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If you get 120volts between the two hot lines, that's not enough voltage for the coil of the third relay. It won't actuate (instead, it makes a rather angry buzzing noise), which leaves both hots on the socket disconnected. I have not seen 208/240 volt relays close at 120 volts, myself.

Yeah, that's why you want a 240 volt relay across both hots switching both to the socket. I've come across a miswired outlet at my house and it makes the last relay make kind of a nasty buzzing noise, but the power to the socket remains off.

I'd like to shoe-horn a plug in here for my EV Sim Mark II. It's a little 2x16 char LCD display with a "backpack" on it. It has 4 DIP switches, a 2.1mm barrel connector for power, and two screw terminals for the J1772 pilot and ground. You hook it up and give it 7-12 VDC and it will show on the...

Yeah. I built a Hydra with two "compact" 50A contactors, but I built it in Polycase's largest WC series box...

You do have to do it right, though. There are a bunch of potential traps that can make the concept of grabbing two opposite phase hots from NEMA 5-15s tricky to do safely.

But that board doesn't fit in Chris' fancy enclosure. Oh wait. Neither does the contactor. Never mind.

Fair enough, but with respect, as a firefighter, you don't see the ones that don't go wrong. Just because it is done wrong does not make it impossible for it to be done correctly. I invite anyone to inspect my work any time. If there's anything I've done wrong, I welcome corrections. In the...

I believe my design is above any reasonable level of "oh my God, what are you doing?!" alarmism. I'm involved in an argument over on the Nissan Leaf forum the tone of which is that it's in fact too conservative. Whether the device as a category could be UL approved or not, I don't know. If I...

I posted a picture on the other thread

Here's what I had in mind. You can add neon indicators across each relay coil. The first two relays have 120v coils, the last one has a 208/240 volt coil. Again, the concept is that unless both hot lines are 120v away from their respective neutral AND the two hots are 208/240 volt away from...

Forgive me for jumping in on this late... but that schematic is not as safe as it can be. What you want to do is use two DPST relays. One pole from each relay is wired in series on each hot line. In other words, you must insure that BOTH relays are on before EITHER hot line gets any power. If...

It only takes one smart guy to start selling a working SuperCharger to CHAdeMO adapter on eBay to change that. And it's not a lot of trouble. It's 67 cents per car (http://www.digikey.com/product-detail/en/ATECC108-SSHDA-T/ATECC108-SSHDA-TTR-ND/4240214) and maybe a few extra seconds at...

Even if they did, unless it was in conjunction with some sort of PKI, it just means having a collection of Tesla VINs to go through. Heck, you can go to a showroom and write down a few. If they did do the PKI thing, then that would pretty much put the kibosh on it. The only attack would be to...

I strongly doubt that they will even offer it to Roadsters. What percentage of the current Tesla fleet is Roadsters? It's got to be less than 1% by now. What benefit do Tesla get from doing the work? And I also strongly suspect that if anyone were to reverse engineer the SuperCharger interface...

My spidey-sense is tingling.

So far as I know, a contactor is just a fancy word for a relay that generally has a line-powered coil rather than one powered by DC. I did a quick google and also found that people call them contactors when they're simply rated for very high power. A relay is always supposed to be able to...

Well, sure, but unless you find a TT-30 (and your car supports high current L1), L1 only happens at 16A. And a universal device will never go higher than 40A because there aren't outlets that go higher than 50A (and they need the 20% derate). I can take responsibility for my own assembly...

I used these for the Mega Hydra: http://www.grainger.com/product/DAYTON-Compact-Contactor-6GNV0 They're more expensive, and they require a contactor adapter, but they're UL and CE approved, which I think has definite value. Besides, if you're willing to spend $400 for J1772 cables (that's a...

You can use line powered contactors with OpenEVSE, but you'll need a contactor adapter to allow the 12VDC relay outputs of OpenEVSE to switch 208/240 volts for the coil. They're $7.50 plus shipping from my store - http://store.geppettoelectronics.com

When two cars are plugged in and only one is receiving power (for whatever reason), the charging car gets 100% and the idle car gets a 50% pilot. At first glance, this would seem to be problematic, since that's more power than is available. In essence, the Hydra is writing a check it can't cash...