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Summary of the most updated regulations regarding the battery enclosure.

Check off regulations that are met throughout the design and manufacturing process, and attach a link to documentation confirming that we have met the related regs.

Current regulation version: ASC2024 Regs Release B

Update whenever there is a new regulation release.

5.2 Vehicle Design Report (VDR)

Under the Battery Protection Tech Report, we require by [TBD]:

  • Block diagram for BPS and component within battery enclosures for each battery type.
  • How firmware or settings will be rendered static and un-modifiable after inspection (i.e. sealed in battery enclosure).

8.3 Protection Circuitry

All protection circuitry should be contained in the battery enclosures, and should be designed to allow for the provided testing procedures to occur during Scrutineering.

  • Safe State refers to a stable electrical shut down condition where the battery pack and all its sub components are completely isolated from all potential current paths exiting the battery enclosure.

8.4 Battery Enclosures

All registered and sealed battery modules, supplemental batteries, battery protection circuitry per Reg. 8.3, and main fuses per Reg 8.5 must be fully contained in enclosures that are electrically isolated from the solar car. The enclosures must be constructed from non-conductive, electrolyte-resistant material. No more than two separate such enclosures may be used for the main and supplemental batteries.

Isolation

  • The resistance measured between the battery terminals and any portion of the solar car chassis shall be greater than 1 MΩ for applied potentials up to 500 V.

Mounting

  • The battery enclosures must be secured to the solar car chassis so as to prevent them or the modules within from coming loose in the event of an accident or rollover.

Marking

  • The top of each battery enclosure must be marked using letters at least 10mm high with “Caution: Chemical Hazard” and “High Voltage” and any other standard hazard markings specific to the type of battery enclosed.
  • The type (i.e. Li-ion of the battery must be marked on the top of the battery enclosure(s) in 10 mm high letters.

Ventilation

  • Ventilation systems must pull exhaust to the exterior of the solar car and must be directly connected to the exterior of the vehicle away from any airstream that may reach the driver. The ventilation system shall be powered by the battery system.
  • Provisions should be made to power this fan from the Supplemental battery in the event of a Battery Protection Fault.

Security

  • To preclude unauthorized access to the battery/enclosure, a seal will be placed to indicate contravention of this regulation. Provisions shall be made to seal the battery/enclosure by the team. Should access to a “sealed” battery/enclosure be needed, the team needs to inform an Official of their intent to access the battery/enclosure, and request the Official to log the activity and retain the seal. Battery exchanges will not occur during the Event without Inspector support.

8.5 Fusing

Main

  • A DC-rated fuse (not a circuit breaker) must be placed first in series with the battery starting at the positive connection within each battery enclosure.
  • Both leads to the fuse must be mechanically constrained to battery enclosure using a fuse block and cover.
  • The fuse rating must not exceed 200% of the maximum expected current draw or 75% of the rated wire current capacity.
  • It must be rated to break the Fault Current due to a shorted pack and protect the relay or switch. (High Speed or Fast Acting Semiconductor Type Fuse)

Branch

  • All other wiring branching off the main bus circuit must have properly sized fuses. Fuses must be located near the branch point, either within the same enclosure or before a reduction in rated conductor ampacity.

Voltage Taps

  • When in the Safe State, residual current draw on any battery measurement tap shall be less than 10 mA.
  • When in the Safe State, any voltage tap leaving the battery box must be current limited to less than 10 mA.

8.6 Power Switch

Main Power Switch

  • Solar cars must be equipped with a Main Power Switch that is principally located within the main battery enclosure. The power switch must be normally open and non-latching.
  • The solar car driver must have overriding control and the ability to turn the power switch off at all times.
  • The power switch control location must be within easy reach of the driver and clearly labeled with the words “POWER”, “ON” and “OFF”. All letters must be 10 mm tall or larger.
  • In the off position, the power switch must isolate battery, motor and array from each other and put the solar car in the ‘Safe State’. In a safe state, all high voltage conductors exiting the battery pack must be electrically disconnected from the pack.
  • The power switch must be DC rated and capable of interrupting an overcurrent condition.
  • The BPS must have overriding control and the ability to turn the power switch off at all times in the event of a BPS fault.

