I have a current loop between 2 locations. Transmitter has power supply and transmits two current levels to the receiver - 10 and 20mA (10mA indicates idle and 20mA indicates signal). The receiver has no power supply. I want to put a battery (thinking 12 x 1.2 NiMH rechargables) on the receiver side. I want to use the idle 10mA to charge this battery. How can I do this? I'm thinking putting a big cap to consume the 10mA and when there's enough charge built up, release it to the battery. Then repeat this loop. I guess I also need to somehow maintain a sufficient charging voltage > 12V. Is this a good approach? How would I implement this? Thank you so much!