Delayed Charging

Is there a way to just not set a preferred slot and still have charging complete right before a planned departure time? I don’t have a lower-rate time period so all I’d like is to have the “next departure only” setting just simply work.

On the other hand, I am on a temperature-based rate plan — when it goes below -12°C (~+10°F), the rate jumps from 4.3¢ (Canadian) to 31¢! — so I’d like to find some kind of smart integration that prevents charging when it gets that cold outside unless I override it. The Grizzl-E Smart is OCPP 1.6 compliant, but I haven’t found anything yet that works with my ecosystems (SmartThings, Alexa, Nest).

 

I know a few that brute force it by putting an appropriate size Definite Purpose Control Contactor (i.e relay) that makes or breaks power to the charger. The relay coil is plugged into a smart plug that that is controlled by IFFT or some other smart app which breaks the connection when the temperature drops.

The Grizzl-E is advertised as OCPP 1.6 compliant but, last I heard, the kids trying to write code to control it have found its not exactly compliant (devil in the details) and their firmware is revised often. It may be straightened out and more stable by now, but that could be an elegant solution. In the end, probably not as reliable as the brute force method.

 

Bummer. Could be so simple to integrate if someone were willing. Double bummer, I have a Jasco 40 Amp Z-wave switch (100-277 VAC single or double pole) that I am retiring from pool pump duty, it would work just fine but I’ve wired my 14-50R with 6 AWG and the Jasco box maxes at 8 gauge.

 

If Grizzl-E could be controlled using Siri, just like ChargePoint, then an iOS automation could be created to get temperature from current weather conditions and stop charging conditionally.

I was able to test this on my ChargePoint. One downside is multiple automations need to be created for it to run periodically as a automated tool.

 

I remember reading this months ago when I was using Lv 1 only, but now that I have my 240V installed and using Lv2, setting delayed charging is much more relevant. Took me a while to find this post! I also remember a stickied thread that mentioned you could set the charge-slot to something like 5 mins before your departure slot to trick the system to have it fully charged right before your departure, but I don't think that worked the 2 times that I tried.

@Puppethead now that a year has passed since you found out the 30 minute magic number, do you have any new findings or tips for delayed charging? In your usage have you always left the charge-slot between 21:00-06:31 for a 07:00 departure, or have you tried a shorter slot?

I will be testing the 29min departure time method over the next few days and will report back!

 

I have my weekday departure time set to 07:30. For summer I have my charge window set 21:00-06:59 and my SE starts charging immediately at 21:00. Come winter (not too many weeks away now), I'll switch my charge window to 21:00-07:01 and it should wait to charge towards the end of the window.

I don't think the actual charge window size matters, other than if it's less than say three hours (or whatever it takes for a full charge). The SE does seem to favor a full charge by departure time over staying in the window.

 

I have an openEVSE. Yep, open source. This is likely the easiest EVSE to integrate a temperature control with. Can you code? If not, a feature request may pique the interest of someone who can.

 

Interesting approach. I like my SE to charge at the end of the window year round. In the summer, that lets the battery cool overnight before charging. In the winter, it gives me a warmer battery (mostly for more power) on my morning commute.

What is your reason for your approach?


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I prefer to have my SE fully charged as soon as possible, in case I need to go somewhere unexpectedly overnight. I'm typically home around 6 pm and my low-cost charge window doesn't start until 9 pm, so plenty of time for the active cooling to cool down the batteries.

Like you, in the winter (when I will experience temperatures well below zero), I delay the charging to the end of the charge window to warm up the batteries before I drive off in the morning. That also helps to stave off the cold-soaking my SE experiences sitting outdoors all day long.

 

Ok, I see. I never really have to worry about enough charge to go back out again in the evening. Even if I did and the car was too low, I’d just take the Bolt.


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I probably won’t get to it imminently, but I’ve sketched a simple mock-up of a “sub-panel” with the Grizzl-E hardwired into the 40 Amp Jasco/GE Zwave relay with 8 AWG, and a NEMA 14-50P pigtailed from the relay to the receptacle. The outlet remains to code, and the accessory relay is wired correctly and capable of handling the Grizzl-E’s maximum draw (set to 32 internally for the SE’s charger). Tiny bit more clutter on the wall and a minor expense for the extra plug and wires, but an easy way to “automate” charging based on outdoor temperatures.

