Process and apparatus for charging a multi-cell battery

• US 5,438,250 A
• Filed: 09/20/1993
• Issued: 08/01/1995
• Est. Priority Date: 09/22/1992
• Status: Expired due to Fees

• Current Assignee: Mentzer Electronic GmbH
• Original Assignee: Mentzer Electronic GmbH
• Inventors: Retzlaff, Werner
• Primary Examiner(s): KINCAID, KRISTINE LYNN
• Application Number:
  US08/124,244
• Time in Patent Office: 680 Days
• Field of Search: 320/15, 320/16, 320/17, 320/18, 320/31, 320/32, 320/43, 320/44
• US Class Current: 320/128
• CPC Class Codes: H02J 7/0019 using switched or multiplexed charge circuits
• CPC Class Codes: H02J 7/00302 Overcharge protection

Abstract

A process for charging a multi-cell battery by the use of a battery recharging device and a device controlled by a microcontroller and containing a potential-free battery recharging device to analyze and optimize the charged state of a multi-cell battery, with a device for the switchable connection of selectable terminal voltages of battery sections or cells by means of a voltage measuring device. The microcontroller generates a charge current control signal for the battery recharging device which is calculated from the control algorithm of the microcontroller such that the voltage of the cell with the respectively highest terminal voltage is brought to and maintained at the level of a desired voltage value. Preferably the voltage threshold value is associated with the respective point in time of a characteristic charge curve recommended as being optimal for the type of cell used. Preferably, cells having a low charge state compared to their charge capacity, as determined by the voltage measuring device and microcontroller, are recharged individually and sequentially with a potential free recharging device during or after a main charging of the composite battery with the battery charger.

Claims

1. A process for charging a multi-cell battery having a plurality of series connected battery cells, by the use of a battery recharger and a device controlled by a microcontroller and containing a potential-free battery recharger to analyze and optimize the charged state of the battery, the device having switching arrangements for connecting one or more of the battery cells one each to one of a plurality of two-wire line pairs, said two-wire pairs are connected to a diagnostic circuit, wherein multipole relays with a number of switching contacts corresponding to the number of said two-wire line pairs are provided as switching arrangements, each relay being connected to one of the two-wire line pairs, wherein the switching contacts of the relays are connected on one side with a junction of the battery cells and on another side with one of the two-wire line pairs that in the series connection of the battery cells, adjacent junctions are alternately connected with different lines of one of the two-wire line pairs wherein each of the two-wire line pairs can be connected to an RC filter having at least one resistor and one capacitor, the capacitor of which can be switched via a bipolar switching member to an input of a voltage measuring device, after junctions of one of the battery cells to be measured, which are connected with the RC filter via two of the relays, have been disconnected from the RC filter,

the process comprising the microcontroller generating a charge current control signal for the battery recharger which is calculated by the microcontroller in such a way that the voltage of one of the cells with the highest terminal voltage is brought to an maintained at the level of an optimal voltage value.

2. A process in accordance with claim 1, wherein one or more of the battery cells with a low terminal voltage are recharged individually and sequentially and in accordance with their charge capacity determined by the voltage measuring device with the potential-free battery recharger, said battery recharger can be switchably connected with one of the two-wire line pairs by a selection network.

3. In a process for charging a battery comprising a plurality of series connected battery cells by means of a battery recharger and a device for analyzing the charged state of the battery, which device is controlled by a microcontroller, the device having switching arrangements for connecting at least one battery cell of the series of battery cells to at least one of a plurality of two-wire line pairs which is connected to a diagnostic circuit, in which a plurality of the two-wire line pairs corresponding to a fraction of a total number of the battery cells in the battery is provided,

wherein multipole relays having a number of switching contacts corresponding to a number of the two-wire line pairs are provided as switching arrangements, each being connected to a line of the two-wire line pairs, wherein switching contacts of the multipole relays are connected on one side with a junction of the battery cells and on the other with the two-wire line pairs,

wherein the battery cells having adjacent junctions are alternately connected with different lines of one of the two-wire line pairs and wherein each of the two-wire line pairs is connected to an RC filter having at least one resistor and one capacitor, the capacitor of which can be switched via a bipolar switching member to an input of a voltage measuring device, after junctions, associated with one of the battery cells to be measured and connected with the RC filter via two of the multipole relays, have been disconnected from the RC filter, the process comprises generating a charge current control signal for the battery recharger by the microcontroller which is calculated by the microcontroller in such a way that the voltage of one of the cells with the highest terminal voltage is brought to and maintained at the level of a predetermined optimal voltage value.

