T8 Fun: Is "Pure" mode really more efficient?
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    1. #1
      Junior Member Kranvagn's Avatar
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      Question T8 Fun: Is "Pure" mode really more efficient?

      Besides just moving the line between EV and ICE power to make it easier to stay in EV mode with your right foot, "Pure" also makes various other tweaks to the vehicle to improve not just EV range but MPG in general over a long haul...but, how _much_ does it help?

      Is it really worth running Pure for longer drives vs. the normal Hybrid mode?
      How about also saving your battery for when it's best to use it (lower speeds) and relying on the ICE for freeway cruising?
      What's the actual gain and therefore is it really worth bothering with all this every time you set out on a drive longer than your EV range??
      And for fun on the flip side, if you start off with a depleted battery, force the ICE to stay on continuously, and 'hold' any regenerated electrical power, how 'bad' does it get?

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      I only run pure mode at the last 2 miles to home so I use more battery than in hybrid mode.

      Once you go on a trip, pure and hybrid doesn't matter. Your gentle driving matters, versus rushing up and braking abruptly.
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    4. #3
      Member lamarguy's Avatar
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      Quote Originally Posted by FusionRedXC60 View Post
      Once you go on a trip, pure and hybrid doesn't matter. Your gentle driving matters, versus rushing up and braking abruptly.
      My experience is to the contrary and his video illustrates that point in the HYBRID vs PURE runs. If you reserve battery for low speed operation (<= 45 mph), you'll get better trip efficiency.
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      Quote Originally Posted by lamarguy View Post
      My experience is to the contrary and his video illustrates that point in the HYBRID vs PURE runs. If you reserve battery for low speed operation (<= 45 mph), you'll get better trip efficiency.
      But either Pure or Hybrid mode doesn't consider speed and run on battery up to 75mph. You have to watch the speed and manually click the "Preserve battery" button to do so. You can do it occasionally but not very practical for real driving.

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    7. #5
      Junior Member Kranvagn's Avatar
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      It would be nice if the system was smart enough to look at your route, ask if you're charging at your destination, and plan ahead to have the battery at effectively zero at the end of your trip having used all electrons on the slowest parts of your journey (maybe even look at some live traffic data while it's at it!). I vaguely remember the sales guy saying it would indeed do that (and my being highly skeptical), but I've sure never noticed any sort of 'planning' like that from the Nav/EV systems.

      I also have a hunch that the MPG cost of charging when driving at full freeway speeds (70-75MPH) is worth the trade if you need electrons for EV driving in bumper-to-bumper traffic ahead on your route. Don't quite have the testing method or data to really figure that out yet...
      Last edited by Kranvagn; 12-19-2019 at 10:06 AM.
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    8. #6
      Member lamarguy's Avatar
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      Quote Originally Posted by FusionRedXC60 View Post
      You have to watch the speed and manually click the "Preserve battery" button to do so. You can do it occasionally but not very practical for real driving.
      I drive in PURE (and toggle HOLD) on most drives. I also use B mode to gradually slow down approaching red lights. Until now, I've always driven a stick, so manual control is something I prefer.

      Up to 45 mph on a flat grade, I also tow my 3,500lb boat in PURE mode. That's probably the most extreme example of efficiency. But, I routinely achieve 30+ mpg towing a boat in the city (~25 miles each way).

      That said, I realize most folks aren't interested in optimizing their efficiency...
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    9. #7
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      I just get in and drive. I fiddled early on, and it was more trouble than it was worth. The best way to get good mpg is to drive steady, leave it in hybrid, use PA and don't gun it too often. In any case, after owning 3 T8's, I am close to being ready for a full electric.
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    10. #8
      Member lamarguy's Avatar
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      Quote Originally Posted by xgman View Post
      The best way to get good mpg is to drive steady, leave it in hybrid, use PA and don't gun it too often.
      That's simply not true.

      If that's your preferred driving, then great. Keep doing it. But, don't claim it's the "best way to get good mpg".
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      It could be worthwhile to get 20 or 30 or even 50 miles on a BEV car by doing hyper-miling.
      But to get 2 or 3 more miles battery range on a PHEV? I won't bother much.

      So I only do one thing, when I am 2 miles from home, I switch to Pure mode. So it saves 2 miles of gas on slow local streets.