The only real drawback to this plan is that it isn’t really “smart,” because it can’t talk to the car like building an OCPP app could. So while I’d like more conditions added to the control (ie “IF [outside temp] <-12°C AND [SOC] >45% THEN TURN OFF [EVSE]”), short of learning yet another New Thing™ and spending way too much time on it, I’m stuck with single-conditional control based on temperature, and having to keep track of the car’s state of charge.

 

I searched for every possible way to make the Grizzl-E “Smart” integrate directly with my smart home ecosystems, to no avail. I don’t even think writing my own OCPP-compliant app and running my own server would work, and I have no intention of spending the winter trying to learn all that. The Home Assistant guys have been beating themselves up over it for years, and still nothing that works consistently or effortlessly.

So I decided to go with hardware. Turns out, a bylaw change has been tabled until 2025, so we’re keeping the pool running. I just ordered an Aeotec 40 Amp Zwave relay instead of reusing the Jasco/GE outdoor unit from the pool pump. I already have an Aeotec in winter Service to control a 5000 W resistive garage heater and it works fine. I’ll remove the 14-50 pigtail from the EVSE (it’s wired with 8/3) and connect it from the receptacle to the Zwave switch on the line side, and I ordered a 3-foot cut of 8/3 SOOW cord from Amazon to go from the switch load side to the Grizzl-E. The switch will mount out of the way on the wall below the outlet and the EVSE. Then a simple routine (automation) that will switch off the EVSE if the outside temperature is below -12°C, but only if there’s less than 100 W going through the switch (it has energy monitoring) so it won’t go dark during a charge.

 

We're now in winter conditions so I set my charge window to 21:00-07:01 (departure time 07:30) and it did indeed wait until the end to charge my SE, finishing charging at 06:51.

 

Where is it winter? You’re like the third person in the forums I visit to say they already have their winter tires on! It hits 69° here today.

ETA: PS: Yes, I know overnight lows are regularly near freezing now in Way Upstate and especially in higher country. That’s why I will eventually look for “intermediate tires” for this car. The rule of thumb is to switch from all season tires to winter tires when the temperature is regularly below 7°C for extended periods, but I’d be willing to bet (based on the noises they’ve been making) that the Eagle F1 summer tires stiffen up somewhere around 12 to 14°C.

 

If your morning drives are 30F or colder, then it's probably time to swap. I am also on winter tires as well.

 

Yeah, its not that cold here (yet). Believe it or not for a city that averages 8 feet of snow every winter, we enjoy a pretty gradual slide from summer to winter, with fairly temperate transitions. On the cars running all-seasons I don’t usually switch until the 7-day forecast calls for a measurable snowfall and sustained cold — usually mid- to late-November. On the smart with its sticky UHP summers, I’d park it when morning drive-time temps were regularly in the low-teens (low-50s), and switch to winters when I did the other cars.

 

Minnesota is serious winter, we're basically like Canada. We even have an ice road now. I don't have my winter wheels on yet, we still haven't had a hard freeze (ground is still warm). But it is cold enough that I want heat in my car, although I'm playing around with just climatizing in the morning instead of delaying the charging. The weather's still above freezing, although my efficiency dropped to 4.3 mi/kWh today likely due to using the heater.

 

I admire you to use SE in such harsh climate as I live in my 30 years in Eastern Europe with quite cold climate but driving ACE cars there with heat accessible I can’t imagine how you doing with - 30 F. In MN using SE daily.In NY I drive a SE 5-10 miles in winter from warm garage I don’t use a heat sometimes a heated sits only and when is snowing I drive Subaru.But in my case is different story I retired and if is snowing or cold I don’t need to be on a road.Did you ever think to put additional 12 volt battery on floor and a small heater to supplement heat and trickle charge battery over night just to not use HV battery for extra heat?

 

Minnesota is extreme. Minnie is one of the hottest places I’ve visited in July — was 109° plus humidity — but one of the coldest, too, in late January it was -36° plus wind. Y’also get tornadoes. The rest of us are wusses.