Battery booster

1. A battery booster for jumpstarting a vehicle having an external battery, the battery booster comprising:

a set of electrical conductors configured to couple with the external battery or with an engine that is electrically coupled with the external battery via a set of battery clamps,

wherein the set of electrical conductors comprises a positive electrical conductor and a negative electrical conductor;

a power supply configured to supply a starting current to jump start the vehicle via the set of electrical conductors,

wherein the power supply comprises a plurality of lithium battery cells arranged to form a lithium battery having a positive terminal and a negative terminal;

a boost switch positioned in-line between the power supply and the set of battery clamps on one of the set of electrical conductors; and

at least one processor configured to output a control signal to close the boost switch as a function of one or more parameters of the power supply, the external battery, or the vehicle.

2. The battery booster of claim 1 , further comprising a relay control circuit configured to control the boost switch,

wherein the boost switch is a mechanical relay having a switch controlled by a solenoid, the solenoid having a first lead and a second lead, and

wherein the relay control circuit comprises a transistor configured to actuate the solenoid via the positive terminal and the negative terminal.

3. The battery booster of claim 2 , wherein the solenoid is connected to the positive terminal via the first lead, and the transistor comprises an emitter connected to the negative terminal, a base configure to receive the control signal, and a collector coupled to the solenoid via the second lead.

4. The battery booster of claim 3 , wherein, in response to the control signal, the transistor electrically connects the negative terminal with the second lead, thereby actuating the solenoid and closing the switch.

5. The battery booster of claim 4 , further comprising a reverse polarity protection circuit configured to disable the transistor when the set of battery clamps are connected to the vehicle in a reverse polarity configuration.

6. The battery booster of claim 5 , wherein the reverse polarity protection circuit comprises a second transistor configured to connect the base of the transistor to the negative terminal.

7. The battery booster of claim 6 , further comprising an over-voltage protection circuit configured to disable the transistor when a voltage of the power supply exceeds a preset voltage level.

8. The battery booster of claim 7 , wherein the over-voltage protection circuit comprises a zener diode and a third transistor configured to connect the base of the transistor to the negative terminal.

9. The battery booster of claim 1 , wherein the power supply comprises an internal heater to heat the power supply or a portion thereof.

10. The battery booster of claim 9 , wherein the internal heater is a positive temperature coefficient (PTC) heater.

11. The battery booster of claim 10 , wherein the PTC heater is positioned between two of said plurality of lithium battery cells.

12. The battery booster of claim 3 , wherein the PTC heater is powered by the lithium battery.

13. The battery booster of claim 1 , wherein the lithium battery is a removable battery.

14. The battery booster of claim 13 , wherein the removable battery is a power tool battery and the battery booster is configured to authenticate the power tool battery.

15. The battery booster of claim 1 , wherein the power supply further comprises a supercapacitor bank that is coupled in parallel with the lithium battery.

16. The battery booster of claim 15 , wherein the battery booster is configured to charge the supercapacitor bank to a charge voltage that is greater than a rated voltage of the supercapacitor bank.

17. The battery booster of claim 16 , wherein the battery booster is configured maintain the supercapacitor bank at the charge voltage for a predetermined amount of time before discharging the supercapacitor bank until a measure voltage of the supercapacitor bank is less than or equal to the rated voltage.

18. The battery booster of claim 17 , wherein the supercapacitor bank is configured to discharge into the lithium battery.

19. The battery booster of claim 1 , further comprising a DC output configure to supply power to a portable electronic device, wherein the least one processor is configured to disable the DC output when a current draw at the DC output is greater than a first predetermined current.

20. The battery booster of claim 19 , wherein the least one processor is further configured to disable the DC output when the current draw at the DC output is not greater than a second predetermined current after a predetermined amount of time.