Monday, December 30, 2019

My own Pacifica Hybrid review

Car and Driver’s 40,000 mile 12-month long-term review ofthe Pacifica Hybrid is not rosy.  We’ve put 44,000 miles on ours in 2.6 years.  Why such a difference?  And, what should Chrysler change for future models?

First, C&D had a bunch of mechanical issues that we have not had.
  • C&D had their hybrid battery (!) replaced under warranty.
  • C&D had two instances of low battery coolant.  Worrisome.
  • C&D had the front anti-sway-bar end links replaced under warranty to fix a squeak.
  • C&D had a stuck cupholder which caused the center console to be replaced under warranty.
  • C&D has had intermittent problems with the Uconnect infotainment system.
  • One of the C&D editors reports that the vehicle at 40,000 miles “feels tired”.

Our Pacifica has had the electronics portion of the drivetrain, the Power Inverter Module (PIM), updated in some way at the dealer.  We have one of the first ones built and we think Chrysler had some teething problems with these PIMs.  Our windscreen was damaged by a flying rock and was replaced, covered by insurance.  That’s it.  We have a lot of confidence in the car.

I think we drive our car differently than the C&D editors do, and I think many aspects of our usage are a lot closer to how most people use their minivans.  We drive 17,000 miles a year in California, mostly commuting, and have a level 2 charger at home.  They put on 40,000 miles, mostly on long trips in northern states, and none of their editors have level 2 chargers at home.  The colder environment in Michigan is a significant difference more similar to most Americans and Canadians usage.
  • Our battery gets a full charge every night, and expends that charge almost every day.  On school days we drop the kids off and the car gets topped up before the trip to work.  Over 2.6 years, that’s about 12,000 kWh we’ve put into the car.  My guess is that C&D’s Pacifica got less than 1000 kWh over their trial period.  Our battery has spent the majority of its life at shirtsleeve temperatures and full charge, and their battery has spent the majority of its life at uncomfortable temperatures, mostly cold, and empty of charge.  I’d like to know if the battery on their vehicle is underperforming, leading to current flow limits that are lengthening the time it takes to start the engine.  Slow starts would certainly make the vehicle feel tired.
  • Our Pacifica seems to get about 30.7 MPG when running on gas only, such as on a long trip to southern California.  C&D’s Pacifica got about the same.
  • Our car goes just over 2 miles per kWh, which is much worse than both a Tesla and the EPA estimates.  The former is due to the far more complex (and lossy) drivetrain, and the latter… ugh.  I can’t even imagine what anyone though MPGe would be useful for.
  • We’re quite happy with 2 miles/kWh however.  At $0.10/kWh, that’s 4.9 cents/mile, less than half the 11.6 cents/mile it costs to run on $3.50/gallon gasoline.  It’s not the $1600 saved that we actually care about, but rather that we spent $1300 on electricity that mostly went to Americans, as opposed to $2900 on gasoline that would mostly have gone to overseas interests directly opposed to our own.  We expect to drive the car for 200,000 miles and expect to save around $12,000, which would cover the extra cost of the hybrid even without government subsidies.

The C&D folks complain about the noises coming from the engine compartment.  I know what this is.  When the engine is running (e.g. it’s cold outside), as you come down to a stop you can hear one of the motor/generators spinning faster, which is disconcerting until you understand that the engine is going at constant RPM and is always connected to the wheels, so the M/G is running backwards, faster, as a generator, to suck up the power and RPMs from the engine and let the vehicle stop.

Once again I think it comes down to a difference in driving style.  When I drive the car it’s mostly in town, where full throttle is not safe.  At part-throttle operation it’s almost impossible to tell when the engine starts, and torque response to throttle position is lightning fast, better than my Honda S2000.  My impression is that the car is very quiet and very responsive.

C&D editors were driving around with an empty battery and probably mashing on the throttle from stopsigns like a bunch of incompetent teenagers.  Because the engine doesn’t run when the car is stopped, there is a transient at full-throttle takeoff where the vehicle (a) has only half power available and (b) has to use some of that power to start the engine.  It’s not great.  I never experience this.  People who want a fantastic stopped-launch experience should get Teslas, perhaps with added noisemakers.

