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Has anyone ever seen or thought about including a crash sensor safety switch? something like this:
Inertia Crash Sensor Switch
Something to ensure no HV coming out of the junction box in the event of an impact. Easy to reset by the driver if triggered accidentally by a low speed bump...
Interesting Question
My answer may well be controversial (but please be nice 😆 ) .. short answer: no

Let me explain, based on experiences with my 1st conversion, an early RHD smart car. This was ideal as small and quite light and with a massive hollow floor, designed for batteries - Lead acid in this case as Lithium was still too new and costly in those days.

The car cut out when my wife was diving – over a bumpy busy level crossing (railroad crossing in the US). Wife in panic mode o_O - luckily cool headed young son knew how to re-set. After 5000 miles and 4 years of being our (almost) free to run local family taxi - poor connections eventually turned ‘just switch on’ ease, into a ‘hunt the bad joint’ annoyance.

Lesson - I now only use waterproof control wiring with a minimum of crimped and soldered connections, and the minimum number of ‘safety’ cutouts.

IMHO reliability along with primary safety (eg power, brakes, handling) must trump multiple safety contactors and cut-out switches and especially crimped connectors.
Wheel Tire Car Vehicle Plant
... even the best lead acid AGM didn't last more than 2 years. and a PIA to change from underneath.
Mark, Dorset, UK
 
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Thank's for this question pat_t. Indeed the TUEV information sheet on 'electric vehicles in the individual approval procedure' says:
5.5 Voltage disconnection in the event of a crash
A disconnecting device shall be provided in the DC link of the electric drive system which, after a crash, makes it possible to de-energize the electrical lines or connections of the power circuit (HV) leading out of the energy storage system (REESS). If, in the case of vehicles with airbags, the disconnecting device is controlled by the vehicle's own crash trigger signal, then proof must be provided that this has no influence on the crash trigger signal.
Until today I've planned to use a Maintenance Service Disconnect with integrated Fuse in each of my two battery packs. Opening them manually triggers via HVIL contacts the Interlock curcuit and that shut off the Main contactor. I did not plan to integrate contactors in each battery pack. That Crash Switch could be used to control those contactors.
Would this be neccessary to meet the requirement of 'Voltage disconnection in the event of a crash'? I've translated the paragraph with deepl, but even in german and as an electric technician I'm not sure how this is meant.
 

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This reads to me as a first responder disconnectable capability, with an optional SRS automated disconnect.

"...makes it possible to de-energize the electrical lines or connections of the power circuit (HV) leading out of the energy storage system (REESS)"

That said, using the HVIL to open the main contactor fails the requirement, imo:

"A disconnecting device shall be provided in the DC link of the electric drive system which, after a crash, makes it possible to de-energize the electrical lines or connections of the power circuit (HV) leading out of the energy storage system (REESS)."

If you have your positive lead exiting the battery box and going to a junction box with your main contactor, which it sounds like you may be doing, you fail the requirement of ensuring there is no high voltage coming out of the battery box.

Further, since we don't chassis ground the negative side of the HV battery, you also need to disconnect the negative wire coming out of the battery box...because in a crash the positive side could short to the chassis.

The principle here is to ensure the first responder, trying to cut you out of that sorry home-converted car you put into a tree after having one too many at your office Christmas party, doesn't get electrocuted for trying to keep you alive or to get your remains into ziplock bags to give to your relatives 💀

😜

In summary, your manual or SRS-initiated HV kill needs to be in the battery box for both positive and negative HV leads coming out of the box.

And if you get clever with trying to put your HV junction box inside your battery box, you ALSO have to ensure other HV lines, like for AC compressors, is on the disconnected side of the disconnect, not the battery side.

Having a resettable device should also fail the safety requirement, since it could get reset by responders or vehicle occupants inadvertently.
 

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At a DIY level (and to circle back to the 120-140v Hyper9) the EV west diagram has been used as the basis of many conversions ...
Circuit component Schematic Font Rectangle Parallel

It was my starting point on last project, having decided on relatively low voltage 120v, 5 x Tesla modules and a standard Hyper9.
 
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Inertial switches are routinely used on production vehicles with engines (to shut off the fuel pump) and for collision safety systems; I've never heard of one tripping unintentionally, and it certainly has never happened to me. If nuisance shut-offs are a problem, I think that the fix is a better switch, rather than omitting a safety system.
 

