16v Lithium battery Weber State Video

Just released is a detailed, but not overly technical, video about the 16v aux lithium battery for those who have it in newer Teslas.
The video has timestamps for easy access to pertinent information. Of most interest might be:

1:50 The jump-start terminals of the Model 3
2:18 Owner's manual jump-start cautions
4:18 Mislabeled 16V batteries
5:29 MUST SEE: Differences between 16V Li-Ion abs 12V Lead Acid battery
7:45 MUST SEE: The push-fit battery 16V electrical connector
8:55 The jump-start terminals of the Model Y
9:28 The Internal self-protection mode of the 16V battery
11:10 MUST SEE: Conditions for the MOSFET to open in protection mode
15:17 What alert is displayed with a bad 16V battery?
15:42 How to recover a 16V battery with an open MOSFET
16:08 The owner's manual method of recovery
17:47 The service manual method of recovery
18:15 Disconnecting the 16V battery
21:12 The Toolbox 3 and service mode methods of recovery

My model 3 is of the legacy 12v system, I found this video quite fascinating and informative.

 

[CMPT PAD]

Just released is a detailed, but not overly technical, video about the 16v aux lithium battery for those who have it in newer Teslas.
The video has timestamps for easy access to pertinent information. Of most interest might be:

1:50 The jump-start terminals of the Model 3
2:18 Owner's manual jump-start cautions
4:18 Mislabeled 16V batteries
5:29 MUST SEE: Differences between 16V Li-Ion abs 12V Lead Acid battery
7:45 MUST SEE: The push-fit battery 16V electrical connector
8:55 The jump-start terminals of the Model Y
9:28 The Internal self-protection mode of the 16V battery
11:10 MUST SEE: Conditions for the MOSFET to open in protection mode
15:17 What alert is displayed with a bad 16V battery?
15:42 How to recover a 16V battery with an open MOSFET
16:08 The owner's manual method of recovery
17:47 The service manual method of recovery
18:15 Disconnecting the 16V battery
21:12 The Toolbox 3 and service mode methods of recovery

My model 3 is of the legacy 12v system, I found this video quite fascinating and informative.

He's a real PROS in battery technology, very practical with easy-to-understand explanations

 

[MikeyC]

Watched this yesterday and I wondered through the whole thing... if it's 16v, is it even possible to retrofit it into an older car or are there other hardware changes? In other words, (doubtful but) if Tesla wanted to offer an upgrade to the lithium battery, could they just install it and update software? Or are there other parts that are different due to the 16v architecture?

Mike

 

[pikeman]

It’s one thing to update firmware, but a hardware change like this has extensive impact on the car’s systems. It’s not an upgrade path for 12v cars.

 

[nate704]

Since Tesla is moving to 40V system, this will also be obsolete soon.

 

[pikeman]

Since Tesla is moving to 40V system, this will also be obsolete soon.

Heck, why not 48v? At least we’ll match up with aircraft systems.
This sounds like engineering out of control! (I will confess to a career in project and supply chain management.)

 

[n2mb_racing]

Since Tesla is moving to 40V system, this will also be obsolete soon.

48V.

 

[n2mb_racing]

I will have to watch. I have tested pulling a rather absurd amount of current from the 16V li-ion in my Model S Plaid. I got up to 111A out of it (1400W). The battery shut down soon after that, but interesting.

It seems it's designed to deliver a really high amount of current for a short period of time. Presumably, enough to bring the car to a stop safely if it is on autopilot and the main battery fails.

 

[pikeman]

I will have to watch. I have tested pulling a rather absurd amount of current from the 16V li-ion in my Model S Plaid. I got up to 111A out of it (1400W). The battery shut down soon after that, but interesting.

It seems it's designed to deliver a really high amount of current for a short period of time. Presumably, enough to bring the car to a stop safely if it is on autopilot and the main battery fails.

For a worst case scenario, I understand. I wonder about the probability of this. Perhaps it’s considered a “must have” to get the FSD considered “safer”?

 

[Made in CA]

Excellent video! Thanks

 

[n2mb_racing]

For a worst case scenario, I understand. I wonder about the probability of this. Perhaps it’s considered a “must have” to get the FSD considered “safer”?

