Portable or hand held vehicle battery jump starting apparatus with battery cell equalization circuit
A portable or handheld device or apparatus for jump starting a vehicle engine having a depleted or discharged starting battery. The portable or handheld device or apparatus for jump starting a vehicle engine includes a rechargeable lithium-ion (Li-ion) battery pack and a battery cell equalization circuit configured to prevent overcharging of one or more individual lithium-ion battery cells, which can cause fire, damage to the battery pack and device or apparatus for jump starting a vehicle, or personal injury to a user.
1. A portable or hand held jump starting apparatus, comprising: a battery comprising a plurality of individual battery cells connected in series; a USB port for receiving a first voltage from a USB power source; a voltage converter configured to convert the first voltage to a second voltage for charging the battery, the second voltage being higher than the first voltage; a battery charge controller that controls a battery charging process for the battery using the second voltage, the battery charge controller being configured to prevent overcharging of the battery; a battery cell equalization circuit connected to the battery, the battery cell equalization circuit comprising: a plurality of individual battery cell equalization circuits, each provided for one of the plurality of individual battery cells; and a plurality of load resistors, each provided for one of the plurality of individual battery cells, wherein each of the plurality of individual battery cell equalization circuits is configured to discharge a particular battery cell by its particular load resistor upon the particular battery cell reaching a cell voltage exceeding a pre-determined upper voltage threshold until the particular battery cell reaches a pre-determined lower voltage level below the upper voltage threshold, and wherein the plurality of individual battery cell equalization circuits are configured to charge lower voltage individual battery cells at a higher rate allowing lower voltage individual battery cells to catch up in voltage to an individual battery cell having a highest voltage.
2. The apparatus according to claim 1 , wherein the battery cell equalization circuit is configured to be enabled or disabled using a single control signal.
3. The apparatus according to claim 2 , wherein disabling the battery cell equalization circuit during active battery cell discharge stops the discharge of the battery cells.
4. The apparatus according to claim 2 , wherein the battery cell equalization circuit comprises MOSFET switches and voltage divider resistors, and wherein enabling the battery cell equalization circuit involves turning on the MOSFET switches electrically connecting the voltage divider resistors that scale down individual cell voltage of the battery cells and feed them to non-inverting inputs of respective comparators, allowing them to sense the individual cell voltages.
5. The apparatus according to claim 4 , wherein disabling the battery cell equalization circuit turns off the MOSFET switches disconnecting the resistors and preventing cell voltages reaching the comparators' non-inverting signals and presenting zero voltage to the comparator's non-inverting inputs, causing their output voltages to be zero, which prevents the load resistors from being connected across the cells.
6. The apparatus according to claim 1 , wherein the battery is a Li-ion battery.
7. The apparatus according to claim 6 , wherein the battery is a Li-ion battery pack comprising a plurality of Li-ion battery cells.
8. The apparatus according to claim 1 , further comprising an output port having positive and negative polarity outputs; a vehicle battery isolation sensor connected in circuit with the positive and negative polarity outputs, configured to detect presence of a vehicle battery connected between the positive and negative polarity outputs; a reverse polarity sensor connected in circuit with the positive and negative polarity outputs, configured to detect polarity of a vehicle battery connected between the positive and negative polarity outputs and to provide an output signal indicating whether positive and negative terminals of the vehicle battery are properly connected with the positive and negative polarity outputs of the output port; a power switch connected between the battery and the output port; and a microcontroller configured to receive input signals from the vehicle isolation sensor and the reverse polarity sensor, and to provide an output signal to the power switch, such that the power switch is turned on to cause the battery to be connected to the output port in response to signals from the sensors indicating the presence of a vehicle battery at the output port and proper polarity connection of positive and negative terminals of the vehicle battery with the positive and negative polarity outputs, and is not turned on when signals from the sensors indicate either the absence of a vehicle battery at the output port or improper polarity connection of positive and negative terminals of the vehicle battery with the positive and negative polarity outputs, wherein the battery equalization circuit is a separate isolated circuit relative to the circuit with the positive and negative polarity outputs, and wherein the microcontroller is connected to and controls the battery equalization circuit.
9. The apparatus according to claim 8 , wherein the power switch comprises a plurality of FETs connected in parallel.
10. The apparatus of claim 8 , wherein the vehicle isolation sensor and reverse polarity sensor comprise optically coupled isolator phototransistors.
