Charge rate intermittently defaults to around 46 amps

[eswimm]

I misunderstood earlier, I thought it was defaulting to 46 amps (from 48 amps).

This is very dangerous! Please stop using the EVSE until it is configured properly. You need to configure it to not exceed the maximum charge rate your circuit is capable of handling safely!

Relying on the charge power setting in the car to not burn your house down is not an acceptable strategy! Your circuit breaker should be tripping, but it sounds as if it's defective. Get a qualified electrician in there to look at the situation.

Gen 1/2 wall connectors had switches to set the breaker rating, Gen 3 or UWC is configured through the web interface (or Tesla One app).

If the wall connector is configured appropriately, it will not allow you to exceed 80% of breaker rating.

As for the effect of voltage sag, it has the opposite effect you described. Voltage sag will deliver less charge rate since the amperage caps based on breaker rating, but higher than nominal voltage (240V) will force the wall connector to drop an amp or two to stay beneath the 11.5kW max. If I get 241-242V the wall connector will kick me back to 46/47A even though the breaker and wall connector are configured to provide 48A.

Excess voltage sag or temperature faults will kick the charge rate down as well, but usually much more significantly than the 1-2A you'll get with high voltage.

If the OP is on a 50A breaker, than his wall connector could pull 46-48A without tripping, but it definitely wouldn't be safe long term.

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[REM]

Can you elaborate on your exact setup? This sounds dangerous and very concerning.

Also, charging at 15-20 amps for the CT is definitely not ideal at all, and should really only be setup that way for long term storage or if you had absolutely no other choice.

 

[mongo]

Also, charging at 15-20 amps for the CT is definitely not ideal at all, and should really only be setup that way for long term storage or if you had absolutely no other choice.

The only downside to charging at 20 Amps is the increased vehicle energy usage over the longer charge period. It reduces heating in cables, connectors, and the charger electronics (plus some slight pack benefits).

Optimum efficiency is achieved when the current dependant losses equal the fixed loses.
Simplifying to just a resistive cable and a constant vehicle load, A (ignoring charger efficiency variations), min loss is achieved when I²R=A.
Solving for current: I = sqrt(A/R)

My WC voltage sags 10V at 48V. That's 480W of loss due to heat. Some is in the transformer to meter run, but it's the highest gauge section, so most is post meter electricity I paid for (on top of being inefficient). So, for my infrastructure, R =10/48 or 0.21 Ohm
Truck load vs ideal current:
100W : 22A
200W : 31A
300W : 38A
400W : 44A
500W : 49A

If the truck is running HVAC for pack conditioning, higher charge currents are more efficient. If not, lower charge current may be (though 20A is likely lower than optimal unless it's a long wiring run). Of course, it depends on the specific installation and wire resistance.

 

[REM]

The only downside to charging at 20 Amps is the increased vehicle energy usage over the longer charge period. It reduces heating in cables, connectors, and the charger electronics (plus some slight pack benefits).

Optimum efficiency is achieved when the current dependant losses equal the fixed loses.
Simplifying to just a resistive cable and a constant vehicle load, A (ignoring charger efficiency variations), min loss is achieved when I²R=A.
Solving for current: I = sqrt(A/R)

My WC voltage sags 10V at 48V. That's 480W of loss due to heat. Some is in the transformer to meter run, but it's the highest gauge section, so most is post meter electricity I paid for (on top of being inefficient). So, for my infrastructure, R =10/48 or 0.21 Ohm
Truck load vs ideal current:
100W : 22A
200W : 31A
300W : 38A
400W : 44A
500W : 49A

If the truck is running HVAC for pack conditioning, higher charge currents are more efficient. If not, lower charge current may be (though 20A is likely lower than optimal unless it's a long wiring run). Of course, it depends on the specific installation and wire resistance.

I have had several situations where I had to plugin to a 15 amp circuit, which typically only gives me 12 amps to work with, and the truck struggled to maintain or build a charge in high ambient temps.

generally speaking, it's probably also better overall to have quick charging times due to the amount of subsystems that need to be active as well. run-time is also an important factor

 

[mongo]

I have had several situations where I had to plugin to a 15 amp circuit, which typically only gives me 12 amps to work with, and the truck struggled to maintain or build a charge in high ambient temps.

generally speaking, it's probably also better overall to have quick charging times due to the amount of subsystems that need to be active as well. run-time is also an important factor

Sure, in winter my truck lost energy at 1200W (240V@5A) when starting with a cold pack (done for science).
But your example is a little different from the poster's setup:
12A @ 120V = 1440W gross
20A @ 240V = 4800W gross, giving 3.4kW extra power for charging, ~3% SOC/hour

Yeah, only the charger is negatively impacted by higher AC currents. Everything else just gets to be on for less time. In the limit, it's always charging and there is 100% on, but zero thermal cycling.

 

[Michael Callahan]

Me. I’m the guy who by far prefers gas. It’s instant temperature control.. char is also not possible the same way on electric

seen the new season?

The power company can shut off your electricity from their office, diversify your energies, i charge my CT from 8kw solar system. Dryer, stove hot water and in floor heat are on lp. I can back the house with the nema 14 50 recp. And last a long time from the 125kwh battery.

 

[roadrunner32]

I misunderstood earlier, I thought it was defaulting to 46 amps (from 48 amps).

This is very dangerous! Please stop using the EVSE until it is configured properly. You need to configure it to not exceed the maximum charge rate your circuit is capable of handling safely!

Relying on the charge power setting in the car to not burn your house down is not an acceptable strategy! Your circuit breaker should be tripping, but it sounds as if it's defective. Get a qualified electrician in there to look at the situation.

Thanks Hauling Ass for the warning. Yes, I had misled everyone by saying 46 amps instead of 48 amps. I do not have a wall charger. I had seen 48 amps on the screen which now I think is momentary until the mobile connecter is plugged in and limits it to 32 amps. Since then I have replaced my entire main breaker panel, it was old and had some corrosion between the stabs where the circuit breakers plug in. That was the reason for lowering the the charge current to 15 amps until I could get the panel replaced. Also I have replaced the standard NEMA 15-40R sockets with the larger Hubbel EV rated sockets.

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