What is the typical max time the 2023 Model 3 can sleep before wakening to top off the low voltage battery? When it awakes, how long does it typically take to top off the new 16V lithium battery? My guess is less than the 2 to 3 hours needed for top off on our 2018. This might be why the phantom drain on the newer Tesla vehicles is MUCH less than our 2018?
-
Want to remove ads? Register an account and login to see fewer ads, and become a Supporting Member to remove almost all ads.
2023 Model 3 has not awaken in almost 5 days to top off the LV battery, normal?
- Thread starter rrolsbe
- Start date
Tam
Well-Known Member
"Wake" is defined by Tesla and not by a customer's observation/perception.
When your car is in a deep sleep, it is still technically awake to wait for commands to open the door, to get firmware updates, to turn on the HVAC for cabin protection and battery protection.
To us, the car is asleep, but to the car, it has never gone to sleep.
Thus, it is reasonable to assume that low voltage recharge is active during what you see as "deep sleep."
I define sleep to be when the HV contactors are open and awake is when they are closed. There are varying levels of power drawn from the low voltage battery when the contactors are open. Guess you could call them different levels of sleep. Unless something has changed, a DC-to-DC buck converter located on the PCS board tops off the low voltage battery and this requires that the HV contactors are closed (ie the car is awake by my definition). Now if the low voltage battery can be trickle charged in some way and not require the use of the PCS or have the contactors closed, that would be great news!
Thanks for your reply!
Regards
Thanks for your reply!
Regards
Last edited:
E90alex
Active Member
Tam
Well-Known Member
The BMS always works even in deep sleep. The BMS controls the contactors. When needed, the BMS will close the contactors to charge your 15.5 V battery.
EEVEE, it tells you the last time the car was seen ie.. Awake, HV contactors closed and the PCS will be either charging or maintaining a float voltage level . I had a 12V battery monitor attached to my 2018 so I could monitor the 12V battery voltage. This 12V monitor can handle voltages up to 20V so I might attach it to the 2023 at some point.
E90alex
Active Member
How often did your 2018 wake to charge the lead acid battery? Seems like your battery was maybe on its way out.
Even todays highly connected ICE vehicles can go weeks if not months without draining the 12V battery.
Even todays highly connected ICE vehicles can go weeks if not months without draining the 12V battery.
The longest time between top offs over the almost five years of ownership was around 31 hours and it took 2 to 3 hours to perform the 12V top off. Tesla replaced the 12V lead acid battery when the PCS was replaced both under warranty. Like you, I had assumed the 12V battery was getting long in the tooth but no change to the 31 hours sleep/2-3 hours top off times.
I’m curious to hear about your phantom drain experience. You might have an issue with your 2018 car.
Recently, my 2018 Model 3 only dropped from 47 to 46% after sitting at an airport for 7 days. It’s had that low level of phantom drain since at least May 2020 quarantine.
From TeslaFi:
E90alex
Active Member
No real answers for you but maybe some guesses.
Could be that lead acid batteries just don’t retain charge as well even without any draw hence needing to recharge more often.
Or Tesla just programmed that in as a precaution since determining lead acid battery charge level and health can be very inaccurate, hence why it’s very often that lead acid 12V batteries die without any prior warning.
The new Li-ion 12V has its own advanced BMS for more accurate readings of SOC and health so it will probably tell the car when it needs to be recharged instead of proactively recharging it even when it may not be needed.
AlanSubie4Life
Efficiency Obsessed Member
Nearly all of this is determined by what the power draw is when the car is asleep. That is basically all that matters (obviously to a lesser extent the power draw when the car is awake matters, but it is less of an issue, especially as sleep power is reduced).
No one seems to have done the analysis for the “new” “12V” batteries, sadly, yet. It’s not that difficult!
