# Tesla Home Charging



## TXSS (5 mo ago)

My home charger uses 0.25 amp during idle. Isn't that a bit much for low current devices these days?
The charger is in idle 80% or more of the time.


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## Klaus-rf (Mar 6, 2019)

Yes, that's high for a device not being used. But it's about the same as my Tesla Wall Charger.


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## garsh (Apr 4, 2016)

My wall connector shows 2.0W while idle, which on my 240v circuit should be about 8mA.

However, I doubt the current transformers I'm using to measure this are very accurate at these low power levels - perhaps yours aren't either?

0.25 amps on a 240v circuit would be about 60 watts! That seems way too high.


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## TXSS (5 mo ago)

garsh said:


> My wall connector shows 2.0W while idle, which on my 240v circuit should be about 8mA.
> 
> However, I doubt the current transformers I'm using to measure this are very accurate at these low power levels - perhaps yours aren't either?
> 
> 0.25 amps on a 240v circuit would be about 60 watts! That seems way too high.


Yes, definitely is high - like a 60 watt light bulb on constantly. I measured this with accurate clamp-on ammeter from main panel. My charger is a normal Tesla wall charger. My "S" uses about 100 KWHrs over a week and the charger at idle uses about 8 KWHr per week - not a conservative number. Too bad Tesla Co. has no avenue that I know of to check this out with them. Thanks for reply.


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## garsh (Apr 4, 2016)

TXSS said:


> My charger is a normal Tesla wall charger.


nit: Wall Connector, rather than Wall Charger.

Do you know which generation Wall Connector it is? Gen3, Gen2, or Gen1?


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## TXSS (5 mo ago)

garsh said:


> nit: Wall Connector, rather than Wall Charger.
> 
> Do you know which generation Wall Connector it is? Gen3, Gen2, or Gen1?


Good question and i am not sure. I believe Gen2 but it came from a friend who got it with his Model 3 several years ago. It indicates that it charges my S at 32 amps. Is there a more positive way to check the model of the connector? I am curious about the nomenclature - if this is a "wall connector", then what is a "charger" or what is the "charger part" of this? Again, thanks for reply.


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## android04 (Sep 20, 2017)

TXSS said:


> Good question and i am not sure. I believe Gen2 but it came from a friend who got it with his Model 3 several years ago. It indicates that it charges my S at 32 amps. Is there a more positive way to check the model of the connector? I am curious about the nomenclature - if this is a "wall connector", then what is a "charger" or what is the "charger part" of this? Again, thanks for reply.


If it came with your friend's Model 3 and is a small, portable unit (not a big, heavy one mounted to the wall) then it is called a mobile charge connector or UMC. And there's no way I can see that it could be using 60W on its own because it is basically a small microcontroller with sensors and a big relay that connects or disconnects power from the outlet to your car's charge port.


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## garsh (Apr 4, 2016)

TXSS said:


> Good question and i am not sure. I believe Gen2 but it came from a friend who got it with his Model 3 several years ago. It indicates that it charges my S at 32 amps. Is there a more positive way to check the model of the connector?


You could take a picture and post it in a reply to this thread.

If it plugs into a 240v NEMA 14-50 outlet, then it's actually a Mobile Connector rather than a Wall Connector. The Mobile Connectors are included with vehicle purchases, and they're limited to 32 amps.



> I am curious about the nomenclature - if this is a "wall connector", then what is a "charger" or what is the "charger part" of this?


Yeah, it's confusing.

For charging from AC, the charger is actually a part built into the vehicle itself. These items that Tesla calls "connectors" are technically an EVSE. Basically, it's just a fancy safety switch.


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## TXSS (5 mo ago)

garsh said:


> You could take a picture and post it in a reply to this thread.
> 
> If it plugs into a 240v NEMA 14-50 outlet, then it's actually a Mobile Connector rather than a Wall Connector. The Mobile Connectors are included with vehicle purchases, and they're limited to 32 amps.
> 
> ...


I believe you are right on all that. I was wrong on the amps i reported (i measured wrong line!). The Tesla wall connector uses 20 to 30 milliamps on idle (not 0.25 amps). My clamp-on ammeter is confirmed accurate. So, the idle would be about 6 watts which is more palatable and would be about 1 KWHr over one week. I would have guessed it should be a slightly smaller number of watts but that is what it is. Thank you for your information and advice. It was worth learning all that.


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## garsh (Apr 4, 2016)

garsh said:


> My wall connector shows 2.0W while idle, which on my 240v circuit should be about 8mA.


I couldn't find accuracy information for my current transformers, so this morning I opened up my panel and used my clamp meter to measure the idle current.

On the lowest setting (20 amp), it displayed 0.03 amps (30 mA). But the accuracy for this meter is listed as ±(2.0%+5), so the actual value is between -20mA and 80mA. In other words, my meter isn't accurate enough at these low levels  

@TXSS, can you share what model of meter you have? I might want to invest in something that can measure these low currents more accurately.


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## TXSS (5 mo ago)

garsh said:


> I couldn't find accuracy information for my current transformers, so this morning I opened up my panel and used my clamp meter to measure the idle current.
> 
> On the lowest setting (20 amp), it displayed 0.03 amps (30 mA). But the accuracy for this meter is listed as ±(2.0%+5), so the actual value is between -20mA and 80mA. In other words, my meter isn't accurate enough at these low levels
> 
> @TXSS, can you share what model of meter you have? I might want to invest in something that can measure these low currents more accurately.


Yes, my clamp-on is a A.W.Sperry DSA-600 "digisnap" multi-meter clamp-on. S/N 951001515 (5C66 - whatever that is), made in Taiwan. My meter indicated 30 mA also but flashed once or twice at 20 mA so i took that as a reasonable 25 mA. Since you went this far, it would not be too difficult to set a low AC voltage across a known resister to get 30 mA (known by accurate voltage and resistance measurement) and insert your clamp on and confirm the reading - at least to a pretty fair accuracy.


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## garsh (Apr 4, 2016)

TXSS said:


> Yes, my clamp-on is a A.W.Sperry DSA-600 "digisnap" multi-meter clamp-on. S/N 951001515 (5C66 - whatever that is), made in Taiwan. My meter indicated 30 mA also but flashed once or twice at 20 mA so i took that as a reasonable 25 mA. Since you went this far, it would not be too difficult to set a low AC voltage across a known resister to get 30 mA (known by accurate voltage and resistance measurement) and insert your clamp on and confirm the reading - at least to a pretty fair accuracy.


I found the manual here. Assuming I picked the correct model, on the 6A setting, it lists a resolution of 0.001 and an accuracy of ± (3.5% + 20).

For a reading of 0.030, that should give a range of 0.009 to 0.051 (9 mA - 51 mA). So, better than my meter, but still not terribly accurate at these low levels.


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## TXSS (5 mo ago)

garsh said:


> I found the manual here. Assuming I picked the correct model, on the 6A setting, it lists a resolution of 0.001 and an accuracy of ± (3.5% + 20).
> 
> For a reading of 0.030, that should give a range of 0.009 to 0.051 (9 mA - 51 mA). So, better than my meter, but still not terribly accurate at these low levels.


There are 3 settings on this for AC amps - 20A, 200A, 600A. It is rather old i suspect at this point but has consistently appeared accurate on what settings i use


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