11. The apparatus of claim 8 , further comprising a plurality of power diodes coupled between the output port and the battery to prevent back-charging of the battery from an electrical system connected to the output port.
12. The apparatus of claim 8 , further comprising a temperature sensor configured to detect temperature of the battery and to provide a temperature signal to the microcontroller.
13. The apparatus of claim 8 , further comprising a voltage measurement circuit configured to measure output voltage of the battery and to provide a voltage measurement signal to the microcontroller.
14. The apparatus of claim 8 , further comprising a voltage regulator configured to convert output voltage of the battery to a voltage level appropriate to provide operating power to internal components of the apparatus.
15. A jump starting apparatus, comprising: a battery comprising a plurality of individual battery cells connected in series; a USB port for receiving a first voltage from a USB power source; a voltage converter configured to convert the first voltage to a second voltage for charging the battery, the second voltage being higher than the first voltage; a battery charge controller that controls a battery charging process for the battery using the second voltage, the battery charge controller being configured to prevent overcharging of the battery; a battery cell equalization circuit connected to the battery in parallel with the battery charge controller, wherein the battery cell equalization circuit includes an individual battery cell equalization circuit for each of the plurality of individual battery cells, and wherein each of the individual battery cell equalization circuits is configured to discharge a particular battery cell upon the particular battery cell reaching a cell voltage exceeding a pre-determined upper voltage threshold until the particular battery cell reaches a pre-determined lower voltage level below the upper voltage threshold, wherein the individual battery cell equalization circuits are configured to charge lower voltage individual battery cells at a higher rate allowing lower voltage individual battery cells to catch up in voltage to an individual battery cell having a highest voltage.
16. The apparatus according to claim 15 , wherein the battery cell equalization circuit is configured to be enabled or disabled using a single control signal.
17. The apparatus according to claim 16 , wherein disabling the battery cell equalization circuit during active battery cell discharge stops the discharge of the battery cells.
18. The apparatus according to claim 16 , wherein the battery cell equalization circuit comprises MOSFET switches and voltage divider resistors, and wherein enabling the battery cell equalization circuit involves turning on the MOSFET switches electrically connecting the voltage divider resistors that scale down individual cell voltage of the battery cells and feed them to non-inverting inputs of respective comparators, allowing them to sense the individual cell voltages.
19. The apparatus according to claim 18 , wherein disabling the battery cell equalization circuit turns off the MOSFET switches disconnecting the resistors and preventing cell voltages reaching the comparators' non-inverting signals and presenting zero voltage to the comparator's non-inverting inputs, causing their output voltages to be zero, which prevents the load resistors from being connected across the cells.
20. The apparatus according to claim 15 , wherein the battery is a Li-ion battery.
21. The apparatus according to claim 20 , wherein the battery is a Li-ion battery pack comprising a plurality of Li-ion battery cells.
22. The apparatus according to claim 15 , further comprising: a vehicle battery isolation sensor configured to detect presence of a vehicle battery connected to the jump starting apparatus; a reverse polarity sensor, separate from the vehicle battery isolation sensor, configured to detect a proper polarity connection between the jump starter apparatus and the vehicle battery; and a power switch configured to electrically connect the power supply to the vehicle battery, wherein the power switch is controlled based on signals from the vehicle battery isolation sensor and the reverse polarity sensor such that the power supply is connected to the vehicle battery when both (i) the vehicle battery isolation sensor currently indicates that the vehicle battery is connected to the jump starter apparatus, and (ii) the reverse polarity sensor currently indicates that the jump starter and the vehicle battery are connected with the proper polarity connection.
23. The apparatus according to claim 22 , wherein the power switch comprises a plurality of FETs connected in parallel.
24. The apparatus of claim 22 , wherein the vehicle isolation sensor and reverse polarity sensor comprise optically coupled isolator phototransistors.
25. The apparatus of claim 15 , further comprising a plurality of power diodes coupled between an output port and the battery to prevent back-charging of the battery from an electrical system connected to the output port.
26. The apparatus of claim 15 , further comprising a voltage regulator configured to convert output voltage of the battery to a voltage level appropriate to provide operating power to internal components of the jump starting apparatus.