Does the $5k P85D upgrade get you a ludicrous P85D or a ludicrous P90D?

[wk057]

There's a limit beyond the main pack fuse, also. The cell level fuses. I tested those and they pop at about a 24A draw on the cell. The cell level fuses are not really replaceable either, so popping one basically means a permanently degraded pack.

At 1500A draw that would be 20.27A per cell. Over 20A through a fuse that clocks in at 0.012" diameter on my micrometer. That's roughly 28 gauge wire. The fuse is roughly 0.3" long, so if it's copper (don't think it is, so probably higher resistance than I'm calculating) it would be about 0.0018 ohms of resistance. Ohms law says that at 20.25A that would be about 0.75W of power dissipating in each cell level fuse. So, that's around 10kW of heat being generated just from these fuses when the pack is under a 1500A load! Yikes. :scared:

Suffice it to say that's a lot of power going through these little fuses, and it might even be a little too close for comfort for me with all those little cell level fuses heating up during a 0-155 launch. We're talking about something like 50Wh of heat generated by just the cell level fuses during a 0-155 run. For comparison, that's the amount of heat put out by a 1kW space heater running continuously for 3 full minutes. If the run lasted 20 seconds, that would mean the fuses were putting out the same amount of heat as a 2.5 ton heating unit (~30k BTU/hr) for those 20 seconds.

If one of those fuses pops you lose 1.3% pack capacity due to the one module having a set of cells that will reach full before the rest. Then when one pops that's 1.3% more power running through the rest so they're more likely to fail now on the next high load event.

I'm sure Tesla knows what they're doing in this department... but that's a lot of fuses. There are 14,208 cell level fuses in the 85kWh pack. Yes, fourteen thousand fuses, plus a main pack fuse. And like I said, if just one of those fuses goes you lose 1.3% capacity (1/74th per fuse in the same cell group). All it would take is just one not being to spec... and there isn't really a way to do quality testing on each fuse...

I don't know about you guys, but if I were to get the $5k upgrade to my P85D I probably wouldn't be doing launches all the time like I do now.

It's worth noting, also, that Tesla's BMS has no immediate way of knowing that a cell level fuse popped. It would only be apparent upon a full or near full charge or discharge. Imagine the car thinking you had 3 miles of range left, then shutting down because the one group of cells is actually at the cut voltage already and draining further could damage the cells? As someone who has hit the single digit miles remaining area multiple times... this would not be pleasant.

I'm not 100% sure where I was going with all of this besides providing some insight into the pack itself. Interpret as you will.

 

[Johan]

There's a limit beyond the main pack fuse, also. The cell level fuses. I tested those and they pop at about a 24A draw on the cell. The cell level fuses are not really replaceable either, so popping one basically means a permanently degraded pack.

At 1500A draw that would be 20.27A per cell. Over 20A through a fuse that clocks in at 0.012" diameter on my micrometer. That's roughly 28 gauge wire. The fuse is roughly 0.3" long, so if it's copper (don't think it is, so probably higher resistance than I'm calculating) it would be about 0.0018 ohms of resistance. Ohms law says that at 20.25A that would be about 0.75W of power dissipating in each cell level fuse. So, that's around 10kW of heat being generated just from these fuses when the pack is under a 1500A load! Yikes. :scared:

Suffice it to say that's a lot of power going through these little fuses, and it might even be a little too close for comfort for me with all those little cell level fuses heating up during a 0-155 launch. We're talking about something like 50Wh of heat generated by just the cell level fuses during a 0-155 run. For comparison, that's the amount of heat put out by a 1kW space heater running continuously for 3 full minutes. If the run lasted 20 seconds, that would mean the fuses were putting out the same amount of heat as a 2.5 ton heating unit (~30k BTU/hr) for those 20 seconds.

If one of those fuses pops you lose 1.3% pack capacity due to the one module having a set of cells that will reach full before the rest. Then when one pops that's 1.3% more power running through the rest so they're more likely to fail now on the next high load event.

I'm sure Tesla knows what they're doing in this department... but that's a lot of fuses. There are 14,208 cell level fuses in the 85kWh pack. Yes, fourteen thousand fuses, plus a main pack fuse. And like I said, if just one of those fuses goes you lose 1.3% capacity (1/74th per fuse in the same cell group). All it would take is just one not being to spec... and there isn't really a way to do quality testing on each fuse...

I don't know about you guys, but if I were to get the $5k upgrade to my P85D I probably wouldn't be doing launches all the time like I do now.

It's worth noting, also, that Tesla's BMS has no immediate way of knowing that a cell level fuse popped. It would only be apparent upon a full or near full charge or discharge. Imagine the car thinking you had 3 miles of range left, then shutting down because the one group of cells is actually at the cut voltage already and draining further could damage the cells? As someone who has hit the single digit miles remaining area multiple times... this would not be pleasant.