      If travel out of town, I don't have chance to recharge so I don't care Pure or Hybrid mode at all.
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    12. #10
      Member lamarguy's Avatar
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      Quote Originally Posted by FusionRedXC60 View Post
      It could be worthwhile to get 20 or 30 or even 50 miles on a BEV car by doing hyper-miling.

      If travel out of town, I don't have chance to recharge so I don't care Pure or Hybrid mode at all.
      No one here is "hypermiling". That trades time for speed (e.g., driving below the speed limit). I certainly don't do that. I try to maximize efficiency without losing time.

      The simple rule is - maximize the amount of time in PURE mode within the EV efficiency range (0 - 45 mph).

      For example, on an upcoming trip to see family (~260 miles), I drive in PURE until I get on the highway (~3 miles) and select HOLD. When I hit small towns (30 - 45 mph) or traffic jams, I unselect HOLD. Rinse and repeat. Driving 5 mph over the speed limit (70 - 80 mph), that nets me 31 - 32 mpg every time.
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    13. #11
      Junior Member Kranvagn's Avatar
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      Quote Originally Posted by lamarguy View Post
      ... I drive in PURE until I get on the highway (~3 miles) and select HOLD. When I hit small towns (30 - 45 mph) or traffic jams, I unselect HOLD. Rinse and repeat. Driving 5 mph over the speed limit (70 - 80 mph), that nets me 31 - 32 mpg every time.
      Yup, that's pretty much it, though I'll add it's best to keep it no faster than 75MPH as much over that and the ICE can't turn off nor can the rear axle regenerate any electrical power downhill slopes.
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      Quote Originally Posted by Kranvagn View Post

      I also have a hunch that the MPG cost of charging when driving at full freeway speeds (70-75MPH) is worth the trade if you need electrons for EV driving in bumper-to-bumper traffic ahead on your route. Don't quite have the testing method or data to really figure that out yet...
      To test, find another T8 and use pilot assist to platoon. One T8 would enable charging while driving and the other would not. So long as both vehicles are similarly charged, equipped, and loaded, the difference should be evident.



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      Quote Originally Posted by callmecjp View Post
      To test, find another T8 and use pilot assist to platoon. One T8 would enable charging while driving and the other would not. So long as both vehicles are similarly charged, equipped, and loaded, the difference should be evident.



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      One T8 is already very rare. Where to find another T8?

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      Still a few months before the scheduled delivery date for my T8 so a question to those of you who already have one: Am I right in thinking that the Hold function maintains the current charge level as opposed to disabling discharge of the battery? In other words if you have a low battery and want to charge it from natural driving, rather than using the separate Charge function, using Hold will simply hold the charge level at the current low level.

      If that is the case, what's the best way of building charge through natural driving? B Mode, Power Mode (to keep the engine running) and a gentle right foot to ensure that ICE is on all the time and the car maximises regeneration?

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      @DoctorAce: Hold will keep your current charge, not adding to it, and only lowering through normal L-ion tech phantom drain over time and I suspect as its used to start your car each time. It's what you'd use e.g. if you were going to go camping and wanted to create a full charge to run your accessories overnight or whatever; Others use it as a method to manually decide when to have more battery power when they want to put it into PURE and eek out a couple miles of EV battery use e.g. before getting home and plugging-in again.

      (I know more experienced T8 owners will correct me if I'm wrong ) Assuming the battery is neither overly hot or overly cold, and it's got room to accept a charge, light braking will do regeneration from all modes. You'll pick up some recharge on downhill as the engine brakes against itself. While people's explanation vary somewhat (I asked similar questions just 3-4 mo ago) it appears "B" will additionally help on regeneration when you lift your foot off the acceleration pedal, by providing additional engine braking.

