Rain Test

Excerpt - FSAE EV 2024 Student Handbook

All EV cars must pass the rain test.

The car must pass accumulator scrutineering, mechanical scrutineering, EV Active scrutineering and Tilt Table Test before the Rain Test can be conducted.

During the rain test, the tractive system must be active, and the drive wheels must be a minimum of 10cm off the ground or removed from the vehicle. It is not allowed to have a driver seated in the car during the rain test.

Cars will be exposed to 2 minutes of water spray then monitored for 2 minutes before test is complete. Once passed, teams/car will receive approved tech sticker.

Teams should be prepared with the necessary equipment to safely keep the driven wheels off the ground.

Vehicles that fail the rain test will be subject to the Red Car Procedure.

Diagram - Tech Inspection Station Flow

Tech Sticker - Rain Test

IN.11 RAIN TEST (EV ONLY)

IN.11.1 Rain Test Requirements

Tractive System must be Active
The vehicle must not be in Ready to Drive mode (EV.7)
Any driven wheels must not touch the ground
A driver must not be seated in the vehicle

Rules Reference - EV.9.1 (Referenced in Explanation)

EV.9.1 Activation Sequence

The vehicle systems must energize in the following sequence:

a. Low Voltage (GLV) System EV.9.2

b. Tractive System Active EV.9.3

c. Ready to Drive EV.9.4

During the rain test, the driver must not be in the vehicle to avoid the risk of electrocution in case of an isolation fault to the chassis. The Activation Sequence (EV.9.1) dictates the safest way to start one's vehicle.

Low Voltage (GLV) System: First ensures that the logic and safety system of one's car is engaged first.
Tractive System Active: High voltage is present outside the accumulator container, requiring the AIRs to be engaged. The AIRs engage only if the shutdown circuit and GLV logic systems check in as OK.
Ready to Drive: The motor(s) will respond to the input of the accelerator pedal.

Why do we want the Tractive System Active without the vehicle being in Ready to Drive?

We want to allow power outside the accumulator to evaluate the insulation integrity of the HV system, which is why we must engage the Tractive System Active. However, also engaging the Ready to Drive state opens the possibility of motor engagement without a driver to brake or control the vehicle, which could be dangerous, since the driver is not allowed inside the vehicle during the Rain Test.

In order to maintain control of the vehicle's motion without a driver at all times, all wheels powered by a motor must be either elevated a minimum of ten centimeters (10 cm) off the ground, or removed from the vehicle entirely during the Rain Test. Though it is presented as an option, removing the wheels is rarely a chosen route because it requires teams to jack up the car and potentially waste a lot of time. Teams should be prepared with the necessary equipment to safely keep the driven wheels off the ground.

Although not explicitly stated in the rules, teams with two-wheel drive have the option to elevate all four wheels off the ground if preferred. This maybe important if a team is worried about the angle of entry of the overhead sprinkler on their electrical system.

IN.11.2 Rain Test Conduct

The water spray will be rain like, not a direct high pressure water jet

a. Spray water at the vehicle from any possible direction for 120 seconds

b. Stop the water spray

c. Observe the vehicle for 120 seconds

The Vehicle must be energized and EV active with the TSAL blinking red. The Car will be sprayed for 2 mins. Then the car will be allowed to “soak” for 2 mins to allow water to pool. Immediately after this the judge will insert the IMD test probes in the IMD banana jacks (polarity is not important). The IMD test box will internally short the the two IMD bananas jacks. The Car’s TSAL must turn from a blink red to a solid green with in 30 seconds of the test boxes initiation of the short.

Cars will be exposed to 2 minutes of water spray then monitored for 2 minutes before test is complete.

Note on IN.11.2.a

Note: IN.11.2.a mentions that water maybe sprayed at the vehicle from any possible direction however the facet is at a fixed position directly above the vehicle.

Car will be positioned under sprinklers roughly were a bulk of the team's accumulator and major electronics are located. Some team's rear wing shielded them from this.

IN.11.3 Rain Test Completion

The test is passed if the Insulation Monitoring Device (EV.7.6) does not react during the entire 240 seconds duration