Model 3: Three phase charging too sensitive to voltage drops?

[rollo.martins]

Dear all

After we do not get clear answers in the German TFF forum I would like the following question to be discussed in this international forum.

Many new European owners experience severe troubles when charging their Model 3 with three phase ac power. Including me. Power is reduced from the possible 11 kW down to sometimes as little as 2 kW.

I have the following setup: I use a Swiss T15 three phase socket which delivers 10 amps at maximum. I set the car to pull 10 A, and I set my mobile wallbox (Crohm) to 10 A either. The car starts by pulling 7 kW for a few hours and then reduces speed drastically. As I said to 2 kW.

At a 22 kW charging pole the full 11 kW is being sustained.

Suprisingly one phase charging at the same T15 plug does not reduce speed at all.

The Crohm Box is able to show current voltages. When charging is started the three voltages drop from around 227, sometimes 230, to 221 or so volts. In the TTF forum I was told that a drop of of more that 3 percent is outside the norm. 230 to 221 would exceed this. So this would explain the reduced speed at three phases. However, the 221 V is still completely inside the norm of absolute voltages (must be above 210 or 215 V, afaik).

However: If I charge at one phase the voltage drop is the same, but the speed is /not/ reduced.

Oddly things do not change if I set the 3 phase charging speed to 6 amps. Still the speed is reduced.

So I would conclude that three phase charging follows a different algorithm than one phase charging. Which is odd. It looks like the Model 3 is more careful at 3 phase charging than at one phase.

Any explanation for this? Is three phase charging too sensitive to voltage drops? Or is one phase charging not sensitive enough? Any solutions? Do you experience the same problems?

(I am aware that it might be wise to have the lines checked by an electrician anyway because the voltage drop is too high - however, if one phase charging is still acceptable, why is three phase charging not?)

Thank you for your thoughts.

 

[eprosenx]

Dear all

After we do not get clear answers in the German TFF forum I would like the following question to be discussed in this international forum.

Many new European owners experience severe troubles when charging their Model 3 with three phase ac power. Including me. Power is reduced from the possible 11 kW down to sometimes as little as 2 kW.

I have the following setup: I use a Swiss T15 three phase socket which delivers 10 amps at maximum. I set the car to pull 10 A, and I set my mobile wallbox (Crohm) to 10 A either. The car starts by pulling 7 kW for a few hours and then reduces speed drastically. As I said to 2 kW.

At a 22 kW charging pole the full 11 kW is being sustained.

Suprisingly one phase charging at the same T15 plug does not reduce speed at all.

The Crohm Box is able to show current voltages. When charging is started the three voltages drop from around 227, sometimes 230, to 221 or so volts. In the TTF forum I was told that a drop of of more that 3 percent is outside the norm. 230 to 221 would exceed this. So this would explain the reduced speed at three phases. However, the 221 V is still completely inside the norm of absolute voltages (must be above 210 or 215 V, afaik).

However: If I charge at one phase the voltage drop is the same, but the speed is /not/ reduced.

Oddly things do not change if I set the 3 phase charging speed to 6 amps. Still the speed is reduced.

So I would conclude that three phase charging follows a different algorithm than one phase charging. Which is odd. It looks like the Model 3 is more careful at 3 phase charging than at one phase.

Any explanation for this? Is three phase charging too sensitive to voltage drops? Or is one phase charging not sensitive enough? Any solutions? Do you experience the same problems?

(I am aware that it might be wise to have the lines checked by an electrician anyway because the voltage drop is too high - however, if one phase charging is still acceptable, why is three phase charging not?)

Thank you for your thoughts.

Howdy from across the pond! It is exciting to hear from folks getting cars in Europe!

Sadly, we have zero experience with three phase here since none of our cars support it. The software for that must all be new to support the European markets.

With that being said- We can talk about our single phase experiences:

So the Tesla checks the voltage when it starts charging and then again constantly as it charges. Regardless of starting voltage, if the voltage drops too much the Tesla assumes this is due to loose connections which could overheat and catch fire and so it is aggressive at backing off on the charge rate or ceasing charging entirely. It sounds like this is what is happening here.

It is unclear what the thresholds are in the US to trigger this and what the implementation may look like in Europe for three phase. That is a lot more complicated!!!

Please report back what you end up figuring out!

It could be a straight up bug, but also, checking out your wiring is likely a good idea anyway. I personally use a thermal imaging camera for this in addition to visual and torque inspections.

 

[LGA737]

Are you charging to 100%? The charging rate does taper when the battery gets to about 90% or so.

 

[NickFie]

US electrical safety regulations limit sustained load, such as EV charge, to 80% of rated supply. This prevents overheat and fire risk.

Please try setting car to use 8 Amps. You will probably be successful.

Our house has 240 Volt, single phase 100 Amp supply to Tesla HPWC. Older Model S with dual chargers can receive 80 Amps for hours without problem.

 

[mongo]

US electrical safety regulations limit sustained load, such as EV charge, to 80% of rated supply. This prevents overheat and fire risk.

Please try setting car to use 8 Amps. You will probably be successful.

Our house has 240 Volt, single phase 100 Amp supply to Tesla HPWC. Older Model S with dual chargers can receive 80 Amps for hours without problem.

Oddly things do not change if I set the 3 phase charging speed to 6 amps. Still the speed is reduced.

When it drops the power, check the display in the car. It will show current charge rate vs max current. Might it be the Crohm reducing the allowable charge current? If so, the max will drop. I'm not sure if the plug temperature or voltage drop change the max also...

With your 6 amp test, it should not be normal voltage drop (60% of 10 amp drop). May be a bad connection on one of the other phases.

 

[MP3Mike]

Have you checked the temperature of the plug/receptacle when it throttles the charging?

 

[rollo.martins]

Thank you for all your answers!!

I will definitely check this with an electrician.

I did not notice any heat at the plug/socket. The car always shows the max current set at the wallbox, not below (I.e, 4/8 A if I have the box at 8 A and the car takes 4), so it looks like it is not the box which is artificially reducing the current (although it could).

 

[eprosenx]

Thank you for all your answers!!

I will definitely check this with an electrician.

I did not notice any heat at the plug/socket. The car always shows the max current set at the wallbox, not below (I.e, 4/8 A if I have the box at 8 A and the car takes 4), so it looks like it is not the box which is artificially reducing the current (although it could).

I just re read this and had another idea:

I wonder if you are having an issue with one of the phases that is not used in single phase charging. Perhaps in between your wall box and the car (in the box or cable or the car itself). A loose wire or connector is my guess.

So the Tesla display if I am not mistaken only displays the voltage on a single phase, so you don’t have sufficient diagnostic information to figure out what is going on. Tesla really needs to make this info available. Voltages measured at the wall box are not helpful to you if the issue is downstream (towards the car) from there.

Also, if you are seeing a lot of voltage drop upstream of the wall box plus a bit more downstream of it perhaps the combination of the two is tripping it.

So yeah, I am guessing you have high voltage drop between the starting voltage and when under load. This is causing the car to back off.

I suspect you have something going on here that needs attention, though it could also be Tesla being too aggressive about the backoff and it may just be that European electrical wiring standards allow for more voltage variation and the car needs to be tuned for that.