Problem with Third party Level 2 Charger at 100% Limit Setting

[Lee SRQ]

I own a 2022 Model Y. I live in a condominium with a PowerCharge Level 2 (32A) charging station at my parking spot. This station is made by Lite-On. The Tesla supplied adapter is used to mate the J1772 universal charging station plug to the Tesla charging port. The station is supposed to shut off when the car finishes its charging session. This works just fine for charging limits below 100%. However, at a 100% charging limit the station does not stop trying to deliver electricity to the car. This poses a safety problem and requires the owner to manually attend the end of the session and turn off the station.

I have never charged to 100% but I was curious about battery degradation over my first year of ownership and Tesla told me to charge to 100% and read the range. (I did so and discovered I had lost about 3.9% in the first year which is within expectation.) But -- low and behold -- when I went to the car to check things out after I had received the message that charging was complete (at 100%), the charging station was still on and trying to deliver electricity. I presume the car did not take the excess electricity. Big surprise to discover this. I then ran about 3% off the car and tried it again with the same result. I then used a different charging station in our condo garage (same vendor; same setup) with the same result, again.

A friend in the garage has a 2023 Y with the same charging system set-up. I asked him to run this test and he discovered the same thing -- no shut off at 100% charging limit. He has not had any difficulty with automatic station shut-off at any other charging limit.

Another friend in the garage with the same charging system set-up has a Kia Ionic 5. He ran the test at 100% and the charging station shut off properly when the car was finished at 100%.

I contacted the Tesla Supercharger unit to see if they had any idea what was going on. The representative told me that perhaps the 100% setting is interpreted by the Tesla as a command to continue charging beyond the charging limit. This is very hard to believe.

Has anybody else experienced this problem with any non-Tesla charging station? Any ideas what's really going on?

 

[Lee SRQ]

Previous post correction...... Hyundai Ionic 5, not Kia.......

 

[jcanoe]

I would not be concerned. When you charge to 100% you will observe that the Tesla Model Y vehicle continues to charge for approximately 45 minutes after the state of charge has reached 100%. During this time the Tesla Model Y's battery management system is performing cell balancing and attempting to better determine the state of charge of the cells within the battery as it approaches 100%.

During this period the charging station may indicate that charging is still taking place. If you observe the charging screen in the Tesla Model Y or using the Tesla app the charging rate will likely show less than the usual maximum kW rate while charging, i.e. less than 7kW. While the Tesla Model Y is charging the battery pack and on-board charger may need to be cooled. This will use some power from the battery that will be replaced by some additional charging.

When daily charging with the charging limit set to something less than 90% the charging session should complete with no indication of any additional charging taking place after desired the state of charge has been reached. (The Tesla Model Y may end charging with 89% when set to 90%. This is not a problem with the battery, just a bug in the charging routine.)

 

[E90alex]

The car is balancing the pack and calibrating BMS at 100% and may continue to draw some power for 1-2 hours until it’s done.

 

[E90alex]

Also the EVSE does not “push” power into the car, the car requests power from the EVSE.

So it will not deliver power to the car unless the car is requesting it and therefore cannot overcharge the car.

 

[Lee SRQ]

I own a 2022 Model Y. I live in a condominium with a PowerCharge Level 2 (32A) charging station at my parking spot. This station is made by Lite-On. The Tesla supplied adapter is used to mate the J1772 universal charging station plug to the Tesla charging port. The station is supposed to shut off when the car finishes its charging session. This works just fine for charging limits below 100%. However, at a 100% charging limit the station does not stop trying to deliver electricity to the car. This poses a safety problem and requires the owner to manually attend the end of the session and turn off the station.

I have never charged to 100% but I was curious about battery degradation over my first year of ownership and Tesla told me to charge to 100% and read the range. (I did so and discovered I had lost about 3.9% in the first year which is within expectation.) But -- low and behold -- when I went to the car to check things out after I had received the message that charging was complete (at 100%), the charging station was still on and trying to deliver electricity. I presume the car did not take the excess electricity. Big surprise to discover this. I then ran about 3% off the car and tried it again with the same result. I then used a different charging station in our condo garage (same vendor; same setup) with the same result, again.

A friend in the garage has a 2023 Y with the same charging system set-up. I asked him to run this test and he discovered the same thing -- no shut off at 100% charging limit. He has not had any difficulty with automatic station shut-off at any other charging limit.

Another friend in the garage with the same charging system set-up has a Hyundai Ionic 5. He ran the test at 100% and the charging station shut off properly when the car was finished at 100%.

I contacted the Tesla Supercharger unit to see if they had any idea what was going on. The representative told me that perhaps the 100% setting is interpreted by the Tesla as a command to continue charging beyond the charging limit. This is very hard to believe.

Has anybody else experienced this problem with any non-Tesla charging station? Any ideas what's really going on?

 

[Lee SRQ]

Thanks for the explanation. I will now rest easy. Given what's be said, I am disappointed that Tesla wasn't able to provide me with that information. (I called Tesla multiple times before I found someone who seemed to understand the question. Nevertheless, no good explanation was offered.) Perhaps I will try this again and leave the system for several hours to see if the charging station turns off. While I have been told that charging to 100% damages the battery, I would think that rebalancing the BMS is a good thing to do and maybe should be done on occasion. Any further comments? Thanks very much.....

