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DIY Home EV Charger

jamesfotherby.com

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Re: DIY Home EV Charger

#71

Post by analog31 »

sokoloff wrote: post #69
hristov wrote: post #50

Earlier quoted context omitted.

I see $200 evse’s on amazon nowadays. Only 32 amps tho. As to why they are so expensive one has to keep in mind these are inherently dangerous so they do not buy the cheapest parts, they have to go through a longish federal approval process and the companies probably have higher insurance costs.

Could you say more about or provide links to this “federal approval process”? It’s the first I’ve heard of it for at-home level 2 EVSE units.

I'm not an EE, but I work with them. As it stands right now, governments don't directly approve consumer products, except perhaps in some rare cases. When my employer gets a new product certified, we take it to a private firm.

As with the misnomers about the "charger" terminology, I could appreciate a layperson getting this confused.

Re: DIY Home EV Charger

#72

Post by dylan604 »

sokoloff wrote: post #70
dylan604 wrote: post #60

Earlier quoted context omitted.

Most people aren't going to DIY something like this. Also, most people think that the price of a product should only be based on the price of its components, and possibly willing to accept a mark up on labor. However, the companies making a thing, whatever that thing might be, also has to make money to be able to pay the people that work for the company, the utility bills, and the rent. There's also the fact that the…

In engineering university, I learned the “retail needs to be 5x the BoM* cost” rule of thumb. For a very high value or very high units product, maybe you could shave that to 4x or slightly less, but there are a lot of hands between the designed part and the retail consumer and none of them want to work for free. * BoM - Bill of Materials (“what stuff goes into this thing?”)

4x was also the minimum retail price I've been taught as well. The wholesale rate has also been anywhere from 50% - 75% of the retail price depending on the negotiations with the retailer. This is ignoring soulless companies like Walmarts/Amazons/etc where you'll never make those numbers. Something people don't always consider that when they buy something from the retailer directly, they typically make more money from that sale than if you bought the same thing from Walmart. Buying something from somewhere like Etsy vs their direct site also takes a healthy chunk.

Re: DIY Home EV Charger

#73

Post by sokoloff »

dylan604 wrote: post #72
sokoloff wrote: post #70

Earlier quoted context omitted.

In engineering university, I learned the “retail needs to be 5x the BoM* cost” rule of thumb. For a very high value or very high units product, maybe you could shave that to 4x or slightly less, but there are a lot of hands between the designed part and the retail consumer and none of them want to work for free. * BoM - Bill of Materials (“what stuff goes into this thing?”)

4x was also the minimum retail price I've been taught as well. The wholesale rate has also been anywhere from 50% - 75% of the retail price depending on the negotiations with the retailer. This is ignoring soulless companies like Walmarts/Amazons/etc where you'll never make those numbers. Something people don't always consider that when they buy something from the retailer directly, they typically make more money fro…

That’s what I find so infuriating about many first-party sites.

I’ll often find something on Amazon and if it seems like it’s from a small business, I’ll check to see if I can buy it direct. (Arguably, this behavior is unethical on my part against Amazon, but whatever.)

I very rarely (like matches Amazon’s.

Look, I tried. I came to you and gave you a shot, but if you want to charge the same item price and also tack on $15 of shipping, I’ve received your message (“please buy it from Amazon; we don’t want to sell it to you direct…”) loud and clear.

I’m usually willing to wait a few extra days, pay the same price, and have worse returns possibility in order for you to double or triple your variable transaction profit, but you’ve got to be competitive.

Re: DIY Home EV Charger

#74

Post by bluGill »

sitharus wrote: post #63
mindslight wrote: post #31

Earlier quoted context omitted.

> would nullify my homeowners insurance What is up with this common refrain? One of the main functions of insurance is to indemnify you against your own negligence. Let's say you turn a small stovetop fire into a house fire by trying to put it out with water - the insurance company doesn't just get to stiff you because you were responsible for causing the problem. Are there actually prevalent and enforceable weasel c…

I don't live in the US (in New Zealand), but this made me check my policies. I'm no longer a home owner but I checked my policy from a couple of years ago, and I checked the contents insurance I currently have (which has indemnity for the rented property as well). An intentional or reckless act wouldn't be insured if it directly causes a loss, but anything else is. There's no exclusion for doing things that are illeg…

There is more than the policy, there is also the law and court caselaw (at least in common law countries). The policy is where they detail things not covered by the others in some way. So you need to check with a lawyer.

Re: DIY Home EV Charger

#75

Post by applied_heat »

sokoloff wrote: post #73
dylan604 wrote: post #72

Earlier quoted context omitted.

4x was also the minimum retail price I've been taught as well. The wholesale rate has also been anywhere from 50% - 75% of the retail price depending on the negotiations with the retailer. This is ignoring soulless companies like Walmarts/Amazons/etc where you'll never make those numbers. Something people don't always consider that when they buy something from the retailer directly, they typically make more money fro…

That’s what I find so infuriating about many first-party sites. I’ll often find something on Amazon and if it seems like it’s from a small business, I’ll check to see if I can buy it direct. (Arguably, this behavior is unethical on my part against Amazon, but whatever.) I very rarely (like matches Amazon’s. Look, I tried. I came to you and gave you a shot, but if you want to charge the same item price and also tack o…

Sounds like the manufacturer just wants to ship palettes of the product to amazon and not deal directly with individual customers and are happy to have amazon make their markup for the service they provide.

