NOVELTY - An electrochemical battery (1) comprises self contained thermoelectric cooling devices (3a-3c) for cooling the battery to optimal operating conditions. The device is electrically connected to cells of battery and external electrical power source. A transfer switch (10) selectively powers the device from the external electrical power source, and with shut down of the external electrical power, the transfer switch redirects power from battery to the device to effect continued cooling of battery.    USE - Electrochemical battery for military vehicle (12).    ADVANTAGE - The battery and the thermoelectric cooling device are stand alone, such that the battery power itself can power the heating/cooling device and/or such device can be powered by vehicle or outside power with condition selective powering of the device. If placed on a vehicle with available power, the thermoelectric cooling device will heat or cool the battery to avoid and regulate excessive thermal excursion for improved operational (discharge) performance. When vehicle power is not available, the device switches to direct powering by the battery itself.    DETAILED DESCRIPTION - An electrochemical battery (1) comprises self contained thermoelectric cooling devices (3a-3c), preferably Peltier device, for cooling the battery to optimal operating conditions. The device is contained within housing of the battery and in proximity to cells contained within the housing, where the device is electrically connected to the cells of the battery and an external electrical power source. A transfer switch (10) selectively powers the device from the external electrical power source, and with shut down of the external electrical power, the transfer switch redirects power from the battery to the device to effect continued cooling of the battery. The battery comprises greater than or equal to 2 lithium ion cells.    DESCRIPTION OF DRAWING(S) - The drawing shows a schematic view of cooling device power transfer from vehicle to internal battery power.    Electrochemical battery (1)    Thermoelectric cooling devices (3a-3c)    Transfer switch (10)    Military vehicle (12)