Recently a woman in the train wondered why her smartphone doesn’t charge properly. And then sometimes it does. But mostly not so much. So it barely makes it through the day.
The reason is simple. People forget that the original function of a cellphone is being a Radio transmitter – and anyone who remembers the bulky Walkie-Talkies of the 1980ies probably doesn’t want them back. Even early cellphones had a rather brick-like appearance and the weight that comes with it. Manly phones!
So the reason for high power consumption of an otherwise idle smartphone is its constant attempts to register at cellphone towers; of course this happens especially frequently while traveling as the phone passes through many cells – which, in Germany, have an expanse of maybe 15 miles max, much smaller in cities.
A second reason is use of the GPS feature of your phone as the GPS receiver is a power-hungry device but I take it you switch that off when you’re worried about your battery charge.
Use Airplane Mode
So, to improve the lifetime of your battery charge, simply switch the phone to “airplane” mode, which has the added advantage of giving you the luxury of being undisturbed and undisturbable, raising your social status amongst your peers instantly.
That does most of the trick.
Now you also know why SOMETIMES your phone runs through its charge like a hungry hog and at other times it doesn’t – that’s when it’s resting relatively closely to the next cellphone tower and can reduce the transmission wattage for the regular status update datagrams it exchanges with that tower. Good reception goes with good transmission, modern cellphones reduce their transmission power as much as they can – also reducing “airwave pollution” in the process – which is important to keep the spectrum free for others who maybe want to phone somebody right now (And, maybe it also calms down those people who fear health risks from cellphone radiation). (I keep my testes wrapped in tinfoil. Just kidding. They’re fine.)
Get Charging Cable
And, another tip I accidentally found out. I needed a new USB-to-Micro-USB cable to connect my phone (a Samsung Note 2, great device for its stylus) to computer/charger because the old one was starting to malfunction.
I had the alternative of buying a 10 EUR cable, or one for 11 EUR (11.3 USD resp. 12.4 USD). The latter one said “Charging Cable”. But, it would also transmit data. The package said “Specially optimized for charging smartphones”.
In other words, they have a tiny bit more copper in that one so higher currents can flow. Does it make a difference? Hell yeah! Charges like a charme now, even when not using the charger but just plugging it into the USB port of my Acer notebook. I am positively surprised.
So, if you have similar problems, look out for one of those. And don’t hesitate to use the airplane mode of your phone every now and then.
Lifetime of Li-Ion Batteries
Final tip: Li-Ion batteries have maximum lifetime if emptied not below 20% and charged not above 80%. I know, the latter is difficult to guarantee absent a sophisticated charging algorithm in the phone – which I haven’t yet seen (some business notebooks have it, notably the old Thinkpads from IBM before IBM sold the business to Lenovo). But, you can try to not discharge it below 20% and that’ll help a lot.
Switch off Cores
Post-final tip: My monster phone (already 4 years old or so) sports 4 ARM processor cores. Frankly I haven’t got use for it – it has an energy saving mode that switches off two of them and the apps I use work just as well. So look out for such an option and try it. I would guess you only need as many cores as you can get if you do video processing on your phone, which I don’t. What I’m doing is some Google Maps, some photography, lots of scribbling notes with the stylus and a painting program, and audio synthesizer programs – all of which are just fine with 2 ARM cores.
That’s it for the energy saving tips.
And About those Cigarette Lighter Plug Rechargers
When travelling with the car and using Google Maps constantly to get traffic jam warnings (works great!) you would like to keep your phone connected to the cigarette lighter plug using one of those 5 EUR chargers.
REMOVE THAT CHARGER when you’re done! These things are simple resistor based voltage dividers! Meaning they produce the 5V for your phone from the 12V of your car by running it through two resistors, to ground, constantly drawing power even when your phone isn’t connected. It takes about a week to suck your car battery dry through a constant trickle of energy. You don’t notice but YOUR CAR DOES!
It is not a problem at all while you’re driving as the car’s generator can easily handle it. But, get that thing out when you’ve arrived.
Update Apr 14: As Yonason below points out this is only true for the really cheap chargers! Yes, there are – usually a bit more expensive – ones that notice when the ignition is off. This requires analyzing cyclical spikes in the battery/generator voltage though, so the cheap chargers simply don’t have the brainpower for that. (The “brain” is in this case probably a 50 cent 8 bit CPU system on a chip; and the cheaper ones don’t need a processor at all so that explains the cost difference.)