Cordless dual-battery electric tool
US5028858A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Dec 1, 1989 |
| Grant date | Jul 2, 1991 |
| Priority date | — |
| Expiry date | Dec 1, 2009 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY10S320/21
- WIPO fieldElectrical machinery, apparatus, energy
- WIPO sectorElectrical engineering
Abstract
A cordless electrical tool has a housing forming a pair of battery mounts, an electrical motor in the housing, respective batteries removably carried in the mounts, and circuitry connecting the batteries in series with each other and across the motor. A cutoff switch is connected in series between the batteries and the motor and can open to electrically disconnect the motor from the batteries. Respective control circuits detect the charge levels of the batteries and open the cutoff switch when the respective charge level drops below a predetermined threshold. Respective light-emitting diodes are provided to indicate which of the batteries is below its permissible charge.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.