With video-heavy apps  draining your phone batteries,  the humble power bank is a must-have accessory.
By Anand Parthasarathy
Bangalore, May 11 2015: To misquote Mark Twain, there are lies, damned lies and  statistics  --- of mobile battery life. As you do your hourly check on Facebook  friends and Twitter tweets, as you open all those  pixel-heavy images and videos sent via  WhatsAp, your phone battery  keeps draining and in next to no time you are disconnected from your world.  'I swear, it was on full charge this  morning!'
Scene II of this tragicomedy is a frantic search for a compatible recharge cable.  Your phone  takes a flat pin. Everyone around you seems to have the  round one. Despair. Desolation.
Would you drive a scooter  over rough roads, without strapping on  a stepney?  Get smart and do likewise for your smart phone. 
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In recent weeks a number of attractive  power banks have been
launched,   ranging from extremely portable to chunky and power-ful. 
We list some of  best and brightest among recent  powerbank
launches  in the Image of the Day feature on our home page.
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Spend a little extra and buy a compatible  power bank -- one that slips easily into your purse or pocket.  There are hundreds of models, from Rs 500 to Rs 5000 or more. It's a problem of plenty -- and    here are  few lessons I learnt the hard way:

• Check the specs of your phone battery. If you have lost the  papers, you can always read the printing on the battery:   Then  buy a power bank  for  a milli Ampere hour or mAh  rating that is 50 percent higher. If you phone has a 2000 mAh battery go for  a 3000 mAh power bank.  Power banks, especially the unbranded ones,  often overstate  their capacity -- so  have a little extra juice. 
• Next,  check the output voltage and current rating printed on  your phone charger cable.  Mostly this will be 5V and 1 A or 2A.  Make sure  the power bank  is rated at least 5V and 1A.

If   you select a power bank  this way, it will be a  safe  buy.  True,  you can charge a phone with a 2000 mAh battery from a 1500 mAh power bank -- it will take a bit longer,  but no damage will be done. But beware of overdoing it.  If you  use a power bank  rated many times your phone battery capacity  --  say a  1500 mAh    phone  from a 10,000 mAh power bank,  your battery ( and phone) may explode.(unless ofcourse the larger capacity  powerbank has a switch to downscale  the current.. as many if the branded  models do)
In an emergency,  a phone power bank can be used to  power up a tablet  or a digital camera, at least for an hour or two.  But if like me, you are a  net book user, it is better to carry a separate power bank for that,  with a capacity of 10000 mAh or more.