Low cost 12V/6A dc-dc for lead acid

[Vindhyachal.takniki]

1. I have a lead acid battery in my board. It needs three outputs: 12V/3A, 12V/3A , 5V/2A. For first two outputs, I will keep single 12V/6A
2. For 5V/2A I will use LM2576 in front of lead acid battery.
3. Since lead acid battery varies from 10.5V to 14V. For getting 12V/6A output. I need some cheap & low component board for it. Efficieny is not as issue here for me. Not want that should be 90% or higher.
Only thing is low cost, like LM2576, only few external components are required.

System should also have a low voltage cut off at 10.5V, otherwise it will drain the entire battery.

4. I had serached for many system. They are all very expensive & also TI webbench also suggest costly systems.

[oldway]

For the 12V outputs, the easiest solution is to use the battery voltage directly from 12V to 10.5V.
This can be done because battery voltage vary very little during the battery descharge.

For voltages higher than 12V (during recharge), use the diode drop principle with relays.
With three diodes in serie, you will have 1.8V drop and consumer voltage will be 12.2V for 14V battery voltage.
Use 3 relays to short circuit the diodes to maintain 12V for the consumer.

[rx8pilot]

How tight of regulation do you need? What types of loads? How low cost is low cost? Are you building one for yourself, or making a product of some sort?

Sent from my horrible mobile....

[Vindhyachal.takniki]

Regulation for buck-boost  if it can match LM2576 performance.
Making a product.

[rx8pilot]

Regulation for buck-boost  if it can match LM2576 performance.
Making a product.

If that is all the information you can offer, I am not sure what I should bother saying. The amount of effort you into this is directly proportional the the help you should expect.