Charging kind of a stupid question

[tony26]

Most of the time I can charge at work on a 240V but when I'm at home I just have a 110V. My question is I keep seeing that people are saying that people should not charge at 100 percent of the Amps because it might trip the breaker. I don't really understand this can someone explain it to me? I feel really stupid but I don't want to get my model 3 and mess it up because I'm charging it wrong at home. I kind of thought it would be easy to just plug it in and start charging but the more I read the more confused I get.

Thanks,

Tony

 

[evnautilus]

Just plug it in and start charging.

 

[Sophias_dad]

Just plug it in and start charging. The ~1 foot adapter plugged into the UMC body will tell the UMC what its maximum current draw should be. On a usual 120V outlet, it'll be 12 amps(of the 15 amps the plug is actually rated for). If you want a bit more speed AND you have a 20 amp outlet(look up Nema 5-20 to see what it looks like) AND you bought a 5-20 adapter from Tesla($35), you'll get 16 amp charging from that 20 amp outlet.

It's not a real big deal if you trip a breaker. That's what they are there for. Just don't reset it without figuring out what the problem was.

 

[cgell]

You can just plug in and charge without worrying. The amperage should automatically set itself.

You are protected by your breaker which is most likely 15 amps for a regular 120v outlet (there are also 20 amp outlets and Tesla sells adapters for them if you have one). The issue is that 15 amps continuously (100%) may burn the outlet or be a fire hazard. It may trip the breaker, but it may not in all cases as I think a breaker requires going above the full amperage to trip. You should only use 80% of the max amps with continuous use such as charging. Therefore, charging on a 120v/15amp outlet should be at a maximum of 12 amps. But again, the car should set itself to 12 amps.

 

[jjrandorin]

Most of the time I can charge at work on a 240V but when I'm at home I just have a 110V. My question is I keep seeing that people are saying that people should not charge at 100 percent of the Amps because it might trip the breaker. I don't really understand this can someone explain it to me? I feel really stupid but I don't want to get my model 3 and mess it up because I'm charging it wrong at home. I kind of thought it would be easy to just plug it in and start charging but the more I read the more confused I get.

Thanks,

Tony

When you are charging at 120v (which is your standard outlet) at home, you may be charging on a shared outlet. By "Shared outlet" it means an outlet in which there are other wall plugs on the same circuit.

For example, you may have an outlet in your garage that you are plugging into, and that same outlet may also be on the same circuit as wall plugs in your residence. Since plugging an EV into a standard outlet comes close to "maxing out" the power that circuit can deliver, if its a shared circuit, and you start something else on that circuit, it can trip the breaker (hopefully) or overload the circuits if the breaker does not trip.

It is VERY common for "regular" outlets to be shared, unless it is setup for EV charging, or some other device that is not supposed to be shared by code (like a microwave, or an electric dryer outlet, for example).

So, advice for charging on a standard wall plug would be to figure out what else, if anything, is on that circuit before you start using it for EV charging for hours and hours and hours (and hours and hours and hours) of charging.

The easiest way to do that, is to figure out what breaker that plug is on, and get yourself an inexpensive tester. something like this:

https://www.amazon.com/Gardner-Bender-GFI-3501-Receptacle-Extension/dp/B00170KUPC/ref=sr_1_16?crid=2NAPCETO14UGQ&keywords=electric+circuit+test&qid=1644370152&sprefix=electric+circuit+tes%2Caps%2C152&sr=8-16

Thats just an example, they sell them on amazon, or any home improvement store close to you. Model kind of doesnt matter for this application. To use this, you would plug it into the outlet you charge on, look in the breaker box and try to find the breaker that matches that outlet, turn off the breaker, and see if the light goes out on that device.

Then, with the breaker still off, you take that device and plug into various other outlets around your home and see if the light comes on (meaning its not on that breaker) or doesnt (meaning it is on that breaker / Circuit). Then, once you figure that out, you will know where you stand. If its on the same circuit with other items, you technically are not supposed to use it for charging, but, you could, as long as you know what that stuff is and that it wont be turned on.

Not the best situation, but at least you would know, and wouldnt likely inadvertently pop your breaker (or worse, overload the circuit and have the breaker fail to pop)

you can also "turn the amps down" as you mentioned people are telling you, so that you dont max out the circuit. Also not ideal from a use case scenario, but thats why you would do that.

Hope that helps to explain.

 

[tony26]

When you are charging at 120v (which is your standard outlet) at home, you may be charging on a shared outlet. By "Shared outlet" it means an outlet in which there are other wall plugs on the same circuit.

