Near annual replacement of 12V battery is typical according to Tesla Service Tech

[Cyclone]

This is so contrary to my experience. 75k miles over two Teslas and 3 years of ownership, never had an issue with the 12v battery, not once. I have to believe there is some common denominator in daily usage scenarios that makes one owner more likely to have issues than another. I've always had this sneaking suspicion that regular daily driving of near to 100 miles and/or the addition of an aftermarket sub that pulls off the 12v is causing some side benefit to the 12v being constantly kept happy with charging/discharging.

Maybe it's location. Jdcorbitt3 is in FL and you're in OH. Heat kills lead acid faster.

Maybe Charlotte splits the difference? I've had my 2013 for 16 months and 25k from when it was delivered (including multiple trips to Miami) and it is still on the same 12v it was delivered to me with.

 

[dhanson865]

AGM can handle a high discharge rate. They are sensitive to over voltage. 13.5v or 2.25v/cell as opposed to 14.4v or 2.4v/cell. It is my understanding that a high current charge can also damage them.

These numbers vary with temperature and the cutoff for AGM is around 120° f.

I am going to monitor my voltage as best as I can.

John

I'm not sure where you are getting those numbers from. Both CTEK and NOCO charge AGM batteries at a higher voltage with their smart chargers than they do old school lead acid.

On top of that Optima specifies they want you to charge the Yellotop AGM using that mode.

Maybe there is an issue with overcharging AGM at the end but during the bulk charging phase they push higher volts no matter the amps.

I trust the smart chargers to do the job and shut off before overcharging the battery.

 

[Jdcorbitt3]

My Odyssey AGM's actually specify a higher current for optimal charging



http://www.odysseybattery.com/documents/US-ODY-OM.pdf

I was misinformed by Mazda. The Charge and discharge rates can be up to 5 times higher. The critical area is the float charge, where over 13.5V can overcharge the battery an damage it. I will look up my source and edit this post. It was a battery manufacturer. This is one source for the charge rate.
http://www.crosspointsolutionsgroup.com/_literature_113836/SVCT-Batteries_and_Charging

As with all gelled and sealed units, AGM batteries are sensitive to overcharging. A charge to 2.40V/cell (and higher) is fine; however, the float charge should be reduced to between 2.25 and 2.30V/cell (summer temperatures may require lower voltages). Automotive charging systems for flooded lead acid often have a fixed float voltage setting of 14.40V (2.40V/cell); a direct replacement with a sealed unit could overcharge the battery on a long drive. (See BU-403: Charging Lead Acid.)

Absorbent Glass Mat (AGM) Battery Information - Battery University
This is where I got the actual voltages.

This is also leading me to believe these cars are experiencing an over voltage in the float stage. I am hoping a software can fix this.

One of the planes I fly had a problem with the NiCad Emergency lighting batteries being discharged completely if the aircraft was not powered up every couple of days. This resulted in the batteries being replaced every 12 months. It took the Aircraft Manufacturer over two years to figure it out. The SB fixed it. It required a small change in the wiring and the installation of a relay. They work great now. The plane can sit for two weeks and the lights will power up when turning them without turing the main batt on.

John

 

[Jdcorbitt3]

From The Odyssey Manual charging ate 15V kills the battery. They are also recommending a float charg of 13.5 to 13.9V charge.

http://www.odysseybattery.com/documents/US-ODY-OM.pdf

To fully charge a 31-PC2150 and 31-800 battery that is routinely discharged deeply, a minimum of 40 amps are required with charger voltage within the range of 14.1V to 14.7V. It is imperative not to exceed 15.0V as this will cause the pressure valves to open and out-gas hydrogen, oxygen and water from inside the battery. This will shorten the life of the battery and cause premature failure. Some portable chargers exceed 15.0V, especially two-wheel garage chargers, so charging voltages should be verified by measuring the charging voltage during the time when the charging amperage is reducing from full output. The deep cycle charging voltage must be within 14.1V minimum to 14.7V maximum.

If a standard automotive charger is used to boost charge a discharged battery because of an accessory left on, it is important to make sure the charging voltage does not exceed 15 volts during charge. A hand held voltmeter can be used to monitor this periodically.

 

[jbcarioca]

Maybe Charlotte splits the difference? I've had my 2013 for 16 months and 25k from when it was delivered (including multiple trips to Miami) and it is still on the same 12v it was delivered to me with.

Possibly. My Dec 2014 was delivered in Charlotte and used there for several months before I bought it as an inventory car. Three months after I bought it the 12v failed, but there has been zero problem in the 18 months/26,000 miles since then. My car has made several trips to Charlotte as well as a good many others.

 

[JRP3]

This is also leading me to believe these cars are experiencing an over voltage in the float stage. I am hoping a software can fix this.

