[cajunfj40]

MightyMirage, thanks again for commenting. I'll be responding to each bit below. Apologies for the length, I did try to edit it down!

the classification between 120v and 900v May be the same on the internet but your only seeing half the picture. potential energy is what counts not a textbook classification. 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.

Well, I wouldn't suggest anyone take a 500v+ panel lightly, nor myself. My point of them being "the same on the internet" (and yes, I am self-aware enough to know that where I'm coming from can look quite silly from an expert's perspective - trust me, I have had similar thoughts in other fields in which I'm more experienced than the commentor I'm reading!) is that I would need to apply the appropriate protective measures and isolation requirements for a 1500VDC system - and that DIYers who have 120VDC or greater battery packs who wish to follow the standards I've found *would need to do the same*. That and, if all I can find is that I need 1500V capable safety equipment, and I find that that equipment makes it difficult to impossible to do the work, I'll likely pick a lower voltage. Unfortunately, under the standards I've found to date, that sticks me under 120VDC. (or lower, see below) There's got to be some other intermediate ratings, or how do we get safe 144VDC DIY systems, let alone OEM 288-402VDC systems? AC forklifts are 80V to stay under certain codes, and previous DC forklifts were lower for similar reasons (I think the codes have changed in the interim).

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

I'm not ready to wire it yet, as I know I don't know enough. (And I don't have the budget yet, either.) This is why I ask questions. What's the difference in danger between a 200V/6000A capable system and an 800V/1500A capable system? Same potential energy, just 4 strings of 1500A short-circuit-capable batteries in parallel, rather than one series string. I'll have the same potential energy in the vehicle whatever voltage I pick - I need kwh for range.

Using 25 used 8V Leaf cells is 200V, each cell is ~62Ah rated, ~50Ah useable, so 10kwh. I want ~40kwh, so 4 strings. I can connect in parallel or series, but all those cells are there. Roughly 1.1 gallons gasoline equivalent, requires 2 wrecked Leaf battery packs. ~25C doesn't seem out of line for dead-short fault current on cells rated at 4-6C continuous.

As for certifications, I have yet to find the correct certs required to work safely on electric buses or the standards to which the internal components/shields/etc. have to be rated to in order to be worked on by an average garage mechanic, which are the closest parallel to what I am contemplating. They are available with 700-800VDC systems, and likely have quite a bit more amperage available - weight takes current to move.

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.

Interesting search - once I weed out all the diet crap I find a lot of Arc Blast information, mostly from/about NFPA 70E. It looks like a 10 calorie panel would fall into the Hazard/Risk Category 3, requiring a multilayer FR coverall rated at 25 cal/cm^2 or better. Class 3 is, well, too high for hobby work.

I found a nice table on Approach Boundaries to Live Parts for Shock Protection that also appears to be geared to protection against Arc Flash, NFPA 70E table 130.2(C). In that table there *is* a more gradual set of steps. From 50-300VAC the chart sets the Limited Approach (have a trained person with you) Boundary at 3ft6in for a fixed, live circuit component. The Restricted Approach (be a trained person) and Prohibited Approach (is what it says on the tin - keep out) boundaries are just "Avoid Contact". Next step up, 301-750VAC is similar, but Restricted Approach is 1 foot, and Prohibited Approach is 1 inch. The next jump is good from 751VAC up to 15KVAC. This doesn't line up with the previous standards I found (no surprise - it is a patchwork out there...) and it sets the "not specified" boundary at 50VAC. That's pretty low.

I'd prefer not to have to design to 15,000V, so this sets an upper limit of 750V at full charge/peak regen. Hmm, it seems NFPA 70E-2012 Table 130.4(C)(b) covers DC, and pushes the 1 foot Restricted Approach Boundary up to include 1000VDC. Still no reason to go above 750VDC, though, to limit my AC voltage capability past the inverter. This also possibly shows why forklifts are the voltage they are, in that older charts were at 50VDC for "not specified" and the newer one I found pushes that up to 100VDC. That would track with an 80VDC AC forklift, as the post-inverter voltages ought to be 50VAC or less. This is still pretty low - I've seen no discussion about proper safety gear for working on common over-100VDC pack DIY EV conversions, and all sorts of pictures where if you open the hood you see bare battery connections, or bare controller connections, etc. I've never seen mention of an arc flash hood or coverall. This isn't to say I don't think it needed, just that the awareness isn't out there about it. Like pictures of people welding in flip-flops (ouch!).

Hmm, are there any rough guidelines as to how to get a DIY EV system down into the Class 1 (or lower) Hazard/Risk category, in terms of voltage and current capability, or am I committed to at least Class 2 at the common 96-144VDC level and the short-circuit capability of modern LiFePO4 batteries of sufficient capacity for acceptable range/acceleration? I'm shooting for 100-200kW acceleration capability and ~80kw continuous. (a Leaf motor is capable of 80kW continuous without overheating, by way of comparison). Class 1 PPE is pretty reasonable - 12.8oz denim or thicker is "good enough" for many organizatons, though a coverall labeled with the appropriate arc rating would be cheap insurance. Safety glasses are needed anyway for auto work, and it doesn't take much to add a pair of rubber gloves and some insulated tools for the electrical work. If I have to wear an arc hood (Class 2 PPE), or insist that auto mechanics do so, that would likely be an effective barrier to my implementing a Class 2 Hazard/Risk rated installation. Can proper enclosures and de-energizing procedures lower the Hazard/Risk category? There's got to be some way - Nissan mechanics don't wear arc flash hoods when working on Nissan Leafs.

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

Thank you for your willingness to answer questions! I hope I don't exhaust said willingness. Part of the insistence on finding the correct codes/standards/etc. for the contemplated voltages is so that I can still take the completed vehicle to a garage for routine non-ev maintenance work without exposing those workers to a hazard they are not trained/equipped to handle.

See, I want to do it right, and a big part of that is doing it safely, and I have trouble letting go of an idea if I can't understand *why* it isn't safe. (NB - doesn't mean I'll do it if I don't understand, just that I'll keep digging until I do understand - or understand that the time required to understand is greater than I am willing to put in - and can then make an informed decision as to whether to proceed.)

Books/internet are not real life, yes - but they are the collected wisdom of the experts that have gone before, and provide valuable background information so I can go get practical knowledge of the appropriate type - including certification if necessary - and/or hire out the bits I cannot do safely to someone who can, and/or find out that the requirements make it budget/time prohibitive to move forward.

Thanks again, this is very useful info!

On a somewhat related note, this has got me wondering about the time as an intern that I got to watch a 15KV substation fed by two separate power grids (the 4 power conduits running from this substation to the plant I interned at were probably 6-8" in diameter) get shut down by the electricians. I had safety glasses, maybe a hardhat. I don't recall any arc flash type gear - everyone else had safety glasses, gloves, maybe a hardhat. I was close enough to see the details of how they used a drill motor powered by an isolated DC system to crank open each set of contacts (in a closed cabinet, motor attached on outside) in the correct sequence. They were safety interlocked so you couldn't crank them down out of sequence without having to deliberately break something first. From your comments, I probably should have been kept much further away, and the rest of the folks there probably should have been wearing a lot more gear...