Gadgetory

I'm pretty sure you've been in the situation where you've got yourself a external battery pack and you've used it to recharge your phone on the go and your phone has got a 3000 milliamp hour battery your battery pack is a 3000 milliamp hour battery pack and yet your phone doesn't reach full charge why is that well let me explain as in my name's Gary Sims from Andrew authority today I want to look at the capacities of portable power banks these external battery packs you can use a charge your phone on the go now the thing about a battery pack is they come in all shapes and all sizes there are big ones and small ones and round ones and square ones and they all have a characteristic which is the capacity and that capacity is normally quoted in milliamp hours and you might say well I've got a phone a galaxy s7 for example has got a 3000 milliamp hour battery I'll get myself a 3000 milliamp hour portable battery pack and then if I want to I can recharge it but actually then you find that when you do try to recharge it doesn't get to 100% doesn't get even near 100% now why is that well to look into this problem I've done two things I bought myself a couple of battery packs of different sizes and I've tested to see how much charging they will actually do and to see how that charging number compares with this milliamp hour capacity number that's quoted on the battery and then the second thing I have done some math to try to work out what's really going on so starting with the battery packs I bought myself an anchor lipstick size portable power banks at 3350 milliamp power unit I also got a small Samsung one that's a three thousand one hundred million power unit and then I got a big one this is the Amazon basics battery pack and that's a 16100 milliamp power unit obviously you can see it's quite a different size to the other ones and so I use them I charge them all up fully and then I had a whole bunch of depleted mobile phone and I started to charge them up to see how things would go now starting with the Samsung which I said it's got a three thousand one hundred million power capacity when I tried to charge up a galaxy s7 for that it went from zero to 71% now that actually gives a figure of 2130 milliamps so from a three thousand one hundred million power battery I managed to get two thousand one hundred and thirteen milliamps of charge out of it now the second battery that I test it was the anchor lipstick size one and that's a three thousand three hundred and fifty milliamp hour battery and when I charged up a mobile phone with that I managed to get two thousand three hundred and thirty seven milliamp hours out of it and then the third one of course I tested was these Amazon basics with its 16 thousand milliamp hour battery now that's pretty huge so I had to charge up several phones one after the other to try to drain that battery but I still didn't get 16 thousand milliamp hours of current out of it what I actually did get was twelve thousand three hundred and eighty so as you can see all three charges whether they were small whether they were from a big company like Samsung whether they were a value pack one like the Amazon one in whatever they were like none of them reach their full capacity so let's try to understand some maths to see why that is now if you look closely on the label of these phones you'll find two numbers one is the capacity in milliamp hours like I've already told you and one is also something called what hours now what hours are actually a much more reliable way of telling about the capacity of a power bank now I'm sure that you remember that what is calculated by multiplying volts by amps now actually when you look at the what our numbers on all of these devices you can divide that by the capacity that's given and it will tell you how many volts the battery is on the inside of the power pack and what you find is that power packs in general have a three point seven volt battery inside of them and that's quite good because most mobile phones most smartphones have a three point seven volt battery inside of them however there's two small problems one is that we do all our charging by USB and so there's a USB port on the battery pack and into your phone now USB runs at five volts so the first thing that has to happen is is that the battery pack has to convert that 3.7 volts into five volts and to do that the amp each has to go down so already you're not running at the full amp capacity of that battery because there's been an up conversion to a different voltage level and then what happens it goes down the USB cable it hits the phone and then the phone will then probably down step that to maybe four point two volt or four point four volts so there are two conversions going on here one and up up step from three point seven to five volt and then in the phone from five volts down to 4.2 or 4.3 for the capacity at 3.7 volts is not what is being used when it comes to charging the phone so there's a difference there and secondly the up conversion and then the down conversion actually lose power because all conversions lose power otherwise we'd have infinity and machines that could just go on putting them forever and ever we wouldn't have any problems but energy gets lost and that's normally lost through heat and you can feel that at the back of your phone when it's charging there is some heat being dissipated now over at the androids comm website I've got all the calculations on how you calculate the actual capacities with the voltages and the amps and the watts and all that kind of stuff go over to Android comm and look for this article however if you want to know my rule of thumb this is what it is a battery power bank will give out two thirds of what it's milliamp hour capacity is so that's really easy if you have a galaxy s7 with a 3000 milliamp hour battery then what you want to do is multiply it by three 9000 divide it by two 4.5 4500 so you want 4500 milliamp hour external battery pack to get one charge out of that phone if you want to charges in that then you're going to need a 9000 and so on and so on if you're being really lazy because you don't want to multiply by three and divide by two then basically just get one twice as big as the battery in your phone and then you're pretty much guaranteed to get yourself a full charge in fact they'll even be a little bit left over so that's really good news so as a summary the battery inside of the battery pack is three point seven volt there has to be an up conversion there has to be a down conversion the battery charges in your phone at around four point four or four point seven volts there's heat loss and the combination of all those things together is that your battery packs only give out two thirds of what's written in the milliamp hour capacity so buy one that's big enough to cope with the battery in your phone my name's go sim from Andrew Authority and I hope you enjoyed this video if you did please do give it a thumbs up also please tell me in the comments your experience of using external power banks how good are they at charging your mobile phone on the go also don't forget to download the authority app so you get access to all of our news and features directly on your mobile phone and last but not least don't forget to go to Android royalty calm because we are your source for all things Android you