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54K miles and 2.5 years on last 12 volt battery before dying...
- Thread starter sorka
- Start date
The hassle of dropping it off, the 10 thousand photos I take before passing custody, the 10 thousand photos of the rental car, and the two trips makes it far more time efficient for me to just do it myself even if the labor was free. I can't get ranger service in the Bay Area...which is kind of ironic.
Yes, the reason is well understood. The car draw 70 watts from the battery continuously even when it is off resulting in it being discharged 50% and then charged to 100% over and over again 6 times a day. Lead acid batteries aren't designed to be continuously cycled.
You've been very lucky. Your battery will fail soon.
thecloud
As rhythm raced inside, the ship came alive
I'm still on the original battery in my P85, which is over 4 years old now. A possibly relevant data point: I don't keep the car plugged in constantly; only when needed to charge. I've also had energy-saving mode enabled since the very beginning. Perhaps the daily power draw is less in that case?
ucmndd
Well-Known Member
Surely you can in Merced though? I’ve had a Fresno-based ranger fix many an issue for me. Great guy.
I always asked for a ranger at first including the first time my battery needed service but was told ranger service wasn't available in Merced OR the Bay Area and that I'd need to bring it in each time.
I'm on my original battery, P85, March 2015 build, 81k miles. In contrast to you, mine is plugged in most of the time.
(Probably jinxing it by writing this. I'll likely get a failed battery message today.
)
I just got the “12V Battery needs replacement” warning light yesterday as I was leaving town for a week.
The person I talked to at Tesla to arrange a Ranger visit told me the battery should last about a month after the light comes on (so don’t worry), and these batteries are now lasting about a year (some time/mileage trade-off)!!!!
- The original battery lasted 26 months and 39k miles
- The second battery lasted 11 months and 15k miles
The person I talked to at Tesla to arrange a Ranger visit told me the battery should last about a month after the light comes on (so don’t worry), and these batteries are now lasting about a year (some time/mileage trade-off)!!!!
Even though your out of the bumper to bumper warranty period due to mileage, that second battery should be fully covered under warranty.
Olds442
Member
Mobile unit told me $250-260 when he replaced mine under warranty summer of 2018. I was curious so i asked.
Just had the ranger out yesterday to replace the 12V battery in our 2015 S85D built in Nov 2015. Got the message Monday- Ranger came out Wed. I'm under the CPO warranty- Car has 33K miles on it. But in the desert 12V batteries are good for about 3 years max in ICE cars, so I suspect it's not too different for EVs. We had the 12V battery in our 2014 car go out almost exactly 3 years after we got it too. So my sample of 2 is these batteries last 3 years in the desert
ElectricLove
Member
Great question!
12V is needed because you don't want to run the HV battery and conversion system all the time, the vehicle has 24/7/365 12V loads so if they were going to run it off the HV they'd be running it all the time and that is bad for a few reasons:
1. the conversion efficiency isn't going to be great at low loads, this means you are wasting energy to the losses constantly.
2. if a vehicle is parked with a low battery and left for a long time (this happens sometimes) the HV battery is the last thing you want to sacrifice so you want another battery there to carry the burden of the 12V loads so that battery can just rest and wait to be recharged.
Tesla actually built the first 100 or so Roadsters under that same assumption that they didn't need a 12V battery, it failed them, they had a few bricked Roadster packs and quickly realized that wasn't the way to go. Any time an EV company tells me they are thinking of doing it the HV to 12V way, I advise them strongly against it!
OK, your second question; small 3 cell li-ion instead... Well that is a nice theory but doesn't work too well unless you design it right, and mostly auto manufacturers (even tesla) don't have a lot of experience with 12V battery designs, it is quite different than high voltage, and to be honest a low-level concern for a big company like TESLA. This is where start-ups like www.ohmmu.com (shameless plug for myself here) come in, we know how to design these batteries to work in the specific vehicles they are going to go into.
