BTX7 Battery on the latest Tesla EPA filings: 80kWh, 350v, 16 modules

[David99]

The 85 kWh pack has a total energy of 81,5 kWh and usable (available) energy is 77,5 kWh, thus the 80P holds more usable energy.

My Model S 85 has 71.1 kWh left. 4 kWh is buffer so only 67.1 kWh usable.

 

[Tintorera]

Cars with the new packs should have 8% more range, so 280 miles instead of 259, they should also have 8% more power.

The 75 kWh packs (BTX5) has 75 kWh with 72,6 kWh usable energy. Do you mean that cars with the 80P (BTX7) has 8% more usable energy available now, or just a potential to be unlocked to ~78,4 kWh available energy?

 

[john pane]

I am questioning the assumption by OP there are 16 modules in the BTX7. I do not see that stated explicitly in the EPA documents and analysis below suggests there are 14 modules in this pack.

80P refers to number of cells in parallel. These packs are 80P84S for a total of 6720 cells. Full 100 packs are 86P96S for a total of 8256 cells.

It appears that modules are wired in series, and parallelization is done within module. This would imply that the fully populated 100kW pack has 16 modules in series, each with 86P6S. 16 modules with a (nominal, not actual) voltage of 25V is a 400V pack, which is what the label says.

On that assumption, I conclude that the BTX7 uses 14 modules, and depopulation within module makes them 80P6S modules. This is what the EPA document states, "100 kWh battery pack module with depopulated cells". This can be accomplished with the 14-module sled and does not require the larger 16-module sled being used for 100kW. 14 modules with a nominal voltage of 25V is a 350V pack, which is what the label says. The label also says 75kWh, but the EPA document shows 79.7kWh.

BTX5 uses 14 modules, each 74P6S, leading to a 350V pack. This is labeled 75kWh but the EPA document shows 73.2kWh.

BTX8 is labeled as 400V, implying it uses all 16 modules -- is it known how many batteries in parallel are used in these packs? These are labeled 85kWh, and that is approximately 16/14 * the BTX5's rating. This leads to a hypothesis they are using the 74P6S, which would be in the range of 85kWh.

So, Tesla may be experimenting with two different ways to achieve an intermediate capacity between 75 and 100 kWh. In the case of the BTX8, they are using the 100kWh sled with the less-dense modules from the 75kWh packs. In the case of BTX7 they are using the 75kWh sled with modules of intermediate density between what was used in the 75kWh and 100kWh packs.

The EPA document states "firmware limits to match 75 kWh pack performance". It seems that it can match that performance on some metric (e.g. 0-60 time) but not necessarily across all of the performance spectrum. On a 0-60 test, BTX7 is faster than BTX5 out of the gate but flatlines at 340kWh, allowing the BTX5 to catch up by 60mph.

The problem with this is that this 340kW firmware limit is very limiting at highway speed. BTX7 seems fairly "dead" when trying to accelerate from 70mph. While I have not done direct comparisons, I'm sure this must be worse than the other battery configurations of current-production S's. I'd like to see the firmware limit removed to make the vehicle more responsive at highway speed.

 

[Peewee]

I just put into the perf topic that my Tesla 75D consistently shows 0-60 times of 3.9x seconds (to be fair, I had a bad run of 4.05 ). It shows BTX5 on the config. I will see if I can find more on the sticker.

EDIT:

Had it on the supercharger today and it didn't slow down when it reached 90%, but the real slowdown is after that point I guess.

 

[BigD0g]

I think this is the future of Tesla batteries. They will be slightly oversized and software locked. The cars will probably lose the pack size from the model number and bagging like the model 3 LR and SR. The idea is that the battery never drops below 5-7% and never is charged much over 90%. This allows for a "reserve" on the bottom end and protection as well as speeding charging by never getting to 100% where charging gets rediculusly slow. I'm also guessing that as the battery ages, some of these software locked miles will be allowed to be used. So if a car is rated at 300 miles, that would be 86% of the total capacity of the battery. As the battery ages, a few precent are freed up to combat degradation. Charging will get slower and slower over many years, but the rated range will remain 300 miles for many many years before the degradation hits 14%, but really 10% because you always have to have the anti-brick 2-3%. This is more about the common owner and not is fanatics. It's about setting expectations for owners that are not as savvy as is forum dwellers. It's about having a million mile power train that has 300+ rated miles for the entire million miles. I'm theory, the software lock could take into account weather and temperature and route planning to allow for more charge dynamically, with the first of maintain as best as possible that 300 Mile range. Obviously, bad weather would be impossible to completely offset as it can lower range by 20% or more, but maybe an extra 10% could make a huge difference. Also, disasters like hurricanes could unlock the 10% of buffer.

