Ha! I shall. One of my many karting dreams is to race electrics like they did in that rotax series with the championship at the end.
I was reflecting on this recently at suoercharged which is a new very fancy indoor facility. The torque off the corner is really special. The problem is when it’s limited like the concession facilities. It’s a very linear accel curve that suddenly peaks. Imagine a 45degree line representing accel and it suddenly flattens out. It’s massively frustrating.
Looking at your video, who did you partner with regarding chassis? What’s the tubing diameter? These look a bit less stout than most (the concession rental ones).
Thank you for sharing the latest BSR video from the Philippines.
BSR adapts the power curves for each track according to its specific characteristics and, of course, the track operator’s plans. BSR’s recommendation is always to create curves that give the feeling that the kart’s top speed never ends. This can be easily achieved by adjusting the power curves at the end. Of course, for lower power levels, customers want a highly limited top speed that can sometimes be reached and felt. This is because the customer desires such conditions for safety reasons.
BSR’s rental kart chassis is built on a 32x2mm chromoly steel base, which is very similar to the material used in racing karts, specifically KZ2 category. The chassis physics are also designed to be very similar, making BSR rental karts lightweight and dynamic, providing a high-quality karting experience while being durable enough to withstand significant impacts.
While I fully support the electric kart movement, unfortunately the club who manages the sprint racing nearest me does not, citing fear of electrocution of workers as the main reason. Same response from SCCA rallycross body, although they do now allow fully electric production cars. I assume your battery cases have two internal contactors that eliminate this possibility, but I’m interested in what materials you use to help educate and win over this irrational fear.
Also, help me to understand what you are saying below. I think I’m missing something since my math doesn’t add up. An output of 27 kW for 20 minutes (1/3 hour) at WOT, assuming an impossible 100% electrical to mechanical conversion efficiency, would require 9 kWh of battery capacity, yet the battery is listed with a usable 5.3 kWh capacity. Are you rather assuming a track with an actual WOT rate of about 58% (ignoring inefficiencies of about 10%), so in actual practice around 53%?
I was referring to electrical shock happening due to an accident, not thermal runaway during charging or any other time. That shouldn’t be possible (without a RUD event of the battery case) as both contactors should open (both positive and negative terminals) anytime the link between the battery and the controller/inverter/motor is broken during use.
Yes, electrical shock, not the fire risk. Basically the fear of something you can’t see.
Formula-1, Formula-E, and FSAE avoid this by using a green/red light to show the status of the Insulation Monitoring Device (IMD) that detects a loss of galvanic isolation (battery not connected in any way to the frame). If red - don’t touch the car and ground at the same time. With a kart, more than likely the steel frame will already be grounded in an accident, but it’s still a possible issue.
A significant difference from other BSR systems is the Low Voltage, which is 48VDC and 96VDC (under 120VDC). Rallycross cars have 400V and 800V systems, with some even pushing up to 1000V, which is lethal for humans. You can safely touch the BSR battery pack with bare hands, even with the terminals exposed. That’s why safety concerns in karting are incomparable to those in electric cars.
Regarding energy consumption, according to BSR data, during a full open throttle on the track, about 20-30% of the lap time (45-50 seconds) is spent at that throttle position, while approximately 10-15% is spent on braking when the throttle is at or near 0. The rest of the time is a combination of throttle positions ranging from 1-99%. This means that a 27kW power unit, with the best driver in a race, will consume no more than 3kWh of energy in a 10-minute session. In a larger track, it may reach around 4kWh in a 15-minute session. Therefore, it is not objectively feasible to calculate energy consumption on a 1:1 basis with 27kW power and energy capacity. The more powerful the kart, the less time spent at full open throttle and more time spent on braking or using power in the mid-range.
It’s different for internal combustion engines because they consume fuel even when idling or braking, but that is not the case for electricity, so the consumption calculations are slightly different.
It is crucial to distinguish high-voltage systems, which are typically used in race cars with 400-1000V systems, as they can be lethal to humans if something goes wrong. Therefore, there are extensive safety measures in place to prevent such incidents, along with powerful multi-level monitoring functions that also monitor for severe accidents. If a high-voltage battery catches fire, the risk is practically eliminated, and the concern becomes the risk of burning rather than a high-current electric shock risk.
In the case of BSR karting, BSR operates under the LOW VOLTAGE regulation, which means that up to 60VDC is considered “Child Safe,” and most people won’t even feel a slight electric sensation when working with exposed terminals barehanded. There is also regulation up to 120V, which is still considered LOW VOLTAGE but requires additional caution as it can pose relatively minor risks, yet it falls under the Low Voltage Directive (LVD). Therefore, even after a severe accident where the battery is damaged, the risk of electric shock in karting is eliminated.
