Can I use a Tesla Supercharger with a Tesla Tap?

[BlueShoes]

here is a picture of the fast charge taper for the Taycan vs. the Model 3 - please please please - I’m not trying to start a Taycan vs. Tesla conversation - this just happens to be in my opinion one of the best, most straight forward and informative charges as the taper that the BMS software implements as the battery gets closer to full - Porsche owners will be gratified to see that the Taper on the Porsche is signficantly less than the Model 3 - this is due to Porsche’s 800V technology, better cooling, and more conservative “buffer” as to how close to actually full they let the battery get.

but there _IS_ a taper, and the car slows down the charging rate as it gets closer to full for battery management reasons…

Dave, I'm curious if there is some factor of the Porsche battery being rumored to not be "exposed" at 100%. There is like a 45 minute youtube video digging into the guts of the car (actually a fascinating watch) and if I recall correctly they indicated that the Taycan does not make 100% of the battery accessible. Conceptually this means that when we see 100% on the meter it's at 90% or whatever. I could see how this would create a faster charge to 100% if 100% isn't really 100%. Of course I don't know for sure if that video is even accurate. Just an interesting thought.

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[daveo4EV]

the chart shows clearly that the maximum available charge rate after 60% SOC is significantly less than the possible maximum charge rate…this is due to the LiON battery chemistry and how LiON behaves a chemical level - a co-worker friend who is a battery engineer for a major tech company explained to me once, you can charge a LiON cell at full capacity to 100% just fine, and it will take the charge - you just can’t do it very many times in a row - you actually damage the LiON cell by doing this and in a relatively short period of time you will lose LiON cell capacity to the point it will no longer accept a charge (he said in as few as 40-50 full charge cycles)

but _IF_ you taper the charge and as you get closer to full, you lower the rate of charge, the LiON cell will last MUCH longer - you can change the charge cycles to well over 1000’s of full cycles…for only minor changes in overall charging time and straight forward “ramping down” of the charge rate as you get close to full.

the basic “rules” for LiON are

1. don’t charge the battery outside it’s ideal temperature range (too hot or too cold an LiON doesn’t like it and will damage the battery decreasing capacity and longevity)
2. don’t discharge the battery outside it’s ideal temperature range (see above)
3. don’t stuff power in at too fast a rate when the battery is close to full
4. don’t discharge the battery to absolute zero % it may not recharge
5. don’t let the LiON battery sit at true 100% for very long
6. don’t keep topping the battery off continuously while it sites idle - i.e. sittings for days/weeks and continously adding power to battery as it falls slightly below 100%
7. full discharge 0->100->0% are the hardest on the batteries capacity and life - partial charge cycles 10->85->15% offer fantastic capacity and overall battery life and are far better for the battery

because of these “rules” I can’t think of an EV on the market where what you see as battery % in the car’s displays is the _ACTUAL_ battery SOC - only the BMS sofware actually knows the true SOC and it keeps that hidden from the user for battery reliability, longevity, and capacity reasons. Overtime the actual factual kWh’s available to the vehicle via the BMS changes such that 100% charge on a 4 year old battery is very different than 100% charge on a 4 day old battery…the battery ages, the sofwtare updates, the capacity changes, the number of charge/discharge cycles accumulate and all this change is kept sane by the BMS software in order to obtain the longest possible life for the EV battery - properly done the BMS software can almost guarantee the effective life and capacity of your EV’s LiON battery will last longer than the expected on road duty cycle for the vehicle (8-15 years) - except if you’re Nissan and you produce an EV called the Leaf - nothing can save you there...

worse case scenario is that the LiON battery still degrades but over a 6-10 year cycle, and at some point you replace the battery - the cost for battery replacement is not out of line as compared to any normal ICE drive train component with 7-12 years usage and 100’s of thousands of miles, and boom you have a new fresh battery for another 300,000 miles.

 

[daveo4EV]

@lay3r3 it’s widely rumored Porsche/Audi have a conservative “top buffer” (i.e. battery capacity the LiON cells have but are never used by Porsche/Audi) - this greatly increases battery longevity and will allow a fast charge rate to “virtual full” - only Porsche/Audi knows for sure and I’m sure it’s one of the most protected confidential aspects of their BMS software - this is why you have a 93 kWh battery in the Taycan, but only 84.3 kWh are available to the car - now how to exactly manage this “buffer” and how much is “top” or “bottom” and how/when/why Porsche/Audi BMS will “tap” this unused capacity is the most closely guarded secret for Porsche/Audi - and the variables are immense and will change over time as Porsche/Audi learn more about their batteries from data in the wild...

one example (and only one) is that LiON even properly managed does lose overall capacity with each charging cycle (very very sligh loss) - so one possible strategy would be to ”tap” the unused capacity in the battery over time - so that over the life of the vehicle/battery it always has the 83.4 kWh available to it so it always has the same range - but the actual battery capacity at the end of the batteries life is far less than the original 93 kWh - but to the “owner” of the car they have not ”lost” range…this is a marketing, engineering, and warranty consideration and is not purely technical - it‘s about managing the “perception” of my EV “losing” range over time and how much you as the vehicle designer are willing to tolerate in terms of product perception.

