Does going to 0% damage the battery?

[TESLER2013]

So I'm new,

I have a question that I started thinking about after I read the owner's manual. In the manual, it says that if you let the battery die, it can damage the battery. So I bought my car from Carvana who bought it an auction. The dates on my carfax are way apart on when it was sold at auction vs. when it was traded in/sold to dealer. So basically, if the car was dormant for so long, the battery obviously died as the battery loses 1% of power per day. So is my battery damaged? Or it got lucky? Or is the manual bs? What are your thoughts. This is the reason I am thinking buying directly from Tesla is better as they probably are keen to this thing. What are your thoughts?

 

[Vipercat]

It is not recommended to go below 20% SoC (State of Charge), but when you do, because you’re on a trip or for whatever other reason, the advice is to charge as soon as you can. Do not let your battery stay at a low SoC or at a high SoC (above 90%).

At the same time; the way the previous owner(s) treated the car (and battery) might be of more influence on current battery health then how Carvana is currently treating it.......

 

[Lasttoy]

Sorry I dont see yr, model? I've driven mine to zero several times.
It's not recommended, but if understand it sat for long time, years or months. No strain on battery should not hurt it. It's still unknown if car went totally dead. Tesla could tell you if you get a nice person on the phone. I called before I bought mine. She told me the entire service history. They can test your battery remotely.

 

[TESLER2013]

Thanks for the replies. It's a 2013 with 57k miles.

 

[Quamera]

So I'm new,

I have a question that I started thinking about after I read the owner's manual. In the manual, it says that if you let the battery die, it can damage the battery. So I bought my car from Carvana who bought it an auction. The dates on my carfax are way apart on when it was sold at auction vs. when it was traded in/sold to dealer. So basically, if the car was dormant for so long, the battery obviously died as the battery loses 1% of power per day. So is my battery damaged? Or it got lucky? Or is the manual bs? What are your thoughts. This is the reason I am thinking buying directly from Tesla is better as they probably are keen to this thing. What are your thoughts?

Letting the battery go to 0% or leaving it fully charged shouldn't actually kill it but every time it happens you will lose a bit of its remaining effective life. How does your range compare to new specs.

 

[TESLER2013]

If I charge to full it says about 260..

 

[Electric700]

If I charge to full it says about 260..

This is good. Your range is set to Rated? If so, you have a negligible loss slightly less than 2% (260 / 265 when new). The other advice is good here -- try to keep it within 20 - 80% on average. Battery balancing should occur at or above 93%, so you can do that 1 - 2 times a year and drive immediately after the charge completes.

Congratulations!

 

[TESLER2013]

This is good. Your range is set to Rated? If so, you have a negligible loss slightly less than 2% (260 / 265 when new). The other advice is good here -- try to keep it within 20 - 80% on average. Battery balancing should occur at or above 93%, so you can do that 1 - 2 times a year and drive immediately after the charge completes.

Congratulations!

Thanks! That is great to hear

 

[TESLER2013]

And yes it was on "rated"

 

[ucmndd]

It is not recommended to go below 20% SoC (State of Charge)...

Whose recommendation is that?

 

[sorka]

Letting the battery go to 0% or leaving it fully charged shouldn't actually kill it but every time it happens you will lose a bit of its remaining effective life. How does your range compare to new specs.

Leaving it at 100% or close to full will accelerate anode cracking. Leaving it near zero won't. The danger of going to zero is that if there is enough imbalance, that some cells or modules could experience negative polarity and then they're toast almost immediately.

Also, going to displayed 0% is not anywhere near close to actual 0%. I wouldn't worry about going to 0%. Just don't leave it there and use as little throttle as possible as you approach it.

 

[Quamera]

Leaving it at 100% or close to full will accelerate anode cracking. Leaving it near zero won't. The danger of going to zero is that if there is enough imbalance, that some cells or modules could experience negative polarity and then they're toast almost immediately.

Also, going to displayed 0% is not anywhere near close to actual 0%. I wouldn't worry about going to 0%. Just don't leave it there and use as little throttle as possible as you approach it.

Yes we must always remember that the indicated 0% and 100% are never the actual 0% and 100% for all Lithium chemistry batteries and some of those sneaky BMS actually adjust their indicated minimums and maximums so it appears that the battery isn't loosing capacity as it ages which has warranty implications.

 

[sorka]

Yes we must always remember that the indicated 0% and 100% are never the actual 0% and 100% for all Lithium chemistry batteries and some of those sneaky BMS actually adjust their indicated minimums and maximums so it appears that the battery isn't loosing capacity as it ages which has warranty implications.

For those that are voltage capped, it's true that 100% indicated is not really 100%. In my case, I'm still not capped(on v8 still) so my 100% indicated is 4.2 volts.

But it's always been the case that 0% indicated is about 5.2% of true SOC. The thing that is really messed up is that the rated range includes the buffer below the indicated 0%.

 

[mspohr]

Leaving it at 100% or close to full will accelerate anode cracking. Leaving it near zero won't. The danger of going to zero is that if there is enough imbalance, that some cells or modules could experience negative polarity and then they're toast almost immediately.

Also, going to displayed 0% is not anywhere near close to actual 0%. I wouldn't worry about going to 0%. Just don't leave it there and use as little throttle as possible as you approach it.

The onboard BMS will keep individual cells from going negative.

 

[sorka]

The onboard BMS will keep individual cells from going negative.

The BMS can't do any such thing nor does it even have a role to play in balancing. The bleed resistors are passive, not controlled. Not only that, there aren't physical charge wires for each module, only voltage sensing wires.

The BMS CAN prevent power draw from the linear string of modules to prevent voltage below 0 based on the weakest module. So in this sense it can prevent a module from going negative by preventing drawing too much power. But even that is only an estimate because because each module has 74 cells in parallel and each cell is not individually measured.

The danger with getting to near 0% is that at rest, without any load, is that the 74 18650 cells in parallel in each of the 96 modules can go negative if they are weak enough to be overpowered by the stronger cells.

 

[mspohr]

The BMS can't do any such thing nor does it even have a role to play in balancing. The bleed resistors are passive, not controlled. Not only that, there aren't physical charge wires for each module, only voltage sensing wires.

The BMS CAN prevent power draw from the linear string of modules to prevent voltage below 0 based on the weakest module. So in this sense it can prevent a module from going negative by preventing drawing too much power. But even that is only an estimate because because each module has 74 cells in parallel and each cell is not individually measured.

The danger with getting to near 0% is that at rest, without any load, is that the 74 18650 cells in parallel in each of the 96 modules can go negative if they are weak enough to be overpowered by the stronger cells.

Tesla BMS does individual cell voltage monitoring and balancing.
Here's a teardown
Pics/Info: Inside the battery pack

 

[sorka]

Tesla BMS does individual cell voltage monitoring and balancing.
Here's a teardown
Pics/Info: Inside the battery pack

Monitoring, but not active balancing.

 

[mspohr]

Monitoring, but not active balancing.

There are small resistors that do balancing.

 

[Daniel in SD]

Passive balancing explanation (switchable bleed resistor):
Passive Battery Cell Balancing | Analog Devices

 

[sorka]

There are small resistors that do balancing.

As I've already mentioned multiple times.

The bleeders are passive. They are not part of the BMS.