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With the current generation of smartphones and their much faster processors and vivid, high-resolution displays, and always-on connectivity, demands on battery performance are now higher than ever.

You may have noticed that, while you are on the road, you're quickly running out of juice. If you have this problem, portable batteries and PD fast charger than what may have come in the box with your device may be the solution.

But not all portable batteries are the same, even though they might use similar Lithium Polymer (LiPo) and Lithium-Ion (Lion) cells for capacity and look very much alike. Plus, modern smartphone hardware from Apple and various Android manufacturers support faster-charging rates than what was previously supported.

If you use the charger that comes in the box of the current-generation iPhone hardware, or if you buy just any portable battery pack on the market, you're going to be disappointed. Ideally, you want to match your charger, battery, and even the charging cable to the optimal charging speeds that your device supports.

There are three different high-speed USB charging standards currently on the market. While all will work with your device using a standard legacy charge mode, you will want to match up the right technology to optimize the speed in which you can top off your phone, tablet, or even your laptop. Let's start by explaining the differences between them.

Legacy USB-A 2.0 and 3.0 charging

If your Android device or accessory still has the USB Micro B connector (the dreaded fragile trapezoid that's impossible to connect in the dark), you can fast-charge it using an inexpensive USB-A-to-USB Micro B cable.

If the device and the 20W USB C PD fast charger white port both support the USB 2.0 standard (pretty much the least common denominator these days for entry-level Android smartphones), you can charge it at 1.5A/5V. Some consumer electronics, such as higher-end vape batteries that use the Evolv DNA chipset, can charge at 2A. A USB 3.0/3.1 charge port on one of these batteries can supply 3.0A/5V -- if the device supports it.

If you are charging an accessory, such as an inexpensive pair of wireless earbuds or another Bluetooth device, and it doesn't support either of the USB-A fast charging specs, it will slow charge at either 500mA or 900mA, which is about the same you can expect from directly connecting it to most PCs.

Many of the portable batteries on the market have both USB-C and multiple USB-A ports. Some of them have USB-A ports that can deliver the same voltage, while others feature one fast (2.4A) and one slow (1A).

So, you will want to make sure you plug the device into the battery port that can charge it at the fastest rate, if you're going to top off the device as quickly as possible.

USB Power Delivery

USB Power Delivery (USB PD) is a relatively new fast charge standard that was introduced by the USB Implementers Forum, the creators of the USB standard. It is an industry-standard open specification that provides high-speed charging with variable voltage up to 20V using intelligent device negotiation up to 5A at 100W.

It scales up from smartphones to notebook computers, provided they use a USB-C connector and a USB-C power controller on the client and host.

Batteries and 3 port PD fast charger that employ USB PD can charge devices up to 100W output using a USB-C connector -- however, most output at 30W because that is on the upper range of what most smartphones and tablets can handle. In contrast, laptops require adapters and batteries that can output at a higher wattage.