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Thanks for the thoughts all. I'm going to go ahead and use it. One other reason for me is that as well as UK-road-legal, I am building my car in the hope of one day using it for UK Club Motorsport, however regulations for the classification of non-OEM Electric Vehicles do not yet exist. To that end I'm following MSA blue book regulations where I can, I suspect such a switch will be stipulated, and it can also be used to trigger a green/red indicator light to signal to track marshals whether the system is "live" or not, as the hybrid electric vehicles in F1 and Le Mans etc already do.
 

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I always like to keep it simple and am fully aware that every connector, contactor or even a security device could fail or at least cause a lot of trouble in case of a malfunction. The other side is the safety of the complete system and the very common used claim 'state of the art' or better 'state of technology' by regulators. So I'm going to use an intertial switch, too. You get them for 30 €/$.

Next protection device somebody? What about an Insulation monitoring device?
State of the art? Sure, every electrical installation got it, because fuses can't cover this failure. I found this one Insulation monitoring device, but no price for it yet.
As always TUEV already covered the topic:
4.4 An insulation fault between a single conductor and the cover/enclosure or body must not result in an immediate shock hazard when touched (one-fault tolerance). An insulation monitoring system is state of the art and therefore recommended for monitoring electrical safety in the vehicle.
 

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I believe the way you interpret that is no leakage current from the HV battery to the chassis/box.

Current has to go from point A to Point B. A single insulation fault is point A.

The only way to get shocked is if there's leakage (or worse, a connection) between a different potential and the chassis or box which becomes point B. You need contact with A and B to become the wire through which current flows 💀
 

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To detect insulation failures before they result in a problem is a preventive measure that I don't want to miss in any electric installation above 48VDC. Maybe especially because it's me who is doing the conversion and I do not believe that I can anticipate all error cases.
Bender, as 'Your partner for electrical safety' mentioned a VDE book about 'Electrical safety in electromobility' and I couldn't resists to order it. I always like to have a reference and collect arguments to have a safe stand in front of the TUEV engineer. Let's see if I'm more concerned than now after reading it.
 

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Again, the primary hazard is not a single fault insulation failure, but existing current leakage or a double insulation/isolation fault.

You can have an insulation failure (dead short to the chassis), and not have a shock hazard if there's no leakage or a secondary path to establish a potential difference.

This is why interlocks are so critical. Both potentials are present for contact when you pull a cover off.
 

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Hey Guys,

I am new here! Excuse me if I post in the wrong section.
I am a member of a university team, building our second racing electric motorcycle. Our project is a little different than yours, but I believe we have some common grounds.We were previously using a sevcon gen4 size4, but looking to try something new. The only interesting choice I found available in Europe (non sevcon) is the Hyper Drive SME ACX1 but I have some second thoughts about this selection. Our motor is the 205W-08011-SSE which is a "Permanent Magnet Synchronous Machine" with a sin-cos encoder according to the manual. I have no doubt about the encoder, but I do not know about the PMSM, as I see that the hyper 9 set's motor is a SRIPM one. From what I found online, everyone is using this controller with the motor that comes with it and there is no info of anyone using it with any other motor (at least I have not found any). Also, no support from Dana-TM4 or NetGain. Do you think it would be possible to configure the controller to work with our motor?

Thank you in advance from any replies!
 

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Hi guys, I have a quick question about gearing. What kind of FDR are you typically using for this motor? I was hoping for around 9:1 (which would mean a wheel speed of 75 mph at 10,000 rpm), but then I noticed the 3,300 rpm maximum continuous rating (which would equate to 25 mph). Would that mean highway driving is out of the question?
 

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Hi guys, I have a quick question about gearing. What kind of FDR are you typically using for this motor? I was hoping for around 9:1 (which would mean a wheel speed of 75 mph at 10,000 rpm), but then I noticed the 3,300 rpm maximum continuous rating (which would equate to 25 mph). Would that mean highway driving is out of the question?
I'm not sure your math is quite right. 4th gear on the Jeep AX15 is direct drive, with a rear differential ratio of 3.07 I calculate 82mph at 3000RPM for 29" tires.
 
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