Hello, I have built a small insulated thermoelectric cooler that I am currently bench-testing. The hot side of the peltier assembly is cooled by a heatsink and fan. I am well acquainted with the limitations of peltiers vs compressor fridges - the application for this unit requires it to be very lightweight and simple.
The cooler is intended to be connected to a deep-cycle lithium battery and to run "flat out" during the daytime while the battery can be charged from a solar or other source. It will get as cold as possible, then, at night, run for as long as possible until the lithium deep-cycle battery cuts off - I think that's around 10 volts with the battery I am testing (I am experimenting with various different plate types and voltages to balance temperature drop achieved, power consumption etc). The unit would then rely on its internal "coldth" and insulation to keep the contents reasonably cool until power is restored. It is accepted that the internal temperature will rise over time.
I have noticed that when I disconnect the cooler, the 'cold side' rises in temperature more quickly than I had expected. I attribute this partly to residual heat from the thermoelectric effect 'soaking' back through from the hot side to the cold, once the Peltier effect ceases and the heatsink is no longer being cooled by the fan.
But I can also see that the heatsink and the peltier assembly, when passive, provide a route for ambient heat to be absorbed and transferred to the interior of the cooler.
My question is: as the battery gets low, rather than allowing the unit to switch off completely, should I switch the Peltier plate to the lowest possible voltage, to maintain a net flow of heat from the cold side to the hot, for as long as possible?
It is accepted the unit will still heat up, but the intention would be to prevent inflow/"push back" against ambient heat coming in via the heatsink, peltier plate and spacer/extender block assembly. A bit like maintaining positive pressure in a room to exclude outside air.
Many thanks for any advice.
The cooler is intended to be connected to a deep-cycle lithium battery and to run "flat out" during the daytime while the battery can be charged from a solar or other source. It will get as cold as possible, then, at night, run for as long as possible until the lithium deep-cycle battery cuts off - I think that's around 10 volts with the battery I am testing (I am experimenting with various different plate types and voltages to balance temperature drop achieved, power consumption etc). The unit would then rely on its internal "coldth" and insulation to keep the contents reasonably cool until power is restored. It is accepted that the internal temperature will rise over time.
I have noticed that when I disconnect the cooler, the 'cold side' rises in temperature more quickly than I had expected. I attribute this partly to residual heat from the thermoelectric effect 'soaking' back through from the hot side to the cold, once the Peltier effect ceases and the heatsink is no longer being cooled by the fan.
But I can also see that the heatsink and the peltier assembly, when passive, provide a route for ambient heat to be absorbed and transferred to the interior of the cooler.
My question is: as the battery gets low, rather than allowing the unit to switch off completely, should I switch the Peltier plate to the lowest possible voltage, to maintain a net flow of heat from the cold side to the hot, for as long as possible?
It is accepted the unit will still heat up, but the intention would be to prevent inflow/"push back" against ambient heat coming in via the heatsink, peltier plate and spacer/extender block assembly. A bit like maintaining positive pressure in a room to exclude outside air.
Many thanks for any advice.