Charge in Time Slot Fail

[JoeC]

Hi all,

I just got my car this week and have now failed twice to have it charge in the middle of the night (when rates are lowest).

The first night it simply didn't charge at all overnight. I set the Charge in Time Slot to midnight to 3p. I can't remember my other settings.

Today at 4p, I reset the Charge in Time Slot to midnight to 3p. I also chose a 3p tomorrow/Friday departure time (not sure why I should need to set a departure time to set a time slot - sometimes I need to charge but don't know when I will next leave home). At 515p, however, the car started charging (almost 7 hours before I wanted it to start).

Anyone know what I (or the car) am doing wrong? I checked the clock on the car and it had the correct time. I also wondered whether the car started charging early to ensure it got to 100% by my 3p tomorrow departure time. I don't think this is it, however, as I still got a warning that the car wouldn't fully charge by my departure time.

Thanks in advance!

 

[JoeC]

Looking at the following text from the manual, I think that the car indeed started charging before the low cost time slot because it was trying to finish charging prior to the departure time.

"The vehicle can also start the charging process
before the selected time window begins
or end it after the selected time window finishes.
The starting point of the charging
process is adjusted so the vehicle can be as
fully charged as possible and, if applicable,
its climate adjusted by the departure time."

If the didn't start charging until midnight (the start of the low cost time slot), it wouldn't have gotten close to 100% by departure time (3p). Given slow Level I charging rates, I am not sure it is possible to confine charging to the low cost time slot, especially if the battery is close to 0% and it would require >20 hours to charge to 100%. Thus, it is prioritizing getting to a full charge, even if it means charging during higher cost times outside of the Charge in Time Slot. This probably wouldn't be an issue with a Level 2 charger as you should be able to get to 100% within 8 hours or so, ideally fully within the low cost time slot.

 

[Greencarguy]

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.

 

[JoeC]

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.

Thanks for confirming this. Yes, I was hoping to save $ and avoid the expense of another EVSE and related electrician expenses. This might be really tough, however. Yes, getting the charge back to 80 or 100% and then using only 15% per day might make overnight top offs at low rates possible on Level I.

You say get it back to 80%. Why did you say 80% instead of 100%? Was this to avoid fully charging the battery to improve longevity? Or is this because charging from 80% to 100% (assuming 20% used per day) is slower than charging from 60% to 80%? I think I have only been getting ~2-3%/hour while charging from 15% to 30% so god forbid it is slower than that.

Tx!

 

[Greencarguy]

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.

 

[cmdonnell]

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.

 

[Puppethead]

I wouldn’t fast (DC)charge beyond ~80-90% because it slows down the charge speed beyond that.

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%.

 

[F14Scott]

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.

 

[JoeC]

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.

Thanks, GreenCarGuy. When did you get the rebate from PG&E? We got the rebate for another charger that we installed in late 2019, but I can't find anything similar on PG&E's website now so perhaps they discontinued the program. The federal tax incentive is still available if we can get it done this year (30%? back).

I could purchase an adapter to use on the Tesla Mobile Connector but this would require swapping parking spots with my wife when needed - she is not a fan : ). Thus, I am trying to figure out the cost of installing an EVSE or 14-30/50 outlet outside, where I will usually park the car. Or, perhaps getting a very long cable on a mobile EVSE that would allow me to use the 14-30 outlet in the garage while parked outside. This would require running the cable under or through the garage door, which doesn't seem good.

 

[insightman]

Thanks, GreenCarGuy. When did you get the rebate from PG&E? We got the rebate for another charger that we installed in late 2019, but I can't find anything similar on PG&E's website now so perhaps they discontinued the program. The federal tax incentive is still available if we can get it done this year (30%? back).

I could purchase an adapter to use on the Tesla Mobile Connector but this would require swapping parking spots with my wife when needed - she is not a fan : ). Thus, I am trying to figure out the cost of installing an EVSE or 14-30/50 outlet outside, where I will usually park the car. Or, perhaps getting a very long cable on a mobile EVSE that would allow me to use the 14-30 outlet in the garage while parked outside. This would require running the cable under or through the garage door, which doesn't seem good.

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.

 

[F14Scott]

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.

 

[JoeC]

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.

Thanks, F14Scott. That would be very cool, indeed. We are currently using a Mobile Connector to charge my wife's Model 3 in the garage. Does the Mobile Connector have the "coordination" capability with a J1772 Wall Connector? Or would I need a (Tesla charging) Wall Connector to speak to the new J1772 Wall Connector? If I need the Wall Connector to coordinate, I am not sure it is worth the expense to upgrade from the Mobile Connector to a Wall Connector at this point. Might still go with the Tesla J1772 Wall Connector outside for the MINI to create options for the future (assuming it provides similar functionality to non-Tesla EVSEs).

Thanks again!

 

[F14Scott]

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.

 

[F14Scott]

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

 

[Smart Wannabe]

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.

 

[JoeC]

Thanks, F14Scott. Great info. Too bad the Mobile Connector (which we already have) doesn't communicate. This means that we would need to also install a Tesla Wall Connector for our Tesla in lieu of the current Mobile Connector/14-30 setup. Is the main benefit of the "communicating" EVSEs that they can share limited electrical capacity between the two EVSEs when running simultaneously?

This would only be beneficial if you run the two EVSEs simultaneously AND you don't have sufficient electrical capacity to run both simultaneously (including two EVSEs on the same circuit or two EVSEs on different circuits but on a constrained subpanel). Correct? Our subpanel is already pretty full so this might be helpful.

Thanks again for helping those of us who are less electrically inclined : )

 

[JoeC]

Yeah, no mixing J1772 and Standard/Tesla Wall Connectors - this aligns with the J1772 product site:

Note: Tesla recommends installing with a 50-amp circuit breaker for maximum power output. For owners with multiple electric vehicles, up to four Gen 2 J1772 Wall Connectors can share available power, making it possible to charge multiple vehicles at home. Power sharing is only possible when connected to other Tesla Gen 2 J1772 Wall Connectors.

What about instead buying two Tesla J1772 Wall Connectors and using a J1772 to Tesla adapter for our Model 3 SR+? The adapter only supports 19 amps, but this isn't much less than 22 amps that we are currently getting through the Mobile Connector and 14-30 outlet. If this works, we get the load sharing and the Tesla J1772 WC isn't too pricey at $415.

 

[F14Scott]

Yeah, no mixing J1772 and Standard/Tesla Wall Connectors - this aligns with the J1772 product site:

Note: Tesla recommends installing with a 50-amp circuit breaker for maximum power output. For owners with multiple electric vehicles, up to four Gen 2 J1772 Wall Connectors can share available power, making it possible to charge multiple vehicles at home. Power sharing is only possible when connected to other Tesla Gen 2 J1772 Wall Connectors.

What about instead buying two Tesla J1772 Wall Connectors and using a J1772 to Tesla adapter for our Model 3 SR+? The adapter only supports 19 amps, but this isn't much less than 22 amps that we are currently getting through the Mobile Connector and 14-30 outlet. If this works, we get the load sharing and the Tesla J1772 WC isn't too pricey at $415.

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.

 

[Pete MINI ES]

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?

 

[ghost]

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).