wemct

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This is undoubtedly true about the dealer/car. Thank you for the reference, so just a follow-up question though . . . I don't see how to actually set the maximum charge? In the general charging profile it only has a minimum. Does it default to the 85%? And if so, how do you override it to 100% for a road trip?
The best way to set a maximum charge percentage is to set up a Timer profile. On those occasions that you need to get to 100%, you can disable all profiles and plug into the AC home charger. Fyi, DC charging automatically bypasses your charging profiles and will continue to charge until you stop or it reaches 100%.

See this link for more information to set up a Max charge percentage using a Timer profile (start on post #17).
https://www.taycanforum.com/forum/threads/taycan-charges-to-100-despite-profile.1242/page-2
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wemct

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This is undoubtedly true about the dealer/car. Thank you for the reference, so just a follow-up question though . . . I don't see how to actually set the maximum charge? In the general charging profile it only has a minimum. Does it default to the 85%? And if so, how do you override it to 100% for a road trip?
You can also look at this link (post #73) to set up a TImer profile.
https://www.taycanforum.com/forum/threads/setting-up-for-charging-in-garage.826/page-5#post-17579
 

TriTaycan

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Great, thank you! Seems clear enough now. Not as simple as it should be IMO, but sounds like if you just setup a single timer one time it'll work fine. If they really want you to not charge over 85% for daily driving they should make it more straightforward and just have you set the maximum charge. I don't have any need/desire to do anything other than just plug in the charger when the car needs charging. I doubt my use case is that rare.
 

Miwa

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What is this 80% recommended maximum charge thing? No one at the dealership said anything to me about this, couldn't find it referenced in the Good to Know. I've also seen people here allude to it, but don't see an obvious way to limit charging to 80% (or any other number) . . . feels like when I plug it in it's just going to charge to 100% (I've only had the car a few days and only plugged in the charger to make sure it works). My understanding is 100% is really only 90% anyway, as they limited battery charge to ensure battery life in a non-overrideable fashion.
In range threads, also be aware that talking about charging to 80% is a time thing. It takes longer to go from 80% to 100% than it does to go from 20% to 80%. Others answered the max charge reasons. Given the warranty and the battery reserved, I'm not going to worry about it.
 

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In range threads, also be aware that talking about charging to 80% is a time thing. It takes longer to go from 80% to 100% than it does to go from 20% to 80%. Others answered the max charge reasons. Given the warranty and the battery reserved, I'm not going to worry about it.
But just to add that the tapering of the charge issue only really occurs with DCFC, standard AC charging is minimally effected by the state of charge as it's only 9.6kW in USA at 40Amps.
 


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long distance travel with an EV is different that an ICE - with the main characteristics being;

speed is the enemy

as speed increases
aerodynamic drag increases - dramatically

until about 40-50 mph all the energy expended on moving the car is over coming mechanic friction and weight - with the amount of energy required to over come aerodynamics being “insignficant” at lower speeds…

however as one gets above 50 mph the portion of power being expended to overcome aerodynmic drag becomes signficant and dominant and overwhelms the basic cost of moving the car

as speed increases the power required to offset the aerodynamic drag has a velocity^2 (squared) component and it gets really expensive really really quickly…

if it costs 10 mythical units of power to to from 50-60 mph, it might cost:

20 incremental units to go from 60-70
40 incremental units to go from 70-80

the chart below is 100% fabricated and does not represent any factual values for _ANY_ vehicle I'm aware of - but it is conceptually accurate as a mental model of how as speed increases the contribution of aero-dynamic loads becomes greater than the linear cost to "just move the car" from a pure mechanical physics point of view (rolling resistance/friction/weight which are constant and linear) - again this is a "conceptual" model to illustrate how when one increases speed the aero component becomes greater than the technical component in a non-linear increasing fashion…

Screen Shot 2020-06-20 at 2.24.51 PM.png

please don't quibble with the actual numbers - they are meaning less - but conceptually accurate in terms of aero dominating cost in a non-linear/increasing fashion…it's a demonstration as an example - and not entirely inaccurate for the theory and illustrative that aero does dominate costs as speed increases - I'll leave it to mechanical/aero engineers to provide a real world model, but will assert the basic change may differ in scale/ratio but not in concept.

you'll note on the chart that aerodynamic drag in this model does not play a significant role until around 50 mph - but from that point forward it starts to dominate incremental cost as speed increases…the chart/model I fabricated was "hand tuned" to achieve this inflection point - but that is representative of real world - where in fact between 40 & 50 mph is where aero starts to appear in cost equations as a meaningingful factor, and by 60-65 mph is a majority factor in cost to move the vehicle…

even though each change in speed only 10 mph (linear) the cost is non-linear - each mph-unit added costs more than the previous mph in incremental costs…

while the units of power above are "made" up the scale/change is not - each mph costs more than the previous mph after 50 mph - and you stack all these on top of one another and pretty soon your Taycan can only drive like 70 miles at say 100 mph…

this gets really really expensive power wise very very quickly - and is also why reducing speed is so effective - you're gaining more range which each mph slower you are going, than losing in terms of speed…

an EV that say can go 300 miles on a full charge at 50 mph, can only go 180 miles at say 70 mph, or maybe only 140 miles at 80 mph…

also there is this strange trade off between faster travel from point a to point b - but because you used more power you’ll have a longer charging stop

for example there is a stretch of I-5 south in California - between two fast charging stops - I-5 is posted speed limit 70 mph, so average speeds are slightly higher - now it is 116 miles between these two superchargers (harris ranch to tejon ranch)