I might be crazy, but I think you already see it with the model 3 that was tested by the EPA at over 340 miles for a car with 310 mile rated range. In the EPA test, they run the car to zero to test range.

How many is you drive 20+ miles with your fuel light on in your ICE? I know I do. It's for those people, you know, normal people.

Technically it's fraud before this. My page / sales invoice clearly shows I bought a 75kW battery, but yet the max capacity of my pack is only 72kW, so I they did not give me what they sold me. This is determined by the BMS system, not the bill of sale. Not that I car, but i'm sure that extra 3 kW could would be nice for something, LOL!

 

[john pane]

BTX8 is labeled as 400V, implying it uses all 16 modules -- is it known how many batteries in parallel are used in these packs? These are labeled 85kWh, and that is approximately 16/14 * the BTX5's rating. This leads to a hypothesis they are using the 74P6S, which would be in the range of 85kWh.

A problem with this hypothesis is that BTX8 would be essentially the same configuration as the BTX4, which was labeled 90kWh.

Edit: maybe the difference between BTX4 and BTX8 is the cell layout within module and perhaps BTX8 uses a "depopulated" module like BTX7? This is speculation, of course.

 

[apacheguy]

My Model S 85 has 71.1 kWh left. 4 kWh is buffer so only 67.1 kWh usable.

Ouch, has this declined a lot recently for you? Are all the modules in good shape?

 

[Krash]

I am questioning the assumption by OP there are 16 modules in the BTX7. I do not see that stated explicitly in the EPA documents and analysis below suggests there are 14 modules in this pack...

Yeah, this is simply a guess on my part by looking at the weight. I assume we haven't had any 16 module 350v packs before. Also the mods are pretty good about fixing thread titles when they contain substantive errors, I am relying on a chance to change it when we are certain. Grin.

 

[David99]

Ouch, has this declined a lot recently for you? Are all the modules in good shape?

Voltages among the cells are all very good. 4 mV difference is excellent. It's just normal degradation I guess. I'm getting 246 miles at 100%.

I think it is very interesting that these new packs have a little extra capacity. Staying away from true 100% and/or going low helps longevity and charge speed.

 

[Reciprocity]

Technically it's fraud before this. My page / sales invoice clearly shows I bought a 75kW battery, but yet the max capacity of my pack is only 72kW, so I they did not give me what they sold me. This is determined by the BMS system, not the bill of sale. Not that I car, but i'm sure that extra 3 kW could would be nice for something, LOL!

You mistook me for someone who was commenting on the past. I am commenting on the future. You should file a suit as you have clearly been wronged in a massively way and the damages should be in the hundreds of dollars.

 

[BigD0g]

You mistook me for someone who was commenting on the past. I am commenting on the future. You should file a suit as you have clearly been wronged in a massively way and the damages should be in the hundreds of dollars.

Naw, like I said it doesn't matter, but it doesn't make it right either. I can care less about 72kw vs 75kw, i'll wait for the AP2 snafu to work it's way through the system. That is a much much bigger issue.

 

[Reciprocity]

Naw, like I said it doesn't matter, but it doesn't make it right either. I can care less about 72kw vs 75kw, i'll wait for the AP2 snafu to work it's way through the system. That is a much much bigger issue.

Really, whats your damages? Do you know how the civil legal system works or just making stuff up as you go along?

Edit: Judge, my car would not drive it self and I got a ticket.. so yeah.. $200 please.

 

[apacheguy]

Voltages among the cells are all very good. 4 mV difference is excellent. It's just normal degradation I guess. I'm getting 246 miles at 100%.

