Patent ID: 8004242

Claim:
In a vehicle comprising a crank battery, a rechargeable auxiliary battery, and an onboard electrical power source separate from said crank battery and said auxiliary battery, a battery charge controller for managing a supply of electrical energy to said auxiliary battery to charge said auxiliary battery, said battery charge controller comprising: means for monitoring a voltage level of said crank battery; means for monitoring a voltage level of said onboard electrical power source; means for electrically coupling said crank battery and said auxiliary battery to charge said auxiliary battery when the voltage level of said crank battery exceeds a first voltage threshold, and for electrically decoupling said crank battery and said auxiliary battery when the voltage level of said crank battery is below said first voltage threshold; and means for electrically coupling said onboard power source and said auxiliary battery to charge said auxiliary battery when: (i) the voltage level of said crank battery is below said first voltage threshold and (ii) the voltage level of said onboard power source exceeds a second voltage threshold, and for electrically decoupling said onboard power source and said auxiliary battery when the voltage level of said onboard power source is below said second voltage threshold.