I'm not 100% sure where I was going with all of this besides providing some insight into the pack itself. Interpret as you will.

I think your observations are correct and they are pushing the envelope here. But we don't know if they changed the fuses on the new 90 packs. However what you said holds true for a current P85D owner who were to upgrade the inverter and main fuse. On the other hand burning a couple of cell fuses and registering this as rapid capacity loss would very likely trigger Tesla's 8-year unlimited pack warranty.

 

[darthy001]

@wk057 But isnt your measurements with an "older" pack? Do we know that the new packs used for the P85D havent improved in this area?

 

[kennybobby]

i tested one of those cell level fuse wires in a beaker with a weak HCl acid solution. It began bubbling slightly and by morning it was completely dissolved. This indicates to me that they are aluminum, and not silver or copper alloy.

 

[McMuggets]

Hi there,

I spoke with someone at Tesla headquarter (i don't know someone in particular, I just dialled the sales line) and he told me that existing P85D owners will be able to upgrade to Ludicrous mode but won't be able to upgrade to 90kwh battery pack has it would be a P85D with a 90 battery pack. All model are based on the battery packs, same reason the 60 owner can't upgrade to a 70kwh battery pack. It's good news for us, P85D owner, who will still have the fastest Tesla on earth. He finised by saying that Tesla decided to make the upgrade possible in good faith with P85D owner!smile emoticon
He

Not sure if your question got answered. It sounds like you can do both a pack upgrade as well as the speed upgrade:


Musk Archives - EV News ReportEV News Report

 

[GregRF]

There's a limit beyond the main pack fuse, also. The cell level fuses. I tested those and they pop at about a 24A draw on the cell. The cell level fuses are not really replaceable either, so popping one basically means a permanently degraded pack.

I've been curious since the announcement, is there just one main pack fuse that gets the new electronics? Or is their a fuse per module? And is there only one contactor or more that get the inconel treatment? (Any pictures of these components from your tear down?)

Just wondering what the $10k is actually buying in the pack (or$5k for existing P85D).

 

[wk057]

@wk057 But isnt your measurements with an "older" pack? Do we know that the new packs used for the P85D havent improved in this area?

I haven't seen first hand, but I've been told that the modules themselves are the same part number in the D packs.

i tested one of those cell level fuse wires in a beaker with a weak HCl acid solution. It began bubbling slightly and by morning it was completely dissolved. This indicates to me that they are aluminum, and not silver or copper alloy.

Interesting! Yeah, I was going to guess aluminum for them, but chemistry isn't really my thing, it's my wife's.

I've been curious since the announcement, is there just one main pack fuse that gets the new electronics? Or is their a fuse per module? And is there only one contactor or more that get the inconel treatment? (Any pictures of these components from your tear down?)

Just wondering what the $10k is actually buying in the pack (or$5k for existing P85D).

From what I understand and have been told the $5k is for parts and labor for the replacement of the main pack fuse and the two main contactors. This is basically the same work that is being done for the contactor replacement on the older packs and most service centers do this now. So, shouldn't be too hard, but it does require the pack be mostly drained and removed from the car, opened, safely modified, resealed, and reinstalled. $5k for that is probably a bit more than the raw sum of the parts and labor. They're selling this as a $10k option on new cars where there isn't even any additional labor involved, just the two new parts (contactors and fuse), and that seems a bit excessive IMO. But hey, people will pay it and they know it. I'd be surprised if anyone actually buys a P85D anymore and if that model even stays available for much longer. But for $5k to get updated parts and 10% more power... not sure you can do that with many (any?) other cars, so, probably not the worst deal.

 

[dsm363]

mod note: difficult to move so many posts and keep the flow of the original thread intact but the argument about Tesla's HP numbers moved here
P85D and P90D horsepower disagreement

I hope the title is ok with everyone

 

[Madartist]

@wk057 Thanks for the info regarding cell level fuses. However, I gotta think that Tesla engineers must have considered and tested that before the upgrade to the ludicrous mode is offered to existing P85D owners. The question is... will you do the upgrade?? Do you think it's safe?

 

[wk057]

@wk057 Thanks for the info regarding cell level fuses. However, I gotta think that Tesla engineers must have considered and tested that before the upgrade to the ludicrous mode is offered to existing P85D owners. The question is... will you do the upgrade?? Do you think it's safe?

Well, like I said, they probably did the testing and ran the numbers. My assumption will be that the area where Ludicrous mode will yield the high kW output will be at very high pack state-of-charge, thus keeping amperage in check, thus protecting the fuses. I definitely don't claim to know better than them in this instance, since they know the details of their own tech better than I would. hehe. Just pointing out that there is ceiling to the power available from the existing packs.

