MemberSeptember 29, 2021 at 3:09 pm
I don’t think any vehicle, three or four-wheeled, has been crash tested. Specifically, I’m interested in how the Aptera performs in the off-set crash test given it its in-wheel drive train.
First, I think the driver and passenger will probably fare quite well.
My concern is more toward how the Aptera would perform in a crash where the wheel pod might be ripped from the chassis which seems more likely with this design.
In the real world this might happen if the Aptera were to hit a telephone pole or some other object – even another car – where the wheel pod is severed from the car.
We know that EVs in general have a master battery switch that emergency service providers are instructed to pull to totally isolate the battery in the event of a crash. But how effective would that power interrupt be if there are loose or sheared power cables to one of the front motors.
I am unaware of any ‘industry standard’ that disables a high voltage car battery automatically in an accident. While this is anecdotal, I’ve reviewed photos of wrecked EVs on copart.com which is where many wrecked EVs are auctioned by insurance companies and many, some with serious damage, appear to have active batteries.
Of course, none of those vehicles feature in-wheel motors. Further, even with enclosed wheels, it becomes obvious that if you look at enough wrecks, wheels are at risk of being not only crushed, but sheared off in a some accidents.
And one would, just from the design of Aptera, have to concede that this vehicle is at greater risk of this kind of accident.
The point is, are the cables to the wheels designed to shear-off in an accident in such a manner that emergency service providers can be certain they won’t be at risk of electrocution?
BTW, the solution could be as simple as putting a lightweight cable strung from the wheel or even a suspension member directly to the battery to pull the disconnect in the event the front suspension is displaced.
MemberSeptember 29, 2021 at 3:17 pm
Some of this may be addressed by the Lordstown Endurance during their testing.
ModeratorSeptember 29, 2021 at 3:33 pm
I hear you but in the end… an autocycle is registered as a motorcycle and does not have to meet a car crash test. But YES Aptera plans to crash test????
MemberSeptember 29, 2021 at 4:20 pm
I understand that Aptera is exempt from crash tests but NO ONE wants a reputation as a death trap for first responders.
Do know that the composite monocoque design of the Aptera cabin and its implications for strength and safety is one of the reasons I’m all in with this project.
Besides, somewhere in the scheme of things, I think safety is close to a first principle.
MemberSeptember 29, 2021 at 5:49 pm
There is zero chance that they haven’t thought of this and figured out a solution. Electrocuting someone after a crash would put them out of business, not just from the lawsuit but from the publicity.
MemberSeptember 29, 2021 at 6:29 pm
Certainly safety is a concern for any prospective vehicle buyer.
It is true that Aptera is most commonly categorized as an autocycle and exempt from auto safety testing standards. but, Aptera has repeatedly said that they will test to full auto safety standards. That means as Joshua Rosen has said in his post, that there is zero chance that Aptera engineers are not acutely aware of safety considerations as they engineer the vehicle. I suspect, since they have made the testing claim public, that they will over engineer safety (Not a bad thing)
Beta engineering is complete and build is in progress. Following Beta there well be two additional versions of Aptera before it goes to “Government testing”
The jury will be “In” when the government testing results are made public. I am confident that those results will put some ICE vehicle safety ratings to shame.
MemberSeptember 29, 2021 at 11:32 pm
By definition start-ups and smaller businesses are stretched to the limit and are forced to do more with less.
An automobile is an extremely complex electro-mechanical contraption; one where unexpected things go wrong all the time. While it is getting better, you must know the entire automobile industry has a less than stellar record in regard crash safety.
I share your overall confidence in Aptera and I too am quite impressed with their open approach based on first principles. I’m sure they have this somewhat rare circumstance covered; probably by direct notice from Elaphe.
But now we’re dealing with Elaphe’s competence and ability to communicate and this particular scenario may or may not have come up and, given ‘everyone knows’ that crash testing is not required for ‘autocycles’ … well, there is a chance; a small chance this particular eventuality may have been overlooked because, well, among those EVs that don’t have in-wheel motors there is no requirement for auto shutoff of the battery; hence the manual main battery disconnect.
Couple that with the Formula 1 open wheel design – If you’ve seen many wrecks you know that the wheels often go cattywonkers and the drivers tend to walk-away. But unlike F1, there are high-voltage cables attached to the wheels on the Aptera.
Then there’s Murphy’s law not to mention the value of an ounce of prevention and the bigger understanding about virtually everything: perfection eludes us all.
MemberSeptember 29, 2021 at 9:47 pm
Good questions, George!
Of some 40 global organizations, the best known in the US are:
- National Highway Traffic Safety Administration (NHTSA), and;
- Insurance Institute for Highway Safety (IIHS).
