What is claimed is:1. A power storage cartridge for placement in a stack with other cartridges arranged along a stack axis comprising:a rack-mountable housing including:an active module having battery cells and cell monitoring electronics disposed within an airtight compartment having two ducts;a passive environmental management module that is sealed to said active module around said ducts to form a sealed rack-mountable housing;an overpressure relief port adapted to vent heat and smoke from a faulty battery cell out of the sealed rack-mountable housing; andcooling fans for circulating air between said active module and said passive environmental management module through said two ducts.2. The power storage cartridge of claim 1, wherein said passive environmental management module includes a heat sink having a plurality of cooling fins arranged parallel to a fin axis.3. The power storage cartridge of claim 2, wherein said cooling fans comprise:an inflow cooling fan that draws air from said passive environmental management module through one of the ducts into said active module; andan outflow cooling fan that draws air from said active module through the other one of the ducts into said passive environmental management module.4. The power storage cartridge of claim 3, wherein said cooling fans circulate air through said cooling fins along the fin axis in a direction from said outflow cooling fan to said inflow cooling fan that is orthogonal to the stack axis.5. The power storage cartridge of claim 4, wherein said cooling fans circulate air between said active module and said passive environmental management module in a loop encompassing a circulating plane that includes the fin axis and is orthogonal to the stack axis.6. The power storage cartridge of claim 2, wherein said passive environmental management module includes a second exterior housing wall with an inner surface having said plurality of cooling fins mounted thereto and an outer surface adapted to contact a cold plate, wherein said second exterior housing wall is adapted to thermally couple said plurality of cooling fins to the cold plate.7. The power storage cartridge of claim 1, further comprising a silicone gasket which forms the seal between the active module and the passive environmental module.8. A power storage cartridge for placement in a stack with other cartridges arranged along a stack axis comprising:a rack-mountable housing including:an active module having battery cells and cell support systems disposed within an airtight compartment having two ducts;a passive environmental management module that is sealed to said active module around said ducts and includes (i) a heat sink having a plurality of cooling fins arranged parallel to a fin axis and (ii) an overpressure relief port that vents heat and smoke from a faulty battery cell out of the housing in a vent direction that is orthogonal to the stack axis and is orthogonal to the fin axis; andan inflow cooling fan that draws air from said passive environmental management module through one of the ducts into said active module and an outflow cooling fan that draws air from said active module through the other one of the ducts into said passive environmental management module, wherein said cooling fans circulate air through said cooling fins along the fin axis in a direction from said outflow cooling fan to said inflow cooling fan that is orthogonal to the stack axis and wherein said cooling fans circulate air between said active module and said passive environmental management module in a loop encompassing a circulating plane that includes the fin axis and is orthogonal to the stack axis.9. The power storage cartridge of claim 8, wherein said active module includes insulation made from intumescent material surrounding said battery cells to absorb heat from a faulty battery cell.10. The power storage cartridge of claim 8, further including an upper and a lower end cap arranged on said battery cells along the stack axis to prevent an explosive thermal event from damaging an adjacent cartridge.11. The power storage cartridge of claim 8, wherein said housing is oriented so that said overpressure relief port is at the top of said passive environmental management module.12. The power storage cartridge of claim 8, wherein said active module includes Lithium ion battery cells grouped into cell packs to collectively produce about 10 kW of output power within 1 to 60 seconds.13. The power storage cartridge of claim 8, wherein said cell support systems comprise a battery cell charger and cell monitoring electronics, and wherein said cell support systems combine about 8 kW of battery cell power and 2 kW of charger power to produce about 10 kW of output power within 1 to 60 seconds.14. The power storage cartridge of claim 11, wherein said active module includes a first exterior housing wall and electrical connectors sealingly mounted in said first housing wall.15. The power storage cartridge of claim 11, wherein said electrical connectors provide operative coupling for charging power input, engagement power output, CANbus diagnostics and Ethernet communications.16. The power storage cartridge of claim 13, wherein said Lithium ion battery cells are grouped into a first pair of cell packs and a second pair of cell packs; and wherein said cell support system include a first charger and a second charger; and wherein the first pair of cell