I'm trying to expand capacity for a Duracell power bank (3.7v 2600 mAh) so I can power my portable RasPi project with it. I've taken a battery (3.7v 2800 mAH) from a cheap tablet and I'm wondering if I just connect the negative of the Duracell to the positive of the Tablet battery then take the negative of the Tablet battery and connect it back to the board of the Duracell power bank, if it will increase the capacity of the power bank and function normally or will it blow up in my face melting it Raiders of Lost Ark style?I'm a novice hobbyist and any pointers would be a huge help.A little more detail about my project: I'm installing a RasPi with RetroPie into an Original Gameboy case for a pretty cool emulator. I've found a step up chip to power the new display but have run into the issue of portable power. I'd like a little more capacity than the batteries that I've seen Ben Heck and others use. Thanks for your time and I hope to hear from anyone