Leave car plugged in at home when not away for a few days?

[Texas Flood]

I chose to leave mine unplugged while away for 16 days because we occasionally have violent thunderstorms here in Houston, plus we’re in the tropical storm season. I charged it to 70% and it lost a total of 30 miles of range (so 10%) over that time.

I checked it with the app four times during the trip. The first time, after 1 week, it had lost 9 miles. On successive checks, it seemed to drain a bit faster. I suspect that the bulk of the losses were due to me checking it.

 

[darth_vad3r]

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It’s about 30-40 feet from where I could park to the closest outlet, 120v, inside the walkout basement. Also, it is an older house. I believe built sometime during the early to late 1970’s. If I drive it to their house in the future I’ll have to buy the $50 foot extension on Amazon you mentioned. The trip is 400 miles each way to their house. The last SC I could charged at is about 60 miles from their house. So, I could charge up to 90-95% (approx 275-280 miles) and once I reach their house I should have about ~200 miles remaining due to lots of curves and steep graded roads.

The way it sounded before, I had thought maybe the 60-mile away SC was out of the way or past your destination.

If it is on the way, that seems totally doable with a (relatively) cheap 120V extension cable. You'll have 200 miles of range left, you might need 100 to get back to that SC for your trip back, so you have 100 miles + nightly charging to drive around while there.

12 x 5mph 120V gives you 60 miles a day. If you are there for say 3 nights, that's 180 miles + the 100 miles to spare, 280 miles for 3nt/4days is 70miles a day of 'local' driving while visiting, to leave you with 100mi to get to the SC for the return trip.

Not sure how much local driving is in the cards. If it's more than 70mi/day you'd need to find some L2's while stopping for groceries or a meal to supplement. If it's a lot less then you'll be totally fine with just 120V. For example if the car just sat, you'd be back to 100% after just 2 nights of adding +60 miles (and that's with you unplugging it during the day ... if you just left it plugged in it would be at 100% in less than a "day" (22 hours).

 

[Rocky_H]

Here's the plug I can use that's just inside their walk-in basement door about 15-20 feet from the driveway. What adapter do I need? I didn't see one that matches it when I looked at the Tesla home charging guide page.

I do have an answer for this at least. That outlet is a 10-50. And yes, you are right that Tesla doesn't seem to have an official plug for that for their 2nd generation mobile charge cable. However, it's perfectly safe and easy to use an extra adapter cable if you are converting between two different outlet types if they are the same amp rating. It looks like the only 50A adapter type Tesla does officially sell is the 14-50. I expect you may have gotten one of these already.

If so, then you can get this adapter cable to convert from the 14-50 plug to the 10-50 plug to use that outlet in the basement.
NEMA 10-50P to 14-50R Adapter for EV – EVSE Adapters

 

[NuttyM3]

I do have an answer for this at least. That outlet is a 10-50. And yes, you are right that Tesla doesn't seem to have an official plug for that for their 2nd generation mobile charge cable. However, it's perfectly safe and easy to use an extra adapter cable if you are converting between two different outlet types if they are the same amp rating. It looks like the only 50A adapter type Tesla does officially sell is the 14-50. I expect you may have gotten one of these already.

If so, then you can get this adapter cable to convert from the 14-50 plug to the 10-50 plug to use that outlet in the basement.
NEMA 10-50P to 14-50R Adapter for EV – EVSE Adapters

That’s what I came up with my research and showed it to my father-in-law. I can back my Model 3 within 6-8 feet from the walk in basement door. Just inside the door about 3 feet is the 10-50 connection. I’ll order the 2ft cable/adapter to go with my 14-50 and it’ll definitely reach.

 

[NuttyM3]

Well, I experimented with leaving my Model 3 unplugged while we were gone and i had a decrease of 18% of range while the car was sitting in my garage for 56 hours. Even though I didn’t need to I did leave Sentry Mode active the whole time for this experiment. Now, for the folks smarter then me ... Is this decrease on par for sitting this long unplugged?

 

[BabyYeggie]

18% decrease over 56 hours is incredibly high. It should be closer to 11km/3%. Did you power off before leaving? Over long periods of idle time, the car seems to be offline/asleep 90% of the time and is online for 3 hours every 18 hours.

 

[Rocky_H]

18% decrease over 56 hours is incredibly high. It should be closer to 11km/3%. Did you power off before leaving? Over long periods of idle time, the car seems to be offline/asleep 90% of the time and is online for 3 hours every 18 hours.

Are you serious? My car does not have sentry mode, so I don't have first hand data, but your statement of only 3% loss over almost 3 days seems way off base for having sentry mode on. Many years of reports were that with good power saving, and things mostly turned off, it was more like 1-2% per day. But sentry mode is a huge energy hog, so I thought I've been seeing people report that if they have sentry mode turned on, it's a pretty solid like 3-4% per day. His number might still be high at 18%, but about 10-12% would not seem too unusual to me.

