LARGE 12 & 14 volt 3 stage charger with a twist....

Hi All,

First of all many thanks for your help with the DC-DC regulator previously, it works a treat

Now I have a much larger (and more complex) project.

I need a 3 stage charger / power supply...

Charger Specs
Stage 1 Constant Current @ 50A up to Stage 2 voltage (i did say large...)

Stage 2 Votages (selectable)
Voltage 1 - 14.4V or Voltage 2 - 16.8V

Stage 3 - When current is less than 10A voltages lowers to
Voltage 1 - 13.62V or Voltage 2 - 15.89V

I also need the unit to work as a powersupply at the stage 2 voltages (again selectable). Not sure if this could be built into the circuite with a switch to defeat the 3rd stage? or of it would be easier to have a seperate set of connections on the front of the box? Basically I would like as much current as possible when on this setting.

I have scoured the net looking for circuit diagrams but am unable to find anything suitably large. You may have noticed I'm far from being an electronics guru, but with a suitable diagram and component list I feel confident I can build it.

Hope you can help!