How to check outlet power output?

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Spacep0d

Well-known member
Joined
Feb 13, 2019
Messages
63
Location
Santa Clarita, CA
Hi there,

I have a garage power outlet which was 'upgraded' by an electrician to stop my large air compressor for tripping the breaker. Is there a way to tell what kind of power it's putting out? I suspect it's a regular 120v outlet, but am curious if there's a way to test this myself? Why did one of my outlets work fine for trickle charging, but the other one did not?

I have the optional Nissan EVSE connected to it (came with the optional DCFC connector in a 2018 LEAF) and it seems to be charging at a decent clip. 62-80% in a little over 5 hours. Perhaps this is normal. Opinions welcome!

Thanks!
 
You are a little confused, possibly by a salesperson. The Nissan EVSE that comes with the Tech kit and the SL is dual voltage: 120 and 240 volts, but it isn't for fast charging. Call it 'midlevel charging'. For DC Fast Charge you need a second port on the car, and a rather large, expensive, very high voltage stand alone charger that overrides the car's onboard charger. I suspect that you are charging at 120 volts (standard looking home outlet plug attached to the EVSE, right?). The outlet, if it really was upgraded, should be on a 20 amp 120 volt circuit. That won't affect the charging rate at 120 volts, aka "L-1."
 
For more clarification, see http://www.mynissanleaf.com/viewtopic.php?p=325438#p325438, https://www.clippercreek.com/three-things-determine-ev-charge-time/ and planet4ever's diagram at https://web.archive.org/web/20150619074649/http://www.mynissanleaf.com/viewtopic.php?p=262630.

Both the stock L1 EVSE and the stock L1/L2 (120 and 240 volt) EVSEs that the Leaf can come with only can do 12 amps * 120 volts = 1,440 watts = 1.44 kW from the wall.

At 1.44 kW, for each hour, 1.44 kWh would've come out of the wall and probably 1.0 to 1.1ish kWh would've gotten added to the battery.

At 120 volts and the way the L1 and L1/L2 EVSEs are set up, I already listed the max station delivery rate: 1.44 kW. To charge faster, you need something with a higher max delivery rate and typically that means charging at 240 volts. If yours came with w/the L1/L2 EVSE, it can output up to 30 amps * 240 volts (240 volts * 30 amps = 7,200 watts = 7.2 kW), but Leaf won't draw that much at 240 volts. It'll draw 6,600 watts (6.6 kW) at max at 240 volts. Thus, the bottleneck here would be the vehicle acceptance rate due to the car's OBC.

A 40 kWh Leaf likely has some user inaccessible capacity at the top and bottom, just like earlier Leafs.
 
Reading the first post again, I think he may have meant 'I have the dual input EVSE that comes with the QC option on the Leaf S.' I'm a little preoccupied with preparing for a long term power outage that may occur here when the high, sustained winds arrive in 12 hours or so...
 
cwerdna said:
A 40 kWh Leaf likely has some user inaccessible capacity at the top and bottom, just like earlier Leafs.

Reports show rated total is 39.46 kWh total, and the usable portion is about 37kWh.
 
Is it 120 or 240v.

A large home shop compressor uses single phase 240v.
Usually they are on a 40 amp or smalller circuit.
 
Spacep0d said:
Hi there,

I have a garage power outlet which was 'upgraded' by an electrician to stop my large air compressor for tripping the breaker. Is there a way to tell what kind of power it's putting out? I suspect it's a regular 120v outlet, but am curious if there's a way to test this myself? Why did one of my outlets work fine for trickle charging, but the other one did not?

I have the optional Nissan EVSE connected to it (came with the optional DCFC connector in a 2018 LEAF) and it seems to be charging at a decent clip. 62-80% in a little over 5 hours. Perhaps this is normal. Opinions welcome!

Thanks!

If the receptacle for your air compressor is a standard configuration like your other garage receptacle, then it should be 120 volts nominal. I suspect your electrician ran larger wire in a new circuit directly from your panel to minimize voltage drop when the compressor starts. 18% gain in SOC from over 5 hours of charging sounds about right for charging at 120 volts. Many garage and outdoor receptacles are fed from GFCI receptacles in bathrooms so the total circuit length is long and that causes excessive voltage drop under load. That is likely why you had trouble with your air compressor and needed a new circuit. Since the charging current is 12 amperes (except when battery is near full charge) when using the 120-volt Nissan EVSE, less energy goes to the battery if the voltage is low and the car may stop charging if the voltage gets too low. Improper ground connections, excessive voltage drop, and heating at the receptacle (due to loose connections) can all cause the car to not charge.
 
Spacep0d said:
Hi there,

I have a garage power outlet which was 'upgraded' by an electrician to stop my large air compressor for tripping the breaker. Is there a way to tell what kind of power it's putting out? I suspect it's a regular 120v outlet, but am curious if there's a way to test this myself? Why did one of my outlets work fine for trickle charging, but the other one did not?

I have the optional Nissan EVSE connected to it (came with the optional DCFC connector in a 2018 LEAF) and it seems to be charging at a decent clip. 62-80% in a little over 5 hours. Perhaps this is normal. Opinions welcome!

