DIY Portable charger project

[K_ennyy]

Hello, I am trying to make a 3 in 1 portable charger, wall plug and charging cable. I have a basic knowledge of electronics and have made a few devices in the past ( A solar lamp and a Bluetooth radio). 

Would anyone be able to help me with how to wire this device? It needs to work like a normal phone wall plug would, use mains power to charge the phone, when unplugged from mains power it needs to switch to the onboard batteries to charge the phone. It also needs a switch to change the power input when plugged into mains power from charging the phone to charging the batteries. 

I have a rough rough idea of what I’d need to do, but would anyone be able to help me with a wiring diagram and components?

Thanks in Advance,

Kenny

 

[Evans Electric]

You lost me half way through to be honest .   Are you talking about a cell phone ?   

Are you talking about a battery unit to recharge a phone  when mains is unavailable ?   

 

[Geoff1946]

If I have understood, you have described a standard pow er bank. 

A normal USB charger keeps the power bank charged. The power bank charges the phone, whether or not mains is on.

Mine cost about £15 and has a 5Ah battery.

 

[Evans Electric]

There you go then Kenny   ...£15  squid  will save all that pharting about .