Uncork 90 kWh HV Battery ($750) ?

[NV Ray]

Last November replaced my 2012 P85, #2446, HV battery for $15k.

90 kWh battery installed but limited to 85 kWh. Cost to uncork the other 5 kWh is $750 plus tax. Would be done over the air.

I know there are many factors, but would you uncork? My initial feeling is the extra 5 kWh range is not worth it.

 

[ElectricIAC]

Seems fair. I normally would say no, because the buffer is helpful but knowing how inconsistent Tesla is on these types of things I would probably jump on the opportunity being in the same boat.

 

[NV Ray]

Seems fair. I normally would say no, because the buffer is helpful but knowing how inconsistent Tesla is on these types of things I would probably jump on the opportunity being in the same boat.

Good points, thx.

On your buffer point, my understanding from the Tesla Service Center is that the way the 90 is limited to 85 is 5 kWh of the battery pack is simply not used. For example there is 90 kWh of batteries in the pack but only 85 is used, meaning I'm carrying an extra 5 kWh worth of unused battery. So by buffer you mean there's more usable upper and lower buffer if I uncork to 90 kWh?

On your "inconsistent" comment, could you elaborate?

 

[maximizese]

For me, I would jump on the opportunity. $750 for ~5kWh of usable capacity is a bargain. 5.6kWh Tesla modules on eBay go for over $1K. The way I see it is there may be a time when you really wish you had that extra 18 miles of range...let's say you're in a time crunch or your stomach is churning and you just within range. Having that extra capacity could come in handy at those moments and you'd be glad you had it.

Anyone know if the Supercharging curve broadens out when you unlock the full 90kWh? Like two identical Model S cars at the same %SOC both with the same battery pack (one unlocked to 90 but the other limited to 85), would the unlocked 90kWh receive more rated miles in the same charging session as the software capped 85?

 

[NV Ray]

For me, I would jump on the opportunity. $750 for ~5kWh of usable capacity is a bargain. 5.6kWh Tesla modules on eBay go for over $1K. The way I see it is there may be a time when you really wish you had that extra 18 miles of range...let's say you're in a time crunch or your stomach is churning and you just within range. Having that extra capacity could come in handy at those moments and you'd be glad you had it.

Anyone know if the Supercharging curve broadens out when you unlock the full 90kWh? Like two identical Model S cars at the same %SOC both with the same battery pack (one unlocked to 90 but the other limited to 85), would the unlocked 90kWh receive more rated miles in the same charging session as the software capped 85?

Wow, $1k for a 5.6 kWh module. And probably not new.

If I recall 16 modules in a 90 kWh pack, so $16K.

You make a good point. Thx.

 

[gaswalla]

Good points, thx.

On your buffer point, my understanding from the Tesla Service Center is that the way the 90 is limited to 85 is 5 kWh of the battery pack is simply not used. For example there is 90 kWh of batteries in the pack but only 85 is used, meaning I'm carrying an extra 5 kWh worth of unused battery. So by buffer you mean there's more usable upper and lower buffer if I uncork to 90 kWh?

On your "inconsistent" comment, could you elaborate?

That is not technically true. It is not as if there are 5khw of cells sitting there, rotting away. In fact, every cell in that 90kwh battery is cycling with charging and discharging. Tesla has software locked the battery in the sense that when when you charge to "100%", it is in fact actually to 94.5% of the 90kwh battery... thus, somewhat ensuring that no cell gets charged up to 100%. In theory, this approach should lead to a long lasting battery. By unlocking the 5.5% of the battery, when you charge to 100%, it will actually be 100%. It is all 'top locked". Quite honestly, the top 5% of the battery is very inefficient when charging as well as when discharging (decreased regen)... pros and cons with unlocking it, I don't think it makes a difference as long as you understand the safety in charging to 100% when it's locked

 

[NV Ray]

That is not technically true. It is not as if there are 5khw of cells sitting there, rotting away. In fact, every cell in that 90kwh battery is cycling with charging and discharging. Tesla has software locked the battery in the sense that when when you charge to "100%", it is in fact actually to 94.5% of the 90kwh battery... thus, somewhat ensuring that no cell gets charged up to 100%. In theory, this approach should lead to a long lasting battery. By unlocking the 5.5% of the battery, when you charge to 100%, it will actually be 100%. It is all 'top locked". Quite honestly, the top 5% of the battery is very inefficient when charging as well as when discharging (decreased regen)... pros and cons with unlocking it, I don't think it makes a difference as long as you understand the safety in charging to 100% when it's locked

Great comments thanks. In my Prius Prime, Toyota doesn't let you charge to 100%. While the charging meter may say 100% it's actually about 84% State of Charge (SOC).

