Goals
- Design a matched battery pack that consists of balanced Li-ion cells
- Design a battery pack and enclosure that provides adequate cooling for the Li-ion cells
- Design mechanically isolated modules that can be removed
- Determine how the pack will be mounted to the car to minimize or dampen vibrations
Background and strategic fit
Battery Pack
The Battery Pack in MSXI consisted of Panasonic NCR18650 Li-ion cells that provided 120 V to our electrical systems. From a high-level perspective, the pack is charged by the solar array, which in turn, provides the power necessary for the car to move. These cells must be pre-approved by race officials. This will consist of a pack built from the 18650 (18mm by 65mm) class of Lithium-ion cells (which are similar in size to AA batteries, which are also known as the 14500 class).
In addition, we need to design an enclosure that allows the battery to be removed and impounded at the end of a race day. At a race, the box will be fitted with tamper-seals provided by the race officials, and should not allow access without removing these tamper-proof seals. The enclosure should also provide mounting points that should be shock-resistant.
Moreover, we should take into consideration what procedures we need to have in place, in the event of a battery incident (along with items that we need to keep in stock in our battery incident kits).
Assumptions
Requirements
| # | Title | User Story | Importance | Notes |
|---|---|---|---|---|
| 1 | Matched battery pack | Build a pack with balanced cells | Must Have | |
| 2 | Cooling | Designing a battery layout and enclosure that accounts for cooling requirements | Must Have |
Questions
Below is a list of questions to be addressed as a result of this requirements document:
| Question | Outcome |
|---|---|
| Are we going to run the pack at a higher voltage? Can we even run the pack at a higher voltage? | Yes. The goal will be to reach a maximum 160V. |
| Are we still planning on using 18650 cells? | Yes |
| Are we still going to use the Panasonic NCR 18650? | No. We are using the LG MJ1 per testing. |
| How are we going to mount the pack in a way that provides shock-absorption? | |
| What will the dimensions of the battery-box be? |