US Patent 8473114 Method of monitoring vehicle batteries

A method for monitoring a vehicle battery includes running a timer while the vehicle and a controller are in off states. The method wakes the control module after a first time increment measured by the timer, and sets a second time increment. If needed, the method samples a first state of charge of the battery, and determines whether the battery requires charging prior to the second time increment based upon the sampled first state of charge. Determining whether the battery requires charging may include comparing the first state of charge to a threshold state of charge, or comparing to a second state of charge measured after the second time increment. A diagnostic message may be sent from the vehicle via a communications path, and, if the battery requires charging, an alert message sent to a receiving point accessible to vehicle operator.