I disagree. A common set top box can be 50-100 watts continuous. The Tesla BMS is always running. I'd rather sacrifice 40 watts continuous rather than have a problem with the $20k big battery due to inattention. Yes, it would be nice for it to be lower. I actually lose <1kWh per day. Also, at the some point, the electronics are supposed to wake up the big battery and charge the 12v battery. It is possible that a bad 12v battery causes the big pack to wake up more often and charge it, which can accentuate the apparent vampire draw. What is embarrassing for Tesla is the failures in the DC-to-DC charging circuitry and the 12v battery quality issues. They should be able to monitor and proactively replace these without waiting until actual failure (preferably through on-board software that detects a bad pattern and alerts the owner).
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I disagree. A common set top box can be 50-100 watts continuous. The Tesla BMS is always running. I'd rather sacrifice 40 watts continuous rather than have a problem with the $20k big battery due to inattention. Yes, it would be nice for it to be lower. I actually lose <1kWh per day. Also, at the some point, the electronics are supposed to wake up the big battery and charge the 12v battery. It is possible that a bad 12v battery causes the big pack to wake up more often and charge it, which can accentuate the apparent vampire draw. What is embarrassing for Tesla is the failures in the DC-to-DC charging circuitry and the 12v battery quality issues. They should be able to monitor and proactively replace these without waiting until actual failure (preferably through on-board software that detects a bad pattern and alerts the owner).
SteveS0353
Member
Lazy design (HW & SW) often leads to power inefficient systems. A STB is wall powered -- who cares how much it consumes. Any battery powered system, albeit with a HUGE battery like the Model S, requires careful attention to detail to minimize power. Yes, the BMS is always running, and that should come under the same scrutiny for power. I agree protecting the big expensive HV pack is the priority, but I still maintain that the vampire load can be 10 times lower and still get the job done.
CHG-ON
Still in love after all these miles
Ohh I am just guessing here, but a solar power storage battery or marine deep cycle battery would probably do nicely.
OR, just get a Costco battery in the largest format that fits the space, and get free replacements if she dies within 30 months or whatever the guarantee is, no cost to you. It is a vehicle application, there should be no arguments.
Anybody know the nearest "group size" of Tesla 12 volter?
Cottonwood
Roadster#433, Model S#S37
I forgot the brand, but Tesla uses a very good, deep cycle, AGM battery; the vampire still sucks the life out of them in a year or two.
Tesla advertises, that Model S needs less regular maintenance than ICE-cars.
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it doesn't need to be. It could go to sleep for 0.9 seconds and then wake up for 0.1 seconds and then go back to sleep for 0.9 seconds during stand by. This is normal behaviour for many battery powered electronics in stand by mode. This would cut stand by consumption by 90%.
SteveS0353
Member
Duty-cycling is one of many techniques for reducing power consumption, and the power saving is indeed a linear function of duty cycle. When they are not being used, it's possible to duty-cycle radios, sensors, CPUs, ..., anything really. I don't subscribe to the position that replacing the 12V battery after a year or two is regular maintenance. Those deep-cycle AGM batteries should remain viable far longer, and probably would if the vampire load / recharge cycles were not so aggressive.
Jaff
Active Member
SteveS0353
Member
The cost and inconvenience of regularly changing the 12V battery is not the issue. My biggest beef with the vampire load / 12V battery issue is that I would have expected a much more elegant design for a vehicle which sets new standards in just about every category. It's not that the Model S is otherwise perfect, there are certainly many opportunities for improvement, and they will be doing that with software releases over time, but the engineer in me cringes when I know the vampire load can be tamed.
Well, maybe Tesla should put together a lithium ion based 12v battery that has far higher cycle life. There are a lot of AGM 12v batteries that are really not designed for a high number of duty cycles - most car batteries for instance. They are designed to have a large burst of energy but almost never cycle down very far. Tesla's 12v application lifecycle is much more like solar batteries. If you tried to stick an automotive 12v battery on an off-grid solar system, you'd have dead batteries pretty quick. At this point, Tesla should be putting in batteries that can last years, even with significant vampire drain. After all, that is basically what a lead acid off-grid solar system does and those batteries will last for more than a year.
Yes, it would be *very* nice if Tesla lowered the vampire drain even further. I suspect the wake up procedure is a nightmare. Of course, we have no clear idea of the what exactly is the big power draw while "asleep" and the various people I've spoken to at Tesla about this situation haven't exactly known the answers. BMS was a frequent response.
This is also one of the reasons why I think we should be able to have a solar panel on the car. Most people think I'm talking about charging the main traction battery - no... I'm talking about helping out the 12v battery to power the BMS and run the systems that allow the Tesla app to function. Maybe, if there is extra juice, to run a fan to reduce cabin heat. At the very least, if the 12v system can be charged through the 12v accessory plug, we can add a solar charger there. However, that 12v outlet gets cut when the car goes to sleep.
