Workplace 110V Charging Issue 9/12A

[brkaus]

I think you're fine. Just keep the current set low, you could even go lower. The car is protecting the wire. Is it still useful to you at that charge rate to meet your mileage need?

As others said, if your planning on staying around, you can see what it would cost to have a 6-15, 6-20, 6-30 or 6-50 installed. Pick the highest of the four you're willing to spend.

 

[gilscales]

Voltage Drop Calculator

Based on a 200 ft run with 14 gauge wire and a 12 amp draw on 120V you can expect voltage to drop below 108V according to this voltage drop calculator so this seems to be the issue.

Crazy thing is according to this calculator when using a 200 ft run if you want to keep voltage drop under 3% then you would have to upgrade to 8 gauge wire! as even 10 gauge would give you a 4% voltage drop.

 

[dylan1016]

It's fine. You only need 1kW an hour. 8 to 9 hrs later and you've gotten 8 to 9kWh, about 12%, which is more than you need on a daily basis.

I agree, 1 kwh is enough for my daily commute.

 

[mswlogo]

I think you're fine. Just keep the current set low, you could even go lower. The car is protecting the wire. Is it still useful to you at that charge rate to meet your mileage need?

As others said, if your planning on staying around, you can see what it would cost to have a 6-15, 6-20, 6-30 or 6-50 installed. Pick the highest of the four you're willing to spend.

There is no reason to set the current even lower. Since it is at 109V I highly doubt the plug is getting hot, which is the only thing it can measure.

Everything is probably running the best it can given the conditions.

Again, it wouldn’t hurt to have it checked out or find out roughly how long the run is and what gauge was used to verify if 109V makes sense or not.

 

[dylan1016]

Hi all,

It seems like I am safe for current set up.

1kwh is enough amount for my daily commute.

The Screen shows "Check for an extension cord or bad utility wiring".
I am not using extension cable. I do not know why it show above message.

with 1KW 109V 9/12 .

My outlet look like this.

Please advise my current set up is safe.

 

[brkaus]

Extension cords cause voltage to drop.

long wire runs cause voltage to drop.

the car cannot tell the difference.

My feeling (and what appears to be the consensus here) is that, while not ideal, your safe.

 

[Nocturnal]

It's not a safety issue most likely. Assuming everything is to code the breaker will protect the actual circuit. Your mobile charger will protect the car.

 

[ivan801]

Just remember, when winter comes it may take 6 out of that 9 amps to keep the battery warm. So you may have to find another way to supplement your charging, such as supercharger or destination charger. You may also want to look into getting CHAdeMO adapter if you have CHAdeMO stations in the area.

 

[Big Earl]

I agree, 1 kwh is enough for my daily commute.

Minor correction:

1 kWh is about 4 miles of range. You mean to say a charge rate of 1 kW is enough for your commute. 1 kW for 8 hours would add 8 kWh of energy, or about 32 miles of range.

 

[Octo]

FWIW, I had a similar setup for six years (Ford Focus EV, BMW i3).

One reason why you get warnings is that the car doesn’t know what causes the voltage drop.

These 120V outlets and plugs aren’t really designed for long time high current use and several hundred plug/unplug events.

After a few years with both my Focus and i3, the plug eventually melted onto the outlet because over time the contact resistance got high enough that the load current caused enough of an IR drop and therefore power loss in the actual connection.

That the Tesla charger reduces current if it detects a voltage drop is a good thing.

 

[timk225]

Dylan, see my video here, I just made it last week. One of the 2 charging stations I went to has the same problem with that charge speed warning popping up, it was only getting 180 volts out of the 208 it should have had.

VIDEO! Garage charging Part 2 - the mad charger returns!

 

[ucmndd]

It's not a safety issue most likely. Assuming everything is to code the breaker will protect the actual circuit. Your mobile charger will protect the car.

A breaker isn’t going to do anything about overheating wire due to high resistance over a long run.

That said, the car is doing what it should, sensing an unacceptable voltage drop under load and backing the current off by 25%. Under those circumstances it’s unlikely to cause a problem.

 

[eprosenx]

Hi all,

I am living at the apartment, I cannot charge my car overnight.

Luckily, my boss installed 110v outlet at parking lot and gave me a private parking spot.

He tried to install NEMA 14-50, but it couldn’t installed NEMA 14-50 due to the wiring issue.

