Patent ID: 7339347

Claim:
An apparatus for reliably supplying electrical energy on an as-needed basis to an electrical system connected between a system positive terminal and a system negative terminal, the electrical system including battery charging functionality, the apparatus comprising: a main battery having a main positive output and a main negative output, the main negative output being electrically connected to the system negative terminal; at least one standby battery having at least one standby positive output and at least one standby negative output, the at least one standby negative output being electrically connected to the system negative terminal; a one-way charging circuit electrically connected between the main positive output and the at least one standby positive output, the one-way charging circuit configured to facilitate charging of and prevent current flow from the at least one standby battery at all times during which the main battery is supplying electrical energy to the electrical system; and a switching device operable in at least two positions to at least selectively electrically connect the system positive terminal to one of the main positive output and the at least one standby positive output, the switching device being operable in a first position to electrically connect the main positive output to the system positive terminal and electrically disconnect the system positive terminal from the at least one standby positive output, the switching device being further operable in a second position independent of the first position to electrically connect to at least one standby positive output to the system positive terminal and electrically disconnect the system positive terminal from the main positive output, wherein, when the switching device is in the first position, the main battery supplies electrical energy to the electrical system on an as-needed basis and both the main battery and the at least one standby battery receive charging current from the electrical system at times during which the electrical system is operational and the main battery is not supplying electrical energy to the electrical system, wherein, when the switching device is in the second position, the at least one standby battery supplies electrical energy to the electrical system on an as-needed basis and only the at least one standby battery receives charging current from the electrical system at times during which the electrical system is operational and the at least one standby battery is not supplying electrical energy to the electrical system, and wherein the main battery and the at least one standby battery never supply electrical energy to the electrical system simultaneously.