Charge dropping to 30A

[G'sinHawaii]

Providing the charger installation was done correctly, its the car, it senses a power spike or surge, and it will cut the charge by 25%, So it will go from 40Amp to 30Amp, as Sabrtooth mentioned, set it lower every charge until it doesnt change, and it is dependent on the power source, so, it can happen or might not, I have found i am less likely to have it drop to 30 by leaving mine at 39...

 

[Barry]

Power company won't care unless you have some amazing amount of money and time. They'll tell you to have an electrician put a recording meter on it. And then will probably still say it's within their limits.

Unfortunately power companies have VERY little overisght.

I disagree with both statements. I had an issue with line voltage being too high a bunch of years ago (when I lived in PA). Called power company and they came out and put a recording voltmeter for 24h. They agreed, did some adjustments at the substation (and reimbursed me for a burned out electric oven coil). They are required to be within 5% of 120V.

On another occasion, I reported RFI to them. They sniffed around and found some bad (arcing) insulators on the poles and replaced them.

Their oversight is your state public utilities commission. I suppose some utlities (and state agencies) can be more cooperative than others, but generally, the utilities don't want to hear from their state commissions.

Regarding the OP's problem, watching the current ramp up and the voltage ramp down is the easiest first step. Next, I'd do a recording voltmeter, if you don't spot anything by watching. If neither yields results, try turning off, one by one, anything in your house with an electric motor, such as A/C, pool pump, etc., that might be sending a spike up the line as it turns on or off.

 

[BBB4000]

Regarding the OP's problem, watching the current ramp up and the voltage ramp down is the easiest first step. Next, I'd do a recording voltmeter, if you don't spot anything by watching. If neither yields results, try turning off, one by one, anything in your house with an electric motor, such as A/C, pool pump, etc., that might be sending a spike up the line as it turns on or off.

We don't have anything drawing a ton of electricity. AC has been off, no pool, the dishwasher and washer/dryer weren't running when this happened. I think what happens is that the car drops the charging from 40A to 30A after about 5-10 min of charging.

How do I do a recording voltmeter?

 

[DrivingRockies]

How do I do a recording voltmeter?

It's a meter that you'll put on different areas to record. Usually start before the main breaker, then on your individual circuit if you don't find a problem there. If it's consistently at 5-10 minutes, a regular meter can show the same issues, if watched, and you can avoid the expense of a recorder.

 

[brkaus]

Just thinking - teslafi.com records the voltage and current every minute.

You could watch a few charge sessions with that running and see if it shows anything. Maybe a few days of recorded charging would show a pattern.

 

[Lloyd]

Our house recently had a 240V installed by the builder and I noticed that the car insists on charging at 30A. I will set the charging to 40A but the next time I charge it is back down to 30A. The voltage reads out at 240-245V by the car.

I saw some threads on this but it does not look like there is anything definitive on why this occurs. Any thoughts on how I should troubleshoot this?

We don't have anything drawing a ton of electricity. AC has been off, no pool, the dishwasher and washer/dryer weren't running when this happened. I think what happens is that the car drops the charging from 40A to 30A after about 5-10 min of charging.

How do I do a recording voltmeter?

I cheap place to start is with this product on an adjacent circuit.

http://www.apc.com/shop/us/en/produ...ta-XP-Home-Server-Multi-Language-/P-SFPCPE302

 

[ccdisce]

There is a lot of good information here so thanks everyone. The builder checked with the electrician who said the wire is 6/4 AWG - although I have not independently verified. Yes, on a 50A breaker, about 8 feet away.

I am confident it is not an issue with the car b/c my previous home had a 240V and I could always charge it at 40A. This only happened at the new house.

Since we still have warranty through the builder the question I now have is, what do I tell the builder to look at? I will need to give them specific ideas to investigate otherwise I am afraid they are going to just pass the blame onto someone/something else. Or is there nothing they can do?