 

[darth_vad3r]

I do have an answer for this at least. That outlet is a 10-50. And yes, you are right that Tesla doesn't seem to have an official plug for that for their 2nd generation mobile charge cable. However, it's perfectly safe and easy to use an extra adapter cable if you are converting between two different outlet types if they are the same amp rating. It looks like the only 50A adapter type Tesla does officially sell is the 14-50. I expect you may have gotten one of these already.

If so, then you can get this adapter cable to convert from the 14-50 plug to the 10-50 plug to use that outlet in the basement.
NEMA 10-50P to 14-50R Adapter for EV – EVSE Adapters

How does that account for no ground? I know the 14-50 "doesn't use the ground" and/or "doesn't use neutral" for EV charging, but I thought maybe the Tesla MC checked ground for safety before allowing charging to proceed? So does this just take neutral from 10-50 and feed it through to ground for 14-50 and leave the 14-50 neutral totally disconnected?

Are there any safety implications with the Tesla thinking the 14-50 ground is "ground" but it's not?

I mean, other than safety implications if you don't heed the warning and try to use this for something other than EV charging. I'm baking that into the cake already. Just wondering about any issues/side-effects during "sanctioned" EV use.

EDIT: OK, I RTFL and see that they do do what I said, and claim it is "safe" ... is that accurate though?

Our EV adapter has been designed to route the ground connection from the 10-50 outlet while leaving the neutral alone. This way you still get a safe grounded connection. The neutral is not used by EV chargers – it’s only used for 120 volt applications such as the timer on an electric dryer. So no additional grounding is necessary as that has been taken care of in the design of the adapter.
​

EDIT2: Wait, isn't this BS? The 10-50 is neutral, not ground, no? Ya that sounds like a load of crap...

NEMA 10s are classified as 125/250 V non-grounding (hot-hot-neutral), and were designed to be used in a manner that indirectly grounds the appliance frame, though not in a manner consistent with most modern practice.
NEMA connector - Wikipedia
​

So my question remains about actual safety, unlike they claim. They say they route the "ground from the 10-50 outlet" which does not exist

 

[darth_vad3r]

Well, I experimented with leaving my Model 3 unplugged while we were gone and i had a decrease of 18% of range while the car was sitting in my garage for 56 hours. Even though I didn’t need to I did leave Sentry Mode active the whole time for this experiment. Now, for the folks smarter then me ... Is this decrease on par for sitting this long unplugged?

Sentry mode means your car never goes to sleep ... until a few days later when your car hits 20% and turns Sentry Mode off.

Don't use Sentry Mode while you are gone for any 'lengthy' amount of time unless you are okay returning to a car with 20% minus ~1%/day after that

 

[darth_vad3r]

Are you serious? My car does not have sentry mode, so I don't have first hand data, but your statement of only 3% loss over almost 3 days seems way off base for having sentry mode on. Many years of reports were that with good power saving, and things mostly turned off, it was more like 1-2% per day. But sentry mode is a huge energy hog, so I thought I've been seeing people report that if they have sentry mode turned on, it's a pretty solid like 3-4% per day. His number might still be high at 18%, but about 10-12% would not seem too unusual to me.

Pretty sure @BabyYeggie must have just missed the bit about Sentry mode on.

 

[Rocky_H]

How does that account for no ground? I know the 14-50 "doesn't use the ground" and/or "doesn't use neutral" for EV charging, but I thought maybe the Tesla MC checked ground for safety before allowing charging to proceed? So does this just take neutral from 10-50 and feed it through to ground for 14-50 and leave the 14-50 neutral totally disconnected?

To answer your piles of questions:
Yes, the 10-XX series of outlets have the two hot lines and a neutral, but no dedicated ground. They are not allowed to be installed new anymore since 1996, but plenty of houses still have them.

Tesla used to sell real adapters for the UMC for the 10-30 and 10-50 outlet types. And yes, they did the obvious thing you are thinking, where they connected their ground line to that neutral in the outlet as if it were the ground. So it's about the same thing these 3rd party pigtails are doing. And it's not really a risky thing, since EV charging is only using the 240V connection, so they are not trying to send any current through that neutral of the outlet anyway.

 

[darth_vad3r]

To answer your piles of questions:
Yes, the 10-XX series of outlets have the two hot lines and a neutral, but no dedicated ground. They are not allowed to be installed new anymore since 1996, but plenty of houses still have them.

Tesla used to sell real adapters for the UMC for the 10-30 and 10-50 outlet types. And yes, they did the obvious thing you are thinking, where they connected their ground line to that neutral in the outlet as if it were the ground. So it's about the same thing these 3rd party pigtails are doing. And it's not really a risky thing, since EV charging is only using the 240V connection, so they are not trying to send any current through that neutral of the outlet anyway.

Ya, I answered most of my own questions in the edit(s), and I know the current doesn't NORMALLY flow through ground, but ... if there's some issue then it does. That's the point of ground, right? So if there's an issue the current will go through neutral here instead of ground.

Just wondering if there's any issues with this.

 

[darth_vad3r]

Tesla used to sell real adapters for the UMC for the 10-30 and 10-50 outlet types.

