Harvesting FULL Power....

[Jim Mac]

I have a circuit on my bench that lowers the input under load.  And the output's maximum power potential exceeds the loaded input.  But when I say "Max Power Potential"  I am referring to open circuit volts X short circuit current..  

According to my understandings, this "MAX POWER POTENTIAL" can almost never be realized in a resistive load..  The math tells us that whatever your max power potential is, exactly 1/2 that power can be utilized through a resistive load under normal conditions. And that can only happen IF the resistance is perfectly balanced to achieve that 50%. 

Under Ideal Conditions-  P Load =  P Max / 2

Lets say my P Max was 12V open circuit X 0.4 Amps Shorted, =  P-max 4.8 watts.  Means my resistive P-load should never exceed 2.4 watts..  And that is ONLY if the resistive load is 30 Ω.

But what if there was a way to use it all?  Consider...

We rectify the output to 12V DC.  Then run the rectified DC in series through a 12V battery.  Now the positive of the battery is outputting 24V..  Then we connect the resistive load from Battery Positive to Rectifier Negative.   Since we have exactly 0.4 amps out of the circuit, the resistive load must be exactly 60 Ω.  This should ensure the resistive load pulls exactly 0.4 amps at 24V, which the circuit can handle.

The resistive load should be dissipating 9.6 watts, which exactly 1/2 came from the battery and 1/2 came from the circuit.  Meaning we should be able to recover 100% of the P-Max.  

In the case above, the load should be exactly 60Ω.

I plan to test this

[Jim Mac]

Well it seems there is always a "Gotcha" waiting for us..  Although the reasoning sounded logical, it didn't work as expected..

It may sound untrue or complicated to grasp, but here's my summary..

The AC from the circuit needs to be rectified, and a bridge rectifier negative terminal gives current 2 paths.  The return current can either go out an AC lead (like it's designed)  OR the current can pass the AC leg and come back out the positive..  You can test this simply by hooking up a FWBR to a battery backwards.  Battery + to Negative DC of rectifier and Battery - to DC+ of the rectifier.  You will have a dead shorted battery...

In the circuit I proposed, we need the batteries return current to avoid the coil and return directly to the battery, And the induction coil's energy to return to the coil..  But the battery current does not want to cooperate with us..  They battery current ends up finding a better path through the negative side of the induction coil, then back to the battery.  This ends up cancelling the majority of our induction..

Aside from possible advanced switching, I am not positive it can be done.  but I shall keep seeking