Battery charger

A battery charger characterized by comprising;

• a storage device storing a map, in which an allowable current value, with which a battery can be charged while a temperature rise of the battery is being suppressed, is mapped based on a battery temperature value and a battery temperature rise value, the allowable current value set at a low value if the battery temperature value is high and set at a low value if the temperature rise value is high;
• temperature detecting means for detecting a present battery temperature;
• temperature rise value outputting means for obtaining the temperature rise value from the temperature detected by said temperature detecting means;
• allowable current value retrieving means for retrieving the map of said storage device based on the temperature detected by said temperature detecting means and the temperature rise value outputted from said temperature rise value outputting means, and for obtaining said allowable current value;
• charging means for charging the battery with the allowable current value retrieved by said allowable current value retrieving means;
• first count value outputting means for determining whether the temperature detected by said temperature detecting means and the temperature rise value outputted from said temperature rise value outputting means belong to a region which tends to occur in a final charging period in the map of said storage device, for outputting a low count value if the temperature detected by said temperature detecting means and the temperature rise value outputted from said temperature rise value outputting means belong to the region which tends to occur at a beginning of the final charging period and for outputting a high count value if they belong to a region which tends to occur at an end of the final charging period;
• second count value outputting means for detecting a battery voltage and outputting a count value if it is determined that a battery state is in the final charging period based on a battery voltage decrease value;
• charge completion determining means for determining completion of battery charge if a sum of the count values outputted from said first count value outputting means and said second count value outputting means exceeds a preset value;
• and
• charge completing means for completing the battery charge based on determination of completion of battery charge by said charge completion determining means.

A battery charger comprising:

• a storage device storing a map, in which an allowable current value, with which a battery can be charged while a temperature rise of the battery is being suppressed, is mapped based on a battery temperature value and a battery temperature rise value, in accordance with at least a final charging period and a period before the final charging period;
• temperature detecting means for detecting a present battery temperature;
• temperature rise value outputting means for obtaining the temperature rise value from the temperature detected by said temperature detecting means;
• charge state detecting means for detecting a battery voltage and for determining whether a battery state is in the final charging period based on change of the battery voltage;
• allowable current value retrieving means for retrieving the map corresponding to the battery state determined by said charge state determining means, based on the temperature detected by said temperature detecting means and the temperature rise value outputted from said temperature rise value outputting means, and for obtaining said allowable current value;
• and
• charging means for charging the battery with the allowable current value retrieved by said allowable current value retrieving means.