      My T8 should get off the ship tomorrow and I'll hopefully have it in the next couple weeks --- so I have a bit of learning with Volvo's mild-hybrid implementation. Like you it appears, I am also someone that tries to understand things before jumping into the pond, so to speak. That being said, after driving 2 different Lexus (full) Hybrids for more than 10 years and then learning the in's and out's of my Tesla over the past 4, if the T8 is your first hybrid, my suggestion is to just drive it like a normal car and don't try to overthink things at first. I have never recommended any new owner think they need to know better to override what the hybrid logic does. Instead, as you drive and become comfortable with your new car, pay a little more attention to the instrument cluster and how regeneration and battery use is working, and in what conditions. Then, as you see how driving conditions and your actions change things, if you want to try and do some of the tricks to increase MPG, go for it -- for me, I learned what I could do in my previous cars, but found most of the time I let the car take care of itself. I knew what I could do in the situations where I wanted to extend range or perhaps get a little better MPG, and where some of the sweet spots were for speed, etc., but I didn't focus on it as much as I thought I would ...just enjoy that T8 when it arrives! I know I will.
      Last edited by BertL; 12-20-2019 at 08:15 AM.
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      T8 PURE mode is not particularly efficient. Depending on gas and electricity costs in your area (some public chargers really bleed out slow charging like our T8s), it can be less economic to drive PURE.
      Personally I don’t mind those occasions since I prefer the “silent” drive.

      The electric motor is stated in the manual to loose efficiency over 35mph. Being 50% less efficient at speeds over 60mph

      Quote Originally Posted by Kranvagn View Post
      It would be nice if the system was smart enough to look at your route, ask if you're charging at your destination, and plan ahead to have the battery at effectively zero at the end of your trip having used all electrons on the slowest parts of your journey (maybe even look at some live traffic data while it's at it!). I vaguely remember the sales guy saying it would indeed do that (and my being highly skeptical), but I've sure never noticed any sort of 'planning' like that from the Nav/EV systems.

      I also have a hunch that the MPG cost of charging when driving at full freeway speeds (70-75MPH) is worth the trade if you need electrons for EV driving in bumper-to-bumper traffic ahead on your route. Don't quite have the testing method or data to really figure that out yet...
      Since the MY19, planning a route really seems to account the best usage of the battery. You notice it specially if it is a long trip with several stops.

      If you charge only at home and the round trip is over the PURE range, plan the final stop near the home charger, sensus won’t allow to set the end of the trip at the current location (if you do the planning at home).

      I haven’t noticed traffic data to make a difference and have to HOLD manually if I see traffic ahead to maximize the battery charge during the slow traffic.

    19. #17
      Member lamarguy's Avatar
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      Quote Originally Posted by Lojo View Post
      T8 PURE mode is not particularly efficient. Depending on gas and electricity costs in your area (some public chargers really bleed out slow charging like our T8s), it can be less economic to drive PURE.


      ICE is ~30% efficient and EV (PURE mode) is ~90% efficient. Unless you're paying an obscene price for electricity, EV is always less expensive.

      $0.89 (full charge, $0.12 kWh) / 18 miles (EPA rating) = $0.05/mile
      $3.05 (premium gas) / 22 miles (EPA rating) = $0.14/mile
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    20. #18
      Junior Member Kranvagn's Avatar
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      Depends on your definition of efficient... From an energy standpoint, as much EV as you can do is always better, bar none.
      From a wallet standpoint, there was that one time I saw a Blink charger at a SoCal Ralph's that wanted $.50/kwh, ffs man... :-P
      Last edited by Kranvagn; 12-21-2019 at 12:55 AM.
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    21. #19
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      Quote Originally Posted by lamarguy View Post

      <img src="http://www.vwvortex.com/Anthony/Smilies/confused.gif" border="0" alt="" title="Confused" class="inlineimg" />

      ICE is ~30% efficient and EV (PURE mode) is ~90% efficient. Unless you're paying an obscene price for electricity, EV is always less expensive.

      $0.89 (full charge, $0.12 kWh) / 18 miles (EPA rating) = $0.05/mile
      $3.05 (premium gas) / 22 miles (EPA rating) = $0.14/mile
      Yes, Electric drivetrains are more efficient converting energy.

      But the T8 peaks at 31mph, increasing consumption/decreasing range.

      Public charging is rarely that cheap in Europe &#x1f642; every town/region has different rates per kWh, minute or start fees (I haven’t visited any country with a single charging operator).

      That cost doubles at highway speeds (consumption gets easy up to 40kWh/100km).

      Basically, no PHEV is a replacement for a BEV, Volvo can’t bring the P8’s soon enough to market.

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