Outdoor Wifi Smart Plug with 120 Volt EVSE

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Active member
Nov 12, 2021
Since I only drive about 2 times a week the biggest annoyance for me is remembering to plug my car in. Lots of times I remember right before or after I crawl into bed. This is super annoying to have to put clothes back on and go into a cold garage in the winter. My garage is not attached and while I don't live in a high crime neighborhood we do get some bad people around here from time to time. Walking out the door late at night isn't without a little bit of risk for me here. Believe me I done it dozens of time since I bought my car almost a year ago. Since it is not good to leave an EV fully charged just sitting I don't automatically plug my car in when I get home. The built in app in the car does not let you skip days.

So I just bought a smart outdoor Wifi plug. It should let me tun on and off the power to the plug through my phone and even has a countdown timer so that I can have the app turn off the power. This way I can have the plug cut the power to the EVSE before the car is fully charged if I know I won't be driving my car for a few days. It will require I do a bit of math to decide how long to let the car charge for. I will aim for around 70%. That should be the ideal percentage if the car is going to sit for 3 to 5 days or more. The app will even let me set a daily charging schedule. It will take a bit of research and monitoring of my battery to figure out how many minutes a day to keep the battery at say a constant 50% charge if I know I won't be driving for a few weeks or month.

I just bought an HBN Outdoor Wifi Smart Plug. ETL Listed rated: 15 Amps, 125 Volts, 1875 Watts. The EVSE that came with my car 12 Amp, 1440 Watts so the smart plug should easily be able to handle it.

I know there are smart Wifi outdoor plugs that will also monitor how much electricity you have used but that wasn't important to me and for $21 on Amazon I think it is a pretty good deal. Has 3 outlets and each can be controlled separately. Not sure what I will use the other two for if at all. There is a near identical one made by the same company for $19 but it just turns on and off all 3 outlets at once.

Anyway, I will let you all know if my $21 experiment works to turn my dumb EVSE into a Smart EVSE. :)

Good news, it Wifi plug works like a charm. :D

The car does give me a message that there was a power loss while charging after turning on the car or radio. Since I know the reason for the power loss is the Wifi plug cutting the power there is no mystery there. The only thing I wish the plugs or Google Home had would be the ability to set a specific date and time on a calendar to turn the EVSE on and off. Not that big of a deal I can set the on and off times by days of the week. This means I can set something a week in advance.

I charged my car for 20 minutes on 12 Amp setting. The Wifi plug did get a bit warm but no more than the EVSE's plug cord. When I ran a 20 minute 8 Amp test both were a bit cooler. Since the default is 8 Amps anyway and with the app being able to scheduled charging times for each day of the week 8 Amps should be just fine 98% of the time. I can still make use of the car's built in app to have the car charged at time of departure.

The cutoff feature of the Wifi's app was pretty easy to figure out too. My guess O-Meter usually says 79 to 80 miles at full charge. So if I want the car to charge to 70% I take 80 multiply by 0.7 and that is 56 miles for 70%. If for example when I get home my range is down to 22 miles take 56 minus 22 means I need to charge 34 miles to get to a 70% charge. 8 Amps give you 3.7 miles of rage per hour. 34 divided by 3.7 is 9.19 hours it take to charge to get 34 extra miles of range thus getting the battery up to 70%. So I just set the Wifi Plug count down to 9 hours 11 minutes and the Wifi Plug will cut power to the EVSE after 9 hours 11 minutes.

I am mainly writing this down to make sure I have it all straight in my head. I sure to all of you these sort of calculations is second nature by now.

If you decide to go the same rout I have make sure whichever Wifi plug you choose is UL or ETL listed so you are sure you will get a quality product that is safe. Also make sure it is 15 Amp and the highest watt rating you can get. The one I got is 15 Amp and 1875 Watt rated. The Spark EV's EVSE charger that comes with the car is 12 Amp 1440 Watts at it highest setting. You do not want to exceed 80% of the rating of the Wifi plug. So 80% of 1875 is 1500 Watts so the Spark's EVSE that comes with the car is well below 80% at 76.8%.

I hope someone finds this info interesting or useful. If I run into any problems or new developments I will be sure to post them here.
FYI - you could just program the Spark for departure time charging mode. In MY manual (2015) it is in the "Programable charging" section starting on page 5-19. the description starts on 5-22, and is mentioned on almost every page until 5-27. Basically, the car starts charging at the exact time necessary for you to be "full" at departure time, based on your current SoC.

Since you don't use many miles per day, calculate how long it takes to add 10% charge to the battery, then multiply by 3 and add that amount of time to your regular departure time. For example, say you normally leave at 8 a.m. If you charge at 120V/12A, you put about 1 kWh an hour into the battery. Say you have 15 kWh capacity left in your battery. 1.5 hours will add ~1.5 kWh. 3x1.5 = 4.5. So, add 4.5 hours to 8 a.m. and you get 12:30. Program departure time for 12:30. When you leave at 8 a.m. , you will have about a 70% charge - every morning. Or, if you'd rather be at ~80% every morning, set charge time for 11 a.m. You just have to remember that on weekends you should unplug the car in the morning (or just not plug it in). Then, it should become your routine to plug the car in every night, and unplug it every morning. You will leave the house every day with 70-80% charge.

