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

[fcharland]

I also have been told the facelifts do have in integrated dc-dc in the battery pack. Very small, 100w. It can power the main contactor coil as well as the BCM that looks out for your wireless keys.

That reduces the # of cycles on the main contactors as well as on the 12v battery

 

[FlatSix911]

Just came back from the SvC, and looks like there is a 3rd gen 12V battery!
Now says DCS "+" on the sticker. See my "old" battery pictured in the background.

Wonder what have been improved...

DCS+ new and improved Deep Cycle Series Plus!

 

[fcharland]

DCS+ new and improved Deep Cycle Series Plus!

Anybody knows what has been improved?

 

[scottm]

I also have been told the facelifts do have in integrated dc-dc in the battery pack. Very small, 100w. It can power the main contactor coil as well as the BCM that looks out for your wireless keys.

That reduces the # of cycles on the main contactors as well as on the 12v battery

dc-dc converter inside the main pack!? That's great news! This has been called out as needed a long time ago on this forum..

Would also explain the reduced vampire drain in newer cars. Maybe not just facelifts but any car with the newer main pack feature of having an internal dc-dc.

The little dc-dc probably powers all the "stay alive" and "keep online" circuits... everything that adds up to the 21 Watt draw I always see on my Ctek when charging the 12v.

Hugely going to extend the 12v battery life.

Kudos Tesla for fixing a problem that had a pretty obvious answer...

 

[fcharland]

dc-dc converter inside the main pack!? That's great news! This has been called out as needed a long time ago on this forum..

Would also explain the reduced vampire drain in newer cars. Maybe not just facelifts but any car with the newer main pack feature of having an internal dc-dc.

The little dc-dc probably powers all the "stay alive" and "keep online" circuits... everything that adds up to the 21 Watt draw I always see on my Ctek when charging the 12v.

Hugely going to extend the 12v battery life.

Kudos Tesla for fixing a problem that had a pretty obvious answer...

... And will reduce main contactors wear, since they'll need to cycle a lot less.

I'm getting out of the SvC, for a problem with the main 400v contactors... S85 2014 pre facelift.

 

[scottm]

I'm getting out of the SvC, for a problem with the main 400v contactors... S85 2014 pre facelift.

Sorry, what are you saying here... ? I am curious because we have same vintage car.

Are you experiencing a contactor issue? Or getting contacts services as part of a campaign / recall?

Thanks!

 

[fcharland]

Sorry, what are you saying here... ? I am curious because we have same vintage car.

Are you experiencing a contactor issue? Or getting contacts services as part of a campaign / recall?

Thanks!

Hey Scott,

A little technical background is needed to be explained, but let's just say that once the 12V battery is at a certain % of charge, your Tesla needs to close the main battery pack contactors, in order to energise the DC-DC converter that will charge back your 12V battery.

Since the constant load (even when your car is parked) is about 50W, your 12v battery needs charging about 4-5 times a day. That means your contactors needs closing at least as many times.

Now if your 12V battery is less used (because of an integrated DC-DC in the battery pack in the newer model s) then it needs less recharging, so less usage of the main contactors.

Now, my HV battery contactors did brake, but nobody told me this specifically why. Not a recall.

 

[Snerruc]

Can anyone verify that facelift cars do have a dc to dc built into the battery?

 

[fcharland]

Can anyone verify that facelift cars do have a dc to dc built into the battery?

I understand a 29 posts french speaking member might not sound credible

This info comes from Montreal SvC.

 

[scottm]

Hey Scott,

A little technical background is needed to be explained, but let's just say that once the 12V battery is at a certain % of charge, your Tesla needs to close the main battery pack contactors, in order to energise the DC-DC converter that will charge back your 12V battery.

Since the constant load (even when your car is parked) is about 50W, your 12v battery needs charging about 4-5 times a day. That means your contactors needs closing at least as many times.

Now if your 12V battery is less used (because of an integrated DC-DC in the battery pack in the newer model s) then it needs less recharging, so less usage of the main contactors.

Now, my HV battery contactors did brake, but nobody told me this specifically why. Not a recall.