I'm sure it's low, but you need redundancy in everything.

 

[gearchruncher]

Heck, why not 48v? At least we’ll match up with aircraft systems.

There are not really any 48V aircraft systems. It's 12V or 28V, and then jumps up to high voltage systems (100V+).
The primary electrical standard for aircraft, DO-160 doesn't even have a 48V category.

 

[KiwiME]

After watching John's video and noting the rather small capacity of the 16V aux battery compared to a conventional lead-acid, I'm wondering if (while parked) the DC-DC runs continuously to supply requirements and the aux battery is just there to handle intermittent inrush currents and emergency shutdown/airbag requirements?
In my Kona charging the lead-acid aux battery requires that battery pack internal contactors close and provide power to the (external to the pack) DC-DC for a set time period,usually 20 minutes every 4 hours. That system load is about 200 watts for the duration as an overhead to whatever the aux battery needs.
Any insights as to where Tesla's DC-DC is located and is it permanently connected to the traction battery?

 

[escparticle]

Watched this yesterday and I wondered through the whole thing... if it's 16v, is it even possible to retrofit it into an older car or are there other hardware changes? In other words, (doubtful but) if Tesla wanted to offer an upgrade to the lithium battery, could they just install it and update software? Or are there other parts that are different due to the 16v architecture?

Mike

I don't think there's any practical way to upgrade to the Tesla li ion battery. There are wiring changes that were pointed out in the video for one, but I do remember reading a while back that there are other components that had to be changed to work with the higher voltage as well.

 

[Gauss Guzzler]

...noting the rather small capacity of the 16V aux battery compared to a conventional lead-acid, I'm wondering if (while parked) the DC-DC runs continuously...

Indeed the change from 500Wh lead acid to a 100Wh lithium suggests that the recharge cycling from the HV pack would need to occur 5X more frequently. Lithium cells are more predictable and can be deep-cycled so it's probably not a 5X difference in practice, but still, even 3X would be significant.

The DC-DC (in the penthouse) is capable of supplying many thousands of Watts (maybe ~10kW?) so it uses large transistors which require a lot of power to activate. This makes the system very inefficient for low power levels and is a major reason why the system disconnects and relies on repeatedly draining/recharging the LV battery when sleeping. It's possible they may have added a tiny secondary DC-DC to trickle charge the LV battery full-time. But I'd bet that they just made the sleep power consumption 3X lower to compensate. Even with Sentry mode, the newer cameras, updated processor, and omitted ultrasonics may be enough to cut power consumption by 3X.

Surely someone on TMC must have a datalog of sleep behavior with the 16V battery by now.

 

[android04]

After watching John's video and noting the rather small capacity of the 16V aux battery compared to a conventional lead-acid, I'm wondering if (while parked) the DC-DC runs continuously to supply requirements and the aux battery is just there to handle intermittent inrush currents and emergency shutdown/airbag requirements?
In my Kona charging the lead-acid aux battery requires that battery pack internal contactors close and provide power to the (external to the pack) DC-DC for a set time period,usually 20 minutes every 4 hours. That system load is about 200 watts for the duration as an overhead to whatever the aux battery needs.
Any insights as to where Tesla's DC-DC is located and is it permanently connected to the traction battery?

The usable capacity of the 16v lithium ion battery is actually almost equivalent to the older 12v lead-acid battery. The li-on battery has a nameplate capacity of 6.9Ah, while the lead-acid has 45Ah.

The li-on battery capacity is mostly usable (lets say 80% usable, with a top and bottom 10% margin). That is 6.9Ah x 0.8 = 5.52Ah.

The lead-acid battery capacity is mostly NOT usable. On a deep cycle battery, about 50% of the capacity can be used. On regular starting batteries only 10-20% can be used. The Tesla OEM lead-acid is not a deep cycle battery, and Tesla only seems to use less than 5% of the battery capacity based on my observations with a battery monitor over 1.5 years. That is 45Ah x 0.05 = 2.25Ah. Even if Tesla used 12% of the lead-acid battery capacity, that is 45Ah x 0.12 = 5.4Ah.