Dont forget to also read "Temporary Charge Mode Override and Cancel" (so you can immediately charge when needed) on page 5-26.
Good idea to have the smart switch as a "cancel charge" button when you wont' be driving every day.

Does the alarm not trigger when you disconnect power from the EVSE? That's what mine did while the doors were locked. Maybe there's a vehicle setting that you have to turn off...
Thanks for the info SparkE. Yes I know about programming a departure time and I actually do use it quite often even with the Wifi Smart Plug. Here is an example. Say I know I am not going to drive the car Monday and Tuesday and the last time I am driving the car is on Sunday. So when I get home on Sunday I plug my car in but the EVSE has no power because the Wifi Smart Plug has turned it off. Every other Wednesday I know I am going over to a friends house and will be leaving at 4 PM. So I program in my car a departure time of 4 PM every Wednesday. On my app on my phone for the Wifi Smart Plug I have it set to turn on the plug for the EVSE at 12 AM Wednesday and to turn off the plug at 6 PM. On weeks that I don't go on Wednesday in my phone I just turn off that Wednesday trigger. By having the phone app turn on and off the Wifi Smart Plug thus controlling the power to the EVSE I can just plug in my car on Sunday and not worry about the car charging on Monday and Tuesday but that it will automatically charge on Wednesday. Wow that all sounded really convoluted. Believe me it is easier in practice.

I really wish Chevy had made a better charging app both for the car and a phone app. It be nice to set reoccurring charges as well as a calendar date. Think Google Calendar notifications type app.

How I have it setup now is those days of the week that I know I will be leaving at the same time every week I have the departure time programmed in the car. Then in my phone app for the Wifi Smart Plug I have it set to turn on the EVSE power at midnight the day of. I let the car then decide when to start charging. On days that I normally don't drive I have a departure time set at 11 AM. If say on one of those days I am leaving at 5 PM I have to manually calculate when to start the car charging to it will be fully charged by 5 PM. As long as I start the car charging before 11 AM I am good. If I forget then I have to go out to the car and set it to charge immediately instead of departure time.

I recently bought a smart 220 volt EVSE that has Wifi built in and supposedly a much better built in app. I haven't installed it yet so I don't know if the new smart EVSE can read the current battery level of the car. My hope is it is smart enough to be able to program in departure time and date and just let the Smart EVSE do all the rest. That way I can just leave the car on immediate charge setting and never have to play with the car's departure time built in app ever again.
Hi Infinion,
When my Outdoor Wifi Smart Plug cuts the power to my 120 Volt EVSE my car doesn't make any sound or alarm. I am pretty sure I turned off the alarm setting in the car's setup. I believe there is an alarm setting if the car is charging and someone unplugs the car before it is fully charged.

I just looked through the whole manual and couldn't find anything. Anyway, just press the home button which is to the right of the on off button of the infotainment. At the bottom of the screen with be "Settings". There are all sorts of settings in there. I believe the one you want is the one that sets off the alarm or honking horn if the car is unplugged while charging. I guess the alarm is supposed to be handy if you are at a public charging station and some jerk decides to unplug your car.

Over all I am really happy with the Outdoor Wifi Smart Plug. It does make controlling when the car charges and when not a heck of a lot easier. It has allowed me to get in the habit of always plugging in my car as soon as I get home even when I know I won't be driving for a few days. I almost regret buying a 220 Volt EVSE that has built in wifi and phone app which I haven't installed yet because the Outdoor Wifi Smart Plug does such a good job.
Maybe you're already doing this or maybe it's already been suggested (can't quite be sure from the lengthy descriptions), but there's a simpler way to use the delayed departure time feature that requires no calculations, and works the same every time so no thought is needed:

Just pick a future time the next day, late enough to ensure enough charge, let's say, 2PM.
(I've never used this feature. Can you set it once and have the time remembered for all future charges?).
Can you set the wifi outlet, not by days of the week, but for a single, one-time charge? Turn on the wifi outlet and set it to turn off (and stay off) maybe 4 hours before that time, say, 10AM (based on your 3.7mi/hr of charge)
Make sure the wifi outlet is set to go on exactly once. Never turn on again automatically.
You can pick the times that mostly work with your schedule, but you never have to change these times.

From now on, all you have to do is plug in the car as soon as you get home and turn on the wifi outlet. The next day, your car will be charged up to ~80%, ready to go, but unplugged. Now there's nothing to calculate, no need to remember to charge before you go and you CAN plug the car in automatically as soon as you get home. If you're not leaving the car idle for many months at a time, it'll still be charged to 80% days later.

If by chance you have one day when you've fully discharged the car, and been out partying til 3AM, and need the car the very next day, just tell the wifi outlet to stay on that one time.