My dailly commuting is only 7 miles one way. So, 110v charging is good to me.

These are the pictures. The outlet is installed next to spring cooler control panel.

View attachment 439144



View attachment 439142



View attachment 439141



It works well, but I could not get 12 AMP, I only could get 9/12 AMP. Is it because of wiring lengths? I think the outlet is far from breaker (+200ft),


View attachment 439145



Do you guys have any idea how to get 12 AMP?

Also, screen says check wiring and extension cable (I do not use) when door is opened.
Screen shows 12/12AMP.

After door closed, it changed to 9/12AMP

Please help me out.

Thanks

Many others have covered this, but most likely the issue is simply the voltage drop due to the wiring distance. If as we suspect this was intended just for a sprinkler controller, whoever installed it probably ignored the voltage drop and installed improperly sized wire. Note that this is allowed in electrical code but advised against (there are not hard requirements in the NEC about voltage drop, just very specific recommendations).

The danger here would be if the wiring connection at the breaker or the receptacle was loose and that voltage drop was causing lots of heat at one of those locations, but nearly certainly this is explained by the wire over that distance. Dissipating that amount of heat over that large a distance is no safety issue at all.

Yes, as others have mentioned the nominal voltage should be 120v, you are seeing less than 110v due to what we presume is the voltage drop over the distance.

Can you please post a picture of the actual receptacle face itself? I want to see if it is a 15a or a 20a receptacle (can tell if it has the sideways notch or not). If it is only a 15a receptacle but you verify it is on a 20a circuit with 12 gauge or larger wire then you could have a 20a receptacle (still 120v) installed and with the right Tesla adapter you would be able to try charging at 16a. It is likely (basically guaranteed) it would back the speed down still, but it is possible it might let you charge at 12a (75% of the 16a) instead of 9a (or it might give up altogether, who knows unless you try it!).

So, charging 9/12 Amp is safe?

It should be checked out to make sure it’s safe. As mentioned, the car is limiting its current because of the voltage drop. This can be due to a number of factors ranging from benign (long wire length) to concerning (improper or loose connections).

If your boss wants to be awesome, he’ll call an electrician out to upgrade the wiring, but that will probably be very expensive. It would be better to run a dedicated 240 volt line out to a parking space and install a charging station (or better get, a dual head charging station that can share one circuit between two vehicles), but that’s also expensive.

Yeah, so if there is any chance that circuit is not used for anything else (or if the sprinkler controller is the only thing and perhaps you could be lucky and it has an auto-ranging power supply good for 208/240v) then you could convert that easily (probably) to 208v or 240v (whatever is available at your place of work, three phase power provides 208v, and single phase would provide 240v).

It's not clear what "the wiring issue" is, but if this is a dedicated 120v run, then my understanding is that it can probably be easily bumped up to 240v, so long as the amperage remains the same. This would double your charging speed -- maybe more, if the wiring is rated for 20A. The electrician would need to replace the outlet with a 240v, 15A (or 20A), 3-wire standard, like a NEMA 6-15 or NEMA 6-20; and you'd need to buy the matching adapter from Tesla for $35. On the other end, the breaker would need to be replaced with a 240v unit.

Of course, this assumes that whatever is causing the drop from 12A to 9A is fixed. Also, if it's not a dedicated run, this approach would not work -- at least, not without sacrificing or re-wiring whatever else is on the same circuit.

Note that if this is a commercial building (which it sounds like) then the circuit you are using right now should be a 20a circuit (not 15a) and it should be 12 awg minimum.

If you are able to get it upped to 208v/240v not only will it double (or nearly double) your charging speed, but also, there may be less voltage loss since you are starting at a higher voltage and the higher voltages don't lose as much. Even if it still backed down by 25% speed wise (amperage), it would still be a ton faster if it was 208v/240v.

What the car is sensing is that there is too much of a voltage drop from when it starts to charge (when it just starts charging and isn’t drawing any power) to when it is drawing 12A. It would be helpful if you could tell us what voltage the car senses when you first start to charge. When it is drawing 0 out of 12A (0/12).

Basically if there is too large a voltage drop, the car thinks there might be something wrong with the receptacle and thus reduces power. However if your case, since you said it was a new receptacle, the problem is probably that the electrician used a thinner gauge wire than he should have given the intended usage.