Yes, I am aware of drain cycles on 12v and so I have installed a Ctek 12v battery maintainer that I plug into the frunk whenever the car is in my garage. (Whether or not the car is also charging the main pack I plug in the Ctek). Sometimes my car sits with Ctek only for the weekend going nowhere and when I drive on Monday it still has exactly same % remaining on main pack as when I parked it days ago.

The contactors are rated for 100,000 cycles for normal duty cycle load (switching loads before full power is drawn). I am surprised yours needed replacement so soon. They should last at least 20 years if you figure on cycling about 12 times a day... for 12v top ups and drive cycles. Must have had a defect and could not carry the load (overheated?).

FYI and somewhat amusing is the contactors are rated for just 1 cycle if switching the main pack with maximum drain energized (e.g. if there's a dead short in the car on the HV side.) In other words, they would weld shut or blow open, probably both, in that order.

 

[scottm]

Can anyone verify that facelift cars do have a dc to dc built into the battery?

Yes you can verify for us because I see yours is a facelift car. Disconnect the 12v battery positive terminal and see if you can still open doors from the fob and connect to car over the app.

If you can, you obviously have a dc-dc built into the main pack! If you can't though, it's probably not a valid test to say that you don't.

Step 2. Reconnect battery.

 

[fcharland]

Yes, I am aware of drain cycles on 12v and so I have installed a Ctek 12v battery maintainer that I plug into the frunk whenever the car is in my garage. (Whether or not the car is also charging the main pack I plug in the Ctek). Sometimes my car sits with Ctek only for the weekend going nowhere and when I drive on Monday it still has exactly same % remaining on main pack as when I parked it days ago.

The contactors are rated for 100,000 cycles for normal duty cycle load (switching loads before full power is drawn). I am surprised yours needed replacement so soon. They should last at least 20 years if you figure on cycling about 12 times a day... for 12v top ups and drive cycles. Must have had a defect and could not carry the load (overheated?).

FYI and somewhat amusing is the contactors are rated for just 1 cycle if switching the main pack with maximum drain energized (e.g. if there's a dead short in the car on the HV side.) In other words, they would weld shut or blow open, probably both, in that order.

Oh then I misunderstood what you were asking.

So yeah... Nobody at the SvC wanted to tell me what happened the contactors. All I know is that the 12v battery drained in less than 3 hours of parking at family's (maybe less).

 

[Larry Hutchinson]

A dc-dc converter will not affect vampire drain. It just eliminates cycling of the 12V battery and actually makes the 12V battery unnecessary.

Vampire drain is due to excessive power use when the car is asleep. This appears to be what changed in the facelift cars. I get about one mile of loss over three weeks in mine.

I believe it is the model 3 that has the converter inside the pack.

 

[fcharland]

You are right that the vampire drain isn't solved. But the 12v battery drain is.

The Model S face lift still has it's external DC-DC. But from what I have been told there, they added a very small one just to get the basic systems online without draining the 12V Battery.

1 mile in 3 weeks?! That is crazy low ! And you car still boots in a few seconds, and responds well to remote control via the phone app?

 

[Larry Hutchinson]

Yes, it boots in a few seconds. Phone app is a bit delayed but fine since I seldom use it.

Although my car is a facelift, it is AP1. I wonder about AP2 with the different electronics.

 

[llavalle]

Can anyone verify that facelift cars do have a dc to dc built into the battery?

It's inside of the pack.. it's a very small PCB and uses the contactor's 12V connection to back-feed the power back to the car.

I'll try to find a picture of the thing.... brb!

 

[wk057]

 

[CUBldr97]

2013 (December) MS85 got the battery light this am. getting replaced on Monday under warranty. Its a CPO vehicle that I got in Feb 2016, so i don't know the age of the actual battery. If i get any more information i will let you all know.

Also the right lower corner lights no longer work, related? I wouldn't think so.

 

[llavalle]

...

Thanks, exactly what I was looking for.

 

[apacheguy]

It's inside of the pack.. it's a very small PCB and uses the contactor's 12V connection to back-feed the power back to the car.

I'll try to find a picture of the thing.... brb!

So does this thing continue to work regardless of the contactor state? I thought there needs to be an easy way for emergency responders to isolate all electricals in the car.