My knowledge of electronics is very limited. I did a quick google

>>1114788
Lithium ion batteries can be wired in parallel, but only if each cell has its own protection circuits and you fully discharge them all before hooking them up, otherwise you'll have horrendous battery memory issues.

Also you won't be able to expand the internal battery of a smartphone. The energy density of lipo batteries is pretty standard, if a lipo battery holds twice as much energy it will be twice the volume.

There are cheap Chinese companies that try to flog high capacity lipo batteries in seemingly tiny form factors but they are all 100% fake. As a hobbyist you should only ever buy lithium polymer batteries from reputable sources like adafruit, a bad lipo could kill you or burn your house down.

Never compress or physically stress them either. The reason the note 7 kept blowing up is because they forced a huge battery into their phone and didn't leave the industry standard 10% expansion room for the battery, as lipo batteries expand when they get warm or are being charged. Inside the batteries are basically two thin metal foils working as the electrodes separated by an electrolyte. Too much pressure and those electrode layers will touch, and massive current will flow between them, creating massive heat and a brown colour in your pants.

>>1114886
I forgot to mention you can only wire the batteries in parallel if they are the exact same battery, no mixing and matching

Just smoosh two batteries together with either peanut butter jam. Jelly works aswell but it will take longer to charge.

>>1114890
thanks moron

>>1114788
everything in your phone is rated for its battery.
wouldn't do it bro.

>>1114788
Put in mind that all Lipo batteries are the same chemical thing, as in they go from 3.6 to 4.2V.

You can do any kind of parallel combination if the charging circuits are in place. Fuck the haters, they don't know shit.

The only problem is that you want 5V from something that only gives less than that so the converter should be robust.

For other uses, like powering phones, they can be added in parallel as much as you want. Won't fucking matter, if one is bad, not holding charge, you pull it from the mesh and change it. You'll notice it warmer than the others.

To make it really explode you need to be some kind of really stupid person, abusing heat when soldering or shorting things out.

When working with these you must be on your guard for those or you'll really put a fire in your pants.

>>1114886
One slight error in your post, Li-ion batteries do not suffer from "charge memory" issues.

>>1114788
The more you know:

http://batteryuniversity.com/learn/article/how_to_prolong_lithium_based_batteries

File: power bank2.jpg (169KB, 1392x998px) Image search: [Google]

169KB, 1392x998px

OP, you're trying to solve a problem that's already been solved a thousand times before.

You do realise that samsung sells higher capacity upgrade batteries for most of their phones?

Thanks for the input guys, I'll look into it and come back later with more precise questions if need be

as for >>1115781
>>1115788
Yeah, I know there are power banks. The point of what I'm wanting to do is two-fold:
-tackle a new project (and learn a bit about electronics before/at the same time)

-change ageing batteries in a bunch of appliances (I hinted at this in my post): I've got a beard trimmer that doesn't really hold charge anymore, a cheap chinese aux to FM transmitter that I'd like to mod, etc...

Also: i don't give a damn about aesthetics (as long as the battery is covered from direct sunlight and other elements, it's fine by me

File: 3 battery bumb.jpg (79KB, 900x506px) Image search: [Google]

79KB, 900x506px

>>1115897

Lipo batteries can becomes bombs if they're pierced, so a good idea would to use an external power bank that already comes in a metal case. you just have to drill a hole and bring out two wires from the batteries in the bank and into your unit. (coz the power banks output 5V and your unit expects 3.7V)

dont use scotch tape like i did (see pic) coz i know one day i'm gonna drop that thing, and then have to rush to get a fire extinguisher.

>>1114788

No, absolutely not

First of all, there just isn't the room for another battery inside of a phone. If you were determined to do this, it would need to be external.

Second of all, the battery of a phone has a lot of control circuitry around it. Any lithium battery will have a charge/discharge controller chip along with power supply that measures the charge of the battery in coulombs.

Anything you do will completely confuse this chip, and it will prevent you from doing anything stupid. No, you cannot remove it

>>1114788
buy an extend battery pack i have a powerbear that is almost 3 times the stock and it works great