Battery temperature management

A method for controlling float voltage to a battery, the method comprising:

• measuring temperature indicative of an ambient temperature in a vicinity of the battery over time;
• estimating a present internal temperature of the battery using values indicative of the ambient temperature for different times and knowledge of at least one thermal characteristic of the battery related to heat transfer from the vicinity of the battery into the battery such that the estimated temperature will vary by approximately exponentially increasing and then asymptotically approaching a steady state value in response to a step increase in the ambient temperature;
• and
• adjusting the float voltage to the battery as a function of the estimated internal battery temperature using a known relationship between float voltage, internal battery temperature, and current.

A system for controlling charge float voltage to a battery, the system comprising:

• a battery;
• a temperature sensor disposed and configured to provide information indicative of an ambient temperature in a vicinity of the battery over time;
• a processor coupled to the temperature sensor and configured to store indications of the ambient temperature based on the information received from the temperature sensor, the indications being separated in time, and to estimate a present internal temperature of the battery based on at least two indications of the ambient temperature and a known relationship between ambient temperature and internal battery temperature, at least one of the at least two indications being previously stored by the processor;
• and
• a charger coupled to the processor and to the battery and configured to provide a float voltage to the battery, a value of the float voltage depending upon the estimated present internal temperature of the battery and a desired current value.