Hi,

I have to create at dual power supply from batteries:

5V @ 500 mA
12V @ 250 mA

I going to be using 2, 6 Volt 5Ahr sealed lead acid batteries and I'm
wondering if it is more efficient/ better to connect them in series or
parallel.

Therefore is it more efficient to have a 6V battery supply and step it up t=
o
12 V and down to 5 V or start with 12V battery and try and get 12 volts
regulated and 5 volts out of it.

When I have a buck regulator, what happens when the input voltage goes belo=
w
the output voltage.  Is there a dropout voltage similar to a linear
regulator? Or, do I just get the unregulated battery voltage at that time?

I'm also looking for a source of pre-made modules around 25 mm x 50 mm at a
cost <  $10 each in ones.  Anyone have a favourite source?

I understand the boost/buck idea, but don't have any experience using these
regulators so any insight of there actual operation would be useful.

Thanks,

Gordon Williams

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