For example, you may have an outlet in your garage that you are plugging into, and that same outlet may also be on the same circuit as wall plugs in your residence. Since plugging an EV into a standard outlet comes close to "maxing out" the power that circuit can deliver, if its a shared circuit, and you start something else on that circuit, it can trip the breaker (hopefully) or overload the circuits if the breaker does not trip.

It is VERY common for "regular" outlets to be shared, unless it is setup for EV charging, or some other device that is not supposed to be shared by code (like a microwave, or an electric dryer outlet, for example).

So, advice for charging on a standard wall plug would be to figure out what else, if anything, is on that circuit before you start using it for EV charging for hours and hours and hours (and hours and hours and hours) of charging.

The easiest way to do that, is to figure out what breaker that plug is on, and get yourself an inexpensive tester. something like this:

https://www.amazon.com/Gardner-Bender-GFI-3501-Receptacle-Extension/dp/B00170KUPC/ref=sr_1_16?crid=2NAPCETO14UGQ&keywords=electric+circuit+test&qid=1644370152&sprefix=electric+circuit+tes%2Caps%2C152&sr=8-16

Thats just an example, they sell them on amazon, or any home improvement store close to you. Model kind of doesnt matter for this application. To use this, you would plug it into the outlet you charge on, look in the breaker box and try to find the breaker that matches that outlet, turn off the breaker, and see if the light goes out on that device.

Then, with the breaker still off, you take that device and plug into various other outlets around your home and see if the light comes on (meaning its not on that breaker) or doesnt (meaning it is on that breaker / Circuit). Then, once you figure that out, you will know where you stand. If its on the same circuit with other items, you technically are not supposed to use it for charging, but, you could, as long as you know what that stuff is and that it wont be turned on.

Not the best situation, but at least you would know, and wouldnt likely inadvertently pop your breaker (or worse, overload the circuit and have the breaker fail to pop)

you can also "turn the amps down" as you mentioned people are telling you, so that you dont max out the circuit. Also not ideal from a use case scenario, but thats why you would do that.

Hope that helps to explain.

Thank you, I totally understand and I will get the tester or one like from Amazon or Home Depot near me. One question is how would I turn down the amps? That's in the car right?

 

[jjrandorin]

Thank you, I totally understand and I will get the tester or one like from Amazon or Home Depot near me. One question is how would I turn down the amps? That's in the car right?

if you need to do that, you can do it in the car, or in the app (provided you have the latest version of the app that supports changing the charging amps). I would recommend doing it in the car, as some have reported some "wonkiness" with doing it in the app.

 

[dmurphy]

Thank you, I totally understand and I will get the tester or one like from Amazon or Home Depot near me. One question is how would I turn down the amps? That's in the car right?

Yes — you can even do it from the app now. Mine is set for 48 amps; you can dial that down to whatever you need. Super easy!

 

[Resist]

Thank you, I totally understand and I will get the tester or one like from Amazon or Home Depot near me. One question is how would I turn down the amps? That's in the car right?

Don't get the outlet tester! Just plug a lamp or anything that can show you it's drawing power from that outlet. If it turns off after the flip the breaker, then that's the right breaker. No need to spend money for a special outlet tester.

 

[RayK]

As a follow-up to @jjrandorin post above about identifying outlets and their breakers and for general information to others ...

Something like this kit:

Amazon.com: Triplett Breaker Sniff-It Automatic Circuit Breaker Locator with Audible and Visual Indication (9650) : Tools & Home Improvement

Amazon.com: Triplett Breaker Sniff-It Automatic Circuit Breaker Locator with Audible and Visual Indication (9650) : Tools & Home Improvement

www.amazon.com

although a little bit expensive, is very useful for determining what outlet is tied to what breaker. It does not require that you shut off any of the breakers to identify outlets. You plug in a small module (signal transmitter) into an outlet, much like the size of the outlet tester jjrandorin mentioned, then go to the power panel and with the scanner (receiver) part of the kit, pass it over all of the breakers twice. One pass to get the signal strengths, the second pass to identify which one was the strongest; it will be the only beep adjacent to the breaker for the outlet. Simple and does not interrupt power to any equipment.

And I would tend to agree with @Resist that you just use a night light if you don't want / need to spend $50 to trace one or two circuits. But I value the capability to figure out what's what without having to possibly cut power to random parts of the house before you find the correct breaker. Especially if you are mapping your entire house since that would entail cutting power multiple times, or having to physically move that night light around to all of the outlets in your house.

 

[Resist]

I think buying that tool, is a more useful option. Good call 10KGM3!