I don't believe that is the case. Somewhere, maybe in this thread, the 12V battery voltage was plotted. As I remember it's not constantly float charged but allowed to cycle within a voltage range. I'd guess this is so the DC/DC converter isn't always running.

 

[wpl3000]

I have 2013 model S and no problem with 12 volt battery. Just did maintenance ones ( replace electrolyte) and recharge .

 

[JRP3]

It should have been a sealed AGM battery from the factory, no electrolyte to add.

 

[Only Trons]

Yes.... sealed AGM batteries...... there should be no electrolyte to add....

 

[mrElbe]

Knock on Aluminum, my 12V battery is still original. Nearly 2 years of ownership and over 106,000 km.

 

[scottm]

Is there correlation of 12v batteries lasting longer in more northern reaches at latitude? .. probably.
Heat kills batteries moreso than cold. SO we have it "lucky" in Canada

2 years 2 months going strong on battery #1. I don't like saying that, because I don't want to jinx myself.

But now I'm hedging my bets and have a c-tek charger on most nights while parked at home.

 

[FlatSix911]

Has anyone tried this battery? ... Tesla Model S Lithium 12V Accessory Battery

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Battery specifications include 10.0V to 14.4V operating range and TRUE 30Ah capacity, unlike our competitors in the Lithium battery market who use terms like Pb Equivalent or Lead-Acid Equivalent we are reporting the actual capacity of this battery as it will perform in the system we have specifically designed it for. (In terms of Lead Equivalent this battery would be ~100Ah)

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BattMobileBatteries.com

 

[whitecotton]

What plane if your dont mind saying? I fly on a citation 2 that originally had nicad...

 

[mknox]

Knock on Aluminum, my 12V battery is still original. Nearly 2 years of ownership and over 106,000 km.

I've had 2 or three, but here's something odd: My wife's 2007 Pontiac Vibe with just under 200,000 km is still on it's original factory 12v battery. Parked outside and still starts like a champ at the current deep-freeze temps we're in.

 

[tga]

I've had 2 or three, but here's something odd: My wife's 2007 Pontiac Vibe with just under 200,000 km is still on it's original factory 12v battery. Parked outside and still starts like a champ at the current deep-freeze temps we're in.

GM seems to make good batteries. I had one last 10 years in MA/NH, and have heard similar stories.

 

[JRP3]

Likely much larger batteries with much lower cycling rates. The S battery is really too small for the amount of cycling the car seems to put it through.

 

[sorka]

Just a guess, but it seems they need a better "float charging" circuit from the DC-DC inverter, so the battery isn't over/under charged, it should last far longer than 12-18 months with a properly designed charging circuit.

That's not the issue. The issue is the battery is cycled from charged to half charged about 6 times a day given the constant draw of the system with the main battery contactors disengaged is 70 watts or so. Lead acid batteries, even deep cycle ones, don't last very long when you constantly charge and discharge them 24 hours a day.

What they really need is a secondary lower current fused solid state relay that can power the systems off the main battery 24 hours a day. You'd still have the accessory battery but it would stay fully charged all the time and would only really be used in case the something catastrophic happens to the main battery.

 

[dhanson865]

I've had 2 or three, but here's something odd: My wife's 2007 Pontiac Vibe with just under 200,000 km is still on it's original factory 12v battery. Parked outside and still starts like a champ at the current deep-freeze temps we're in.

Does it have the Smart Key System? SKS is a heavy vampire drain.

I know it doesn't have the other heavy drain. EVs/Hybrids have the high voltage disconnect motor that drains the 12v every time you turn the car off and on. Prius/Leaf/Tesla they all have it and it is hard on 12v batteries if you don't get the charging algorithm to account for every possible driving pattern.

Short trips are hard on the 12v because the HV pack/inverter isn't charging the 12v long enough to offset the HV disconnect motor drain.

Have a driver that forgets things and goes back to get something out of the car just after it shuts off? Bam you just used the HV disconnect motor twice without running the car anywhere.

Have a driver that sits around using the lights, radio, fan without starting the car, and you drain the 12v. If you don't have SKS or HV disconnect draining it a traditional ICE will recharge it enough to recover. Do that in a hybrid or EV one time too many and bam you just killed the 12v.

Put the same 12v in an ICE vehicle with no HV disconnect and it won't have any problems.

 

[gregd]

What they really need is a secondary lower current fused solid state relay that can power the systems off the main battery 24 hours a day. You'd still have the accessory battery but it would stay fully charged all the time and would only really be used in case the something catastrophic happens to the main battery.

Or, better yet, float the 12v battery from a small power supply powered from "shore" when plugged in at home.

 

[Zetopan]

Has anyone tried this battery? ... Tesla Model S Lithium 12V Accessory Battery

That looks quite risky to me. The seller's feedback ratings are as a buyer, not a seller and $400 for a battery with zero history is also not a good sign. They will not even start shipping this battery until next year, so there are zero user ratings on it.