Since the electrician couldn’t install a 14-50, I am betting that he used an available conduit (correct? Was there any trenching involved in the receptacle install?). And it’s probably a 1/2 inch conduit. And for such a long run, he probably got lazy and installed 14 gauge wire instead of 12 gauge since that’s all you “need” for a 15A circuit. But the long run makes the voltage drop when drawing 12A.

If I am correct, there isn’t a safety issue. The voltage drop occurs solely to the long length of thin for the distance wiring.

At any rate, I would ask that an electrician look at the receptacle to make sure it is installed correctly (use the screw terminals, not the stab terminals, this is important), and also ask him if it is possible to upgrade the wire if the receptacle looks ok.

Otherwise, you’ll be stuck at 8A or whatever.

Yeah, so you have hit the nail on the head about the conduit size. I am making a wild guess that the circuit is a 20a circuit, the wire size is 12 gauge (standard for a 20a circuit, but not sufficient to maintain voltage over that distance), but that maybe the receptacle is only 15a (easily changed). I am guessing the original installer did not bother upsizing the wire as they should have (to 10 gauge or larger) since they knew it was just for a sprinkler controller which takes virtually zero power. The more recent electricians just probably installed a receptacle off the existing circuit.

So the question is the conduit itself: There is a good chance it is larger than 1/2 inch. Even if it is 1/2 inch it is possible that slightly larger wire could be pulled into the conduit. Maybe a new 208v/240v circuit could be added in addition to the existing 120v circuit (would probably require new wire for everything). Pulling in new wire is not a very large job compared to digging up the parking lot...

Voltage Drop Calculator

Based on a 200 ft run with 14 gauge wire and a 12 amp draw on 120V you can expect voltage to drop below 108V according to this voltage drop calculator so this seems to be the issue.

Crazy thing is according to this calculator when using a 200 ft run if you want to keep voltage drop under 3% then you would have to upgrade to 8 gauge wire! as even 10 gauge would give you a 4% voltage drop.

Yup! Voltage drop on our really low voltages here in the US is brutal. ;-) That is why we have utility transformers every 200-300 feet down every road in neighborhoods. I am guessing that the wire is 12 gauge FWIW... Note that the panel feeding this may also be a significant distance from the transformer, so there may be loss before it even gets to the panel.

Going up one wire size would likely resolve this issue, but yeah, to be properly in spec fully may require going up two wire sizes!

But yeah, try running the math with say 240v (or 208v). That is likely much more favorable. ;-)

Good luck and please report back on your resolution if you get any! I really will pile on that in the winter you need a lot more energy for the car if you live somewhere it gets colder. Note that you might also check around to see if there is anywhere closer to an existing electrical panel that a receptacle might be able to be installed that was cheaper to do or that was closer to the transformer...

 

[Rocky_H]

Can you please post a picture of the actual receptacle face itself? I want to see if it is a 15a or a 20a receptacle (can tell if it has the sideways notch or not). If it is only a 15a receptacle but you verify it is on a 20a circuit with 12 gauge or larger wire then you could have a 20a receptacle (still 120v) installed and with the right Tesla adapter you would be able to try charging at 16a. It is likely (basically guaranteed) it would back the speed down still, but it is possible it might let you charge at 12a (75% of the 16a) instead of 9a (or it might give up altogether, who knows unless you try it!).

Trying a 5-20 cannot possibly do anything helpful. It is already demonstrated that 12A causes too much voltage drop and makes it reduce the current level. Going higher than 12A obviously would even more so trigger that reduction. So the only thing that could make this any better would be if you can find some level in between, like 10 or 11 amps, where you might be able to squeeze out a little bit faster charging speed while still staying under tripping that auto-reduction. A 5-20 Tesla plug with the higher current values doesn't do anything for you.

I kind of get what you may have been thinking: running at a higher level makes it back off to 3/4 of the max, so the lowered value would be 12/16 instead of 9/12, but it will try that lowered 3/4 level and see if it reduces the voltage drop to an acceptable level, and if not, then it will cut off completely. So if it went from 16 to 12, we already see that it thinks 12 is bad, so it probably will stop charging altogether. I think keeping with the 5-15 plug and testing out 10 or 11 amps would be the only thing that might be a little bit useful.

 

[Nocturnal]

A breaker isn’t going to do anything about overheating wire due to high resistance over a long run.