Thanks!
Check out this diagram looking at your outlet. 240v outlets look different than 120v outlets and even 120v outlets come in different styles, depending on amperage.
I'm guessing if your outlet is 120v it may be 20a, in which case even if sticking with 120v you could purchase an aftermarket EVSE(around $200) that could give you 16a 120v charging or about 33% faster than you have now. Even if your just going to stick with your OEM 12a 120v EVSE you still might want to consider plugging it into your compressor outlet(just make sure the compressor doesn't start if your car is charging) as that outlet probably has better wiring(probably 12G) which would give you less heat loss than an iffy 15a circuit.
https://en.wikipedia.org/wiki/NEMA_connector#/media/File:NEMA_simplified_pins.svg
 
SageBrush said:
OP, post photos of your outlet and compressor plug.
Or ask your electrician :D

Wow, thanks for all of the helpful replies. Sorry I sound like such a noob here, but I'm learning!

The outlet is definitely the standard 3-prong outlet you'd see on 120v receptacle, not the 240v 'washing machine' style plug. And, someone mentioned the bathroom connection with GFI or some such...that's exactly right. He had to check the bathroom GFI and upgrade something so the initial run of the large compressor wouldn't either cause the lights to dim or trip the breaker. That's the same outlet I'm using for the trickle charger.

Yes, I'm using the Nissan LEAF EVSE with the adaptor plug for 120v standard outlet. The charge rate is not bad at all. As a test, I let it run (with the timer) and got it to 100% this morning (150 miles range indicated) before driving it off to a meeting. That was the first time I ever saw the car at 100% charge.

So, with level 2 charging, this will use the same amps (12) but give me much faster charging at 6.6 kW? This is much more efficient isn't it? From what I read, I will have more efficiency and cheaper with respect to electricity costs, right?

Thanks!
 
Spacep0d said:
So, with level 2 charging, this will use the same amps (12) but give me much faster charging at 6.6 kW? This is much more efficient isn't it? From what I read, I will have more efficiency and cheaper with respect to electricity costs, right?
On the first no. In order to charge at 6.6 kW at 240 volts, it'll need to be 27.5 amps.

6600 watts / 240 volts = 27.5 amps

Yes, it is more efficient to charge at 240 volts than 120.
 
L-2 charging can use 12 amps (15 amp circuit) or 16 amps (20 amp circuit) but at twice the voltage. So yes, a low power L-2 setup can be double the charge rate of an L-1 setup. Most of them are rated for more amps, though, so you get higher multiples of the L-1 charge rate.
 
^^^
Indeed. Clipper Creek sells L2 EVSEs with as low as 12 amp output (requires 15 amp circuit) like the LCS-15 at https://store.clippercreek.com/level2?sort=p.price&order=ASC.

And yep, 12 amps * 240 volts = 2,880 watts = 2.88 kW.
 
Supplied Level 1 EVSE's are all at 12A. After market EVSE;s like the OpenEVSE can be set to 16A (80% 20A). The 12A EVSE is at (80% of 15A). That is safe for all outlets in goods condition.
 
Your test of charging 18% in a little over 5 hours works out to ~ 12 Amps at 120V


I few guesses then:

You have a 120V wiring upgraded to allow 20 Amp burst, 16 Amp continuous

If you want to charge at 240V you have to replace the outlet and the breaker (presuming your panel can accommodate the load and has space for the physically larger breaker.) Doing so would allow 0.240*16 = 3.84 kW charging, about 3x faster than you have.
 
Charging on 240v is more efficient.
Converting 240v AC to 380v DC is a lot easier than converting 120v AC to 380v DC.
 
Spacep0d said:
I have a garage power outlet which was 'upgraded' by an electrician to stop my large air compressor for tripping the breaker. Is there a way to tell what kind of power it's putting out?
The previous comments aren't wrong, but they didn't actually answer this question.

https://www.amazon.com/Proster-Multimeters-Multimeter-Voltmeter-Backlight/dp/B01FU6YFFE/

Just look for a "multimeter". They range from very cheap, to very expensive; for this purpose, a very cheap one will do. Set it to AC voltage mode, and carefully insert a probe into each of the two "slits" on the outlet. That will show you what the voltage really is (not just what it should be, as the plug shape will tell you).

If you're not comfortable with that, consult an electrician.
 
wmcbrine said:
Spacep0d said:
I have a garage power outlet which was 'upgraded' by an electrician to stop my large air compressor for tripping the breaker. Is there a way to tell what kind of power it's putting out?
The previous comments aren't wrong, but they didn't actually answer this question.

https://www.amazon.com/Proster-Multimeters-Multimeter-Voltmeter-Backlight/dp/B01FU6YFFE/

Just look for a "multimeter". They range from very cheap, to very expensive; for this purpose, a very cheap one will do. Set it to AC voltage mode, and carefully insert a probe into each of the two "slits" on the outlet. That will show you what the voltage really is (not just what it should be, as the plug shape will tell you).

If you're not comfortable with that, consult an electrician.

Thank you all. Such great info here. ;)
 
Spacep0d said:
Hi there,

I have a garage power outlet which was 'upgraded' by an electrician to stop my large air compressor for tripping the breaker. Is there a way to tell what kind of power it's putting out? I suspect it's a regular 120v outlet, but am curious if there's a way to test this myself? Why did one of my outlets work fine for trickle charging, but the other one did not?

I have the optional Nissan EVSE connected to it (came with the optional DCFC connector in a 2018 LEAF) and it seems to be charging at a decent clip. 62-80% in a little over 5 hours. Perhaps this is normal. Opinions welcome!

Thanks!


All you can do is check the breaker. If your compressor is on a normal circuit then it may be a 20A breaker.

The stock Leaf EVSE is set for 12A (80% of 15A). That is the NEC max for a 15A circuit.

As long as your compressor has a plug on it it draws less than 15A. If it is hard wired then it could be anything. There are 20A outlets with an extra slot but they are rare.
 
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