Automatic vegetation watering apparatus and method

A method for automatically extracting liquid water from air with an automatic plant watering device, comprising:

• sensing a moisture level of soil,
• energizing a thermoelectric module to reduce a cold face of the thermoelectric module below 32 degrees F.,
• thermally conducting the cold face to a condensation member to reduce a temperature of a wall of the condensation member to below 32 degrees F.,
• maintaining the temperature of the wall of the condensation member below 32 degrees F. for more than an hour in order to collect a layer of frost on the wall of the condensation member,
• terminating the energization of the thermoelectric module to permit the temperature of the wall of the condensation member to rise above 32 degrees F., so that the layer of frost on the wall will become melt water,
• collecting the melt water and retaining the melt water until a temperature of the melt water rises a desired amount above 32 degrees F.,
• dispensing the collected melt water onto the soil.

An automatic plant watering device comprising:

• two thermoelectric modules each having a hot face and a cold face,
• a power supply connected to energize the thermoelectric modules in parallel providing sufficient power to produce a heat flow in the thermoelectric modules to reduce a temperature of the cold faces below 32° F.,
• two first heat sinks, each thermally connected to one of the two hot faces,
• two air moving devices, each arranged to provide a flow of air over at least a portion of one of the first heat sinks,
• two second heat sinks, each thermally connected to one of the two cold faces,
• two containers, each filled with a liquid and having thermally conducting walls thermally connected to one of the two second heat sinks, and each with at least one of said walls exposed to ambient air, the containers being configured to allow a temperature of the at least one exposed wall to reduce below 32 degrees F. when the thermoelectric modules are energized, and the liquid having a freezing temperature sufficiently below 32 degrees F. so as to maintain a liquid state while said thermoelectric modules are energized,
• a water collection chamber positioned below the exposed walls of the containers and configured to hold collected melt water from said exposed walls of the containers,
• a temperature sensor positioned to sense a temperature of melt water collected in the water collection chamber,
• a valve positioned in an outlet of said water collection chamber and controlled by said control to selectively open and close said outlet,
• a moisture sensor probe, and
• a controller configured to control the energization of the thermoelectric modules upon receipt of an appropriate signal from the moisture sensor probe for a period of time in excess of an hour to cause a temperature of the thermally conducting walls of the liquid containers to be maintained below 32 degrees F. during such period of time, so as to cause a build-up of frost on said exposed walls and thereafter to deenergize the thermoelectric modules to permit the temperature of said exposed walls to rise towards ambient temperature,
• the controller including at least one indicator light configured to provide an indication of a state of the automatic plant watering device.