Battery Backup for Project - Guidance Needed!

Okay,

I have a project that needs at minimum 7.5 Volts of battery power.
It has a 9 Volt Walwart (Power Adapter) Attached.

I need Schematics for a battery backup system for it (Sort of like a UPS)

  1. It can be any type of rechargeable battery(s), but it needs to be supply at minimum 7.5v (9v would be ideal)
  2. The battery pack needs to power the project, in-case of a power outage.
  3. When Power comes back on, it should re-charge the battery.
  4. It needs to be able to prevent over-charging.

It's being to be built into a PCB Board I'm designing.

Can someone give me any ideas or supply basic schematics for this?

this might make a good starting point? http://www.adafruit.com/products/390

That doesn't meet the minimum the 7.5v (or 9v) power requirement.

Browse www.maxim-ic.com.
Search power management/batteries
Need a multi-cell battery charge control chip, to charge 3 Li Ion or 3 LiPo batteries.
Or 2 of you can live with 7.4V when on the low side (will be around 8.4V when charged).
You can even find charge control chips that will disconnect the battery string when they get too low so they don't over-discharge.

There are other sources as well.

I used to visit Ballston Spa, my parents had friends that lived there. Ages ago now.

Can you give me any tips on selecting a chip?

I want it to be as simple as possible. The less components required, the better.

  1. It needs to charge 3 Li-Po Cells.

  2. Charging Time Doesn't matter.

  3. Remember, it's going to be a UPS Type Battery Backup.
    It must be able to run the device while charging, and seamlessly switch to battery when the power goes out.

***EDIT:
Something Similar to this, but one that can charge 3 cells (And the USB Features are not needed).

http://www.maxim-ic.com/datasheet/index.mvp/id/4002

This might be the kind of charge/discharge monitor you are after.
http://www.maxim-ic.com/datasheet/index.mvp/id/6223