emini

• Q1 Yes.
• Q3 Yes, a plug such as an anderson disconnect should be allowed in place of a switch and such disconnects should be allowed in a battery compartment when non-venting batteries are used.
• Q5 Yes, Over current devices should be allowed within the battery compartment(s) Why would they be forbidden within the battery compartment? 2.2(1) (c) allows flame proof switches and relays within a battery compartment, fuses should not emit flames if they are of good quality and used within their ratings. 2.2(5) NOTE (d) recommends fuses near the electrical middle of the battery, but 2.2(5) (b) forbids fuses within the battery compartment, making this recommendation harder to follow in some cases.
• Q9 A manual ground fault detection system should be mandatory, with an automatic system preferred. I have not had time to find a suitable automatic system so would hesitate to mandate an automatic system.
• Q10 I agree that a simple single potentiometer design is not safe enough. This is a problem as some existing and in-progress conversions likely only use a single potentiometer throttle. I believe a single potentiometer with broken wire detection and a "pedal up" switch inhibiting the traction system is sufficient, with a dual potentiometer preferred. Would a single hall effect sensor be sufficient? My own vehicle has a single potentiometer with broken wire detection, which I am uncomfortable about. Is this sufficient? I will likely add a pedal up inhibitor, but the details of doing this are not trivial due to the design of my control electronics.
• Q12 No.
• Q13 Yes, with an explanation that a proper pre-charge circuit will protect the main contactors
• Q14 No, I think it sufficient to require cables be marked with the voltage ratings by the manufacturer or documentation provided to require this.
• Q15 Yes, but not to the same level as the FIA. The FIA's "insulation resistance to ground" test is equivalent to the ground fault detection requirement in 2.4(1)(f). 2.4(1) NOTE 3 suggests that a ground fault is permissible so long as it is "safe". The FIA's 250k or 500k Ohm requirement is not possible with a brushed motor or flooded lead acid batteries. A maximum ground fault current should be allowed, so higher voltage systems must maintain a larger resistance to the body. For example a 150V system with a 5k Ohm ground fault will have a maximum ground fault current of 30mA, while a 300V system with the same ground fault will have a maximum ground fault current of 60mA. I am unsure what is achievable in a flooded lead acid battery vehicle with a brushed DC motor without super-human maintenance. Note well that testing the insulation resistance should not be done with a multimeter set to the resistance scale -- a low resistance ground fault will likely destroy the meter.
• Q16 Yes. Live parts should be covered by strong materials.
• Q17 Yes, but 5 seconds is too fast and will cause the discharge resistor to run hot while the vehicle is in use. 1 Minute would be safe. Siemens placed a warning to wait 1 minute before servicing on my controller.
• Q18 No. This requirement has several parts. Most obviously inappropriate is the requirement that the battery cell manufacturer attest to the safety of the battery. Most lithium battery packs are assembled by the owner, so the manufacturer is unlikely to be available for comment on the battery pack. Note the preceding wording requires the cell manufacturer manufacture the cells, but does not comment on assembling the battery pack. A requirement that the cell manufacturer assemble the battery, or that the cell manufacturer attest to the safety of a customer assembled battery would prevent most or all electric conversions using lithium batteries. Requiring the battery management system monitor the temperature of the battery is a good thing, but it's not clear how many of the commercially available battery management systems do this. Requiring batteries that are prone to thermal runaway to retain the manufacturer's monitoring and safety system is a good idea but doesn't say anything about such cells that are supplied without any monitoring and safety system. The Battery Management System issue is highly contentious at the moment. It is clear that a bad Battery Management System is worse than no battery management system for Lithium Iron Phosphate based batteries. Mandating that there be a battery management system may or may not cause more problems than it solves with this chemistry.
• Q19 No. This is already covered in 2.4(1) (a). I don't believe any additional instrumentation is required to warn of danger during maintenance since the battery box already has a high voltage warning on it, and turning the car off does not make the battery safe.
• Q20 Yes, you already do in 2.2(1) (b).

In addition to answers to the numbered questions, I have the following comments:

• The Note in 2.2(2) suggests typical operating temperatures of -10 to 40 degrees C. This is incorrect. Most electric motors operate happily with internal temperatures well over 100 degrees C.
• 2.4(1) (c) requests a "handbrake on" indication to the driver. Why is this required? For cars that did not have this indicator as original equipment, this is a fairly complex requirement. Is the presence of a handbrake lever next to the driver in the "handbrake on" position sufficient to satisfy this requirement?
• The last sentence in 2.4(1) NOTE 4 should read "This should be done between the body and several electrical positions within the battery, for example at the most negative battery, the most positive battery somewhere in the middle of the battery. If the body is non-conductive, then ground fault detection testing should conducted between the battery and all metal structural members near the battery." We want to detect a ground between any potential within the battery and the body (which, if it's all-metal, is always at the same potential). My wording around non-conductive body issues is somewhat clumsy, sorry.
• Section 5 "Ground fault detector" definition is wrong. We are not looking for an "imbalance in current between the energised conductor and the return neutral conductor since:
  1. there is no such thing as a neutral conductor in an electric vehicle
  2. if current flows in the ground fault, we already have a potential fire
  What we are looking for is a connection between the battery and the body of the vehicle. No current flows through the first ground fault. I would word this section as "means a device that detects a connection between the battery and the body of the vehicle. Such a connection will allow a current to flow through the body of a person who is simultaneously touches the body of the vehicle and part of the battery during maintenance. A second connection between the body and different part of the battery will allow current to flow through the body, potentially causing a fire or damaging the battery."

In New Zealand, modified vehicles need to be signed off or "certified" by an engineer. In the 1990s an effort was made to create rules governing the certification of Electric Vehicles but it was never completed and the rules are now quite out of date. The Low Volume Vehicle Technical Association have been updating these rules over the last year or so, addressing a number of shortcomings with the old draft. They are now publicly requesting feedback.

I've already had a hand in the new draft document and I'll be posting my feedback here (and to the LVVTA) in the next few days. If you are building an electric vehicle or thinking of doing so, you should read the draft and submit feedback by the end of the month (8 days!).

There is room for another row of cells in front of the two shown, but this row will have to be slightly lower since the front of the car curves down. There is enough height in the middle to put cells above the motor where it protrudes through the plywood, higher than the rest.