2021 Model 3 never ramps back up after temporary amp restriction by EVSE

[Ampre Sand]

I just confirmed an weird Model 3 charging behavior via my OpenEVSE, which we have set up with some home automation scripting to automatically restrict charging current to 5A when other high loads are in use (water heater, hot tub, etc), so as to avoid demand charges from the utility. After starting at 40A, and later in the cycle the EVSE temporarily reduces the pilot signal to 5A, the car does obediently ramp down to 5A. However, when the pilot signal goes back up to 40A available, the car remains at 5A and never ramps back up to 40A.

This means the car cannot be trusted to charge overnight on L2, whether at home or out and about traveling. It really sucks to expect the car to be fully charged in the AM, when instead it got stuck at whatever transitory minimum the EVSE advertised.

I know this used to work correctly for the first year I owned my Model 3. Something must have changed? It still works correctly for my LEAF, so I know it's not the EVSE.

Anyone else seeing this?

 

[GtiMart]

When you look at the car after your EVSE has resumed back up to 40A, does it show 5/40A or does it show 5/5A ? IF it's 5/40, you could maybe use the Tesla API to bring back the charging to 40A since the car sees there is more availability? If it's 5/5A then the car doesn't know and there's not much you can do.

 

[Ampre Sand]

When you look at the car after your EVSE has resumed back up to 40A, does it show 5/40A or does it show 5/5A ? IF it's 5/40, you could maybe use the Tesla API to bring back the charging to 40A since the car sees there is more availability? If it's 5/5A then the car doesn't know and there's not much you can do.

Both the iOS app and the car shows 5/40A once the EVSE has raised the limit, so the car indeed detects the limit has gone back up. It's just that the car isn't ramping back up its actual charging power to the original level in response.

I found another thread on here describing a similar problem with power-sharing two Tesla Wall Connectors, where charging power is split until one car is done / leaves... the remaining car no longer ramps up. Maybe the same bug?

It's almost like the EVSE's temporary limit is changing the "max power" slider in the car and app instead of leaving that alone and just drawing as much as allowed at any one time.

Interesting idea to use the unofficial API to workaround a (potential) bug in Tesla's software. As a software geek that actually sounds like fun. It wouldn't fix the problem outside of my own house, and ideally Tesla is the one that needs to fix their charging algorithm. It used to work correctly. Of course, since there is no way to submit feedback or bug reports to dear Tesla...

 

[jjrandorin]

Both the iOS app and the car shows 5/40A once the EVSE has raised the limit, so the car indeed detects the limit has gone back up. It's just that the car isn't ramping back up its actual charging power to the original level in response.

I found another thread on here describing a similar problem with power-sharing two Tesla Wall Connectors, where charging power is split until one car is done / leaves... the remaining car no longer ramps up. Maybe the same bug?

It's almost like the EVSE's temporary limit is changing the "max power" slider in the car and app instead of leaving that alone and just drawing as much as allowed at any one time.

Interesting idea to use the unofficial API to workaround a (potential) bug in Tesla's software. Ideally Tesla is the one that needs to fix their charging algorithm. It used to work correctly. Of course, since there is no way to submit feedback or bug reports...

I have 2 wall connectors in power sharing (Gen 2s), and they work perfectly the way you would expect them to, including with the second car ramping back up to 48amps when the 1st one is done.

 

[ai4px]

I just confirmed an weird Model 3 charging behavior via my OpenEVSE, which we have set up with some home automation scripting to automatically restrict charging current to 5A when other high loads are in use (water heater, hot tub, etc), so as to avoid demand charges from the utility. After starting at 40A, and later in the cycle the EVSE temporarily reduces the pilot signal to 5A, the car does obediently ramp down to 5A. However, when the pilot signal goes back up to 40A available, the car remains at 5A and never ramps back up to 40A.

This means the car cannot be trusted to charge overnight on L2, whether at home or out and about traveling. It really sucks to expect the car to be fully charged in the AM, when instead it got stuck at whatever transitory minimum the EVSE advertised.

I know this used to work correctly for the first year I owned my Model 3. Something must have changed? It still works correctly for my LEAF, so I know it's not the EVSE.

Anyone else seeing this?

I was seeing it on my MY. Just seems to have been fixed on 2022.28.2