Of most interest to the Aptera community, NHTSA does rollover and roof crush resistance testing, and the dreaded “moose avoidance” test. IIHS does the frontal and offset crash tests that you specifically mention.
As for front wheel separation concerns, there are three pretty robust copper cables attached to the in-wheel motors that may retain the wheel’s attachment to the body. In that sense, they are somewhat similar to Formula 1’s kevlar wheel retention requirement that keeps the wheels attached to a crashing car.
In regards to your concerns about power disconnects, as far back as 2002, MINI Coopers had a power disablement system that triggered when the car experienced a very strong jolt. I know because a friend I was following suddenly pulled off to the side of the road and I stopped to help. He had hit the mother-of-all-potholes. We couldn’t figure out what happened so he called MINI who told him where the reset mechanism was. I don’t know if that’s a regulatory requirement here, but if so, I suspect there’s one or more vehicle subsystems supplier that could provide them to Aptera.
MemberSeptember 29, 2021 at 11:14 pm
MemberSeptember 30, 2021 at 7:15 am
Most EVs have a battery disconnect system so if a crash is detected the battery is automatically isolated.
The battery is always “live” unless each cell has been discharged professionally, but it can be disconnected completely from the car very easily by opening emergency-disconnect contacts. EVs have been out for a while now and they know what they’re doing.
MemberSeptember 30, 2021 at 7:43 am
Putting on my EE hat, I have zero concerns about there being an electrical hazard if a wheel is sheered off. The power to the wheel motors is managed by the motor controllers. Under normal circumstances power will only be applied when the car is moving, when it’s stationary, after a crash for instance then no power is applied. In addition to that the load is always being measured. If there is a short, possible after a crash, no power will be sent to the wires. The power supply in your PC have overcurrent detection which shuts it down if a short is detected, a modern power supply doesn’t blow up or even blow a fuse if there is a short. Those power supplies are much cheaper devices than the motor controller in an EV. In the case of an open wire the motor controller will sense that there is no load and likewise send no current to a open circuit. That’s just the usual operation. Undoubtedly there will be crash sensors that cause the whole electrical system to shutdown.
As for maintaining the integrity of the passenger compartment, that’s not my area of expertise but I believe them when thy say that it will be extremely safe. Composites are one of Aptera’s core competencies. The NHTSA and IIHS tests will be extremely important to Aptera’s future, they know this and it has to be at the top of their priority list.
MemberSeptember 30, 2021 at 9:32 am
Great! All my concerns are now whisked away. Silly me, I learn something new every day 🙂
MemberJanuary 22, 2022 at 11:16 am
As a former Tesla electrical engineer and an ex solar car engineer, I can assure everyone that this won’t be a problem.
EVs have a wire in the high voltage harness called HVIL – it stands for High Voltage Interlock Loop. It’s connected between the battery management system and all consumers of the HV battery (inverters, heaters, HVAC, etc) and also serves as the first responder emergency power cutoff (the “cut here in event of crash” wire in every EV).
It’s a communications wire where the consumers of HV constantly sends a “keep alive” signal to the battery (usually at 1kHz or more). In the event of a crash where the HV harness is damaged (or when the onboard crash detector detects a crash), the devices connected to the battery management system HVIL line will simply stop sending the “keep alive” signal and the battery will simply shut off (either by contactor opening or by blowing a pyrotechnic fuse)
I can confidently promise that people won’t be electrocuted by having a wheel shear off!
MemberJanuary 22, 2022 at 11:38 am
Thanks for the explanation from your training an experience.
However, if the battery shuts off the motors will stop working then I would be stuck in the water and either have to push the Aptera out or get a tow. Is that right?
And for those in snowy climates resulting in wet wheels and motors will they experience motor failure failure form this feature or do you think wheel heat will keep it from happening?
MemberJanuary 22, 2022 at 12:28 pm
Hai-Yue! Alain/SunCat Solar here. I’m glad to see you here at the Aptera Forums.
MemberJanuary 22, 2022 at 9:20 pm
Coming from a automotive and racing background, safety wise I would like to see the front hubs secured with cables to the body frame. Very scary watching a wheel go flying into a crowd.
ModeratorJanuary 23, 2022 at 7:15 am
They already are connected with electrical cables and cooling hoses (and the suspension arms). We only need to make them reasonably strong and well connected. No way are Aptera wheels by themselves going rolling down the road.
MemberJanuary 24, 2022 at 7:08 pm
Electrical, coolant lines and brake lines are not strong enough in an offset collision or a collision with a curve at speeds over 40 mph. None of those lines or cables are attached to the hub assembly. I was mentioning it as only an additional safety idea.
- This reply was modified 5 months, 1 week ago by Vernon Michael Gardner.