Peltier Project: 50% PWM --> alternate circuit switching for increased performance? Hi all, I have a project where I am making a drink cooler device using four peltier devices which can draw up to 30amps or 24 volts each. we are considering battery power (pretty ridiculous but anyway..) and were considering Lithium polymer batteries. http://www.maxpoly.co.uk/shop/index.php?main_page=product_info&cPath=3&products_id=85 my thinking is that 2 of these could provide 15volts at up to 110 amps (we should be fine with 20-25amps per module) constant current with a capacity of 216000 joules which should last 4-5 cycles. we are planning to use PWM with a control circuit to monitor temperatures and output the correct voltage which would provide the current giving us the best COP to extend the battery life. as the peltier devices are very high power and dissipate a lot of heat we would probably only run them at under 0.5 PWM so the high voltage and current is mainly so that we can select the optimum PWM for whatever temperature the device is at. I was wondering if there was a way to split the circuit in two so that 2 peltiers were separate from the other two and they could be alternately PWM controlled so that while one was off, the other could be on. high frequency 1000Hz + is required as the peltiers do not like low frequency cycling. this would let use more of the battery performance allowing us to have up to 30V through the devices at the same current by putting the batteries in series as only half the current would be needed. any thoughts on all of this please? and the main question:what would I use to switch alternately between 2 circuits at high frequency? im thinking this would be added in series after PWM is applied which would let us control the PWM separately to stop the device overheating. side question: is there a simple way of powering this device off mains power as high current power supplies are expensive!! at the moment we are having to restrict ourselves to low currents Thanks for your time!