BPS Fault Dash Indication

  • The driver is to have an illuminated dash indication of a BPS fault to provide warning of an automatic opening of the Main Power Switch.

External Power Cut Off Switch

  • For emergency use, a Main Power Switch control must be present on the exterior of the solar car. It must be possible to actuate the exterior Main Power Switch off with overriding control at all times.

Location:

  • The switch location shall be on the solar car’s exterior near the cockpit on the driver’s side of the car. The switch must be on an upward-facing surface; it may not be placed on surfaces that are angled to such that the surface normal is pointing below the horizon.

Operation:

  • Only “Push” switches are allowed. The actuator must be colored red, and at least 20mm in diameter (non-round pushbuttons must be large enough to fit an inscribed 20mm circle).
  • Actuation of the external switch must also illuminate the BPS Fault indication including BPS Fault Dash Indicator. The switch shall be a latching type switch.

Marking:

  • The external actuator must be clearly marked by the international marking of a red spark within a white-edged blue equilateral triangle with a minimum side length of 150 mm.
  • In addition, clear directions how to operate the actuator must be displayed using letters 10 mm tall or larger.

Covering:

  • The external actuator may be covered with a colorless transparent cover.
  • Without the use of tools or significant force, it must be demonstrated that the actuator may be easily operated thru the cover.
  • The cover must be labeled in such a manner as to how to operate the actuator thru the cover. The blue triangle marking may be located on the cover, but must not obstruct the view of the actuator.

8.7 Cables

Cable Sizing

  • All electrical cables must be properly sized for expected system currents.

8.8 Control

Cruise Control

  • Relevant only if we decide to implement cruise control, which may possibly be used to run the car at a steady “optimal” speed during the race.

  • If the solar car is equipped with cruise control, it can only be activated by the driver. The cruise control must be designed to automatically deactivate when the brake controls are manually actuated by the driver, or when the car is shut off.

8.9 Electrical Shock Hazards

  • All exposed or easily exposed conductors, junction boxes, solar cells, etc., operating at greater than 32 V must be protected from inadvertent human contact and must be marked “High Voltage” in letters at least 10 mm high.
  • Exposed carbon fiber is conductive so care should be taken to ensure electrical components are isolated from it. Any covers allowing access into the enclosures must be firmly secured.

8.10 Impound

Battery enclosures shall be designed such that they can be Impounded per Regs 12.18 and 14.12.B. Enclosures may either be removed from the vehicle and placed in an impound box or impounded in the vehicle.

Impound Box

Teams utilizing the impound box option shall provide an impound box that fully contains the battery enclosure(s) per Reg. 8.4 and meets the following requirements.

  • The box shall have provisions such that an Official can secure it with a maximum of two (2) locks/seals.

  • The impound box must be constructed such that it does not contain external hardware that can be removed to gain access to the battery box without breaking the seal(s).

Impound In Vehicle

Teams utilizing the impound in vehicle option shall provide a robust impound solution that allows the event organizers to lock/seal any high voltage battery power connectors/conductors.

  • The solution shall seal any main battery high voltage power connectors/conductors such that the team cannot charge the battery from external energy sources. This includes the battery box lid(s), and any air inlets/outlets that could allow access to high voltage connections, as well as any power connections to the motor, solar array, etc.
  • The solution shall have provisions such that an Official can secure it with a maximum of four (4) locks/seals. Additional locks/seals may be applied during Scrutineering so long as they do not need to be broken every time the vehicle is impounded.
  • The battery box shall be constructed such that it does not contain external hardware that can be removed to gain access to the battery box without breaking the seal(s).

10.4 Fasteners

  • All fasteners must be of suitable type, strength, and durability for their application. Friction, glued, or press fit assemblies will not be accepted in critical areas as the sole means of retention.
  • For glued or press fit assemblies, a pin is required. The pin diameter shall be ¼ of the tube’s outer diameter. A press fit roll pin is acceptable for this application. Set screws intended to transmit torque or force will not be accepted. Fasteners must meet the following minimum requirements:

Bolts

  • Bolts used in critical areas must at minimum meet SAE grade 5, metric grade M8.8 and/or AN/MS specifications.
  • Bolts must be of the correct length, and extend at least two threads beyond the nut.
  • Bolts in tension must not have shaved or cut heads.
  • All fasteners should be properly torqued.
  • U-bolts are not allowed in critical areas.