The interval between wake cycles is determined by how much energy is allowed to be drawn from the 12V/“12V” battery (and of course the sleep power). No idea on that either. In the case of the 12V it seems that a couple hundred Wh was about the max (about 40% of capacity?). No idea what the numbers are for the Li-ion “12V.”
Also can all be deduced through careful observations.
Have to be sure to ignore the initial BMS adjustments though after initial park/sleep cycle.
So the big question is whether the sleep power has been reduced in more recent model years. That’s what primarily determines phantom drain for a properly behaving vehicle. I doubt the idle power has changed that much (but maybe if they can recharge that 16V more quickly the impact could be mitigated as the OP suggested).
Still, the real win would be from reducing sleep power (since any reduction in sleep power automatically means proportionately less time spent awake).
No one seems to have done the analysis for the “new” “12V” batteries, sadly, yet. It’s not that difficult!
The interval between wake cycles is determined by how much energy is allowed to be drawn from the 12V/“12V” battery (and of course the sleep power). No idea on that either. In the case of the 12V it seems that a couple hundred Wh was about the max (about 40% of capacity?). No idea what the numbers are for the Li-ion “12V.”
Also can all be deduced through careful observations.
Have to be sure to ignore the initial BMS adjustments though after initial park/sleep cycle.
So the big question is whether the sleep power has been reduced in more recent model years. That’s what primarily determines phantom drain for a properly behaving vehicle. I doubt the idle power has changed that much (but maybe if they can recharge that 16V more quickly the impact could be mitigated as the OP suggested).
Still, the real win would be from reducing sleep power (since any reduction in sleep power automatically means proportionately less time spent awake).
Last edited:
fholbert
Active Member
EEVEE Mobility | Home
EEVEE Mobility
https://eeveemobility.com
https://eeveemobility.com/
There is a phone app for Android and IOS
This app has never woken the car it just gets the data when the car is awake for some other reason.https://eeveemobility.com/
Thanks for the info. Looks like your 2018 sleeps for 3+ days, mine never got even close to that. For about the first year+ anytime my 2018 was awaken for any reason, it would stay awake for around six hours hammering the 12V battery at 14.5 volts. This behavior changed with a firmware update. After the firmware change(s), it correctly charged the 12V at about 14.5V then dropped back to a float voltage level of around 13.5V. I speculate this early behavior was not good for the lead acid battery? Guess since my 2018 was recently totaled this problem does not apply to me anymore!
Yeah, I too would like to see a detailed analysis. I will report back when my car wakes up to top off the low voltage battery (assuming it is not much longer as I need to drive it Saturday). Currently it has been sleeping for 5 days and 14hrs. I have a DC current clamp but do not believe it would work well given the low current draw while sleeping? It was easy to read the inline current draw with the lead acid battery, not so much with the new connector used with the lithium battery.
My 2023 Model 3 finally woke up after 6 days and 14 hours. It was awake for less than 30 minutes,. The EEVE app does not give me a wake up time only last time seen. I assume it woke up to top off the 16V lithium but it could of been to check for new firmware etc. Went from 239 Miles/82% to 237 Miles/81%.. Very impressive!
AlanSubie4Life
Efficiency Obsessed Member
Pretty sure. I have been using the app for almost a year and it has worked well. I believe the car might have to be awake for around five minute or it might not catch it. My Bluetooth battery monitor would show all 12V battery states over a 31 day period, I found it to be an very valuable for detecting potential issued. The specs indicated the power draw was 1ma (never verified that).
AlanSubie4Life
Efficiency Obsessed Member
Good that it cross-checked well with the battery monitor.
The battery monitor is great; may be time to rig it up on the 16V. Seems like the only way to really know for sure.
Two miles over 6 days is about 3W so it does seem to suggest potential reduction in sleep power.
However, the first sleep cycle should be neglected (due to BMS adjustments). So hard to say. And possibly adjustments could occur on any cycle, I guess.
It does seem like it would have been low-hanging fruit for them to reduce sleep power. Curious whether they did.
Similar threads
