Backup supply - 12V sealed lead charge from 12V wall adapter

[darksir]

Hi boys,
plase can you help me with this idea?
I need backup power supply for 12V application. This application will be supplied from 230 to 12V/0,5A wall adapter.
Do you have any idea? Step-UP converter from 12V to 14,5V and diodes? I know only 2577 step-up converter and this will be very big and expensive.

Do you know any SMALL , cheap and good Step-UP for 12V dry battery charging from 12V supply? Application without inductor be EXCELLENT, but I think it is impossible :???:

Many thanks for any tips,
Petr

 

[D.A.(Tony)Stewart]

This is basically a UPS design on a small DC scale.

12V 6 watts max.

How long does it need to run with AC power down?

What battery technology do your prefer? tiny? cheap? or reliable? "cant say all in one sentence " ha.
How many are you making? budget?

Consider SLA 12V batt.(bigger seal lead acid) & SLA charger or Li-ion with charger

or use universal Laptop charger $35 ~65W and surplus Li battery & charger cut from old notebook with step-down DC-DC 12V buck converter for a prototype or single use application.


The Best answer comes from the Best question. Where are your functional design requirements and budget?

 

[darksir]

I´m sorry for not good description of my problem...



Now I attach schematic of my idea. Aku will be Sealed Lead 12V 1,3Ah. I need about 6 hour backup - device have consumption about 50-200mA / 12V. This will be professional circuit so I need fabrication design - not notebook adapter, wall charger for sealed aku, etc.
Step-up or charger must be add as another board on existing or new PCB of main device - i need only add connector for acumulator.

I need circuit, which will be fully functional with disconnected backup battery and accaptable voltage from adapter must be 10V-15V - I don´t will supply adapter for final device...

Thank you for any tips od step up or another solution of backup circuit.
Petr