 

[jjrandorin]

Don't get the outlet tester! Just plug a lamp or anything that can show you it's drawing power from that outlet. If it turns off after the flip the breaker, then that's the right breaker. No need to spend money for a special outlet tester.

Sure, that works if you want to cart around a lamp. That little tool also has the added benefit of showing if it thinks the outlet is wired correctly. They cost between $5 and $10, which is the cost of an average fast food lunch, so its not like I recommended something thats expensive. Spending the cost of a big mac to not have to cart a lamp around would be something many would prefer, but to each their own.

@RayK

I have a circuit sniffing type tool like that as well, and find it very helpful for the reasons you mentioned. With that being said, as you mention, that tool is a bit more expensive, and would be helpful if one was trying to map out where all their breakers go, or determine what breaker a specific outlet is on without any back and forth to check, or needing two people with a phone, saying "did that turn it off?".

 

[Resist]

Doesn't have to be a lamp, it can be anything small you can plug in that shows power to it. Why buy a special tool you may only use once? Makes no sense when can even just plug your phone into the outlet and if it stop charging after you throw the circuit breaker, then that's the correct breaker.

 

[3sr+buyer]

Don't get the outlet tester! Just plug a lamp or anything that can show you it's drawing power from that outlet. If it turns off after the flip the breaker, then that's the right breaker. No need to spend money for a special outlet tester.

The outlet testers are inexpensive, and could also tell you if the outlet is miswired (swapped hot/neutral, or missing grounding).

However, if you do not have an outlet tester, a lamp works. Or you can use something loud like a vacuum cleaner or boom box so that you can tell by sound whether switching the breaker or removing the fuse disconnects the outlet.

 

[BigNick]

The outlet testers are inexpensive, and could also tell you if the outlet is miswired (swapped hot/neutral, or missing grounding).

However, if you do not have an outlet tester, a lamp works. Or you can use something loud like a vacuum cleaner or boom box so that you can tell by sound whether switching the breaker or removing the fuse disconnects the outlet.

Back in the 90s I bought one of those inexpensive testers, was probably $5 back in the day.

I've probably used it a half-dozen times since. Plugs into a NEMA 5-15 or 5-20 and if the two amber lights come on without the red light, your outlet is good, it has a sticker on it showing the types of faults it can detect (no ground, hot/neutral swapped, etc) and what the light codes mean.

There are probably more advanced ones these days with LCD screens that tell you what is wrong and give instructions on how to fix it. I'm guessing they are $50 or more, and probably have seven safety warning stickers on them.

Edit: it's one of these:

https://i.ebayimg.com/images/g/WiMAAOSwq4leTrgR/s-l600.jpg

And this seller is on crack:

SPERRY INSTRUMENTS 3 LED plug in circuit tester socket check | eBay

Find many great new & used options and get the best deals for SPERRY INSTRUMENTS 3 LED plug in circuit tester socket check at the best online prices at eBay! Free shipping for many products!

www.ebay.com

 

[3sr+buyer]

Back in the 90s I bought one of those inexpensive testers, was probably $5 back in the day.

Here is one of the inexpensive ones:

Gardner Bender Outlet and GFCI Tester GFI-3501 - The Home Depot

The Gardner Bender GFCI Outlet Tester was ergonomically designed for today's electrical professional. This unit plugs into any standard 120-Volt outlet and indicates the wiring condition of the outlet.

www.homedepot.com

 

[RayK]

And this seller is on crack:

I have had an older version of an outlet checker like that for over 20 years (doesn't have the GFCI button). It came from Radio Shack (remember those?). I don't think it cost more than $10. It came in handy when I checked all of the outlets in the home I had just moved into. It uses red and green LEDs so there's no confusion as to the color of the indicator.

 

[BillRadio]

Harbor Freight has a version of the circuit finder for $22. I think I'll get one.

 

[smatthew]

If I remember correctly those cheap circuit testers can miss several electrical problems.

Three-Lamp Circuit Tester: Valid Tester or Night-Light?

Popular with electricians and electrical inspectors, this device is inexpensive. You can easily use it to test a receptacle for correct polarity. But is it giving you a false ...

www.ecmweb.com

 

[davewill]

I will add that it never hurts to check the outlet and plug at the wall after a half hour or so of charging to verify that nothing is getting hot. Warm is fine, but if anything is getting too hot to keep your hand on, stop using the outlet and get it checked out. You can also take the cover plate off and look for signs of heat (discoloration).

I try to do that every month or so to make sure everything is OK. I also do that on the car end after the plug going into my Rav4EV burned up.

Yes, yes, I know that the mobile adapter has a thermistor to sense that kind of thing, but if the heating is farther back in the outlet, it might not trip.