Use garage door opener power for slow (15-20A) charging?

[ralph142]

Well that settles it. I am sure yours is just like the OP's.

read up, there are a lot of ifs

 

[Akikiki]

...But there's a Tesla service center near by, in case something have-to-have comes to my attention.

Service Centers can charge cars too. Might be a good idea to drop by second day there with a basket of muffins. You might make a friend and they let you charge once a week to get max range. Nice to know you would have an alternative if needed.

 

[wwu123]

From what I know about circuit breakers (which is not much), they are not all designed to trip instantaneously at the rated current, nor should they, so 21A through a 20A circuit will take a lot longer to trip than say 30A, which will be less than 40A through that circuit.

A garage door opener may draw close to 10A starting watts for an instant, but is closer to 4-6A during most of the few seconds of operation. Adding that brief load on top of the UMC's 12A does not seem like it would or should trip a breaker. Actual breaker behavior may vary though...

Also, aren't additional outlets in many garages wired to the same outlet as the one for the GDO. Yes, some homes have a dedicated circuit, but many do not. Thus there may be no difference in drawing power from the outlet the GDO uses, vs another outlet one the same branch circuit, as far as the wiring and breaker is concerned....

 

[Feathermerchan]

I charged my Model 3 from the same outlet (15 amp circuit) as my garage door opener for a few months before I installed the 240V circuit. I had no problems.

 

[M3BlueGeorgia]

I've only ever seen garage door openers that were plugged into 15A outlets, never hardwired, but my sample size is small. Note that if it's a 15A outlet, you'll only be able to pull 12A from it.

Done that while visiting one of my daughters. 12A continuous.

Opening and closing the garage door didn't cause the breaker to pop, and since its such a shortterm additional current load, I wouldn't have expected it, but that would be something to watch out for.

Suggest you get a 10 or 15 ft 12 gauge extension cable so you don't have to hang the Mobile Connector from the ceiling.

 

[Rocky_H]

I have a few thoughts on this. Yeah, garage door openers are almost always plugged into a ceiling outlet. And yes, I would use an extension cord to get that down to near the floor somewhere where you could plug into it. But don't just grab any old extension cord. Most of them use pathetic 16 gauge wire. That is way too thin for long term heavy current. Either ordering one or checking at hardware stores, it's not hard to find cords that use 12 gauge wire. Please get one of those.

And then the other thing is that since you know you will be sharing it on a circuit with other stuff and using an extension, I would probably turn the amps down in the car a little bit, to maybe 8-9 instead of leaving it at 12A.

 

[brec]

I found my 5-15 adapter. I also have a 12/3 25 ft. extension cord that I've been carrying in my trunk as a just-in-case. Would the extra 10-15 ft. of length lose noticeable efficiency?

 

[Akikiki]

Likely to depend on the quality/gauge of the wire. Can't you test it before you need it?

 

[brec]

Likely to depend on the quality/gauge of the wire. Can't you test it before you need it?

I also have a 12/3 25 ft. extension cord [emphasis added]

I.e., 12 gauge, 3 conductor

 

[Feathermerchan]

I think you should be fine. Test it at home before you go.
Just like camping equipment.

 

[Shaggyy]

I charged my Model 3 from the same outlet (15 amp circuit) as my garage door opener for a few months before I installed the 240V circuit. I had no problems.

Sorry for the old thread bump, but did you use an extension cable/splitter at all? If so, was 12 gauge the go to?

I am trying to brainstorm a charging solution for a garage that has a singular 20 amp outlet that is taken up by the garage door opener. I know that there is a GFCI with this single outlet so that helps me feel like the following would not be a "sketchy" thing to do. I am thinking I will need some kind of 12 gauge splitter to create another outlet for the Tesla charger to plug in, and will also need to mount that charger in the ceiling of the garage (I will likely just stick that on top of the opener itself. I would likely limit the amps on the car so as not to accidentally trip the GFCI.