packs are disposed between the first exterior housing wall and the first charger; and wherein the second charger is disposed between the first exterior housing wall and the second pair of cell packs.17. The power storage cartridge of claim 16, further including a baffle disposed in said active module between said first pair of cell packs and said second pair of cell packs dividing an interior space of said active module into two portions, wherein the baffle is spaced from said first exterior housing wall to direct air to circulate from said inflow cooling fan towards said first exterior housing wall.18. The power storage cartridge of claim 12, wherein one pair of cell packs is spaced and oriented so that an axis of the inflow cooling fan extends between the one pair of cell packs; and wherein the other pair of cell packs is spaced and oriented so that an axis of the outflow cooling fan extends between the other pair of cell packs.19. A power storage cartridge for placement in a stack with other cartridges arranged along a stack axis comprising:a rack-mountable housing including:an active module having battery cells and cell support systems disposed within an airtight compartment having two ducts;a passive environmental management module that is sealed to said active module around said ducts and includes a heat sink having a plurality of cooling fins arranged parallel to a fin axis, wherein said passive environmental management module includes a second exterior housing wall with an inner surface having said plurality of cooling fins mounted thereto and an outer surface adapted to contact a cold plate, wherein said second exterior housing wall is adapted to thermally couple said plurality of cooling fins to the cold plate, wherein said passive environmental management module includes an overpressure relief port disposed in said second exterior housing wall that is adapted to vent heat and smoke from a faulty battery cell out of the housing into an exhaust manifold behind the cold plate; andcooling fans for circulating air between said active module and said passive environmental management module through said two ducts.20. A power storage cartridge for placement in a stack with other cartridges arranged along a stack axis comprising:a rack-mountable housing including:an active module having battery cells and cell support systems disposed within an airtight compartment having two ducts;a passive environmental management module that is sealed to said active module around said ducts and includes a heat sink having a plurality of cooling fins arranged parallel to a fin axis, wherein said passive environmental management module includes a second exterior housing wall with an inner surface having said plurality of cooling fins mounted thereto and an outer surface adapted to contact a cold plate, wherein said second exterior housing wall is adapted to thermally couple said plurality of cooling fins to the cold plate, wherein said passive environmental management module includes a removable desiccant pack; andcooling fans for circulating air between said active module and said passive environmental management module through said two ducts.21. The power storage cartridge of claim 20, wherein said heat sink is disposed between said overpressure relief port and said desiccant pack along the fin axis.22. A power storage cartridge for placement in a stack with other cartridges arranged along a stack axis comprising:a rack-mountable housing including:an active module having battery cells and cell support systems disposed within an airtight compartment having two ducts;a passive environmental management module that is sealed to said active module around said ducts and includes a heat sink having a plurality of cooling fins arranged parallel to a fin axis, wherein said passive environmental management module includes a second exterior housing wall with an inner surface having said plurality of cooling fins mounted thereto and an outer surface adapted to contact a cold plate, wherein said second exterior housing wall, wherein said second exterior housing wall is made from a highly conductive, corrosion-resistant metal and is adapted to thermally couple said plurality of cooling fins to the cold plate; andcooling fans for circulating air between said active module and said passive environmental management module through said two ducts.23. A power storage cartridge for placement in a stack with other cartridges arranged along a stack axis comprising:a rack-mountable housing including:an active module having battery cells and cell monitoring electronics disposed within an airtight compartment having two ducts;a passive environmental management module that is sealed to said active module around said ducts to form a sealed rack-mountable housing; andcooling fans for circulating air within the sealed rack-mountable housing between said active module and said passive environmental management module through said two ducts.24. The power storage cartridge of claim 23, further including an overpressure relief port to vent the sealed rack-mountable housing.25. The power storage cartridge of claim 24, wherein the sealed rack-mountable housing is adapted to contain gas leakage from the battery cells thereby protecting personnel.26. The power storage cartridge of claim 25, wherein the passive environmental management module includes an outer wall adapted to contact a cold plate.