Battery chargers and charging methods
AssigneeMakita Corporation
InventorKazuyuki Sakakibara
Life of this patent
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Abstract
A battery charger and a charging method capable of charging a battery are described. The current temperature of the battery is detected (in step S12) and a battery temperature increase rate is calculated based upon the detected temperature (in step S14). An allowable current value is then retrieved based upon the detected temperature and the calculated battery temperature increase rate, which allowable current value permits charging of the battery while preventing excessive battery temperature increases (in step S16), and the battery is charged using the allowable current value (in step S20). Thus, it is possible to charge the battery within a short period of time while preventing the battery temperature from excessively rising.
Claims22
A method for charging a battery, comprising:
- (a) detecting a battery temperature repeatedly at an interval,
- (b) detecting a battery temperature increase rate repeatedly at the interval,
- (c) selecting a charging current from a map containing a plurality of allowable charging current values, wherein the selection is made based upon the detected battery temperature and the detected battery temperature increase rate, and
- (d) supplying the selected charging current to the battery until a next interval,
- wherein a smaller but not zero charging current value is prescribed for a higher battery temperature, a smaller but not zero charging current value is prescribed for a higher battery temperature increase rate, and a larger charging current value is prescribed for a lower battery temperature and a lower battery temperature increase rate within the map.
A battery charger comprising:
- a memory storing a map containing a plurality of allowable charging current values, wherein battery temperature and battery temperature increase rate are the only indices for the map, and wherein a smaller but not zero charging current value is prescribed for a higher battery temperature, a smaller but not zero charging current value is prescribed for a higher battery temperature increase rate, and a larger charging current value is prescribed for a lower battery temperature and a lower battery temperature increase rate within the map;
- a processor arranged and constructed to execute instructions for:
- (a) determining the battery temperature based upon signals generated by a battery temperature sensor,
- (b) determining the battery temperature increase rate based upon the battery temperature,
- (c) selecting the allowable charging current from the map based upon the battery temperature and the battery temperature increase rate, and
- a source of charging current coupled to the processor and the battery, and arranged and constructed to supply the charging current to the battery based upon the allowable charging current value selected from the map.
A method for charging a battery comprising:
- monitoring battery temperature and battery temperature increase rate of the battery, and
- adjusting charging current supplied to the battery based only on the battery temperature and the battery temperature increase rate, wherein the charging current is selected from the group consisting of:
- (i) a relatively high current, if the battery temperature and battery temperature increase rate are relatively low,
- (ii) an intermediate current, if the battery temperature is relatively low and the battery temperature increase rate is relatively high, or if the battery temperature is relatively high and the battery temperature increase rate is relatively low, and
- (iii) a relatively low but not zero current, if the battery temperature and battery temperature increase rate are relatively high.
An apparatus comprising:
- means for monitoring battery temperature and battery temperature increase rate of a rechargeable battery, and
- means for adjusting charging current supplied to the battery based only on the battery temperature and the battery temperature increase rate, wherein the charging current is selected from the group consisting of:
- (i) a relatively high current, if the battery temperature and battery temperature increase rate are relatively low,
- (ii) an intermediate current, if the battery temperature is relatively low and the battery temperature increase rate is relatively high, or if the battery temperature is relatively high and the battery temperature increase rate is relatively low, and
- (iii) a relatively low but not zero current, if the battery temperature and battery temperature increase rate are relatively high.
Dependencies are inferred from the claim text.