Battery Pods | Cornell University Autonomous Underwater Vehicle Team

The battery pods provide Nova's electrical power. Each pod contains a Thunder Power TP4450-6SHP lithium polymer battery pack and a custom printed circuit board to handle monitoring and battery safety.

The pod has two underwater connectors, one for charging, the other for discharging. While in use on the vehicle, only the discharge connector is plugged in. The charge connector allows for the batteries to be charged without opening the pod. A pressure relief valve prevents any excess buildup of pressure during charging.

Battery Pod Datasheet

Electrical Specifications

Pod Voltage	22.2 V Nominal
Pod Capacity	4450 mAh
Max Current (continuous)	98 A
Max Current (Burst)	178 A

Mechanical Specifications

Weight (in air)	4.43 lb
Weight (in water)	.58 lb
Depth Rating	200 ft
Dimensitions	3.75"W x 4.75"H x 11.55"L
Materials	Acrylic and 6061 Aluminum

Nova’s battery pods are designed to be cradled by two "J" shaped supports into which they are pinned. These supports are bolted directly to the frame. This makes accessing the pods very easy for the operator of the vehicle.

Battery pod section view

The section view above illustrates the pressure vessel design. The front cap has a slot in it so that it can be epoxied directly onto the hull. The back of the hull is epoxied directly onto a collar with a bevel designed to accommodate a double bore o-ring seal which should seal more reliably than the prior face seal design.

Battery pod hull assembly

Triton’s battery pods are designed to come apart into two main assemblies. Shown above is the hull assembly, which consists of a front cap, plastic hull, and rear sealing collar. It can be seen that no electronics or external connections are integrated into this assembly. Additionally, there is nothing mounted to the front cap so that the battery pods can be stood on end for temporary storage.

Battery pod equipped rack assembly

This is the second main assembly which consists of the rear end cap with connectors, pressure relief valve, and o-rings as well as the battery pod rack with battery and pod board. By positioning the pod board on top of the rack, a significant amount of the pod must fill with water before the pod board will be damaged. The battery will be zip-tied in place. All of the electronics and external connections are in this assembly, which shortens the assembly/disassembly time and reduces the complexity during repair.

Battery pod bare rack assembly

As seen above, the design of the battery pod rack is very simple. It consists of two flat beams and two thicker plates, called the beams and bulkheads respectively. There are a total of 7 clearance holes and 8 tapped holes. The diagram also illustrates how the battery pod rack is cantilevered from the rear end cap, utilizing three screws and a shelf built in to the rear end cap.

Battery pod rear end cap

The rear end cap is a fairly complicated piece. It includes two bore o-ring glands for sealing, a flange for mounting the pod to the vehicle frame, and a three point shelf for supporting the battery pod rack. The rest of the front of the end cap is machined out to allow for installation of the Seacon connectors and Deep Sea pressure relief valve.