@70 mph that is 99 minutes travel time
@75 mph that is 93 minutes travel time
@80 mph 87 minutes
@85 mph 82 minutes

now the car can easily do a 116 mile run at 85 mph - but if you leave harrish ranch with 85% battery you arrive at Tejon ranch with 12% battery (plenty of buffer) and you’re therefore in for a nice solid 25 min charger stop to get back to 85%

making the total travel time 82 minutes + 25 minutes = 107 minutes

however if you shave 10 mph off your speed and take 93 minutes - you’ll arrive at Tejon ranch with just over 34% battery and require only an 15 minute stop to get back to 85% battery

making the total travel time 93 minutes + 15 = 108 minutes

so for both speeds the total travel time is about the same because while to travel between fast chargers is faster the increased energy consumption causes you to spend longer at a fast charger to recover the increased energy consumption…

but more importantly - the reduced consumption lets you go sooooooo much further - at the slower speeds you can skip the stop altogether at Tejon ranch and push the car further south to stop at the Castaic fast charger - where at 75 & 80 mph you simply can’t push the car that far and that fast.

if you want to reduce charging stops - reduce the speed and you’ll be amazed, amazed I tell you, how far the car can go on a single charge - and because of the relationship between speed, consumption, and charge rate you’ll be very very hard pressed to reduce overall travel time given the longer stops at the fast chargers.

having driven over 300,000 miles with EV’s the actual travel time differences by driving 5-7 mph slower are inconsequentical, but the time saved due to reducing time at fast chargers more than makes up for the slower speeds - and in some cases changes a 3 fast charger segment into a 2 fast charger segement by cutting out a full charging stop you can save 20-30 minutes…

at speeds of 65 mph or less the Taycan is easily a 270 mile vehicle, at speeds of less than 58 mph I wouldn’t be surprised at easy 330 miles of range - once you start pushing 70 or greater in _ANY_ EV the range starts to drop quite quickly due to the dramatic increase aero-dynamic drag…

how do I maximize range at 75 mph? easy don’t drive 75 mph - drive 65 mph and you’ll get more than 20% better range…

note this all also true for ICE cars - but given that they are only 20% efficient with fuel (you’re wasting most of it on waste heat anyways) and “fixed” refueling time of 7 minutes or less - the increased consumption is not offset by increased fueling time - there by allowing you to reduce overall travel time by driving faster at the consequence of increased fuel consumption.

at 65 mph I’d say the Taycan is easily 216 miles, however I”m not so sure at 75 mph or greater - also you have to plan your charging stops - as the distance you think you’re driving may be difference that where the fast charging stops are…EV road tripping requires a little planning up front, and I highly recomend using plug-share to evaluate the reliability of fast charging options along your route.

now in ideal circumstances the Taycan can go from 5% to 80% battery in a 22 minute fast charging stop (EA 350 kW charger)

but it can go from 30%-80% in about 12 minutes at the same charging stop - saving 10 minutes

that charge savings will be magnified at the more common 150 kW chargers and dramatically magnified if you’re stuck using a 50 kW fast charger…

in racing weight is the enemy - I understood this, but until I actually raced, I didn’t really understand it - shaving weight has sooooo many benefits that magnify one another it’s just hard to comprehend until you experience it for yourself - it’s just plain simple that weight shaving is the best way to improve performance of any car, but in racing more so.

for road trips with an EV - there is a virtuous cycle with speed shaving - the dramatic range increase for even a 2-5 mph adjustment in speed is just simply huge due to the reduced aerodynamic loads…

at 68 mph on innodrive cruise control you will have _ZERO_ range anxiety and when it does come time to stop at a fast charger the charging time savings will be impressive, even more impressive is driving 64 mph might allow you to skip the fast charging stop all together and simply charge overnight at your destination…at a minimum it will change a 2 fast charging stop trip into a 1 fast charging stop trip…

range and speed are not each other’s friend when you’re traveling with a budget of less than 3 gallons worth of kWh’s (about 90 kWh).
Fucking hell Dave you need to get out a bit more mate.
 

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daveo4EV

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updated original post and now have the drag formula where velocity is squared!! - the video is well worth a watch and highlight the geometric (vs. linear) requirements to go incrementally faster…
 

daveo4EV

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