Does going to 0% damage the battery?

[Daniel in SD]

As I've already mentioned multiple times.

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

You're going to have to draw or find a circuit diagram of this. This is how I assume it works:

The switch is controlled by the BMS.
This is the chipset used in the Model S: http://www.ti.com/product/BQ76PL536A
Not sure about the Model 3.

 

[Darmie]

This is a good question. How is it known if there is any damage to the battery if the vehicle reached 0 percent? First off, is there any battery damage or degradation if the battery reaches 0? If so, what damage is occurring while at 0 and how much damage continues to happen with time? I'm asking for monetary reasons. So, if there's actual damage, how would the value be calculated? I know there is no set scale and there SO MANY variables.

 

[sorka]

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.

Re-read this because the thread was re-awakened. Re-reading this and it looks like what I implied is that 74 cells wired up in parallel sitting there all by their lonesome selves can result in some cells going negative due to influence from neighboring parallel cells. This is not true and not what I actually meant. Cells in parallel that are higher SOC will balance out with cells of lower SOC through the bleed resisters.

 

[ucmndd]

This is a good question. How is it known if there is any damage to the battery if the vehicle reached 0 percent? First off, is there any battery damage or degradation if the battery reaches 0? If so, what damage is occurring while at 0 and how much damage continues to happen with time? I'm asking for monetary reasons. So, if there's actual damage, how would the value be calculated? I know there is no set scale and there SO MANY variables.

Reading between the lines of your post, you don't have any reasonable claim to damages because the [shop | valet | drunken uncle] let your car's battery drain to zero, unless you can demonstrate... actual damage.

Does the car not accept a charge any more? Has the range substantially reduced and can you prove causation to the discharge event? Did your battery catch fire and burn your house down or something?

If you plugged the car back in and it started charging and everything seems fine, then everything is fine.

 

[mspohr]

Re-read this because the thread was re-awakened. Re-reading this and it looks like what I implied is that 74 cells wired up in parallel sitting there all by their lonesome selves can result in some cells going negative due to influence from neighboring parallel cells. This is not true and not what I actually meant. Cells in parallel that are higher SOC will balance out with cells of lower SOC through the bleed resisters.

I think that would be "going negative due to the influence of neighboring SERIES cells" Parallel cells all have the same voltage.

 

[sorka]

I think that would be "going negative due to the influence of neighboring SERIES cells" Parallel cells all have the same voltage.

Exactly which could still have if the car is just sitting there but only if the SOC got really really low. If the circuit is broken completely when the contactors aren't engaged, then the BMS could keep from turning them on to charge the 12 volt battery but over enough time, the onboard monitoring circuitry in the battery itself would eventually run battery so low that some cells will experience negative polarity.

 

[mspohr]

Exactly which could still have if the car is just sitting there but only if the SOC got really really low. If the circuit is broken completely when the contactors aren't engaged, then the BMS could keep from turning them on to charge the 12 volt battery but over enough time, the onboard monitoring circuitry in the battery itself would eventually run battery so low that some cells will experience negative polarity.

The BMS only lowers the voltage of cells that are "above average", It connects a resistor across the high voltage cells to drain charge. It will not drain cells below zero. It will not drain cells below the voltage of the low voltage cells.
Cells can only go negative if the surrounding series string is drained and some of the cells in the string have high voltage and some have low voltage. However, this is what the BMS is designed to prevent by draining individual high voltage cells.

 

[sorka]

The BMS only lowers the voltage of cells that are "above average", It connects a resistor across the high voltage cells to drain charge. It will not drain cells below zero. It will not drain cells below the voltage of the low voltage cells.
Cells can only go negative if the surrounding series string is drained and some of the cells in the string have high voltage and some have low voltage. However, this is what the BMS is designed to prevent by draining individual high voltage cells.

That's not what I said and you missed my post about how the bleed resisters keep balance.

 

[Darmie]

Reading between the lines of your post, you don't have any reasonable claim to damages because the [shop | valet | drunken uncle] let your car's battery drain to zero, unless you can demonstrate... actual damage.

Does the car not accept a charge any more? Has the range substantially reduced and can you prove causation to the discharge event? Did your battery catch fire and burn your house down or something?

If you plugged the car back in and it started charging and everything seems fine, then everything is fine.

Yes, you did good job reading between the lines. Yes, the car was being borrowed and it was driven down to 0 miles and not charged. Found 120V to charge with and the car did. 4 hours later waiting on a flatbed to take it to a SC, it appeared to not be charging. I reached out to tesla and they were showing over 5pct on the battery even though the UI showed 0pct so all was well. Thought the 12V battery would be dead but all was well. Car charges fine and Teslafi shows nothing unusual.

 

[brkaus]

I’ve been down to 3 miles. Made it home and car charged on 240v.

On a regular plug it may take a while before it gets above the bottom buffer so it could show 0 for a bit.