My understanding is Tesla is different - charging meter says 100% and it is indeed 100% SOC. Correct?

 

[gaswalla]

That is true (100% is 100%) on a typical Tesla that does not have a software-locked battery. Your analogy is pretty good, with your current software lock, it is sort of like the Prius Prime's battery. Only thing is that you only have 5% of the battery software locked.. that sort of seems like an ideal situation in my opinion

 

[ucmndd]

I'd personally not bother as you can get basically all the benefit without paying the extra $750.

Charge your "85" to 100% and you've really only charged the battery to ~94%. So you can daily charge to like 95% with no particular worry about degrading the battery.

The only time you'd really see the benefit of those extra 5kwh is when you charge the newly unlocked battery to a REAL 100% for a road trip or something. Do you have a regular trip you take where the extra 5kwh makes the difference between having to stop or not? If so I might consider it. If not, there really isn't much of a reason.

 

[NV Ray]

I'd personally not bother as you can get basically all the benefit without paying the extra $750.

Charge your "85" to 100% and you've really only charged the battery to ~94%. So you can daily charge to like 95% with no particular worry about degrading the battery.

The only time you'd really see the benefit of those extra 5kwh is when you charge the newly unlocked battery to a REAL 100% for a road trip or something. Do you have a regular trip you take where the extra 5kwh makes the difference between having to stop or not? If so I might consider it. If not, there really isn't much of a reason.

Thx. Good points. So it's your opinion that my battery usage theory in post #3 is incorrect? Instead of only 85 kWh currently being used and 5 kWh (almost a whole module) not used, ALL battery cells are being used but only charged to about 95% State of Charge?

 

[ucmndd]

Thx. Good points. So it's your opinion that my battery usage theory in post #3 is incorrect? Instead of only 85 kWh currently being used and 5 kWh (almost a whole module) not used, ALL battery cells are being used but only charged to about 95% State of Charge?

Yes. Batteries are software capped by limiting the maximum charge of the entire pack - not by disabling some portion of cells.

 

[a10ha10ha7]

Last November replaced my 2012 P85, #2446, HV battery for $15k.

90 kWh battery installed but limited to 85 kWh. Cost to uncork the other 5 kWh is $750 plus tax. Would be done over the air.

I know there are many factors, but would you uncork? My initial feeling is the extra 5 kWh range is not worth it.

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whats your 100% voltage shows when you at chademo chargers? 405 before the upgrade? if it was me i would find out which state of charge of the battery will the upgrade unlock. but tbh doesn't matter if the unlock is at the discharged or charged side 750 doesnt sound like its not worth it.

 

[ucmndd]

if it was me i would find out which state of charge of the battery will the upgrade unlock.

Software locks are at the top end of the battery (i.e. limiting max charge). I’ve confirmed this personally.

 

[JimmyB]

For $750 I'd probably do it - you'll likely get (most of) it back at resale time, even if you don't use it all that often.

 

[ElectricIAC]

For $750 I'd probably do it - you'll likely get (most of) it back at resale time, even if you don't use it all that often.

Will they at least rebadge the car?

 

[NV Ray]

Will they at least rebadge the car?

My understanding is uncorking will change display on both screens from P85 to P90. Physical P90 badge on the outside of the rear hatch costs around $20 from the Tesla Service Center. My 2012 (and most 2012 MS) did not come with outside badging so I would keep mine the same as original.

 

[NV Ray]

I've decided to keep status quo - 90 kWh pack software limited to 85 kWh.

Decision made after feedback from posts in this thread and phone conversations with @howardc64 , @Recell , and @wk057 .

For my driving I don't need the extra 15-20 miles range. Further, I like the feeling that I have a built in top buffer. Having a top buffer is similar to my Prius Prime with an 8.8 kWh Lithium Ion HV battery - when charge meter says 100%, State of charge is actually around 84%.

 

[Recell]

@NV Ray, that’s a great way to look at it.

 

[meomyo]

why doesnt tesla just give owners the full capacity on new batteries when you already paid 70+k for the car and owned it for x amount of years..this nickle and diming the customer is silly to me. If you are also forking out what...12-30k mORE for the batter after you already bought the car years earier it seems silly to limit the battery and then extort the customer of the %5.

 

[Recell]

indeed, the $750 is for the most part unnecessary, since the top 10% of your battery pack is only used in the very first leg of a road trip and you can ultimately ‘uncork’ it for free simply by increasing your charge level by 10% (or in @NV Ray’s case, by 5%) to capture the additional charge capacity, with no impact on the life of your battery pack.