Having the ability to recharge your phone when you are not anywhere near a power source is becoming a normal concern. And if you have both a tablet and a smart phone to worry about, the stress level tends to grow as a result. Moving around a lot during the day visting people means that I am never at a location where I can really charge up my tablet and smart phone. And since both are used for business, I must have enough power in them to last until I get home. That is a big problem. There are solutions for this problem, but they are single solutions to charge up a device one at a time. That is not exactly what I need to keep up with things. But, there are a growing number of battery chargers which have the ability to charge up multiple devices and with plenty of power to give even more after that. One of the growing number is the MyCharge Summit which comes with a 3000 mAh battery at a relatively decent price to give you some peace of mind.
And given that the MyCharge Summit is about the size of a smart phone, you are not adding a large device to your bag of tech items. Read Build Your Own Power Bag With MyCharge Summit