Some manufacturers in karting use 350V systems, which are considered high-voltage systems. As a result, these manufacturers do not allow anyone to repair or use their karts without special training or instructions. However, this does not apply to BSR.
Not to contradict you on this point, but I have personal experience with 48 VDC telecom systems and have seen a technician weld a wrench to a shorted battery terminal. It is not the volts that make it dangerous, it is the amperage behind it. We wore both thermally and electrically insulated gloves while working with live current. I think what Bryan is asking is do you have a safety measure in place that would cut line voltage in the event of a short? It could be something as simple as a fusable link or a circuit breaker.
I have seen some pretty nasty crashes in karting. One of which took off the entire side pod when it struck a barrier at speed. Your batteries are mounted on the side pod. In the event there is a crash and somehow the leads become shorted to the chassis or any other expose metal surface, do you have a way of cutting power from the battery pack?
I don’t mean to sound pessimistic. Karts are exposed and not surrounded by a roll cage like automobiles are. You can build a certain amount of protection around the cells, but not the kart. Statistically speaking, there are probably more accidents on the motorways than at racetracks on any given day. That does not mean they do not happen. Racing is an inherently dangerous sport. We accept that or we wouldn’t do it. It is also why we require so much safety gear compared to the average commuter.
Just to reiterate, I like what your company is doing and fully support the development of Electric Karting. I just want to know that the average person with no specialized training can deal with whatever situation comes along.
Thanks for explaining what you were saying, those load levels now make much more sense.
It is interesting that there is an European standard calling anything less than 120v low voltage, and less than 60v child safe. I certainly wouldn’t as any compromise to the skin such as a cut or wet skin greatly lowers the resistance and can cause shock or muscle lock. So in the name of racing safety (and hopefully someday convincing our origination members) I would really like to see an interlock system added with dual contactors in each battery case to disable the electric charge on both paths when any “HV” / control cable comes unattached. Small up-front costs for liability avoidance, even for your 48/96v systems.
Anyhow, I do greatly appreciate what you’ve done thus far to get this beyond the hobbyist builder/racer, with an overall solid design. Even if I may have to drive 3 hours each way to run one in anger.
Low voltage refers to electrical systems or devices that operate at relatively lower voltages, typically below 50 volts. Here’s why low voltage is considered safer:
Resistance: The human body has a certain amount of electrical resistance. At low voltages, the body’s resistance is typically enough to limit the flow of electric current through it. This means that when exposed to low voltage, the amount of current passing through the body is relatively small, reducing the risk of electric shock.
Tissue Penetration: Low voltage has less electrical energy, which limits its ability to penetrate the body’s tissues deeply. The electrical current tends to flow along the surface of the skin, resulting in milder effects and lower risk of severe tissue damage.
Reduced Electric Arcs: Low voltage systems produce smaller electrical arcs or sparks compared to high voltage systems.
Of course, any form of electricity is potentially dangerous, just like fuel, and under specific circumstances, accidents can occur. We are all aware that any lapse in attention can have consequences. However, there are major categories that eliminate 95% of risks without even reaching a specific threshold. In such cases, 95% of situations do not escalate beyond the level of a possibility, and we focus on addressing the remaining 5% of potential scenarios. This is where BSR steps in to enhance safety measures and, most importantly, to educate the public about recognizing and handling risks or even preventing them from arising in the first place.
Yes, the higher the air temperature, the more challenging it is to provide cooling solely with air. That’s why it’s crucial to prepare the kart thoroughly before each race and ensure proper cooling. If needed, additional cooling methods can be employed that are below the air temperature (within a reasonable range). During the race, the motor, batteries, and other components generate the most heat, and within 15 minutes, the highest heat transfer occurs from the inside to the outside.
It is relatively easy to manage the air temperature up to 85 degrees Fahrenheit. However, it is certainly possible to operate efficiently up to 105 degrees Fahrenheit, which just requires a bit more attention during the preparation process before the race.
The key recommendation is to prepare the kart thoroughly before your next race. In BSR championships, air ventilators are typically used, and if needed, the ventilators are supplemented with CO2 or, in a simpler version, the ventilator is covered with a moist cloth. This is a natural way to cool the air temperature, similar to how it is done in desert regions to cool the air in houses by blowing it through a moist environment. These are simple and cost-effective tricks that athletes often utilize in extremely hot races.
Thank you, Gary, for your support and enthusiasm. It’s great to hear that you’re also building your own kart and showcasing its capabilities on the track and setting records. Anyone who demonstrates their skills and educates the public helps people better understand technology. Together, we can achieve more.