To further answer this second question with what is perhaps the biggest issue from an OEM stand-point; TEMPERATURE! as extreme cold charging of lithium batteries leads to plating and ruins the battery, to avoid this certain things can be done in the design. This is a big part of what I'm doing with my Ohmmu company, we are working on ways to improve this extreme cold weather performance. Most auto manufacturers follow an "automotive standard" 12V battery operating temperature range; this range is -40C to +85C (-40F to 185F). For any off-the-shelf lithium battery solution that range is untenable, impossible to guarantee. As we work forward with our technologies and strategies we hope to get to the point where we can provide the exact same range in our spec! At this time, we are getting closer and closer, while the reality is that for a tesla the 12V battery never hits those extreme temperatures and so they really don't "need" to spec their 12V that way, but its a standard thing so they do it...
I will tell you, without specifics, we (Ohmmu) are presently working with OEM's to deploy lithium 12V systems as OEM in the future! It's a very exciting thing and I am very passionate about it and believe we will get there!
Sorry to be so long-winded here!
12V is needed because you don't want to run the HV battery and conversion system all the time, the vehicle has 24/7/365 12V loads so if they were going to run it off the HV they'd be running it all the time and that is bad for a few reasons:
1. the conversion efficiency isn't going to be great at low loads, this means you are wasting energy to the losses constantly.
2. if a vehicle is parked with a low battery and left for a long time (this happens sometimes) the HV battery is the last thing you want to sacrifice so you want another battery there to carry the burden of the 12V loads so that battery can just rest and wait to be recharged.
Tesla actually built the first 100 or so Roadsters under that same assumption that they didn't need a 12V battery, it failed them, they had a few bricked Roadster packs and quickly realized that wasn't the way to go. Any time an EV company tells me they are thinking of doing it the HV to 12V way, I advise them strongly against it!
OK, your second question; small 3 cell li-ion instead... Well that is a nice theory but doesn't work too well unless you design it right, and mostly auto manufacturers (even tesla) don't have a lot of experience with 12V battery designs, it is quite different than high voltage, and to be honest a low-level concern for a big company like TESLA. This is where start-ups like www.ohmmu.com (shameless plug for myself here) come in, we know how to design these batteries to work in the specific vehicles they are going to go into.
To further answer this second question with what is perhaps the biggest issue from an OEM stand-point; TEMPERATURE! as extreme cold charging of lithium batteries leads to plating and ruins the battery, to avoid this certain things can be done in the design. This is a big part of what I'm doing with my Ohmmu company, we are working on ways to improve this extreme cold weather performance. Most auto manufacturers follow an "automotive standard" 12V battery operating temperature range; this range is -40C to +85C (-40F to 185F). For any off-the-shelf lithium battery solution that range is untenable, impossible to guarantee. As we work forward with our technologies and strategies we hope to get to the point where we can provide the exact same range in our spec! At this time, we are getting closer and closer, while the reality is that for a tesla the 12V battery never hits those extreme temperatures and so they really don't "need" to spec their 12V that way, but its a standard thing so they do it...
I will tell you, without specifics, we (Ohmmu) are presently working with OEM's to deploy lithium 12V systems as OEM in the future! It's a very exciting thing and I am very passionate about it and believe we will get there!
Sorry to be so long-winded here!
laalan
Member
Just received the dreaded 12 volt needs service. Appointments out in Mid February. Hope the battery lasts that long. Orange County CA
I'm glad there's a 12V warning. Apparently our 2013 Fiat 500e also has a low 12V warning indicator as well; ours is a 2013 with 64K miles on the original battery. Our 2007 Lexus Rx400h seems to go through batteries every 25months; one month shy of the free battery replacement (but it is a 50% pro-rated replacement). There's no low 12V battery indicator on the Lexus, but you get the feeling when the window motors slow down and it's time to grab the multimeter & battery tender. I'll keep an eye out on our newly acquired 2013 MS 85; if only the battery were easier to access.
electric_feel
The Electric Baron
I had a separate issue that was serviceable by Mobile Service. While waiting for that appointment to be scheduled, my 12V warning came up, so they were able to deal with multiple issues with techs out at the house this week. I bought my 2013 MS used in 2016, and this is the first time I've seen the 12V warning. I looked through all the other service invoices I have, and none of the previous appointments list replacing the 12V. Then again, the invoice I just got doesn't mention replacing the 12V battery, but the mobile techs did replace it, so who knows how long that battery was in my car before getting replaced.
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