[thingstodo]

To respond to the original question:

- higher voltage makes leakage current more of a concern. I have yet to find a frame leakage or ground fault system that I would put in a car. I plan to install 100 Kilo-ohm resistors and contactors on either end of my Leaf battery pack and measure for current across a 1K resistor. That should give me about 4V if there is an un-intentional connection to the frame while I am running the test. Much less if there is not a solid connection to the frame.

One of the links below shows how much current is uncomfortable through to damaging for the human body. My goal is to use any reasonable means to reduce the likelihood of a shock, or the severity of a shock if it is not reasonable to avoid it completely.

Originally Posted by MightyMirage

the classification between 120v and 900v May be the same on the internet but your only seeing half the picture.

For AC, I think it's the same classification from 50 VAC to 1000 VAC - low voltage

For DC, there appears to be no low voltage, medium voltage, and high voltage classifications similar to AC. Low voltage is mentioned as 48V and below (now it seems like 100V and below), but since they discuss mostly lead-acid ... it's more like 55V charged and almost 60V for the floating charge.

125VDC, which is what a lot of electrical switch gear uses in substations, does not get described as a classification in what I have read. Most of the people who deal with this voltage work for power companies ... and they don't have to follow electrical code for some reason ... maybe they don't want their systems to have arc flash categories.

This document, listing just the changes for DC and arc flash, sets the shock rating at 100 VDC. I don't remember this one, I must admit.

http://www.ieee-pes.org/presentations/gm2014/2756.pdf

There are some guidelines for calculating arc flash on DC, but batteries are not common in industry above 125 VDC. The DC buss on VFDs or ASDs, DC drives ... plus larger installations of solar arrays. I have asked for some rules of thumb and our consultants have a few. And as the document above mentions, they are quite conservative.

- use contactors to isolate packs and sources
- use fuses to limit arc flash risk
- fuses should trigger in 5 cycles, or about 1/10 of a second, for a large overload (10X expected current)
- review the fuse curves whenever anything is changed on the system to make sure they are still going to protect you

We don't do arc flash calculations on any AC source of 208V three phase below 75 KVa, since it does not sustain an arc and the transformers involved don't have the thousands of amps (KA) that appear to be a big part of the energy in an arc flash.

DC is a different fish - the voltage does not cross 0V 60 times per second so once an arc is established it does not extinguish as quickly without outside help - from a fuse, or a contactor, or a breaker ... or vaporized copper.

potential energy is what counts not a textbook classification.

I would argue that amps are the enemy, but voltage causes amps to flow. Perhaps I am splitting hairs.

i can tell you, nobody takes a 500v+ panel lightly whatsoever. green shields, cotton clothes with outer blast garments, leather covered in rubber gloves are the basics.

At 8+ calories, you missed the bella clava and the face shield unless that's what 'green shields' means. And I think the leather is on the outside to protect the rubber insulation on the gloves from damage.

the potential energy built up in a 1500amp system at 800vdc is a freight train of pain.

1500A for an intentional load on a battery system is quite large. Even at 50C on a lithium cobalt battery chemistry - you'd need 30 a-h cells. And about 200 of them to reach 800V. A small fortune indeed. Easily controlled by a properly sized fuse.

However, 1500A into a short circuit is not all that much. If you expect 1500A on your system for 5 seconds (I can't imagine the speed you'd be going after 5 seconds of acceleration at 1500 amps), have the fuse trigger (melt and clear the fault) at 1500 amps for .. 7 or 8 seconds,

It is *FAR* easier to get 1500+ amps from a 144V lithium iron pack (10C is only 150 a-h cells), or parallel packs of cells, or any of a host of lithium chemistries that people are using. The amps give you the heat, which gives you the blast. Voltage gives you the safe distance between un-insulated conductors or terminals.

i know you don't like hearing this but truly stay away from these voltages unless you are certified. I've been doing high voltage electrical work for ten years, and your asking, on the internet,how to safely wire, insulate, and operate something that can kill you from 5 feet away...

Perhaps a bit dramatic, but a warning that should be listened to and protected against.

Here is another reference from industry

http://www.battcon.com/PapersFinal20...rc%20Flash.pdf

From what I have read, and what I have experienced:
- size your fuses well. Make sure that the fuses will interrupt the voltages you are using. And make sure that your pack can supply enough current to trigger the fuse element in a reasonable time. Like the 1/10 of a second I mentioned earlier. A 1000 amp fuse is useless if your used Leaf pack can only put out 800 amps!
- split your pack into lower voltages. I thought 48V was reasonable, but it appears that 100V is OK as well. The separate packs connect in series when you turn the key or start the charger. Split the pack segments with contactors.
- use vacuum contactors, rated for the TOTAL voltage you are using, + 25%. If you are a paranoid (like I am) use one on the positive pack and one on the negative pack plus one between each pack segment. Make sure that the main contactors both open. I'd like the contactors that split the packs to verify open as well but I'm not sure how to measure that one. Perhaps that will be part of the leak detection or Ground fault.
- I'd add a DC breaker as well. It's harder to find these at higher voltages, but they exist. A 300A, 125V DC breaker on the battery side will let the controller do 1000 amps of motor current for a 5 second acceleration

Google search the requirements for entering a 10 calorie panel and ask yourself if you really think it's worth it still, because after all, i do believe this is where you would fall.

if you have a specific question ide gladly try and answer it for you, though.

There have been very few tests of DC for arc flash. The two that I've seen video of (I don't have links) were based on NO FUSES since they were for 125 VDC in a substation. With no fuses and no other protection, the flash and the bang are impressive. So USE FUSES! In my opinion, that is what will keep you from death, or from skin burns bad enough that you'll wish you were dead.

I'm a bit worried about water-proofing where people normally put battery packs. I have opted to put the batteries in the cabin with me, replacing the back seat. There is a sturdy frame around the batteries, a lexan cover to keep conductive stuff from falling inside, etc. But my my provincial insurance rep (the last one I asked) mentioned that I would have to seal the battery case and vent it outside the cabin. That would be inconvenient, and would effectively make the batteries the same temperature as outside ... which means no driving the car in winter. When I get it done, I will put the car in front of a vehicle inspector and get a written list of things they want changed ... and I hope I can convince them that the venting thing is not required since the electrolyte is quite non-toxic. If the batteries start to vent, I need to get out in a hurry ... and whether they are vented internal or external to the car will not matter much.