Securing of Fasteners

  • All structural and other critical fasteners (bolts, nuts) must have an acceptable form of securing such that the fastener cannot loosen or be removed unintentionally. Acceptable methods of securing are:

  1. Bolts with flex-loc type nuts or other nuts that use flexure as the means of locking and are reusable.

  2. Bolts with pre-drilled shafts and castle nuts with cotter pins installed to prevent loosening

  3. Bolts with pre-drilled heads and/or nuts properly safety wired with stainless steel wire from 0.024” (0.6 mm) to 0.032” (0.8 mm) diameter conforming to Mil Spec MS20995C. The safety wire between fasteners and anchor points must be twisted to prevent loosening rotation of the fastener.

  4. In blind hole applications, bolts with pre-drilled heads properly safety wired.

  5. Other methods of securing fasteners may be deemed acceptable at the discretion of the Inspector.

  • Securing methods that are not acceptable are Nylon lock nuts, "lock" washers, Loctite, or lock nuts that use thread distortion as a means to secure the nut. Lock nuts with thread distortion are not considered to be reusable. Other methods of securing fasteners where the above methods are not appropriate may be considered at the discretion of the Inspector. Non-critical fasteners need not be secured with lock nuts.

Buckles and Straps

Plastic luggage type buckles or single push release straps are not considered acceptable means of securing any Critical Area.

  • If nylon type straps are used in securing any Critical Area, ratchet type straps (without hook terminators) shall be used.

Critical Areas

For application of the above critical areas are defined to include: steering, braking, suspension, seat mounts, safety harness, drive train, battery box, ballast carrier, and parking brake.

12.18 Impound

All battery enclosures shall be secured overnight by the Observer in the impound configuration (Reg 8.10) that was inspected during Scrutineering.

  • Teams should recognize that they will need additional power sources if they have to power or troubleshoot vehicle systems while batteries are impounded.

  • Headquarters should be appraised of special issues for impound.

Impound Times

  • Impound time starts at 8:00 pm each evening and ends at 7:00 am the following morning. Teams that fail to properly impound will be assessed the impound penalty as per Reg. 15.4.M.

    • Ensure that enough time is allocated to finish impounding BEFORE the impound time starts.

  • Run impounding procedures to figure out how much time is needed for impounding.

14.12 (FSGP) Charging/Impound

All battery enclosures shall be secured overnight in impound configuration by the Inspectors. Headquarters should be appraised of special issues for impound.

Charging

All solar cars may begin the Track Event with a fully charged battery pack. Once the Track Event begins, charging may only occur using the solar car’s array in designated charging areas.

  • Charging from other sources will result in a penalty associated with Official FSGP laps completed to that point, reference Reg. 15.4.J.

  • All charging of solar car batteries shall be monitored by a team member. Unattended charging of the solar car batteries is strictly prohibited.

  • A charging area will be provided for the teams. Internal combustion generators will not be permitted within the charging area. Only solar car charging may occur within this designated area.

Impounding

  • All registered and sealed batteries must be secured in the impound configuration (Reg 8.10) that was inspected during Scrutineering and will be secured by the Inspectors.

  • Batteries must be impounded by 8:00 pm each evening and will be released from impound at 7:00 am the following morning.

  • Failure to impound batteries will result in a penalty associated with Official FSGP laps completed to that point, reference Reg. 15.4.M.

15.4 Penalties

  • Disturbing Official Battery Seals: Solar car batteries will be marked with an official seal. Disturbing these seals in a manner that prevents proper identification by Inspectors may be penalized as though all of the battery modules affected had been replaced as in Reg. 15.4.L.

  • Failure to Impound: A 2 mile penalty may be assessed for every minute that the team fails to Impound their batteries.

  • Securing of Fasteners: Failure to comply with Reg. 10.4.B Securing of Fasteners will result in a penalty of 1 mile per bolt per day per instance where proper securing is not applied. The Head Mechanical Inspector shall determine which noncompliant fasteners must be brought into compliance with Reg. 10.4.

  • Ignoring BPS Fault Indicator: A 2 mile penalty will be applied for each occurrence that the team ignores the BPS Fault Indicator and continues to drive along the route.

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