You may want to call your electricity provider and mention to them what you are observing.
They may want to send over a tech to put a voltage recorder on your feed to see if moving your house up one notch on the distribution transformer taps is warranted....'.low batteries will get the volts'

 

[BBB4000]

Gauge of wire?
Please say 6 awg copper

AMP breaker?
Please say 50

Distance to panel?
Please say less than 100 ft

I just talked to the builder. They said they used 6awg aluminum instead of copper. The electrician said that copper is more conductive. I may be able to get the builder to replace the wire with copper. Could aluminum vs copper make that big of a difference?

 

[brkaus]

I just talked to the builder. They said they used 6awg aluminum instead of copper. The electrician said that copper is more conductive. I may be able to get the builder to replace the wire with copper. Could aluminum vs copper make that big of a difference?

Shouldn’t make that much difference for 8ft. But if the rest of the circuit is marginal it could push over the edge.

But I personally wouldn’t like it.

 

[JPUConn]

6AWG aluminum should be fine for 50 amp breaker running 40 amp continuous on an 8ft run.

Have you contacted your utility to ask if they could explain service related voltage drops?

 

[BBB4000]

6AWG aluminum should be fine for 50 amp breaker running 40 amp continuous on an 8ft run.

Have you contacted your utility to ask if they could explain service related voltage drops?

I have not. What should I say to them so they don't try to blow me off or blame the car or circuit installation?

 

[demundus]

I have not. What should I say to them so they don't try to blow me off or blame the car or circuit installation?

Probably exactly your situation. If they push back just explain that you already have Tesla looking at the logs from their end, and the car is incredibly complex when it comes to keeping itself safe from overvoltage and other surge issues. It doesn't limit itself for no reason, and you've observed the drop yourself with a meter, so you would appreciate a check on the line side while you continue to explore the vehicle side.

 

[BBB4000]

Thanks guys. Will give this a shot and see what the power company says.

So don't have the builder swap out the aluminum wire for copper?

 

[demundus]

Thanks guys. Will give this a shot and see what the power company says.

So don't have the builder swap out the aluminum wire for copper?

If he's gonna do it for nothing (add copper cost), I don't see why not. Copper has more ampacity at that gauge but Aluminum should still be able to pull 40a continuous at 6awg. You're good either way imo, but im so far from an electrician its not even funny.

 

[BBB4000]

If he's gonna do it for nothing (add copper cost), I don't see why not. Copper has more ampacity at that gauge but Aluminum should still be able to pull 40a continuous at 6awg. You're good either way imo, but im so far from an electrician its not even funny.

I am going to see if they will do it at no cost to me - since it was an oversight of the builder. Turns out my house was the first one that got 240V in the garage for a car and homes built later started getting copper. That should be enough for me to convince them to swap it out for free.

 

[brkaus]

I am going to see if they will do it at no cost to me - since it was an oversight of the builder. Turns out my house was the first one that got 240V in the garage for a car and homes built later started getting copper. That should be enough for me to convince them to swap it out for free.

If they used aluminum, it’s critical that they terminated it properly into breakers/outlets rated for aluminum.

 

[BBB4000]

If they used aluminum, it’s critical that they terminated it properly into breakers/outlets rated for aluminum.

is this something I can verify on my own or does it require an electrician?

 

[brkaus]

is this something I can verify on my own or does it require an electrician?

Honestly, beyond me.

The outlet and breaker should be marked Al. But I don’t know if there is done sort of standard convention where that would be.

It was also standard to apply anti-oxidant to the connection. I’m not sure if that is still the case.

My understanding is aluminum expands differently when warmed, so the connections come loose. It also oxidizes, so can increase resistance (and heat).

 

[Mirlen]

Is this into a HPWC? They call for copper only into the HPWC termination... So if so, that's more ammunition to have them switch it to copper, material cost is minimal...

 

[brkaus]

Is this into a HPWC? They call for copper only into the HPWC termination... So if so, that's more ammunition to have them switch it to copper, material cost is minimal...

I’ve been picturing this as a 14-50 outlet.