Charge in Time Slot Fail

Yes, the departure time is the culprit. The wall charger takes a very long time, so it is over-riding your charge parameters to assure your car gets charged. Try going to a fast charger to get it to 80% first, and then see if it charges in your desired slot when you are home. I wonder if you can use a smart outlet with it? You may eventually want to install a level 2 charger if you can, it makes life easier.

 

I wouldn’t fast (DC)charge beyond ~80-90% because it slows down the charge speed beyond that. This is a function of all BEV and only happens with the DC fast chargers. You will notice that all EV’s on the market talk about their fast charge time in 20-80% state of charge. Also, if you are charged to 80%, you will probably be able to just home charge the last 20% in the cheaper electricity window. The car has a buffer built in, so I am not hesitant to charge to 100%. That is also what is in the manual. That buffer allows the car to fast charge near 50kw for a higher battery percentage before throttling at DC charger. If you end up installing a home level 2 charger, reach out to your electricity provider. PG&E gave me money towards my smart charger, so I really only paid for having the new breaker and wall box installed. That expense varies based on if you have room in your breaker box, and how much new wire they need to run.

 

From other discussions I have seen that there is move 'overhead' (i.e. current lost that isn't taken as a charge) in Level 1 charging, so while you probably need Level 2 charging to be able to hit the window at night when you'd prefer to charge, you also will lose less electricity to overhead.

I've seen different numbers thrown around so I won't bother quoting a figure - but depending on how much of a discount you're getting overnight it could make up the cost of EVSE/install over time.

 

I believe it's true with all charging, just most noticeable with DC fast charging. The charge rate slows down near the end to avoid overcharging.

And with the MINI it's ABC – Always Be Charging. There is no risk by charging to 100%, MINI has built in the buffers to keep things simple. This means MINI's 100% is in reality similar to Tesla's 80%.

 

AFAIK, there's no way to stop the MINI from charging to full, once it has begun charging, shy of manually unplugging it or using a smart connector or outlet that can be remotely toggled off.

We have discovered that if your departure time is within or up to 30 minutes after your cheap rate window, the MINI will begin charging at some time it selects within the window to finish on time (or sometimes a couple of minutes late).

But, if you set your departure time at least 31 minutes after your cheap rate window, the MINI will begin charging at the opening of the window.

However, the MINI prioritizes a full charge and will begin charging as early as it thinks it needs to, to reach 100% by departure time, including before the window, if necessary. For this reason, and because of the increased efficiency of charging at high Wattage, if you have a significant nighttime power discount, it would be worth it to have L2 installed in your home.

 

I'd look into the Tesla J1772 EVSE--IF it can be connected to your existing Tesla EVSE. The way @F14Scott explains how two Tesla EVSEs can work together on the same circuit sounds ideal.

 

Yeah, if the Gen 2 J1772 Tesla wall connector can talk to your Tesla connector (is yours a Gen 2?) via the communication cable (and there remains a question whether the two dissimilar yet both "Gen 2" connectors can talk to each other), then you are a simple electrician's job away from a super slick setup: the same breaker, some new wire, and a second connector, with either/both able to be used at all times, with zero need for planning loads, etc. Well, maybe not zero, if you are doing strict cheap power windows and/or have very big discharges in both cars at the same time, but generally, my wife and I just plug in and go without a thought.

 

Here's my understanding of the current Tesla EVSE state of the art:

Wall connectors

Gen 2 HPWC - What I have x2. Up to a 100A breaker. Chain up to four together with the communication cable. All can share the same breaker or have separate breakers. Only communicates with other Gen 2s, via a cable. Not for sale, anymore.

Gen 3 Wall Connector. Up to a 60A breaker. Chain up to 4 via WiFi. Each connector needs its own breaker. Only communicates with other Gen 3 connectors, via WiFi.

Gen 2 J1772 Wall Connector. Up to a 50A breaker. Is stated to be able to connect via cable to other Gen 2 1772 connectors. Unknown if that means it will talk to the Tesla-nozzled Gen 2 HPWC (like mine, above).

Plug in connector
Tesla Portable connector. Great piece of gear. Up to 32A on a NEMA 14-50. Versatile plug options via different pigtails. I keep one in my MINI, instead of the factory connector. But, no talky to anything; it's a standalone connector.

I'm probably boring the other forum members with my setup, but I'll repeat it for you, for clarity:
Two Gen 2 HPWCs. Both are on the same 60A breaker. They are connected to each other with a comm cable. To "my" connector, I leave a Tesla to J1772 adapter attached, and I also keep another identical adapter in my car, since my experience has shown me there is a robust and free Tesla destination network out there, and because it allows me to use my Tesla portable connector with the MINI

With my two communicating Tesla connectors, I can plug or unplug either or both cars at any time, in any order, without restriction. Worst case, they both want to charge at the same time, and both get 24A each, automatically. Alone, they get 48A for the Tesla or 32A for the MINI.

 

Well, ratfarts. According to this video, the Tesla J1772 Gen 2 does NOT talk to the "regular" (like mine) Gen 2 HPWC.

 

my perspective is that the car is normally driven during peak electricity rate. and even if u start charge before below peak hours it might be just 15% of your whole session. So the average cost is still close to the lower rate. Now i just plug in anytime and let it charge.

 

This plan would work. However, I've not played with the J1772 to Tesla adapter; does the car dial down its draw automatically to not overload the adapter, or do you have to do that manually via the touchscreen? Because, frankly, I don't trust software, envisioning the car's rebooting or a firmware flash resetting the draw back to full blast.

To answer your other question, "yes," the advantage of having linked EVSE is that they can apportion the limited power intelligently.

Take me, for instance. 60A was all my panel could spare. But, my Tesla and MINI draw 48A and 32A respectively. I could never charge them together; I would have to use timers and be sure I didn't have timer overlap. If one car were charging on its timer and I wanted to charge the other car, I'd have to shut off that timer before initiating the other car. I'm not sure my wife would have been up to the decision matrix, and I could have done it, but it would have been a source of concentration and worry.

But now, with the intelligent sharing, we plug in and charge whenever we want: alone, together, immediately, on timers, absolutely any permutation. Worst case, we each get 24A until one of us is full, and then the other gets up to 48A. Never any chance at overload.

 

To be honest, I don't think you're saving much at all by charging at night versus daytime - a few cents, maybe? Certainly not worth the hassle. Anyone have more exact information beyond just my hunch?

 

You have to check w your electric company. I switched to an ev plan: 9 cents/kw super off peak; 30-something cents off peak; 60-something cents on peak. Estimated to save over $1k over a year (2 EVs in our household).