Any tips would be appreciated! Happy to provide a photo of the outlet if necessary.

 

[spsheridan]

Sorry for the old thread bump, but did you use an extension cable/splitter at all? If so, was 12 gauge the go to?

I am trying to brainstorm a charging solution for a garage that has a singular 20 amp outlet that is taken up by the garage door opener. I know that there is a GFCI with this single outlet so that helps me feel like the following would not be a "sketchy" thing to do. I am thinking I will need some kind of 12 gauge splitter to create another outlet for the Tesla charger to plug in, and will also need to mount that charger in the ceiling of the garage (I will likely just stick that on top of the opener itself. I would likely limit the amps on the car so as not to accidentally trip the GFCI.

Any tips would be appreciated! Happy to provide a photo of the outlet if necessary.

Jumping in here. Your suggested approach should work fine with a few caveats:
1) GFCI will likely not be the breaker that is tripped if you draw too much current through the 20A circuit. GFCIs sense an imbalance between the supply and return conductors (such as leakage current flowing through the ground path) and very quickly trip the circuit. But GFCIs don’t trip if you simply draw too much current when the circuit is behaving normally. In that case, the breaker in your electrical panel that controls that outlet would likely trip.

2) You probably will not be able to use the garage door opener while charging your Model 3. Doing so would likely trip the 20A breaker in your electrical panel.

3) Your garage door opener likely has a standard 3-prong NEMA 5-15 plug which is limited to 15A. If you get a splitter, it will need to have outlets compatible with a NEMA 5-15 plug. If you have a 20A outlet, you could get a 20A splitter that will handle both 15A and 20A plugs. In this case, you could buy a Tesla 5-20 adapter to plug your mobile connector into the same splitter as your garage door opener. Your charge rate would be limited by the 20A circuit and you would get about 4 miles/hour of charge. If you have a 15A outlet, you could buy a Tesla 5-15 adapter and get about 3 miles/hour of charge.

Here's an Amazon link for a 20A splitter that handles 15A and 20A plugs: 20 Amp T-Blade Splitter with Power Indicator Light
Here’s the link for Tesla NEMA Adapters. Gen 2 NEMA Adapters

 

[M3BlueGeorgia]

Put a 5-20 splitter in there.

Garage door openers use about 5 amps, so limiting the Tesla to (say) 12 amps should work fine. Experiment to determine how much you can pull without tripping the breaker when using the garage door opener while also charging the car.

Since 12 amps is the the maximum you can pull from a 5-15 outlet, why not use it

Get a 5-15, 12 gauge extension cord to bring an outlet down to ground level and therefore allow you to plug and unplug the Mobile Connector without needing a step ladder.

Note: If you only ever park one vehicle (the Tesla) in the garage at one time, you could use a 5-20 extension cord and pull 16 amps, providing you remember to unplug the car before opening the garage door. Most people, in my experience, enter the house through the garage door so it tends to get opened a lot, which would make this approach non-viable. However, you [[might]] be able to pull 14 amps without overloading the breaker.

 

[Shaggyy]

Wow, I did not expect to see such detailed responses when I hopped on for the evening - thank you both very much for your tips and pointers. I was unaware that the GFCI is different functionally than a breaker, so I certainly will limiting the charging I am doing at home.

I appreciate you two!

 

[M3BlueGeorgia]

Wow, I did not expect to see such detailed responses when I hopped on for the evening - thank you both very much for your tips and pointers. I was unaware that the GFCI is different functionally than a breaker, so I certainly will limiting the charging I am doing at home.

I appreciate you two!

Trivial extra advice: Use LEDs on the garage door opener light, trivial amperage draw.

 

[Akikiki]

That's a good idea, but be aware that not all LEDs will work without causing interference of the GDO itself. Amazon has specific GDO compatible LED bulbs. Lots will work, but if you have problems opening/closing via the car, remember to check the LED bulb.