Buried in one of the Model S sticky threads, there was a post by a guy wondering why his Escort radar detector was throwing "High Voltage" warnings on his new 2021 Refresh Model S.
The short version of this story is that the Refresh cars have a fairly significant change to the 12v (let's call it the Low Voltage (LV) system from here out) system.
The refresh Model S (and I'm assuming this to be the case for the X, too, although I have been too lazy to verify it yet) DOES NOT have a 12v lead acid battery. Instead, it has a lithium battery, but as of right now, I'm not sure of the exact chemistry.
Check out this video at the timestamp:
He states that the pack is 1p/4s. What this means is that there are four cells wired in series. The nominal voltage for a lithium cell is 3.7 to 4.1 (and occasionally 4.2) volts. This means that when the battery pack is powering the low voltage system, the potential voltage for the LV system is between 14.8v and 16.4 volts. There is the potential of the high end being 16.8 volts if the cells used in the pack are capable of 4.2v at max charge.
In the post I mentioned about the guy having "High Voltage" warnings going off on his Escort, he mentioned that this only happened after the car was shut down, ie, the LV battery pack is powering the LV system, and since the LV battery pack was charged, it was doing so at 16.4-16.8 volts. Yet he didn't get this warning when the DC/DC convertor was powering the LV system, which I'm assuming means that when the DC/DC convertor is powering the LV system, it does so at 14.2 volts, which is what it always has been in Tesla cars up til now.
Also note that in the Owner's Manual for the Refresh S, it states that AC inverters plugged into the LV system must be capable of supporting an input voltage of 16 volts.
So the purpose(s) of this thread...
And also, please feel free to fill in any missing information, as well as correcting anything I've gotten wrong. Any additional information you can add is greatly appreciated.
Let's get the gaps in our knowledge filled in here so that people don't end up frying LV accessories.
The short version of this story is that the Refresh cars have a fairly significant change to the 12v (let's call it the Low Voltage (LV) system from here out) system.
The refresh Model S (and I'm assuming this to be the case for the X, too, although I have been too lazy to verify it yet) DOES NOT have a 12v lead acid battery. Instead, it has a lithium battery, but as of right now, I'm not sure of the exact chemistry.
Check out this video at the timestamp:
He states that the pack is 1p/4s. What this means is that there are four cells wired in series. The nominal voltage for a lithium cell is 3.7 to 4.1 (and occasionally 4.2) volts. This means that when the battery pack is powering the low voltage system, the potential voltage for the LV system is between 14.8v and 16.4 volts. There is the potential of the high end being 16.8 volts if the cells used in the pack are capable of 4.2v at max charge.
In the post I mentioned about the guy having "High Voltage" warnings going off on his Escort, he mentioned that this only happened after the car was shut down, ie, the LV battery pack is powering the LV system, and since the LV battery pack was charged, it was doing so at 16.4-16.8 volts. Yet he didn't get this warning when the DC/DC convertor was powering the LV system, which I'm assuming means that when the DC/DC convertor is powering the LV system, it does so at 14.2 volts, which is what it always has been in Tesla cars up til now.
Also note that in the Owner's Manual for the Refresh S, it states that AC inverters plugged into the LV system must be capable of supporting an input voltage of 16 volts.
So the purpose(s) of this thread...
- Please be aware of the changes to the voltage of the LV system in refresh cars
- There is no lead acid 12v battery in refresh cars
- Things plugged into the LV system must be able to take up to 16v
And also, please feel free to fill in any missing information, as well as correcting anything I've gotten wrong. Any additional information you can add is greatly appreciated.
Let's get the gaps in our knowledge filled in here so that people don't end up frying LV accessories.
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