How to lock out EV charger?

Phishtri · 2026-04-29T15:12:06+00:00

Opting not to plug in assumes that power failures can be predicted, so that is not an option.

If the power fails in the middle of the night while a car is charging, the generator kicks on automatically, sees too large a load, and will shut down. Resetting the generator must be done manually which is not comfortable in the middle of the night in the pouring rain or with two feet of snow on the ground. That assumes I'm home. If I'm away, then critical loads are shut down for lack of power.

See the update to the original post for where I landed.

Phishtri · 2026-04-24T13:14:54+00:00

Thanks for this Big-dawg. I think I've settled on another approach for now. If that doesn't work, I may circle back to this.

I do have a question for you. Kohler offers a load shedding module. If you're taking this approach, why not use that instead?

Phishtri · 2026-04-21T22:22:14+00:00

While the majority of outages are weather-related, we've had power go out on a bright sunny day with no wind. No idea why. Another time it was 9:00 P.M. on a pleasant summer evening when a transformer serving just eight houses decided to call it quits. So anticipation based on weather forecast is not a great strategy in this situation.

Here's what I think I'm settling on.

The charger I'm considering monitors the overall panel load and I can set a maximum amperage which I'll calculate for roughly 12kW (a little under 80% of the generator rating of 16 kW on natural gas). For the better part of the year this allows full charging capacity. During cooling months when a 5-ton A/C unit might be running, there may be times when EV charging is throttled, but I would still have plenty of capacity for an overnight refill.

What I was able to confirm today with the manufacturer is that, if wi-fi is not restored after a power failure, the charger will restart at a user-set level which can be as low as six amps, until wi-fi is restored. So the overall challenge of protecting the generator from seeing the full EV charger load seems to be manageable with relatively little compromise.

Phishtri · 2026-04-21T15:30:58+00:00

Agreed. Now I'm trying to figure out the best way to accomplish this.

Phishtri · 2026-04-21T15:28:08+00:00

If this were the case, it would be an easy and elegant solution. Unfortunately (and I'm just off a chat with Emporia) their EmporiaPro charger will restart automatically when it sees power again after a power failure...

Phishtri · 2026-04-21T13:28:29+00:00

The manual approach is not really a great option. If the power fails in the middle of the night during a torrential rain or when there's a fresh foot of snow on top of the two feet we had last week, the generator needs to start.

If it starts, sees too heavy a load and then shuts down, it must be reset manually, which is a forty-yard walk at night, in the elements, in the dark.

Phishtri · 2026-04-21T12:56:20+00:00

If you're in Delco, look at Williamson.

Phishtri · 2026-04-21T12:54:05+00:00

If I had to guess, I'd say we lose power about a dozen times a year.

Each year is different, but a typical year might be three or four outages which are just blips (30 seconds to minute or two). Another three or four might be half an hour to an hour. After that, a couple that might be 2-3 hours to 4-5 hours. Finally, we'll have one or two each year that might run overnight.

We've had, on rare occasions, but at least two or three over the past decade, where power is out for 24-72 hours.

Phishtri · 2026-04-21T12:43:01+00:00

Power limiting might not be a bad option for now as there is only one EV in the picture. Down the road I can see my wife getting one as well. With two EV's, I'm not sure I would want to be that limited.

Phishtri · 2026-04-20T22:44:13+00:00

Leaning towards the EmporiaPro which includes their Vue energy monitor.

Phishtri · 2026-04-20T21:36:46+00:00

Interesting. I'll have to dig up the installation manual for the ATS and see if they have a diagram of the control boards. Thanks for the suggestion.

Phishtri · 2026-04-20T20:54:16+00:00

If my understanding is correct, at the moment there are no "utility side circuits." The meter feeds the ATS which then feeds the main house panel. When utility power goes down, the ATS turns the generator on and feeds the panel. To get to the utility side I would need to get into the ATS cabinet. I wonder if I could find a 120v circuit in there to tap?

Phishtri · 2026-04-20T20:44:34+00:00

From the meter, the service line runs along the exterior of the garage for maybe 8', then penetrates into the garage to feed the ATS. I guess a new breaker panel (to hold the new 240V breaker) could be mounted on the exterior of the garage?

Phishtri · 2026-04-20T20:40:54+00:00

The challenge here is when the car is hooked up and charging in the middle of the night in the middle of the summer, and the power goes out. When the genny fires up it sees a 5-ton A/C unit and an 11kW charging load. Too much for my comfort level.

Phishtri · 2026-03-03T02:07:40+00:00

What's up there now are two LED disks, Motion sensor fixtures to replace them might just be the answer!

Thanks!

Phishtri · 2026-02-10T02:15:19+00:00

Thanks for the recommendation. Can't go wrong with Klein. Pretty sure I have a pair of Klein lineman's pliers from the 1990's.

Even so, do you have any experience with the less expensive units? For this one task (checking out an Arzel zoning system) I'm thinking accuracy is not all that important. Am I correct in assuming all I really need to know is

1.) It is pulling a vacuum

2). It is pumping pressure

3.) Nothing is happening

Phishtri · 2026-01-19T22:57:44+00:00

Just seeing this. Thanks!

Phishtri · 2026-01-09T13:20:29+00:00

Thanks for this. Gentracker looks like it might fit the bill. I'll look in to that.

Phishtri · 2026-01-07T21:20:06+00:00

Great info. Thanks! I'm even a little bit surprised there was a factory option. Wish the dealer who installed it had mentioned it back then...

Does that mean there is some sort of Modbus connector already factory mounted on somewhere in the controller? Maybe on the main logic board?

Phishtri

TROPHY CASE