 

[n2mb_racing]

Indeed the change from 500Wh lead acid to a 100Wh lithium suggests that the recharge cycling from the HV pack would need to occur 5X more frequently. Lithium cells are more predictable and can be deep-cycled so it's probably not a 5X difference in practice, but still, even 3X would be significant.

The DC-DC (in the penthouse) is capable of supplying many thousands of Watts (maybe ~10kW?) so it uses large transistors which require a lot of power to activate. This makes the system very inefficient for low power levels and is a major reason why the system disconnects and relies on repeatedly draining/recharging the LV battery when sleeping. It's possible they may have added a tiny secondary DC-DC to trickle charge the LV battery full-time. But I'd bet that they just made the sleep power consumption 3X lower to compensate. Even with Sentry mode, the newer cameras, updated processor, and omitted ultrasonics may be enough to cut power consumption by 3X.

Surely someone on TMC must have a datalog of sleep behavior with the 16V battery by now.

I assume the HV stays on with sentry mode. The consumption is huge with the new computer. 230W average in sentry mode.

 

[Gauss Guzzler]

Ah yes, I believe you are correct @n2mb_racing

 

[gearchruncher]

The DC-DC (in the penthouse) is capable of supplying many thousands of Watts (maybe ~10kW?) so it uses large transistors which require a lot of power to activate. This makes the system very inefficient for low power levels and is a major reason why the system disconnects and relies on repeatedly draining/recharging the LV battery when sleeping. It's possible they may have added a tiny secondary DC-DC to trickle charge the LV battery full-time. But I'd bet that they just made the sleep power consumption 3X lower to compensate. Even with Sentry mode, the newer cameras, updated processor, and omitted ultrasonics may be enough to cut power consumption by 3X.

Surely someone on TMC must have a datalog of sleep behavior with the 16V battery by now.

It's my favorite poster that likes to pretend they are a EE and make things up, but gets it all wrong.

The PCS DC/DC is not 10kW. It has no reason to be. Hell, it's only a 11kW AC/DC converter, meaning the max current it deals with at 240V is 48A, stepping this down to lower current at the 350V+ pack voltage.

Yet you think it can do 850A at 12V? Why? What 12V loads are on the car that come anywhere near to 10kW?

The DC-DC needs to be on while driving, so you'd think they would design this to be super efficient in the load ranges it sees while driving, which are not much higher than when charging the battery.

The reason the car is inefficient when charging the 12V battery is that the CONTACTORS have to be on. Not because of conversion efficiency. The contactors appear to be in the 200W range. So when it's charging the 12V battery at the 8A or lower charge current, it's pulling about 300W from the HV pack, but only using 100W usefully. But it's still more useful to charge the battery at 8A, then discharge it at 0.5A or less, than it is to leave the 200W contactors on all the time.

Any insights as to where Tesla's DC-DC is located and is it permanently connected to the traction battery?

It's literally inside the battery. But it's not always connected to HV. The contactors must be engaged for it to see pack voltage.

The li-on battery capacity is mostly usable (lets say 80% usable, with a top and bottom 10% margin). That is 6.9Ah x 0.8 = 5.52Ah.

Additionally, as covered in the video, the Li-Ion is only charged to 80% . An advantage here is that it can be charged at 2C when in the 10-80% range. Which is WAY faster than the 8A limit on the Lead Acid, which tapers to under an amp at the top of charge. So the car needs to be awake less time to put the same energy into the Li-Ion battery, increasing overall efficiency.

 

[KiwiME]

Yeah, I thought 10kW was a bit absurd. The Kona’s DC-DC draws around 200 watts off the traction battery including the contactors, plus whatever it takes to support the 12V system load.
There must be trade offs between aux battery capacity and the frequency of cycling wear on the charging hardware.
I suggested to John over at Weber Auto that a 24 h 16V system voltage log would be an interesting talking point.
Has anyone tried a BM2 logger on their 16V Tesla?
The primary advantage I’m seeing of Tesla’s 16V system is that its BMS can request support as needed rather than having to rely on a timed query which may be too late to save an auxiliary battery.