 

[jcanoe]

Thanks for the explanation. I will now rest easy. Given what's be said, I am disappointed that Tesla wasn't able to provide me with that information. (I called Tesla multiple times before I found someone who seemed to understand the question. Nevertheless, no good explanation was offered.) Perhaps I will try this again and leave the system for several hours to see if the charging station turns off. While I have been told that charging to 100% damages the battery, I would think that rebalancing the BMS is a good thing to do and maybe should be done on occasion. Any further comments? Thanks very much.....

I would not routinely charge to 100%, leave the battery at 100% for any length of time (especially in warmer temperatures.) The Tesla Model Y BMS will do whatever is needed to maintain the battery and perform and needed cell balancing. You can help this by making sure you don't have Sentry mode (or Summon Standby if you purchased Full Self Driving) set to be active at your home location.

The Tesla Model Y will remain in Standby mode whenever Sentry mode or Summon Standby are active. This prevents the Tesla Model Y from entering sleep mode. The BMS periodically needs to measure the open cell voltage (OCV) of each of the cells in the battery pack to provide data points for the BMS algorithm used to accurately determine the state of charge of the battery. The Tesla Model Y must be in sleep mode before the BMS can collect the OCV measurements.

 

[Lee SRQ]

I would not routinely charge to 100%, leave the battery at 100% for any length of time (especially in warmer temperatures.) The Tesla Model Y BMS will do whatever is needed to maintain the battery and perform and needed cell balancing. You can help this by making sure you don't have Sentry mode (or Summon Standby if you purchased Full Self Driving) set to be active at your home location.

The Tesla Model Y will remain in Standby mode whenever Sentry mode or Summon Standby are active. This prevents the Tesla Model Y from entering sleep mode. The BMS periodically needs to measure the open cell voltage (OCV) of each of the cells in the battery pack to provide data points for the BMS algorithm used to accurately determine the state of charge of the battery. The Tesla Model Y must be in sleep mode before the BMS can collect the OCV measurements.

OK. From your answer I gather that the BMS doesn't need to have the battery charged to 100% to perform cell balancing and, now that I understand what's happening at 100% charge limit, to leave well enough alone. So I will not perform my little "test" to see if the charging station actually turns off sometime later with the limit set to 100%. Thanks again for this assistance..... This information will be passed to my colleagues in the building as well as to the folks at PowerCharge.

 

[E90alex]

OK. From your answer I gather that the BMS doesn't need to have the battery charged to 100% to perform cell balancing and, now that I understand what's happening at 100% charge limit, to leave well enough alone. So I will not perform my little "test" to see if the charging station actually turns off sometime later with the limit set to 100%. Thanks again for this assistance..... This information will be passed to my colleagues in the building as well as to the folks at PowerCharge.

Yes, it’s not needed for Model Y to charge to 100% once in a while to calibrate the BMS. So don’t do it all the time but also don’t be afraid to charge to 100% if needed for a longer trip.

Also some other manufacturers have a hidden top battery buffer so indicated 100% is not truly 100%. Or their BMS is simply programmed differently and that’s why they just stop charging immediately at 100% indicated.

 

[jcanoe]

OK. From your answer I gather that the BMS doesn't need to have the battery charged to 100% to perform cell balancing and, now that I understand what's happening at 100% charge limit, to leave well enough alone. So I will not perform my little "test" to see if the charging station actually turns off sometime later with the limit set to 100%. Thanks again for this assistance..... This information will be passed to my colleagues in the building as well as to the folks at PowerCharge.

If you want to charge above 90%, i.e. 95% that takes much less time than charging to 100%. When there were few to no Superchargers (seems like yesterday) then charging to 100% was often a necessity. These days with 5,000 Supercharger locations and 50,000 charging stalls, globally, when you travel in the lower 48 states in a Tesla vehicle you are rarely more than 100 miles from a Supercharger.

(With internal combustion engines the manufacturers caution against overfilling the fuel tank of a modern vehicle. This can cause fuel to flow into the activated charcoal canister that is part of the fuel vapor recovery system. Not the same thing as charging to 100% but seemed to fit the scenario.)

 

[fhteagle]

The only thing you need to worry about is if the L1 and L2 pins of the J1772 are depowered prior to removing the plug. This should happen as soon as the ground to proximity circuit is opened by a switch attached to the thumb latch on the J1772 handle. Depending on the EVSE, there should either be an audible click of physical contactors, a change in status lights, or both observable from the unit _immediately_ on every J1772 handle button press event. If your EVSE is built with a solid state relay, there won't be an audible click.

I disagree that L1 and L2 remaining hot after the Tesla finishes a charge cycle is a safety concern, and therefore not worth your attention.

en.m.wikipedia.org/wiki/SAE_J1772

 

[davewill]

The only thing you need to worry about is if the L1 and L2 pins of the J1772 are depowered prior to removing the plug. This should happen as soon as the ground to proximity circuit is opened by a switch attached to the thumb latch on the J1772 handle. Depending on the EVSE, there should either be an audible click of physical contactors, a change in status lights, or both observable from the unit _immediately_ on every J1772 handle button press event. If your EVSE is built with a solid state relay, there won't be an audible click.

I disagree that L1 and L2 remaining hot after the Tesla finishes a charge cycle is a safety concern, and therefore not worth your attention.

en.m.wikipedia.org/wiki/SAE_J1772

The thumb switch does not "open" the proximity circuit, it changes the value of the pulldown in the proximity circuit. Removing the plug opens the circuit. The car is only required to stop pulling current when the button is pressed, it doesn't have to actually command the EVSE to open it's contactors. Teslas do open the circuit, but LEAFs do not, for example.

You should be able to hear the EVSE open it's contactor in most cases. In fact, I'm not sure that solid state relays are allowed, they didn't used to be.