A for upgrading and safety, losing cell level fuses isn't really unsafe to the driver or anything. If my pack starts losing miles rapidly Tesla is going to be replacing it since that wouldn't be normal degradation. So, not too worried there.

I may very well do the upgrade (and already contacted service about how/when/etc) if for no other reason than to go back to the track and fix this particular situation: 2014 Tesla Model S P85D vs 2015 Nissan GTR NISMO (1/8th mile drag) - YouTube

 

[gg_got_a_tesla]

From what I understand and have been told the $5k is for parts and labor for the replacement of the main pack fuse and the two main contactors. This is basically the same work that is being done for the contactor replacement on the older packs and most service centers do this now. So, shouldn't be too hard, but it does require the pack be mostly drained and removed from the car, opened, safely modified, resealed, and reinstalled. $5k for that is probably a bit more than the raw sum of the parts and labor. They're selling this as a $10k option on new cars where there isn't even any additional labor involved, just the two new parts (contactors and fuse), and that seems a bit excessive IMO. But hey, people will pay it and they know it. I'd be surprised if anyone actually buys a P85D anymore and if that model even stays available for much longer. But for $5k to get updated parts and 10% more power... not sure you can do that with many (any?) other cars, so, probably not the worst deal.

It's $5k *plus* labor.

Quote from Musk's blog post (emphasis mine):

This option will cost $10k for new buyers. In appreciation of our existing P85D owners, the pack electronics upgrade needed for Ludicrous Mode will be offered for the next six months at only $5k *plus* installation labor.

There was one post late yesterday that the labor costs are $1,600 for a total of $6,600 as per the quote that they got from a service center. Can't find the post now.

 

[wk057]

It's $5k *plus* labor.

Quote from Musk's blog post (emphasis mine):



There was one post late yesterday that the labor costs are $1,600 for a total of $6,600 as per the quote that they got from a service center. Can't find the post now.

Interesting. That conflicts with that I've been told so far, but labor isn't going to be too terrible anyway even at the service center's $150/hr. Either way, it's still less than the $10k ($13k) to get it on a new vehicle.

 

[sorka]

Per Elon's blog post "The net result is that we can safely increase the max pack output from 1300 to 1500 Amps."
Here are my calculations:
For the current P85D
Fuse/Contactor Limit: 1,300 Amps
With a nominal operating pack voltage of 366v
Max Power = 1300x366 = 475.8KW
414kw is probably the result of a software safety limit to 87% of max fuse capacity. (475x87% = 414)

For the new P85D
Fuse/Contactor Limit: 1,500 Amps
With a nominal operating pack voltage of 366v
Max Power = 1500x366 = 549KW (736 hp)
87% of 549kw = 477.6 KW (640 hp)

So the fuse/contactor update for the P85D-Ludicrous allows Tesla to tap an additional 64 kW from the battery, leading to the 2.8s 0-60mph performance boost.

What is interesting to note is that Tesla still has some room for improvement. The maximum power rating for both motors combined on the P85D is 568 kW (or 762 HP), so if an even better fuse can be found, then additional power can be tapped leading to even better performance (assuming no issues with other factors such as traction, battery pack & wiring, etc)

The P85D is more efficient than an AWD ICE car at putting power to the wheels. Typical AWD ICE cars lose 20 to 25% given all the drivetrain components they have to go through. The P85D based on my VBOX testing is only losing 10% from the battery to the wheels which is remarkable. So a 691 hp ICE AWD car that loses only 20% would put 552 hp to the wheels. A 640 hp AWD P85D would put 576 hp to the wheels ..... in theory

- - - Updated - - -

There's a limit beyond the main pack fuse, also. The cell level fuses. I tested those and they pop at about a 24A draw on the cell. The cell level fuses are not really replaceable either, so popping one basically means a permanently degraded pack.

At 1500A draw that would be 20.27A per cell. Over 20A through a fuse that clocks in at 0.012" diameter on my micrometer. That's roughly 28 gauge wire. The fuse is roughly 0.3" long, so if it's copper (don't think it is, so probably higher resistance than I'm calculating) it would be about 0.0018 ohms of resistance. Ohms law says that at 20.25A that would be about 0.75W of power dissipating in each cell level fuse. So, that's around 10kW of heat being generated just from these fuses when the pack is under a 1500A load! Yikes. :scared:

Suffice it to say that's a lot of power going through these little fuses, and it might even be a little too close for comfort for me with all those little cell level fuses heating up during a 0-155 launch. We're talking about something like 50Wh of heat generated by just the cell level fuses during a 0-155 run. For comparison, that's the amount of heat put out by a 1kW space heater running continuously for 3 full minutes. If the run lasted 20 seconds, that would mean the fuses were putting out the same amount of heat as a 2.5 ton heating unit (~30k BTU/hr) for those 20 seconds.

