How much is too much for charging extremes?

[jflaplante]

I try to take good care of my X75D battery. Because of some of my trips, when I charge to 100%, I drive it in the following 30 minutes and when I go bellow 5%-10% I charge it immediately after. I never let it sit at either extremes.

About 2 monts ago, my X was at the SC to replace the heating element/fuse which wasn't working, I was coming back from a trip when I dropped it off and my charging limit was set at 100%, by the time I realized it and wanted to lower the limit, it was already at 100% and it sat like this for 1-2 days, loosing a few % per day until I went to get it back. I asked the SC to do something to lower the SoC but they told me that it takes more than that to damage the battery.

Last week, the return leg of a 2,000km trip was interrupted by a charging problem. Neither the Chademo or Level 2 was working and no superchargers were in this area. The car was towed for 500km to the nearest SC and it was also confirmed that the supercharger wasn't working. It was -20c outside and at the time of the problem it had 20% left, they day when the tow truck picked it up, 8% and when it arrived at destination 1%. It has now been sitting at 0% since last Friday (3-4 days). This is beyond their control as it cannot charge in any way. My question is:

How much is too much to have a direct effect on battery degradation and what is Tesla's responsibility to it?

Thanks for your inputs?

JF.

 

[ajdelange]

I don't think the problem is with leaving it charged to 100% so much as it is charging it to 100%. That is known to degrade battery life but not to the extent that you can't safely do that from time to time. If the car thinks you are charging too high too much it will issue a warning message to you.

It sounds as if you have a problem with the car's charger though it could be something in the battery too. Not clear on exactly who has the car. Sounds as if it is in Montreal but not sure since you said there were no superchargers around when trouble hit and there is one in Magog which certainly isn't that far from Sherbrooke.

 

[ewoodrick]

Don't worry about it. Indeed sitting at 100% for a long time can decrease the battery life slightly. (sitting at 100% for a year drops life a few percent)

I'm not a real fan of sitting at 0%, but I suspect that at indicated 0%, that there still is some untouchably reserved charge and the battery gets completely disconnected.
Checking the state is waking up the car and running the 12v battery down. Taking a lead acid to 0% definitely isn't a good thing to do. It may have to be replaced.

Why can't it be charged? 120v if nothing else.

 

[MorrisonHiker]

About 2 monts ago, my X was at the SC to replace the heating element/fuse which wasn't working, I was coming back from a trip when I dropped it off and my charging limit was set at 100%, by the time I realized it and wanted to lower the limit, it was already at 100% and it sat like this for 1-2 days, loosing a few % per day until I went to get it back. I asked the SC to do something to lower the SoC but they told me that it takes more than that to damage the battery.

If you were monitoring the SoC via the app, couldn't you just turn on the heat to drain the battery?

 

[jflaplante]

If you were monitoring the SoC via the app, couldn't you just turn on the heat to drain the battery?

The heater was not working, that was the reason it was in the SC that particular time!

 

[jflaplante]

I don't think the problem is with leaving it charged to 100% so much as it is charging it to 100%. That is known to degrade battery life but not to the extent that you can't safely do that from time to time. If the car thinks you are charging too high too much it will issue a warning message to you.

It sounds as if you have a problem with the car's charger though it could be something in the battery too. Not clear on exactly who has the car. Sounds as if it is in Montreal but not sure since you said there were no superchargers around when trouble hit and there is one in Magog which certainly isn't that far from Sherbrooke.

The problem occurred when I wanted to DC fast charge in Godbout, Québec (no cell reception there!) 550km from the nearest SC in the City of Québec. I live in Sherbrooke but they only wanted to tow it the Québec SC. They called me today and the problem was a corroded pin between the charging port and the charger. It couldn't charge 120v/240v/DCFC or Surpercharge so it was impossible to charge the battery until the found the problem this afternoon...The purpose of my post was more with the effects of extremes SoC (0% and 100%) and not with the car's problem itself.

 

[ajdelange]

Did they tell you what caused the corrosion? I noticed that when I brought the car into garage with some snow on it that some of the melt was dripping into the charge port. This was not comforting.

 

[jflaplante]

Did they tell you what caused the corrosion? I noticed that when I brought the car into garage with some snow on it that some of the melt was dripping into the charge port. This was not comforting.

I asked if it was a chemical corrosion or an over current corrosion et he told me it was an infiltration of some sort. This particular section of the wiring harness can be reached by the elements. The repair was approved by the engineers in California, if they didn't approve it, they would have need to change the whole wiring harness and almost take the whole car appart in the process!

 

[jboy210]

Somebody correct me if I am incorrect. But, I seem to remember reading somewhere, that if the battery pack drops too low it will disconnect from the bus to prevent vampire loads (12 V battery charging, heater, etc) from dropping it any further.

 

[ajdelange]

I don't know if you are right or not but if the battery is damaged by complete or near complete discharge that would be a prudent thing to do.

Of course if the voltage gets low enough there won't be enough juice to hold the contactors closed and it will happen anyway.

 

[Rocky_H]

Somebody correct me if I am incorrect. But, I seem to remember reading somewhere, that if the battery pack drops too low it will disconnect from the bus to prevent vampire loads (12 V battery charging, heater, etc) from dropping it any further.

Yes, I remember hearing a few years ago the steps in order of what happens, and it does eventually get to the main battery pack being disconnected from the rest of the car with some small remaining bit of energy left for protection, and it can remain in that state for some months with the main battery being in a relatively safe unchanged state of charge.

Of course if the voltage gets low enough there won't be enough juice to hold the contactors closed and it will happen anyway.

Yes, that does kind of take care of itself in this kind of situation, since it takes energy from the 12V system to connect the main battery to the other electrical systems, and if unpowered, it will be disconnected/isolated.