JRP3
Hyperactive Member
DC/DC should power up when the 12V battery voltage drops to a specified level and keep the battery charged, just like a battery charger. If it doesn't I'd say there is a problem with the DC/DC converter.
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Cyclone
Cyclonic Member ((.oO))
Well that didn’t last long. My last 12v lasted almost four years. Since one got out in in early March and I already got the replace 12v message. Similar to last time, I noticed this week I had much higher vampire drain, but I figured it was because of the fall weather. Guess it was both.
If your getting a good amount of Vampire drain then your 12v is taking a beating. The HV pack doesn't just discharge on it's own, the contactors have to be engage to run the systems either 12v (13.2) or HV (350/400). If your car isn't going to sleep then the 12v systems are working hard on something and everytime that 12v gets to 12.4 or 12.5v then the DC/DC kicks in and supplies 13.2v from the HV battery. This is where the HV Vampire drain comes from on most normal cases. If your car is actively charging then the DC/DC contactors are closed and keeping the battery at 13.2v. I think some of the people here that drive lots of miles a day and charge from home will see long life in their 12v batteries. Due to driving keeps the battery at 13.2 and while charging for the 4 or 5 hours at night does the same. Cycling the Lead Acid battery so many times takes a toll on it. I use a NOCO Genius and my car will loose maybe 1% over 4 or 5 days if I have it parked in the garage. If my car isn't in sleep mode then the NOCO helps but a trickle charge doesn't make up for what the car uses. I haven't tried to put the NOCO on 13.6 supply mode yet and keeping the car awake but may give it a try for test run.
dabbler
Member
I have been going on my fourth year with out replacement of the 12V battery. I also charge from home on a regular basis (HPWC). Good to know that regular home charging extends the life of the 12V battery. I don't see any change in vampire drain over the years. I suspect that when replacement time comes, I will be doing this myself.
BrokerDon
Active Member
Another data point. We just returned from a 4 month trip out of the country with our 2015 P85D (40,000 miles) plugged into our HPWC charging at 60A. With our Tesla set to maintain 80% we didn't receive a "replace battery" warning and our range is almost identical after a couple of drives to < 10% charge then recharge overnight on our HPWC.
YMMV
Lasttoy
Active Member
After reading this, I will go next week and get new one. I have no clue how old mine is. At least 4+ yrs.
You didn't need to replace your 12v after I met you at Rocky Mount when it went dead? It's still holding out after it went dead, I thought for sure it wouldn't come back.
BrokerDon
Active Member
UPDATED data point. Our 2015 P85D (software version 2020.4.1) still has it's original 12V battery after 54,500 miles / 4.5 years plugged into our HPWC charging to 90% nightly at 60A / 240V using our gen 1 Tesla Wall Connector.
Not sure why our 12V battery has lasted so long based on other Tesla owner's comments but not complaining. Our Tesla has never left us stranded nor had excessive or lengthy repairs... Unlike several other ICE cars we've owned. Super happy.
Not sure why our 12V battery has lasted so long based on other Tesla owner's comments but not complaining. Our Tesla has never left us stranded nor had excessive or lengthy repairs... Unlike several other ICE cars we've owned. Super happy.
Early on (e.g. 2012-2014) Tesla had a bad batch of 12V batteries and didn't have the charging algorithm right. I had a couple of batteries proactively replaced during that time (no charge). The last battery has lasted five years and is still fine. Mostly what you're seeing is the forum effect where there are lots of complaints because mostly people post with complaints and few post with "situation normal". Also the ones with complaints tend to post the same complaint several times, so each issue is multiplied. Also, because it's Tesla, there are a few "complaints" from non-owners.
thecloud
As rhythm raced inside, the ship came alive
webbbcam
not-so-junior member
FlatSix911
Porsche 918 Hybrid
I just received the early warning to replace the 12V battery... has anyone had this covered under the ESA, Extended Service Agreement?
JPP
Active Member
FlatSix911
Porsche 918 Hybrid
Change it yourself. Battery is 76 bucks or so. I did it for my 2016 model a. Took about 30 minutes. Less now that I know what to do.
Cheburashka
Active Member
$440 to replace a 12V battery is pretty absurd. That quote seems to imply that it's over an hour of labor, which is not true.
Remember that there are several different generations of car here:
- Original Model S. Battery wasn't designed to be easy to change and there's a lot of disassembly to get it out.
- Model S from the "D" models onwards (even if not ordered with dual motor): same battery life, but battery now much easier go get at.
- Model S from around the time of the facelift (not sure if this change was actually simultaneous with the facelift): new 12V output from the main battery, so that vampire load is satisfied directly and no longer causes cycling of the 12V battery - should give longer life.
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