Lithium cell recharging
US5897973A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Mar 5, 1997 |
| Grant date | Apr 27, 1999 |
| Priority date | — |
| Expiry date | Mar 5, 2017 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH02J7/0016
- WIPO fieldElectrical machinery, apparatus, energy
- WIPO sectorElectrical engineering
Abstract
Excessive charging of the weaker cells in a battery of lithium cells, during potentiostatic charging, is prevented by providing each cell (S) with a bypass circuit (12) including a MOSFET (T). An integrated circuit (Y) monitors the cell voltage, and if the design voltage of the cell (S) is exceeded the circuit (Y) provides a signal to the gate of the MOSFET (T) so that part of the charging current (I) bypasses that cell (S), while most of the charging current flows through the cell (S). The bypass current flows only while each of the other cells in the battery are coming up to the design voltage, so that little power is dissipated in the bypass circuit (12). If the cells are balanced, so they accept charge equally, then the bypass circuit never carries current; if the cells are not balanced, they will be brought near to balance over a few charge/discharge cycles.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.