if Porsche put in a 150 kWh battery - and only let you use 70 kWh of it via BMS software - they could virtually guarantee no range loss over 15 years - cause in that 15 years you only ever get to use 70 kWh and they can keep that up almost indefinitely via software capacity management…

now the truth is somewhere between 50% and 100% true battery capacity and will change over time as Porsche tunes their batteries and their BMS software - the question we can’t answer is what are porsche’s internal goals for the battery at 12 years old or something like that - it’s the job of the BMS software to achieve those goals given how LiON behaves - and again those goals are very very very confidential.

 

[daveo4EV]

properly managed LiON batteries have been shown to last for 1000’s of fast charging cycles with “acceptable“ capacity loss - you must manage battery temperature and charge rate and overall SOC range of the LiON cells

and it’s the fast charging cycles that have the most potential impact - L1/L2 charging impacts are minor in the grand scheme of things vs what one badly managed fast charging 0-100% run could do.

now 1000’s of cycles doesn’t sound like a lot for a product that‘s supposed to last 10-18 years…but really it is - cause how many of those can you really do in a day?

let’s say the cycle count for “acceptable” losses is 1850 cycles - for some marketing/engineering/product-design definition of “acceptable” - 15% capacity loss for example? number’s pulled out of thin air as an example

• one full fast charge cycle a day means the battery will last 5.06 years with an expected loss of 15% capacity vs. new
• one full fast charge cycle a week means the battery will last 35.57 years with an expected loss of 15% capacity vs. new

also each cycle represents a certain number of miles driven - so if your average range is 243 miles per full charge cycle - 1850 cycles * 243 miles = 434,750 miles driven - so we’re saying for our product - after 400,000 miles - and all of those miles were fast charging miles - there will be 15% loss with the capacity of the battery…

I can go to market with a product with those kind of numbers - and offer an 8 year/150,000 mile warranty on the battery…see how this works?

and these are “full” charge cycles - 0 to 100% - anything less that a “full run” and you elongate the number of cycles in the batteries expected life…

now I don’t know the exact expected MTBF cycles for any EV vendor’s LiON cells (they tend to keep that secret) but I do know the modern chemistries are expected to last 1000’s of fast charge cycles when properly managed - exactaly how many 1000’s? - that I don’t know and very few people actually do know.

buy you should be able to see from my crude model above that it’s fairly easy to expect these things to last many years given that you really don’t fast charge from 0-100% all that often - and since it is fast charging - even _IF_ you are fast charging 4 times a day from 0-100% which means you’re going to miss your battery warranty targets - you as the vehicle manufactures can see that happening on the car in the BMS software and you can adjust the charge rate in that’s car’s BMS software to hit the warranty targets of 8 years,/100,000 miles…i.e. if you’re abusing the battery with “excessive” fast charging sessions, you can increase battery longevity by simply lowering the maximum charge rate that vehicle/battery accepts…just control it in software and ”boom” you hit your warranty targets - but 6 years in that Taycan may no longer be “allowed” to achieve any where close to it’s original 270 kW charge rate because the BMS software is managing for longevity and warranty targets…

but this is all pure speculation on my part, but it’s what I would do if I was the engineer - because it’s why we have BMS software on these modern EV’s - to manage the battery - and what it is managing? why the warranty claims of course.

I can find all sorts of verbage and wording in my EV battery warranties about capacity, age, miles and what not - but not one single character/word about what I can expect the maximum charge rate to be during the warranty period - hmmmmmmm - wonder why they left that out? Perhaps it’s because that _IS_ the magic lever the BMS software manipulates to achieve the warranty targets - if you control the charge rate - you control the longevity of your LiON cells - pure and simple - and we only need these things to last 8 years/100,000 miles…after that it’s the customer’s problem if they want a new battery.

I fully expect the Taycan’s battery could easily be useable at 350,000 miles with less than 15% overall capacity loss - but I’d be super surprised if I pulled into a EA 350 kWh charger and saw anywhere close to 270 kW charge rate on that particular battery…

 

[andrewket]

I’d love to see the charge curve for a Taycan with the battery friendly option on. I suspect for the 93.4kWh packs it would be a straight line at 200kW from nearly 0% to just shy of 60% SOC. And then assuming you only used the battery friendly option, what the difference is in degradation in 5000 kWh steps.

 

[jvdsanden]

Just got my car, and for various reasons, I haven't had my garage updated. So, I'm charging more than most. Trying to figure out how/where to get the most bang for my time. 350kw Electrify America is the best but they're not convenient. Does anyone know if I can use a supercharger with a Tesla Tap?

This will not help you, but this only possible in the Netherlands (CCS), Tesla had opened 10 of its super chargers to be used by all brands.

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