NEDRA- Drag Racing
NEDRA was the first EV sanctioning body to codify its safety requirements and to provide guidelines for on-track safety. It’s Emergency Services Guidelines For Competition Electric Vehicles was created with specific goals: “In order to better protect drivers, crew members, spectators, and emergency service responders at these race venues, a set of recommended Best Practices have been developed. These procedures are applicable for emergency, unplanned events such as a vehicle fire, high voltage battery fire, crash, or other incident involving custom-built competition electric vehicles.”
John Metric, NEDRA President, told us, “Dealing safely with high voltage requires a different skill set than dealing with flammable fuels, for pit crew and track support employees. In both cases, we try to keep it contained, but making torque means letting the ‘fuel’ out in huge rushes and refilling it slowly in the pits and containing it when there is a crash. It is that care where the ‘fuel’ differences come in.”
Unlike Formula E, where the cars and battery packs and configurations are all effectively identical, vehicles involved in electric drag racing can range from stock Tesla sedans to homebuilt specials to 200-mph Top-Fuel style dragsters. Finding a common set of rules to ensure the safety of everyone involved is a challenge.
Metric notes that there are significantly fewer moving parts inside an EV "engine". “There is less chance of mechanical failures sending parts flying. Crankshafts, connecting rods, pistons, valves, superchargers, belts, pulleys, intake manifolds, driveshafts, flywheels, clutches,” he said. “In my dragster motors there is the rotor and two bearings. That's it.”
Battery fires in EVs are a popular social media topic and, given the relatively small number of EVs on the road today that makes it difficult to find definitive numbers, it appears road EVs are slightly less prone to fires than ordinary internal combustion engine (ICE) vehicles. Fighting an EV fire can be more involved than suppressing a gasoline fire. Tesla has a set of guidelines for first responders that recommends flooding an EV fire with at least 3,000+ gallons of water and letting the vehicle burn itself out if the water is not effective. “One thing EVs have going for them is that battery is usually slow to become involved in fire, allowing driver extraction and time for fire crews to get to the vehicle,” noted Metric. “If I could change the industry, I would mandate a fire hose access point in battery designs. Perhaps hidden behind one of the body panels—a direct fire hose hook up,” he said.
Lithium is highly reactive, however in only rare situations does elemental lithium metal exist in a battery—lithium ions themselves are not a fire hazard. The organic solvent used as an electrolyte inside a lithium-ion battery is highly flammable and is in fact what burns (along with plastic cases and separators) when a lithium-ion battery catches fire. Because the battery cell contains a large amount of energy in a small space, damaged lithium-ion cells that have an internal electrical short can generate enough heat to reignite a fire, even a day or more after the initial EV fire was extinguished. For this reason, it is advised that a wrecked EV be stored outside and away from other vehicles, in the unlikely event it should reignite. Overcharging or improperly charging a lithium-ion cell can also cause lithium metal spikes (dendrites) to form on the carbon-graphite anode, which can short out the cell and, depending upon the cell chemistry, cause a fire. Modern chargers and battery management systems (BMS) largely eliminate this possibility.
Because drag racing takes place over a very short time (usually around ten seconds) and distance (either an eighth or a quarter-mile), the type of battery used has not been an issue when it comes to safety. “NEDRA members, while following our sanctioning body rules, have experimented with everything from lead to nickel to lithium-ion and even capacitors,” said Metric. “Our members have had a great track record of not causing nationwide viral videos of EV's on fire. So right now, I would say there is no clear safer battery,” he added.
In 2014, about the same time that Formula E was getting off the ground, a small team in eastern Pennsylvania began working on an electrically powered sports racing car to compete in nationally sanctioned amateur road-racing in the US.
EVSR (a part of Entropy Racing) got off the ground by repowering existing SCCA Spec Racers with an electric motor and controllers and commercially available lithium iron phosphate (also called lithium ferrous-phosphate, or LFP) cells. The company entered and competed in various racing and Hillclimb events (including the legendary Pikes Peak and Mount Washington Hillclimbs), and even participated in a 12-hour endurance racing event.
Racing electric vehicles on a permanent road racetrack presents its own set of different safety challenges when compared to racing Formula E on a temporary street circuit, or quarter-mile EV drag racing. Charles Greenhaus, owner, project manager, and chief engineer of EVSR, told Design News, “Tesla recommends that you use at least 3,000 gallons of water to extinguish one of their cars. This is not practical for most tracks and even if they had the equipment and capacity to do so, the delays and disruption to an event would be insurmountable. The alternate recommendation is to let it burn... Again, not an option in the middle of an event.”
Greenhaus feels that sanctioning bodies and tracks are behind on their readiness for EVs. “I feel strongly that most tracks are not ready for a significant lithium-Ion fire and with that assumption, I think that comprehensive and verifiable emergency response procedures should be presented and in place to deal with the specifics of a particular chemistry before being allowed to be on track,” he told us. Experience has been a good teacher: “Over our 7 years of running EVSR in all types of events we have learned a lot. We have crashed the cars, vented and even ignited packs and run them in all temperatures and conditions,” he said.
Many events run by EVSR are sanctioned by the Sports Car Club of America (SCCA) which does not have a set of rules regarding EVs. “EVSR worked very closely with our local region SCCA as well as the national offices of SCCA in 2013/14 to create a regional rule set for our cars that everyone felt confident with. It involved battery chemistry and containment. It detailed construction and weight changes (as opposed to an ICE car) and most importantly we documented anticipated response and equipment requirements and we created a comprehensive safety guide for first responders as well as a single page ‘cheat sheet’ for course workers so that everyone knew what to expect in an emergency,” said Greenhaus.
Greenhaus credits the lack of EV-related drama that EVSR has experienced to the specific battery chemistry the team uses in its cars. “It would appear that the only thing that burns on a lithium iron phosphate battery cell is the plastic casing and the actual chemistry seems to just vent hot gas and vapor,” he explained. “Our worst incident happened recently and was about 4 minutes from detection on track until suppression in the paddock which required less than 3 gallons of water to cool the batteries sufficiently to eliminate further damage or risk,” Greenhaus told us.