Supplemental/Aux Battery - Revision 1 Notes

Replaceable batteries required to power some components of the car. (Need to update this more)

Supplemental Battery Constraints:

The battery shall be able to energize protected LV systems until the main battery is energized

The battery shall be able to power protected and emergency systems in the case of a fault condition

The battery shall be mounted to the LV cutoff board and be easily swappable

The battery shall be able to power the average load until the end of the race day (8 hrs)

The battery cannot overheat

Voltage:

Nominally 12V, however voltage levels should not be altogether too significant as voltage is further downregulated to logic levels on each individual board.

Energy Capacity:

Required Capacity: 4.9 Ah

Current Demand:

Battery Choices

Batteries investigated over multiple areas are found in the attached file.

Final Battery Choice

The final battery chosen is the Maha Powerex Precharged 10000mAh D cell battery in a string of 10 cells, as it has already been purchased. It has a capacity of 120Wh, and can deliver an approximate maximum constant discharge rate of 10A (verified via call to Maha)

Thermal Constraints

As the D cell battery has an internal resistance of 18mOhm at full discharge, the maximum heat generation will be 2.0072448W for 5 minutes, assuming the horn is running.

Using a temperature rise calculator, it was determined that if a 10cmx10cmx10cm cube-shaped enclosure with 1cm thick PET walls, with a heat generation of 4W and the ambient temperature is 30 degrees, the temperature would rise by only 2.67 degrees

Open

(module design coming later)

Amendment to Battery Constraints – 2023-07-19:

Energy Capacity:

Required Capacity: 4.9 Ah

• Must be easily swappable