Yes, it would be *very* nice if Tesla lowered the vampire drain even further. I suspect the wake up procedure is a nightmare. Of course, we have no clear idea of the what exactly is the big power draw while "asleep" and the various people I've spoken to at Tesla about this situation haven't exactly known the answers. BMS was a frequent response.
This is also one of the reasons why I think we should be able to have a solar panel on the car. Most people think I'm talking about charging the main traction battery - no... I'm talking about helping out the 12v battery to power the BMS and run the systems that allow the Tesla app to function. Maybe, if there is extra juice, to run a fan to reduce cabin heat. At the very least, if the 12v system can be charged through the 12v accessory plug, we can add a solar charger there. However, that 12v outlet gets cut when the car goes to sleep.
Many norwegians have reported the "12V batteri problem - replace soon" message. Seems like a factory pushed message to a group of cars? I too have changed 12V battery little less than a year ago. Never had any problems, so the only issue has been the message in the dash 
Only problem for me now is that the 12V message prevents the car from installing new updates, and I have an update waiting which fixes 3G problems that we have here in Norway (car loses mobile coverage several times a week and the main screen needs reboot to make it work again). This means that sometimes I`m unable to preheat the car, and a reset takes about 5-10 minutes before 3G starts working=no internet radio on short trips
Only problem for me now is that the 12V message prevents the car from installing new updates, and I have an update waiting which fixes 3G problems that we have here in Norway (car loses mobile coverage several times a week and the main screen needs reboot to make it work again). This means that sometimes I`m unable to preheat the car, and a reset takes about 5-10 minutes before 3G starts working=no internet radio on short trips 
kevincwelch
Active Member
Heh.
My Model S has been serviced more times in 2 years than my Honda Accord and Civic were combined for a total of 10 years.
S is way more fun to own though.
CHG-ON
Still in love after all these miles
Heh.
My Model S has been serviced more times in 2 years than my Honda Accord and Civic were combined for a total of 10 years.
S is way more fun to own though.
That totally sucks and is my big fear. After owning Acuras for years, I am totally used to NEVER having a problem. They need almost no maintenance at all and nothing has ever gone wrong in them. I don't know how they do it. I just hope my new girl is a good girl! And YES, much, much more fun in every way.
It is easy to find out what drains the battery.
put an amp meter on the whole battery to get an idea of total draw over time and plot it. Then pull each fuse and run branch circuits through the amp meter and plot over time, repeat for each branch.
Then you know what is taking power.
Is everything necessary?
Duty cycle branches of your own choosing when the car is off by brutally interrupting the branch at the fuse box, using some timer. Close all branches when "IGN" is detected for drivability.
Or, what if you just power down the whole car nightly after a full charge? Wonder if that really means power down dead or vamps still draw? I guess something has to be listening to power back up again. Does this take the key on the window trick... Ive never powered down.
put an amp meter on the whole battery to get an idea of total draw over time and plot it. Then pull each fuse and run branch circuits through the amp meter and plot over time, repeat for each branch.
Then you know what is taking power.
Is everything necessary?
Duty cycle branches of your own choosing when the car is off by brutally interrupting the branch at the fuse box, using some timer. Close all branches when "IGN" is detected for drivability.
Or, what if you just power down the whole car nightly after a full charge? Wonder if that really means power down dead or vamps still draw? I guess something has to be listening to power back up again. Does this take the key on the window trick... Ive never powered down.
carrerascott
FUEL FTR
Argh. We were planning to take the Tesla on our Thsnksgiving travels tomorrow. The 12v warning light came on today. Tesla service said don't drive it. No loaners available by tomorrow and I'm 3 hrs from service center. Have to drive gas car now. Boo.......
sgblank
Member
Add another March 2013 Model S that just got the 12V battery needs service message.
Ranger coming out next week to replace it.
I'm wondering if the first cold(ish) night in Northern California had anything to do with it.
When I called service they said the voltage looked OK now (13 volts).
I wonder if low temps are triggering a temporary under voltage flag.
Ranger coming out next week to replace it.
I'm wondering if the first cold(ish) night in Northern California had anything to do with it.
When I called service they said the voltage looked OK now (13 volts).
I wonder if low temps are triggering a temporary under voltage flag.
EarlyAdopter
Active Member
Oh, bummer!
Did you let them know about your upcoming trip? Maybe they can send a service tech down to your house to swap the 12V battery. Took a tech less than 30 minutes to swap mine in the parking lot at work.
Or if the service center is in your direction of travel, maybe you could stop off there for a short pit stop.
carrerascott
FUEL FTR
Ours happened today when it was 74 out.... Can ranger do this on site or does it need to go to service center?
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