4. A process in accordance with claim 3, wherein one or more of the battery cells with a low terminal voltage are recharged individually and sequentially and in accordance with their charge capacity determined by the voltage measuring device during or after charging of the battery with the potential-free battery recharger, which potential-free battery recharger can be switchably connected with one of the two-wire line pairs by a selection network.

5. A process for continuously analyzing the charge state of a battery having a plurality of series connected battery cells and selectively recharging the battery cells which comprises:

a.) providing a battery having a plurality of series connected cells;

b.) providing a plurality of two-wire line pairs;

c.) providing an analysis circuit comprising a first selection network comprising a plurality of switching relays, each of said relays being connected to one of said battery cells and to one of said two wire line pairs;

each of said two-wire line pairs being connected to a monitoring network, an output of said monitoring network being connected with an analog input of a microcontroller, and the output indicates the highest voltage on said two-wire line pairs;

each of said two-wire line pairs being further connected with a second selection network capable of switching the two-wire line pairs to a battery recharging device;

an output of said second selection network being further connected to a filter assembly having at least one RC filter;

said at least one RC filter being connected to a third selection network which is in turn connected to an input of a voltage measuring device;

an output of said voltage measuring device is applied to an input of the microcontroller;

said microcontroller generates a charge current control signal for the battery recharging device;

a current detection device connected to a negative pole of the battery and a ground input terminal of a current measuring device;

said current measuring device having two inverted operational amplifiers, a negative supply of each of said amplifiers is connected to ground or a negative terminal of the battery, and inputs of each of said amplifiers are connected to the current detection device, outputs of each of said amplifiers being connected to an additional input of the microcontroller;

d.) analyzing the charge state of said battery cells with the analysis circuit;

e.) generating the charge current control signal for the battery recharging device by the microcontroller which is calculated from a control algorithm of the microcontroller in such a way that the voltage of one of the cells with the highest terminal voltage is brought to and maintained at the level of a predetermined optimal voltage value.

6. A process in accordance with claim 5, wherein the cells with a lower terminal voltage than said predetermined optimal voltage value are recharged in accordance with their charge capacity as determined by the voltage measuring device.

7. A system for charging a multicell battery which comprises

a.) a battery with a plurality of series connected cells;

b.) a plurality of two-wire line pairs;

c.) a first selection network comprising a plurality of switching relays, each of said relays being connected to one of said battery cells and to one of said two wire line pairs;

d.) each of said two-wire line pairs being connected to a monitoring network, an output of the monitoring network is connected with an analog input of a microcontroller, wherein the output indicates the highest voltage on said two-wire line pairs;

e.) each of said two-wire line pairs being further connected with a second selection network capable of switching the two-wire line pairs to a battery recharging device;

an output of said second selection network being further connected to a filter assembly having at least one RC filter;

f.) said at least one RC filter being connected to a third selection network which is in turn connected to an input of a voltage measuring device;

an output of the voltage measuring device is applied to a second analog input of the microcontroller, wherein the microcontroller generates a charge current control signal for the battery recharging device;

g.) a current detection device connected to a negative pole of the battery and a ground input terminal of a current measuring device;

said current measuring device having two inverted operational amplifiers, a negative supply of each of said amplifiers is connected to ground or a negative terminal of the battery, and inputs of each of said amplifiers are connected to the current detection device, outputs of each of said amplifiers being connected to a third analog input of the microcontroller.

8. The system of claim 7 wherein the monitoring network comprises a voltage divider and a diode network with a common cathode.

9. The system of claim 7 wherein the second selection network is capable of switching an energy supply from the battery recharging device to one or more of the battery cells by means of one of the two-wire line pairs.

10. The system of claim 7 wherein the second selection network comprises two quadripole relays.

11. The system of claim 7 wherein the battery comprises from 2 to about 40 cells.

12. The system of claim 7 wherein the third selection network comprises a relay with two alternating contacts.

13. The system of claim 7 wherein the voltage measuring device comprises two voltage limiting resistors, four limiting diodes, two balance resistors, a filter capacitor, an operational amplifier, a feed-back resistor and a ground resistor.