I suspect most of us own a battery bank. It feels like device battery life is generally getting better, particularly in standby, but also we're using them more and with the odd exception (*cough* Lenovo P2 *cough*) batteries aren't really getting bigger. Having a backup option in your bag always feels sensible. So how do you choose which battery bank to buy? Getting the right one for you can be surprisingly complicated given the options available. So we'll help you choose!
Cables or no cables
This is one of my biggest things when I choose a battery bank. I really like to have all the various cables built in to whatever I buy. I don't want to actually have to carry the battery bank, a USB cable to charge it, maybe a USB cable or two to charge USB-C or microUSB devices and another one in case I need to charge my daughter's iPhone or iPad. If I can get it all built in, great - that's what I look for.
An example of one such device is the iWalk Scorpion 12000mAh, which packs the USB charging cable, USB-C, microUSB and lightning cables into a slim form factor. Note: This device doesn't have a USB-A out, so that's another thing to think about (you can get a mix of the two).
It's all very well having a battery bank, but how do you know how much capacity is left in it? How do you know if you need to charge it? Most battery banks have an indicator of some sort, but they vary from a single LED to a fully featured OLED display. Check out the Omnicharge Omni 20 USB-C for an example of complete info overkill (but I love it). I find a happy medium is a LCD percentage display.
Capacity (and therefore size)
It's really tempting just to order the highest capacity battery bank you can find (and I've done this a few times!), but the flip side of doing so is that it'll be really heavy to carry around. When choosing a battery bank you need to balance capacity vs weight together with how you plan to use it. If you find out the capacity of your phone battery (e.g. 3000mAh) you can roughly extrapolate what the battery bank will give you. A 6000mAh bank isn't actually going to charge your phone twice (as there's some energy loss) and the numbers will also be impacted if you have your device on and in use while charging, but it's useful as a rough guide. I tend to have one monster and one small bank for different uses.
Not all, but a growing number of devices now support fast charging. There are a number of different standards - Qualcomm QuickCharge 2,3,4,4+, Huawei FCP (Fast Charge Protocol) and SCP (SuperCharge Protocol), OnePlus / Oppo Dash Charge plus USB-PD (USB-C Power Delivery). Find out which standard your device needs and try and buy one that's compatible (and pick up one that supports as many as possible). Don't just think about power-out, think about power-in too - battery banks can take a long time to charge, so if you can fast charge them too, that's really useful. [Note: some battery banks can do 'slow charging' too, to look after device batteries and to charge low capacity devices].
Pass through charging
Not all battery banks support the ability to charge the bank and a connected device at the same time. This is really worth having, because if your phone and your battery bank are flat when you go to bed, it's super useful to be able to plug them into one charger and have them both ready to go in the morning.
Don't buy a battery bank from the pound shop. Just don't. Try and use a reputable supplier with positive reviews and look after your battery bank. Like any Li-Ion battery, bad things are going to happen if you abuse it, pierce it etc. etc. so just be careful.
Aside from the battery bank itself, some come with add-on items. A case of some description is nice if, like me, you're a bit obsessive about keeping things looking good as new. Many battery banks will ship with a short charging cable. Some very high capacity power banks can even take a 3 pin socket and output 240V.
Let us know which battery bank you've bought / are going to buy and what is important to you.
Edited by PaulOBrien