Winter plugging in with time-of-use rate plan

[MattVT]

Following the mantra of Always Be Charging, I've got myself into the habit of plugging the truck as soon as I get home, every time I get home. I get a reminder to plug the truck in 15 minutes after I get home if I've forgotten, and another at 9:15pm if the truck is unplugged but home.

Always Be Charging.

Except it's not. Because we're on a time-of-use rate plan, and our EVSE (Emporia Pro) has the hours programmed in so that it won't charge the truck during peak hours which are 1-9pm, Monday-Friday. So even if it's plugged in, it's not actually charging unless it's during off-peak hours.

And as best I can tell, it's not just "won't charge" the truck, but also "won't let the truck maintain battery temperature" either - I guess it's pretty dumb and there's no negotiation about "why" the truck wants power, so it just cuts the truck off during those hours.

It gets pretty cold here in Vermont - last night we got down to -5°F (-20°C) and didn't get above 20°F (-7°C) all day. If today is like yesterday, it'll be 5°F (-15°C) by the time the charger lets the truck have some power at 9pm.

If I'm understanding correctly, the truck will not do anything to heat the battery if it isn't plugged in. The truck does know that it's plugged in, but charging is paused - if I look in FordPass via HACS, I can see "EV Plug: CONNECTED" but "EV Charging: PAUSED". So technically the truck is plugged in and knows it, but will it do any battery heating?

Does anyone know how often the truck would actually be pulling grid power to heat the battery in conditions like these, assuming it did have access to power?

I'm wondering about whether it's worth configuring my charger to allow the truck to "charge" during peak hours, but only if it's already at the maximum configured SoC (90% for me, most of the time). That would essentially mean it's only using peak-hours power to maintain the truck, but not to actually charge it.

Also, what happens if I limit the charge current to something like 5A? Will the truck still run the battery heater?

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[richguy82]

Not helpful, but I’ve wondered a similar thing myself. I’m considering setting up the schedule entirely in FordPass instead of Emporia to see if this would allow for preconditioning in non charging periods. As of right now, I have a window from 7-8 am opened up in Emporia to allow for preconditioning when I leave at 7:55am. Unfortunately, Dec-Feb means this is during peak hours (5-10am). I don’t want the truck to charge, just prep.

 

[Lightning Rod]

Bookmarked.

 

[mr.Magoo]

Does anyone know how often the truck would actually be pulling grid power to heat the battery in conditions like these, assuming it did have access to power?

I'm in Michigan and while it doesn't get crazy cold we do see negative F a few times per year.

I do NOT follow ABC because my charger is outside and I want to keep the truck in the (detached) garage.

My battery health is still 100% after three years so while my practice might not be ideal, it certainly isn't causing severe damage either.

So I wouldn't worry about it in the first place.

The answer to your question is a bit of "how long is a piece is string" since it'll depend on the weather/temperature.

Last night mine was charging to about 1am and the warmup sequence kicked for 10min around 8am, but it was only around 15-20F outside.

 

[chriserx]

AFAIK, it's obviously less than ideal for it to be frozen, but most of the problems I've heard about are related to charging frozen batteries of this type and not necessarily 'storage'. There is also some temporary loss of power when discharging a frozen battery but I've never seen anything about permanent loss.

 

[Athrun88]

I have my ToU schedule set up in the truck (8pm to 6am, M-F; anytime, Sat/Sun), my Chargepoint Home Flex, while it can also set a schedule, I leave it as is. I found that the truck will draw power at night from time to time as needed for whatever is required; whether that's for warming the battery, topping up the HVB, whatever. It'll also trigger the preconditioning in the morning even outside of the set charging hours (I have my departure time as 7:30am) as long as it's plugged in.

TL;DR - If you set your charge schedule on the truck, it seems it'll do what it needs to do off shore power.

 

[electricpig]

We allow charging from the EVSE anytime, but set the EVs to off peak hours. That way they can still draw power if needed for vehicle health, heat or cold

 

[topher10]

I agree with others. I also have an emporia, but I set charge times on the truck, not the charger. That way it’s the trucks choice when to charge.

I’m not sure if that matters for battery maintenance, though.

 

[electricpig]

I agree with others. I also have an emporia, but I set charge times on the truck, not the charger. That way it’s the trucks choice when to charge.

I’m not sure if that matters for battery maintenance, though.

Someone posted a few days ago detailed graph of power draw by their truck vs time. Turned out there was a short but repeating spike of energy draw from the truck. So it will use the wall power, and Ford says as much in there recommendations to plug in during very cold and very hot weather if possible to maintain vehicle health. So yes it will use EVSE power to maintain battery temp.

 

[TaxmanHog]

Does anyone know how often the truck would actually be pulling grid power to heat the battery in conditions like these, assuming it did have access to power?

Last year I did several test for spontaneous battery warming process, the events typically occur with severe cold conditions (under 20 degrees) between midnight and 6am well before my regular departure time frame at 7:55 am, kick off would occur up to an hour prior if the temps are moderate 30 to 40 degrees, ie. ~6:50 am

If you can loosen up the TOU constraints to have the Emporia offering energy after 11 pm , you should see power flowing in the middle of the night.

 

[TaxmanHog]

Also, what happens if I limit the charge current to something like 5A? Will the truck still run the battery heater?

To low, It needs 30+ amps at 240 v

 

[TaxmanHog]

By the By I'm doing the spontaneous battery warming analysis on this thread next Tuesday morning.

CHARGING IN THE WINTER

 

[fhteagle]

AFAIK, it's obviously less than ideal for it to be frozen, but most of the problems I've heard about are related to charging frozen batteries of this type and not necessarily 'storage'. There is also some temporary loss of power when discharging a frozen battery but I've never seen anything about permanent loss.

There's is one other issue, which is charging to a high SOC while warm to hot and letting it cool without dropping the SOC on it. This can drive a certain type of degradation, but I can't remember specifically which one.

That being said, Ford's 90% displayed SOC was actually like 85% raw SOC shown in CarScanner last I looked (I need to check the raw cell voltages as that is what actually matters more). So about the ~87% (~4V/cell) that my old Volt called 100% on the display. It charged warm and got cold for years, and I didn't have unusual degradation...

 

[chriserx]

There's is one other issue, which is charging to a high SOC while warm to hot and letting it cool without dropping the SOC on it. This can drive a certain type of degradation, but I can't remember specifically which one.

That being said, Ford's 90% displayed SOC was actually like 85% raw SOC shown in CarScanner last I looked (I need to check the raw cell voltages as that is what actually matters more). So about the ~87% (~4V/cell) that my old Volt called 100% on the display. It charged warm and got cold for years, and I didn't have unusual degradation...

That likely has more to do with storing the cells at full charge than anything. From my understanding of it from worst to least worst for the cell and this is before any design mitigations.

1) Charging below cell temp -32F
2) Charging above cell temp ~120F
3) Storing cell above 90% SOC long term (Depends on ambient where exactly this goes, but the higher the ambient, the higher this goes)
4) Cell charge depletion (especially long term)
5) Fast charging
6) High discharge rate at low cell temp
7) Storing cell above 80% SOC long term
8) Charging cell above 80%
9) Number of full charge cycles

The Lightning has mitigations for them though
1) Battery warming
2) Battery cooling
3) 100% displayed SOC is actually ~92% cell charge
4) Deep sleep, possibly others
5) Variable charge rate to minimize impact
6) Battery warming
7) There could be mitigations but unknown to me
8) 80% displayed SOC is actually ~73% cell charge, reduced charge speed, battery cooling
9) C'est la vie, c'est la mort

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