Wall charger V3 shows lower voltage.

[SLWORD]

While waiting for my MYLD to be delivered next month, I installed Tesla wall connector V3. It appeared to work normally with no error LED code.

When I was trying to configure the connector on its interface, I noticed the grid voltage is only 230v. I measured the two hot terminals within the connector with a multimeter, it clearly showed 240v. All these measurements were taken without load.

Maybe not a big deal, just curious. Anyone can explain it to me?

 

[qdeathstar]

Where did you measure voltage at? I know you said within the connector, but I’m. It sure what that means. We’re you charging when that screenshot was taken?

 

[jcanoe]

Test some other 120V outlets and you probably find 115V there too. This is not an issue, common in older neighborhoods where the grid is fully loaded. If you observe a large voltage sag while charging when there may be an issue with the wiring.

The voltage I observe when charging at Level 2 and 32 amps varies from 238V down to 231V depending on the season, time of day. Neighborhood and house was built circa 1963 (60 years ago). I did upgrade my service to 200A and have a new panel installed in 2013. Distance from panel is ~70 ft. I believe the wiring is 8/3 rated for up to 55 amps. The charging circuit is protected by a 50 amp breaker and terminates at a 14-50 receptacle.

 

[Tham]

Unfortunately, I can’t really explain the reading you’re seeing. We did, however, have our gen 3 wall connector professionally installed this morning and last I checked, it was reading 237.xV. Maybe small variance in voltage is expected and normal - not sure, but at least you’re not alone!

Edit: I also noticed your max output current is lower than mine, but I think this can be configured on a case by case basis - someone please correct as needed.

 

[SLWORD]

Where did you measure voltage at? I know you said within the connector, but I’m. It sure what that means. We’re you charging when that screenshot was taken?

I measured voltage between two hot terminals in the connector wire box, see circles terminals in the picture below(the picture was downloaded form internet). No, it’s not charging while taken the screenshot.

 

[SLWORD]

 

[SLWORD]

Test some other 120V outlets and you probably find 115V there too. This is not an issue, common in older neighborhoods where the grid is fully loaded. If you observe a large voltage sag while charging when there may be an issue with the wiring.

The voltage I observe when charging at Level 2 and 32 amps varies from 238V down to 231V depending on the season, time of day. Neighborhood and house was built circa 1963 (60 years ago). I did upgrade my service to 200A and have a new panel installed in 2013. Distance from panel is ~70 ft. I believe the wiring is 8/3 rated for up to 55 amps. The charging circuit is protected by a 50 amp breaker and terminates at a 14-50 receptacle.

I have seen voltage drop during peak time. I am sure it’s not because of it. I took the screenshot showing 230v grid voltage, then, open the connector and measured the actual voltage between two hot terminals and got exact 240v. Two measurements were taken while not charging and only several minutes apart. It’s possible within these several minutes, the voltage could change but not likely.

 

[SLWORD]

Unfortunately, I can’t really explain the reading you’re seeing. We did, however, have our gen 3 wall connector professionally installed this morning and last I checked, it was reading 237.xV. Maybe small variance in voltage is expected and normal - not sure, but at least you’re not alone!

Edit: I also noticed your max output current is lower than mine, but I think this can be configured on a case by case basis - someone please correct as needed.

Thanks. That’s good relief for me. I thought it wasn’t installed properly. What really puzzled me it that at two hot terminals in the connectors’s wire box, the reading by multimeter showed exact 240v, while the connector’s configuration interface showed 230v. It’s small enough not to be worried. Just curious what causes this discrepancy.

 

[jcanoe]

I don't understand how you were able to measure the voltage at the charging connector. The connector is not powered until the Tesla vehicle and the Wall Connector agree on the charging amperage for the session and the relays in the Wall Connector close.

 

[SLWORD]

I don't understand how you were able to measure the voltage at the charging connector. The connector is not powered until the Tesla vehicle and the Wall Connector agree on the charging amperage for the session and the relays in the Wall Connector close.

The terminals in the wall connector directly wired to circuit breaker in the electrical panel. In principle, if one circuit has no load, anywhere in the circuit has the same voltage. Voltage is always there, just no current.

 

[qdeathstar]

Perhaps the blades that connect the evse to the evse base aren’t making good connection… or maybe the resistors they’ve used to for the divider for measuring the voltage are slightly out of spec….

 

[jcanoe]

The terminals in the wall connector directly wired to circuit breaker in the electrical panel. In principle, if one circuit has no load, anywhere in the circuit has the same voltage. Voltage is always there, just no current.

