finally to the battery. For a pass-through charging power bank, this river can branch off to its output ports or wireless charging spots, nourishing both the battery pack itself as well as connected devices.

All of this is controlled by circuits located in the power bank. The circuits play a grand balancing act called prioritization: How much power is available to pass to the connected device? How much is left over to charge the power bank itself? There’s a neat logic to these input and output factors. If the power bank itself needs to be topped up, there will be less power available to distribute to other devices.

Prioritization also determines charging speed. Speeds will be slower when one branch of the river is dispersed to the power bank’s battery. If the battery doesn’t need anything extra, however, all the water can flow into your devices, with no loss in charging speed. In technical terms, the power input will equal the power output.

Let’s examine this with some real numbers. The Power Bar’s input port is max 30W. There are three wireless charging spots: two Qi spots (7.5W each) for your iPhone and AirPods, and one spot for your Apple Watch (5W). If you’re pass-through charging all three at the same time, those 30W are more than enough to cover the 20W total power draw.

When not to use pass-through charging

There’s no reason to use pass-through when only one device requires charging. It’s more efficient to plug the gadget into wall power directly. But for all other situations where there’s just a single outlet at your disposal and you have more than one device in need, pass-through charging can help.

YouTube video from Einova about the Power Bar

Is pass-through charging safe?

But is pass-through charging safe? Though the answer is yes, there are a few considerations to keep in mind.

First, it’s a more inefficient recharging method in terms of both time and energy. Since the power bank is so considerately sharing power with a connected device, less is available to replenish its own battery. Consequently, the power bank must be plugged in for longer to reach full charge.

A second issue is possible heat damage, as internal temperatures can rise when power banks are left charging for longer periods. Lithium-ion batteries — the rechargeable kind found in consumer electronics — are damaged by prolonged exposure to heat.

All this doesn’t mean that pass-through charging is dangerous, however. As long as your power bank is constructed with the appropriate quality and safety measures, any additional heat will be safely regulated and the battery will remain cool.

So what should you look for? One important credential is USB-IF certification. This seal of approval ensures that your power bank’s vital USB-C port effectively regulates power flow. This, in conjunction with an input/output Power Delivery port, ensures that power is always delivered in accordance with the needs of the connected devices.

If you are primarily charging your iPhone, AirPods, or Apple Watch, however, the most important logo to look for is MFI certification. MFi-certified power banks adhere to Apple’s stringent quality standards for third-party accessory manufacturers and are guaranteed to be safe and compatible with the corresponding Apple device.


Using the right wall charger is critical for pass-through. Does your power adapter deliver the power bank’s maximum input? If the power adapter is underpowered, so will the power bank’s pass-through charging function.The best power adapters aren’t simply the ones with the highest wattage, however. You want strength combined with agility: less The Hulk, more Spider-Man. A USB-C Power Delivery charger like Sirius 65W will detect the power bank’s input needs and adjust the power accordingly. Sirius 65W delivers the maximum power of 65W in its name, but thanks to PD, it detects when the Power Bar requires less power and adjusts accordingly. As a result, there’s no danger of overpowering (and potentially overheating!) the connected device.

The Power Bar and pass-through charging in action

The Einova Power Bar can pass-through charge three Apple devices simultaneously.

The benefits of pass-through charging can be illustrated with the Power Bar, Einova’s multi-device wireless power bank for Apple devices.

In a public place and notice both your iPhone and your AirPods are running low? A pass-through power bank, such as the Power Bar, eliminates the need to compete with strangers for power outlet territory. In coffee shops, libraries, or airports, plug in the Power Bar and set them to charge on the two Qi spots.

The Power Bar also solves that awkward hotel-room-power-outlet-scramble. Most hotel nightstands have just two measly sockets hidden behind them — and invariably, the radio alarm clock hogs one of them. There’s a better option than plugging your smartphone into the remaining socket and abandoning your Apple Watch and AirPods to charge in the bathroom or on the floor.

Instead, use the Power Bar to charge all three devices simultaneously. Voilà! You just transformed the power bank into a 3-in-1 wireless charging dock. Wake up the next morning to three fully-charged batteries. After checkout, turn it back into a power bank. Connect your MacBook Air or iPad to the Power Bar’s USB-C port for on-demand backup power during the day.


Pass-through charging makes external batteries much more useful. For entrepreneurs or creatives, or anyone that relies on Apple wireless devices all day, the Power Bar is the versatile pass-through power bank that empowers you to stop worrying about low power — and instead, start creating.

Still have questions about pass-through charging? Leave a comment below!