Battery pack design and method
In at least one embodiment, provided is a battery pack for a vehicle including battery pack for a vehicle, the battery pack having a firebox for enclosing batteries, an electronics compartment, thermal insulation surrounding the firebox and the electronics compartment, and heat pipes. The heat pipes may include firebox heat pipes contacting the firebox on an evaporator end and extending to an exterior surface of the battery pack on a condenser end, and electronics compartment heat pipes extending from within the electronics compartment on an evaporators end and extending through the thermal insulation to the exterior surface of the battery pack on a condenser end.
1. A battery pack for a vehicle, the battery pack comprising:
a) a firebox for enclosing batteries;
b) an electronics compartment;
c) thermal insulation surrounding the firebox and the electronics compartment; and
d) heat pipes comprising:
(1) firebox heat pipes adjacent to the firebox on an evaporator end and extending to an exterior surface of the battery pack on a condenser end; and
(2) electronics compartment heat pipes extending from within the electronics compartment on an evaporators end and extending through the thermal insulation to the exterior surface of the battery pack on a condenser end.
2. The battery pack of claim 1 , wherein the firebox heat pipes comprise variable conductance heat pipes.
3. The battery pack of claim 1 , wherein the electronics compartment heat pipes comprise variable conductance heat pipes.
4. The battery pack of claim 1 , wherein the firebox heat pipes comprise variable conductance heat pipes and the electronics compartment heat pipes comprise variable conductance heat pipes, and wherein the firebox heat pipes comprise variable conductance heat pipes comprising a first operating temperature range, and wherein the electronics compartment heat pipes comprise variable conductance heat pipes comprising a second operating temperature range.
5. The battery pack of claim 1 , wherein the thermal insulation comprises at least one of: a) an aerogel; or b) a vacuum panel insulation.
6. The battery pack of claim 5 , wherein the thermal insulation comprises polyimide foam.
7. The battery pack of claim 1 , wherein the thermal insulation comprises an outer layer comprising vacuum sealed NANOPORE.
8. The battery pack of claim 7 , wherein the thermal insulation comprises an inner layer comprising SOLIMIDE.
9. The battery pack of claim 1 further comprising a pyrolytic graphite sheet secured to an exterior surface of the firebox.
10. The battery pack of claim 9 , wherein pyrolytic graphite sheet secured to the exterior surface of the firebox secures the evaporator end of the firebox heat pipes to the firebox.
11. The battery pack of claim 1 further comprising a pyrolytic graphite sheet secured to an inside of the firebox.
12. The battery pack of claim 1 further comprising a pyrolytic graphite sheet secured to an exterior the thermal insulation.
13. The battery pack of claim 12 further comprising a first pyrolytic graphite sheet and a second pyrolytic graphite sheet secured, wherein the first pyrolytic graphite sheet is secured to an exterior of the thermal insulation and wherein the second pyrolytic graphite sheet is secured over the condenser end of the firebox heat pipe to the first pyrolytic graphite sheet.
14. The battery pack of claim 1 further comprising a pyrolytic graphite sheet secured to an exterior the thermal insulation, and wherein the pyrolytic graphite sheet secures the condenser end of the firebox heat pipes to the thermal insulation.
15. The battery pack of claim 1 , wherein the further comprising a pressure relief vent extending through the firebox and the thermal insulation to an exterior of the vehicle.
16. The battery pack of claim 15 , wherein the pressure relief vent further comprises:
a) a vent hole extending through the firebox and the thermal insulation to an exterior of the vehicle;
b) a vent hole plug; and
c) a pressure relief frangible vent cover at least partially covering the vent hole plug to retain it within the vent hole.
17. The battery pack of claim 16 , wherein the pressure relief frangible vent cover is adapted to at least partially cover the vent hole plug until the thermal runaway gases force the vent hole plug from the vent hole.
18. The battery pack of claim 16 , wherein the pressure relief frangible vent cover comprises:
a) a frangible flexure comprising a vent plug cover portion and a weakened region; and
b) a pad portion surrounding the frangible flexure, the pad portion being separated from the vent plug cover portion by a gap between the vent plug cover portion and the pad portion, the pad portion being connected to the frangible flexure by the weakened region.
19. A method for thermal management of a battery pack, the method comprising:
a) containing batteries and battery electronics within a firebox;
b) surrounding the battery pack with vacuum panel or aerogel insulation;
c) interposing polyimide foam between the firebox and the aerogel insulation; and
d) providing heat pipes extending from inside the insulation to outside the insulation,
wherein providing heat pipes comprises providing variable heat pipes comprising a first set of heat pipes having a first operating temperature range adjacent to the electronics and a second set of heat pipes having a second operating temperature range adjacent to the firebox.