I misunderstood, thought you were somehow measuring voltage at the pins on the charging connector that gets inserted into the charge port on the Tesla vehicle. No way there should be any voltage or current on the hot pins of the charging connector until a charging session has been initiated.

 

[Sophias_dad]

This is nothing to be concerned with. Voltage from the grid changes all the time plus or minus 5% is commonplace, the electric company won't do much about it until its nearly 10% regularly. Yes... that's 216 volts, and I've seen it. The electric company came and checked on it, then a few weeks later they replaced the transformer feeding my house and a few others. I still see it dip, but not often below 230.

 

[SLWORD]

Perhaps the blades that connect the evse to the evse base aren’t making good connection… or maybe the resistors they’ve used to for the divider for measuring the voltage are slightly out of spec….

It makes a lot of sense to me. Thanks!

 

[josahua]

Voltage drop is only observed under load. How long is the run from the panel to the charger (dont forget to add the 24ft for the charger cable length, etc.)? What is the wire size?

A good voltage drop calculator is southwire app. 3.7% seems excessive for the install but cant tell without the data above but its nothing to worry about. One thing that is common in installs is terminals needing retightening due to stranded wire relaxing after the initial torque causing voltage loss.

If truly nothing is under load for both these measurements, you are describing voltage loss. (Beyond the internal terminal side it sounds like). This can be for a number of reasons (some already mentioned like corrosion on the blades, poor seating, etc.). Be more interested to see the voltages under load before you go further. Any excessive heat from the charger is what I would look for.

 

[josahua]

Voltage drop is only observed under load. How long is the run from the panel to the charger (dont forget to add the 24ft for the charger cable length, etc.)? What is the wire size?

A good voltage drop calculator is southwire app. 3.7% seems excessive for the install but cant tell without the data above but its nothing to worry about. One thing that is common in installs is terminals needing retightening due to stranded wire relaxing after the initial torque causing voltage loss.

If truly nothing is under load for both these measurements, you are describing voltage loss. (Beyond the internal terminal side it sounds like). This can be for a number of reasons (some already mentioned like corrosion on the blades, poor seating, etc.). Be more interested to see the voltages under load before you go further. Any excessive heat from the charger is what I would look for.

and amps allowed to be delivered by the charger.

 

[ATPMSD]

I noticed the grid voltage is only 230v. I measured the two hot terminals within the connector with a multimeter, it clearly showed 240v.

The most likely reason is a difference in the meters (quality and calibration) in your multimeter versus the meter in the wall connector, therefore, I would not worry about it. One thing I would do is tighten the electrical connections in the wall connector as it is not unusual for them to loosen a bit after initial install. Make sure the power is off, of course.

Tesla wall connector V3

Very monitor point, you have a Generation (Gen) 3 wall connector not a V3. V3 is a term used for Tesla SuperChargers e.g. V1, V2 & V3.

 

[SLWORD]

Voltage drop is only observed under load. How long is the run from the panel to the charger (dont forget to add the 24ft for the charger cable length, etc.)? What is the wire size?

A good voltage drop calculator is southwire app. 3.7% seems excessive for the install but cant tell without the data above but its nothing to worry about. One thing that is common in installs is terminals needing retightening due to stranded wire relaxing after the initial torque causing voltage loss.

If truly nothing is under load for both these measurements, you are describing voltage loss. (Beyond the internal terminal side it sounds like). This can be for a number of reasons (some already mentioned like corrosion on the blades, poor seating, etc.). Be more interested to see the voltages under load before you go further. Any excessive heat from the charger is what I would look for.

I can confirm it was not under load because I used a clamp meter double confirmed the current was only about 0.3A when the wall connector was on but not charging (my MYLD hasn’t delivered yet.) Retightening the screws seemed improve the voltage by less than 1 V, I’ll check its torque and make sure it’s 50 pound-inch.

 

[SLWORD]

The most likely reason is a difference in the meters (quality and calibration) in your multimeter versus the meter in the wall connector, therefore, I would not worry about it. One thing I would do is tighten the electrical connections in the wall connector as it is not unusual for them to loosen a bit after initial install. Make sure the power is off, of course.



Very monitor point, you have a Generation (Gen) 3 wall connector not a V3. V3 is a term used for Tesla SuperChargers e.g. V1, V2 & V3.

Yes. I often got confused by Gen. and V. Thanks for pointing out! I’ll double check the torque to the spec.

 

[josahua]

Forgot to ask, is this a new or used charger?