I think it is very interesting that these new packs have a little extra capacity. Staying away from true 100% and/or going low helps longevity and charge speed.

Wait, your nominal full pack energy is 67 kWh and yet you get 246 miles on a range charge? I have 76 kWh and get 258 miles. @wk057 showed that rated miles is directly relatable to pack capacity by a constant. Something is not adding up here.

Following his formula for your vehicle, I calculate that you should only get 227 rated miles at 100%.

 

[dennis_d]

Wait, your nominal full pack energy is 67 kWh and yet you get 246 miles on a range charge? I have 76 kWh and get 258 miles. @wk057 showed that rated miles is directly relatable to pack capacity by a constant. Something is not adding up here.

Following his formula for your vehicle, I calculate that you should only get 227 rated miles at 100%.

It's not a fixed value, it's controlled in by car config VAPI_ratedWattHourPerMile, for 75D the value is 286, for 75 (RWD) 298
For X100D it's around 330

 

[LargeHamCollider]

The 75 kWh packs (BTX5) has 75 kWh with 72,6 kWh usable energy. Do you mean that cars with the 80P (BTX7) has 8% more usable energy available now, or just a potential to be unlocked to ~78,4 kWh available energy?

The latter, supercharging will still get a boost though.

 

[David99]

Wait, your nominal full pack energy is 67 kWh and yet you get 246 miles on a range charge? I have 76 kWh and get 258 miles. @wk057 showed that rated miles is directly relatable to pack capacity by a constant. Something is not adding up here.

Following his formula for your vehicle, I calculate that you should only get 227 rated miles at 100%.

The CAN bus says my pack capacity is 71.2 kWh and the buffer is 4 kWh. Those two numbers are coming directly from the CAN bus. For the 85 the reference consumption is something like 300 Wh/m I believe. That would be 237 miles of range. I do get 246 rate miles (Range Mode is off) when charging to 100%. So yes, something doesn't add up.

I think the rated range is based on driving the car down to the point where it shuts off (not when it shows zero). The reason I think this is because the battery percentage shown to the driver is not the true percentage. The CAN bus shows the real % and it goes 5% "lower". In other words, when the car shows 0% the true value is 5%. Fully charged is 100% on both, though.

 

[apacheguy]

It's not a fixed value, it's controlled in by car config VAPI_ratedWattHourPerMile, for 75D the value is 286, for 75 (RWD) 298
For X100D it's around 330

Yes, I appreciate that. Which is why I said "Following his formula for your vehicle,..."

 

[john pane]

Based on these info/assumptions from below:

• The BTX5 has 14 74P6S modules and EPA documents show capacity of 73.2kWh.
• The BTX7 has 14 80P6S modules and EPA documents show capacity of 79.7kWh

Possible further confirmation that this may be right:

• Ratio of number of batteries in these two packs: 1.081
• Ratio of kWh capacity according to EPA documents: 1.089

I am questioning the assumption by OP there are 16 modules in the BTX7. I do not see that stated explicitly in the EPA documents and analysis below suggests there are 14 modules in this pack.

It appears that modules are wired in series, and parallelization is done within module. This would imply that the fully populated 100kW pack has 16 modules in series, each with 86P6S. 16 modules with a (nominal, not actual) voltage of 25V is a 400V pack, which is what the label says.

On that assumption, I conclude that the BTX7 uses 14 modules, and depopulation within module makes them 80P6S modules. This is what the EPA document states, "100 kWh battery pack module with depopulated cells". This can be accomplished with the 14-module sled and does not require the larger 16-module sled being used for 100kW. 14 modules with a nominal voltage of 25V is a 350V pack, which is what the label says. The label also says 75kWh, but the EPA document shows 79.7kWh.

BTX5 uses 14 modules, each 74P6S, leading to a 350V pack. This is labeled 75kWh but the EPA document shows 73.2kWh.

BTX8 is labeled as 400V, implying it uses all 16 modules -- is it known how many batteries in parallel are used in these packs? These are labeled 85kWh, and that is approximately 16/14 * the BTX5's rating. This leads to a hypothesis they are using the 74P6S, which would be in the range of 85kWh.