Keeping a constant voltage on a battery

Hi,
I would like a constant 12v output from 4 lantern batteries rated at 6V each with a maximum of 7V and end point 3.6V. 2 batteries in series wired in parallel to the other 2 in series is my current simple idea. The problem with this is that as the batteries loose voltage the output will decrease from 14V to 7.2V but I will need that to stay at 12V.

How can I fix this?


Thanks in advance.

There is always more than one way. You could use a buck-boost converter or put all your ducks (batteries) in a row (series) and use a 7812 voltage regulator. The converter method will get a lot better use out of your batteries. The series way is real simple to build.

I suggest putting all the batteries in series, and using a buck converter. That is the easiest type of efficient conversion. If the load is very variable, then it could be worth having more than one converter.

A 7812 converter will work but the efficiency is only about 50%

It comes down to the current you need to draw at 12v.

3.6v endpoint? Talk about suck'n them dry.

I second Diver300's suggestion though it would be nice to know what they are powering or what the load current is.