Re: DIY Home EV Charger

#76

Post by dylan604 »

sokoloff wrote: post #73
dylan604 wrote: post #72

Earlier quoted context omitted.

4x was also the minimum retail price I've been taught as well. The wholesale rate has also been anywhere from 50% - 75% of the retail price depending on the negotiations with the retailer. This is ignoring soulless companies like Walmarts/Amazons/etc where you'll never make those numbers. Something people don't always consider that when they buy something from the retailer directly, they typically make more money fro…

That’s what I find so infuriating about many first-party sites. I’ll often find something on Amazon and if it seems like it’s from a small business, I’ll check to see if I can buy it direct. (Arguably, this behavior is unethical on my part against Amazon, but whatever.) I very rarely (like matches Amazon’s. Look, I tried. I came to you and gave you a shot, but if you want to charge the same item price and also tack o…

Yeah, sites willing to accept the full retail price and not discount the shipping to match a larger vendor's site, then of course they're firing their footgun with both barrels. There's a reason places will offer free shipping with minimum purchase prices that ensures there's enough profit made to cover the cost of the shipping.

The hassle of inventory/shipping logistics is something people with no experience easily do not consider.

Re: DIY Home EV Charger

#77

Post by jacquesm »

amluto wrote: post #68
jacquesm wrote: post #55

Earlier quoted context omitted.

If only it was just the tradespeople. I've had an electrical inspector argue that I should route the ground from my windmilltower into the house and bond it to the distribution panel rather than to ground the windmilltower at the base of the tower . So in case of lightning strike (which is pretty much a given) that would invite that lightning into your home right at the distribution panel. People may be following 'th…

I don’t know the whole setup, but the inspector is likely right. When you have a feeder to an outbuilding (or external structure or piece of equipment or subpanel or basically anything else), you supply it with the intentionally current-carrying wires and the ground. (Ground may be called “equipment grounding conductor” or “protective earth” or perhaps something else in your jurisdiction. It’s a wire or the metallic…

> I don’t know the whole setup, but the inspector is likely right.

That's an interesting start to your comment. So you don't know the whole setup but you do know the inspector is likely right.

Well: if he was likely right he would have not shied away from putting it in writing. What happened was that halfway into the conversation he realized he was wrong, hightailed it out of there and simply didn't want to admit that he was wrong.

I do know the whole setup. And I have spent enough time installing high stuff made out of metal (mostly: antenna masts) to know that the last thing you want is to give lightning a short path into your dwelling.

His whole experience seemed to be based on simple domestic installations, and instead of just admitting that he didn't know exactly what to do and to go look it up or ask someone more experienced to look it over he dug in. Human nature, I get it, but this is safety we're talking about and the amount of flak the OP is getting in this thread from people that likely have more experience with keyboards than with real world engineering is telling. Just like you: they don't know the whole setup but they'll argue that it is unsafe, will void your insurance, will get you investigated for arson(!) and might kill your kids.

You last paragraph is exactly the problem: he outright forbade me to ground at the base of the tower because that was in his opinion unsafe. But it wasn't his life and property that was at stake.

I've seen up close what lightning will do to various pieces of gear, it isn't pretty, to put it mildly and you make sure you keep it as far away from your house as you can. And have spark gaps to ground at the point of entry for your power cable, just in case.

Finally: the proof of the pudding is in the eating. When after a year we pulled the tower down again there was evidence of multiple strikes on the nacelle body at the top of the tower, all of which were dealt with gracefully, to the point that we didn't even realize the machine had been hit. What helped is that for the whole installation we had a massive amount of help from an experienced wind turbine vendor who took an interest in our project.

Re: DIY Home EV Charger

#78

Post by _ea1k »

jtagen wrote: post #28

Given what's in this, why are EVSEs so expensive? Given the quantities we see, the $150 range should be more than enough for a decent profit.

A lot of it is the connector and cable. Good connectors are surprisingly expensive.

Re: DIY Home EV Charger

#79

Post by balls187 »

sib wrote: post #42
balls187 wrote: post #32

Earlier quoted context omitted.

First, it’s a bit more complicated than that—unless you went ahead and installed a 60A line without checking if your service(s) can handle the additional load. Advice like this is what gets people to screw up. Second, what’s the material difference between a 40A circuit and a 60A circuit? A few extra hours overnight to charge?

Well, there are times when you're not charging overnight (e.g., get home with low battery, realize you only have 3 hours before next outing) and you get 50% more charging done in the same time, without having to go out to a Supercharger / DCFC. Or, as in our case, we have two EVs - speed is useful sometimes.

So you installed 2 60A circuits?
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