If one of those fuses pops you lose 1.3% pack capacity due to the one module having a set of cells that will reach full before the rest. Then when one pops that's 1.3% more power running through the rest so they're more likely to fail now on the next high load event.

I'm sure Tesla knows what they're doing in this department... but that's a lot of fuses. There are 14,208 cell level fuses in the 85kWh pack. Yes, fourteen thousand fuses, plus a main pack fuse. And like I said, if just one of those fuses goes you lose 1.3% capacity (1/74th per fuse in the same cell group). All it would take is just one not being to spec... and there isn't really a way to do quality testing on each fuse...

I don't know about you guys, but if I were to get the $5k upgrade to my P85D I probably wouldn't be doing launches all the time like I do now.

It's worth noting, also, that Tesla's BMS has no immediate way of knowing that a cell level fuse popped. It would only be apparent upon a full or near full charge or discharge. Imagine the car thinking you had 3 miles of range left, then shutting down because the one group of cells is actually at the cut voltage already and draining further could damage the cells? As someone who has hit the single digit miles remaining area multiple times... this would not be pleasant.

I'm not 100% sure where I was going with all of this besides providing some insight into the pack itself. Interpret as you will.

It seems like it would be prudent for the software to do serious limiting unless the pack was cool enough and even then limiting the duration of power to very small windows. I'd be perfectly satisfied with only having full power for 4 or 5 seconds at a time. I really don't see myself ever doing 1/4 mile drag races. I want the extra power for those 3 second 50 - 90 passes and then I'm done for a while.

 

[kirkbauer]

As a new P85D owner I'm very interested in the Ludicrous upgrade option. However I'm still not exactly clear on what charge levels I need to get the current 3.1s (anybody have any good sources on that)? I wonder what charge level I need to get 2.8s? I wonder if it affects performance at lower charge levels? In other words, say at 50% charge I do 0-60 in 3.5s (I have no idea what the number actually is), would Ludicrous mode perhaps give me 3.2s at 50% battery?

 

[jsimon77]

That is a great questions. I find that I can only get 3.2 when I'm charged at 90% or higher. Also interested to know what 0-60 times I'll get at various charge levels.

 

[sorka]

That is a great questions. I find that I can only get 3.2 when I'm charged at 90% or higher. Also interested to know what 0-60 times I'll get at various charge levels.

I'm able to get 3.2 at 65% SOC but the peak power is quite a bit less resulting in lower acceleration from 45+MPH. At 90% I'm seeing 3.1, so there's a slight penalty from 45 to 60. The speed from 0-33 MPH is totally traction limited and is the same regardless of the SOC at least down 65%.

 

[MagSJ]

Palo Alto service center told me today they heard it was $5k for parts and that the installation was another $5k. They admitted they didn't have anything official, but that was the "rumor". Hopefully this rumor is way off and it is closer to the $1,600 previously mentioned as even at Tesla's $150/hr that is a lot of hours working on the car. That means not only is it major surgery on the car, but also that it will take a long time to work through the backlog of cars getting upgraded. Not going to be very happy if this ends up at the same $10k after both Elon and the blog make it sound like they are giving existing owners a good deal.

 

[sorka]

Palo Alto service center told me today they heard it was $5k for parts and that the installation was another $5k. They admitted they didn't have anything official, but that was the "rumor". Hopefully this rumor is way off and it is closer to the $1,600 previously mentioned as even at Tesla's $150/hr that is a lot of hours working on the car. That means not only is it major surgery on the car, but also that it will take a long time to work through the backlog of cars getting upgraded. Not going to be very happy if this ends up at the same $10k after both Elon and the blog make it sound like they are giving existing owners a good deal.

Well it can't because Elon clearly said existing P85D owners were getting a discount which they wouldn't if they're going to charge the same $10K. So let's see, $5K in labor would be about 33 hours???

There are past posts implying the contactors only take a few hours at most to replace. How much longer could it take to replace the fuse after that?

 

[gg_got_a_tesla]

Well it can't because Elon clearly said existing P85D owners were getting a discount which they wouldn't if they're going to charge the same $10K. So let's see, $5K in labor would be about 33 hours???

($5k in parts + sales tax on that) + ($5k in labor + no tax on that) is still less than ($10k + sales tax on a new car that's also forced to upgrade to 90 for an additional $3k + sales tax).

QED :-|

 

[sorka]

($5k in parts + sales tax on that) + ($5k in labor + no tax on that) is still less than ($10k + sales tax on a new car that's also forced to upgrade to 90 for an additional $3k + sales tax).

QED :-|

Don't forget to count the lower yearly registration fees which were based on the purchase price