That said, the car is doing what it should, sensing an unacceptable voltage drop under load and backing the current off by 25%. Under those circumstances it’s unlikely to cause a problem.

How do you figure? Longer wire will increase resistance which requires more amps. Right? Using the same item on a long cord is more likely to trip a breaker. I suppose I might be over simplifying the issue.

 

[davewill]

Can you please post a picture of the actual receptacle face itself? I want to see if it is a 15a or a 20a receptacle (can tell if it has the sideways notch or not). If it is only a 15a receptacle but you verify it is on a 20a circuit with 12 gauge or larger wire then you could have a 20a receptacle (still 120v) installed and with the right Tesla adapter you would be able to try charging at 16a. It is likely (basically guaranteed) it would back the speed down still, but it is possible it might let you charge at 12a (75% of the 16a) instead of 9a (or it might give up altogether, who knows unless you try it!).

... I kind of get what you may have been thinking: running at a higher level makes it back off to 3/4 of the max, so the lowered value would be 12/16 instead of 9/12, but it will try that lowered 3/4 level and see if it reduces the voltage drop to an acceptable level, and if not, then it will cut off completely. So if it went from 16 to 12, we already see that it thinks 12 is bad, so it probably will stop charging altogether. I think keeping with the 5-15 plug and testing out 10 or 11 amps would be the only thing that might be a little bit useful.

I actually think you both have a point. The 5-20 adapter might well stabilize at 12a, or it might do exactly what @Rocky_H said. Before trying it, the OP might want to be aware that trying a 5-20 adapter might also result in tripping the breaker, if the load of the car, the long wires, and anything else on the circuit adds up to too much. At some workplaces, this would be embarrassing.

Setting the car to 10 or 11a is a good idea,but might well not help. The OP may well just have to be grateful he's getting 9a in this situation.

 

[dylan1016]

Thank you all for the information, I really appreciate all of the answers.

I will stick with the current setup (I really do not want bother my boss, he is super busy), and will ask my boss to insall NEMA 14-50 or similar stuff later depending on my contribution at work.

I've been working here only 1.5 years, I believe it it too eary to request intalling EV Charger only for my personal EV. ( I am the only one who drives EV)

I would like to request after I being imporatant employee in this workplace (Bank)

 

[Rocky_H]

How do you figure? Longer wire will increase resistance which requires more amps. Right? Using the same item on a long cord is more likely to trip a breaker. I suppose I might be over simplifying the issue.

You are going on an assumption that doesn't apply here. It depends on how the plugged in appliance is designed to behave. You are thinking of how some types of appliances, like maybe some motors, are built to always try to stay on a certain performance point--like spinning at a certain RPM--and that takes a certain amount of fixed power. So if voltage drops, the device will request and draw more current to compensate for it.

Tesla cars don't work that way. The current is set at a fixed point on the screen, and it's not trying to maintain a constant power level. If the voltage is lower, the power is lower, and the current stays the same, so it won't be pushing harder on the breaker to get closer to tripping.

 

[Dmagyar]

My $.02 is the “electrician” that was hired drilled through the side if the irrigation controller and attached the bell box and tapped the existing #14 conductor supplying it. The circuit running back to the building probably is 200’, thats why you’re getting the high voltage drop. That 1/2” PVC conduit has available space to add more wires, in this case a pair of #10 for a better 240 volt dedicated circuit to facilitate your charging. Ask your boss if the building owner gets any rebates for adding charging stations, which are up to $7,500 in some area’s?
Problem is, that conduit may already be broken and getting pulled apart by the growth of the vegetation, it also seems quite shallowly buried, meaning problems with its integrity are more suspect. Good luck

 

[timk225]

I finally had enough of not being able to charge at work today. I said the hell with it, I'm gonna try my 5-20 in that outlet!

I brought my charge adapter to work with me and mid morning, with few people in the building, I plugged it up for 5 minutes to get some numbers.

With the charge cable just plugged in, before the amps begin to ramp up, I have 121 volts. At 16 amps draw, it drops to 114 volts. If I dial the amps down to 8 or 10, the voltage floats around 117 to 118. I didn't get any power quality warnings.

114 volts at 16 amps was getting me 6 mph of charging.

Dammit manager, let me charge here!!!!! I think I'm due for a performance review, I'll offer charging instead of a pay raise, which I'm sure would be tiny anyway.