Energy management for hybrid fire fighting vehicle

1. A fire fighting vehicle comprising:

a chassis;

a front axle coupled to the chassis;

a rear axle coupled to the chassis;

a powertrain coupled to the chassis, the powertrain including:

an engine;

a battery pack; and

an electromechanical transmission electrically coupled to the battery pack and selectively mechanically coupled to the engine, the electromechanical transmission configured to (i) generate energy based on a mechanical engine output provided by the engine, (ii) selectively provide the energy generated to the battery pack for storage as stored energy, and (iii) selectively provide a mechanical transmission output to at least one of the front axle or the rear axle using at least one of (a) the stored energy in the battery pack or (b) the energy generated based on the mechanical engine output;

a fluid tank coupled to the chassis and configured to store a fluid;

a pump configured to provide the fluid from the fluid tank to a fluid outlet; and

a power divider positioned between the engine, the pump, and the electromechanical transmission, the power divider including a first interface coupled to the engine, a second interface coupled to the pump, and a third interface coupled to the electromechanical transmission; and

a controller configured to:

monitor a state-of-charge of the battery pack; and

operate the engine, the power divider, and the electromechanical transmission such that the state-of-charge is maintained above a minimum state-of-charge threshold that is sufficient to facilitate (i) accelerating the fire fighting vehicle to a driving speed of at least 50 miles-per-hour in an acceleration time and (ii) maintaining or exceeding the driving speed for a period of time, wherein an aggregate of the acceleration time and the period of time is at least three minutes.

2. The fire fighting vehicle of claim 1 , wherein the controller is configured to prevent charging the battery pack above a maximum state-of-charge threshold that is less than 100% state-of-charge to prevent accelerated degradation of a state-of-health of the battery pack.

3. The fire fighting vehicle of claim 2 , wherein the controller configured to adaptively reduce the maximum state-of-charge threshold as the state-of-health of the battery pack degrades.

4. The fire fighting vehicle of claim 1 , wherein the controller is configured to:

monitor a depth-of-discharge of the battery pack during a discharge event; and

prevent the depth-of-discharge from exceeding a depth-of-discharge threshold to prevent accelerated degradation of a state-of-health of the battery pack.

5. The fire fighting vehicle of claim 4 , wherein the controller configured to adaptively adjust the depth-of-discharge threshold such that the state-of-charge can be further depleted during discharge events as the battery pack degrades.

6. The fire fighting vehicle of claim 1 , wherein the controller is configured to:

monitor a temperature of the battery pack; and

prevent the temperature from exceeding a temperature threshold to prevent accelerated degradation of a state-of-health of the battery pack.

7. The fire fighting vehicle of claim 1 , wherein the electromechanical transmission is configured to accelerate the fire fighting vehicle from 0 to 50 miles-per-hour in the acceleration time of 30 seconds or less while the fluid tank is at a maximum fluid capacity, wherein the maximum fluid capacity is at least 1,000 gallons, and wherein the engine has a power output of less than 750 horsepower.

8. The fire fighting vehicle of claim 7 , wherein the maximum fluid capacity is at least 2,500 gallons.

9. The fire fighting vehicle of claim 8 , wherein the maximum fluid capacity is at least 3,000 gallons.

10. The fire fighting vehicle of claim 9 , wherein at least one of (i) the rear axle is a tandem rear axle or (ii) the front axle is a tandem front axle.

11. The fire fighting vehicle of claim 9 , wherein the fluid tank is a water tank, further comprising an agent tank coupled to the chassis, the agent tank having a maximum agent capacity of at least 150 gallons.

12. The fire fighting vehicle of claim 7 , wherein the power output of the engine is less than 650 horsepower.

13. The fire fighting vehicle of claim 12 , wherein the power output of the engine is less than 600 horsepower.

14. The fire fighting vehicle of claim 7 , wherein the electromechanical transmission is configured to accelerate the fire fighting vehicle from 0 to 50 miles-per-hour in the acceleration time of 28 seconds or less while the fluid tank is at the maximum fluid capacity.

15. The fire fighting vehicle of claim 14 , wherein the electromechanical transmission is configured to accelerate the fire fighting vehicle from 0 to 50 miles-per-hour in the acceleration time of 25 seconds or less while the fluid tank is at the maximum fluid capacity.

16. A fire fighting vehicle comprising:

a chassis;

a front axle coupled to the chassis;

a rear axle coupled to the chassis;

a powertrain coupled to the chassis, the powertrain including:

an engine;

a battery pack; and

an electromechanical transmission electrically coupled to the battery pack and selectively mechanically coupled to the engine, the electromechanical transmission configured to drive at least one of the front axle or the rear axle;

a controller configured to:

monitor a state-of-charge of the battery pack; and

operate the engine and the electromechanical transmission such that the state-of-charge is maintained above a minimum state-of-charge threshold that is sufficient to facilitate (i) accelerating the fire fighting vehicle to a driving speed of at least 50 miles-per-hour in an acceleration time and (ii) maintaining or exceeding the driving speed for a period of time, wherein an aggregate of the acceleration time and the period of time is at least three minutes.

17. The fire fighting vehicle of claim 16 , wherein the acceleration time is 30 seconds or less, and wherein the engine has a power output of less than 750 horsepower.

18. The fire fighting vehicle of claim 17 , wherein the acceleration time is 28 seconds or less, and wherein the power output of the engine is less than 650 horsepower.

19. The fire fighting vehicle of claim 18 , wherein the acceleration time is 25 seconds or less, and wherein the power output of the engine is less than 600 horsepower.

20. A fire fighting vehicle comprising:

a chassis;

a front axle coupled to the chassis;

a rear axle coupled to the chassis;

a powertrain coupled to the chassis, the powertrain including:

an engine;

a battery pack; and

an electromechanical transmission electrically coupled to the battery pack and selectively mechanically coupled to the engine, the electromechanical transmission configured to drive at least one of the front axle or the rear axle;

a controller configured to:

monitor a state-of-charge of the battery pack;

monitor a temperature of the battery pack;

monitor a depth-of-discharge of the battery pack during discharge events;

prevent (i) charging the battery pack above a maximum state-of-charge threshold that is less than 100% state-of-charge, (ii) prevent the depth-of-discharge from exceeding a depth-of-discharge threshold, and (iii) prevent the temperature from exceeding a temperature threshold to prevent accelerated degradation of a state-of-health of the battery pack;

adaptively reduce the maximum state-of-charge threshold as the state-of-health of the battery pack degrades; and

adaptively adjust the depth-of-discharge threshold such that the state-of-charge can be further depleted during subsequent discharge events as the battery pack degrades.