On 3/18/08, Grant Brown <grant@sitedoc.com.au> wrote:
> Hi List
>
> I need some sort of battery back up switch IC that can do the following
> things
>
> The back up battery will be two 12Vdc 220 AH lead acid battery's set up
> in parallel in order to have a 24Vdc backup supply. I am open to other
> suggestions so long a s the amp hour rating is maintained.
>
> The system main power source is a 24Vdc rail that supply's 20Amps.
>
> What I need is an IC or device that will do the following,
> (1) Maintain the backup battery voltage and health.
> (2) Provide automatic switch over to the backup battery on main power
> failure.
> (3) Notify the system of the backup battery switch over event.
>
> The device can be one that uses an external MOSFET for the main load
> switch if required.

Maybe without switching ? Maintain the battery fully charged from a
27-30V current supply, in parallel with the load. Once a day turn off
automatically the power supply and discharge 10-15% from the battery
on the load. At chargingh time assure the amount of current for load
and for charging (this is possible only for quasiconstant current on
load),
ie 20A load and 4A charging = ~24A from the current supply.
You have only to monitor the current flow in/from battery and the
battery voltage.
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