Looks like they still sell 10-30's for gen 1 and 2 MC.

I guess a 10-30 Tesla adapter and a 10-30R-to-10-50P adapter would also work here and give you 24A at 240V ... which would be slower than the 32A the 14-50R-to-10-50P pigtail would let the gen 2 MC max out at.

 

[NuttyM3]

Are you serious? My car does not have sentry mode, so I don't have first hand data, but your statement of only 3% loss over almost 3 days seems way off base for having sentry mode on. Many years of reports were that with good power saving, and things mostly turned off, it was more like 1-2% per day. But sentry mode is a huge energy hog, so I thought I've been seeing people report that if they have sentry mode turned on, it's a pretty solid like 3-4% per day. His number might still be high at 18%, but about 10-12% would not seem too unusual to me.

I’m not sure if that’s high or not but at work today with my car parked for 8 hours the range decreased 3%, so from my amateur analysis at least this is consistent with my unplugged ‘away from home’ experiment. That would be 9% for 24 hours and 18% for 48 hours. So, since I was at 55-56 hours of being unplugged I’m guessing the range was close to turning over at 21%.

 

[NuttyM3]

Looks like they still sell 10-30's for gen 1 and 2 MC.

I guess a 10-30 Tesla adapter and a 10-30R-to-10-50P adapter would also work here and give you 24A at 240V ... which would be slower than the 32A the 14-50R-to-10-50P pigtail would let the gen 2 MC max out at.

if I get the 10-50 adapter cable from EVSE and use my 14-50 Tesla adapter am I still getting 32A like I do at home?

 

[St☰v☰]

I’m not sure if that’s high or not but at work today with my car parked for 8 hours the range decreased 3%, so from my amateur analysis at least this is consistent with my unplugged ‘away from home’ experiment. That would be 9% for 24 hours and 18% for 48 hours. So, since I was at 55-56 hours of being unplugged I’m guessing the range was close to turning over at 21%.

At work, I lose 1 mile per hour; both sentry and climate on. When home, it's always plugged in.

 

[Rocky_H]

and I know the current doesn't NORMALLY flow through ground, but ... if there's some issue then it does. That's the point of ground, right? So if there's an issue the current will go through neutral here instead of ground.

It sounds a bit like you still have this a bit misunderstood. It's a neutral line in the circuit. Very commonly those do have current flowing through them with most appliances. That's what made the 10-XX series dual voltage 120/240. They did flow current through that line. An EV will not. And 10-30 or 10-50 outlets are almost always on a dedicated circuit, so there isn't anything else feeding current onto that neutral. So I can't picture what kind of issue there could even be. It is more safe with an EV plugged into it than a dryer.

Looks like they still sell 10-30's for gen 1 and 2 MC.

I guess a 10-30 Tesla adapter and a 10-30R-to-10-50P adapter would also work here and give you 24A at 240V ... which would be slower than the 32A the 14-50R-to-10-50P pigtail would let the gen 2 MC max out at.

Well, sure, but why intentionally give yourself less charging speed? Using that is doing exactly the same wiring hookup as the 14-50 to 10-50, but you would not be gimping yourself on current capability for no reason. I don't get that at all.

if I get the 10-50 adapter cable from EVSE and use my 14-50 Tesla adapter am I still getting 32A like I do at home?

Yes, it's just moving the wiring connections to let the car get access to what is in the outlet, and charging speeds will be exactly the same.

OK, those follow-ups about losses with sentry on sound more like what I had been hearing.

 

[NuttyM3]

It sounds a bit like you still have this a bit misunderstood. It's a neutral line in the circuit. Very commonly those do have current flowing through them with most appliances. That's what made the 10-XX series dual voltage 120/240. They did flow current through that line. An EV will not. And 10-30 or 10-50 outlets are almost always on a dedicated circuit, so there isn't anything else feeding current onto that neutral. So I can't picture what kind of issue there could even be. It is more safe with an EV plugged into it than a dryer.


Well, sure, but why intentionally give yourself less charging speed? Using that is doing exactly the same wiring hookup as the 14-50 to 10-50, but you would not be gimping yourself on current capability for no reason. I don't get that at all.


Yes, it's just moving the wiring connections to let the car get access to what is in the outlet, and charging speeds will be exactly the same.

OK, those follow-ups about losses with sentry on sound more like what I had been hearing.

Thanks for the education lesson and information. It helps make my decision that much better.

 

[mfitz]

A bit off topic, but I will be away all of February (live outside Toronto) and need to know if the 220v charger will also keep the 12v battery charged.

Thanks

 

[Rocky_H]

A bit off topic, but I will be away all of February (live outside Toronto) and need to know if the 220v charger will also keep the 12v battery charged.

Thanks

The car always takes care of that no matter what. It monitors the state of the 12V battery, and if it is getting low, it will do a little top off from the main battery pack. That is actually what is going on when people see that the main battery "lost" 2 or 3 rated miles overnight. All of that idle draw is 12V loads from the computer systems. And that pulls from the 12V battery. So a few times a day, it is having to refill that out of the main battery pack.