I want to build a booster pack ! I have 4 1500 CCA batteries in a box on wheels I bought at a auction ! (not a good idea) but anyway it is like a cart that hauls the 4 batteries and I would like to use the 4 batteries to boost start my big 24 volt Caterpillar scrapers and dozers. That is easy but I would also like to wire the box to have the ability to jump start with the same cart and use just 2 of the batteries to boost start a 12 volt system what is the easy and cheap way to wire the box for both applications?? Can anyone help?

What voltage are the batteries? The best way would be to use SB connectors to make the connection to the jumpers. You can mark one as 24 volt and the other as 12 volt. Then just plug into the one needed for the task at hand. Also the 24 volt SB can be used for charging the batteries as a 24 volt set or use a 12 volt standard charger on the 12 volt side. Just be sure to allow enough time to get the batteries to full charge.