They also complained about there not being an EV-only option on this car.  Hello?  All you have to do is stay under 75 MPH and 85 kilowatts with a battery showing any more than 0% and it’ll keep the engine off.  Sheesh.  Where the hell do these people drive?

Before I get going on what I’d like to see on an updated Pacifica, I’d like to point out how much untapped potential there is in the drivetrain.  In particular, during a full-throttle launch to 70 mph it does not rev the engine anywhere close to maximum power.  It barely gets the engine to its torque peak at 60 mph, and as a side effect it needs only 22 kilowatts from a battery sized to deliver 85.  With an upgrade to MG A’s inverter electronics and cooling (neither of which would require any changes to anything else), the Pacifica could get near it’s torque peak at just 10 mph and actually send 20 kilowatts back to the battery while doing a full acceleration run (power generation starts to roll off just before 60 mph).  That’s not helpful to the vehicle as it is, but keep it in mind as you read the following.  It’s incredible to realize that a slightly modified vehicle could deliver 105 kilowatts to… I dunno… another motor perhaps?

I should also point out that the Pacifica beats the crap out of its battery.  A Tesla P100D in ludicrous mode will drain it’s 100 kWh battery at 582 kW, which is a rate of about 6 C.  Regen charging is limited to 60 kW, or 0.6 C, and DC charging is limited to 150 kW, or 1.5 C, and frequent use of DC rapid charging is known to limit battery life.  The Pacifica will discharge its 16 kWh battery at 85 kW, which is 5.3 C, and regen braking sometimes gets as high as 40 kW, which is 2.5 C.  These numbers seem awfully high for a company that doesn’t have much internal expertise in batteries.

With that out of the way, let’s talk about what I’d like to see in our next Pacifica.  Basically, I’d like to see Chrysler have options that put the Pacifica into direct competition with the Expedition, Suburban, Yukon, and Sequoia, without making the basic minivan too expensive.  Chrysler does not compete in the big luxury SUV market and their hybrid can win it.
  • $0k: 2 inch tow hitch.  It’s completely stupid the vehicle doesn’t have it standard.  Fix this.
  • $4k option: 4 wheel drive.  Our previous Grand Caravan had 4WD and the lack of it in the 2017 Pacifica nearly broke the deal.  Electric rear wheel drive will be a huge improvement in so many ways:
    • Getting around in snow.  Yes, even in California we visit the snow for fun, and dislike screwing around with chains which you frequently need here if you don’t have 4WD.
    • Increased electric deceleration.  I have no problem with the brake feel but I suspect it can be made better with 4 wheel balanced regen.  In particular I suspect limited traction braking while turning will get better with balanced regen.
    • Increased efficiency, as the rear electric-only drivetrain will be more efficient than the hybrid drivetrain up front.  Also, we’ll get more regeneration, but I think that’s a smaller effect.
    • Balanced tire wear.  Because all acceleration and nearly all deceleration is handled by the front tires, they wear excessively fast.  Spreading the accel/decel loads will reduce the total wear.
  • $6k option: Bigger battery.  16 kWh means something like 11 kWh of actually usable capacity.  About 56% of our mileage is driven from the plug.  (The vehicle reports a much larger electric fraction because the engine only runs some of the time once the battery is depleted.)  A 28 kWh battery would put an end to engine usage on most weekdays for us.  The rear stow&go must stay.  I just do not believe there is a packaging problem for a 28 kWh battery, as the area under the front seats is underutilized.
    • The bigger battery will reduce battery wear by spreading peak regeneration loads over more cells.  Charging batteries fast is hard on them, and I’ve seen our Pacifica push 40 kW into the battery, which is a 2.5 C rate.  Tesla is very aggressive with their battery but limits regen to under 1 C.  Increasing to 28 kWh would reduce the Pacifica to 1.4 C.
    • Tesla has proven that consumers will pay more for a bigger battery.  They charge $8,000 more for an extra 12 kWh and make most of their sales with the larger batteries.  I think Chrysler could charge an extra $6k for the 16->28 kWh upgrade and see it on almost every sale.  Estimates for Chrysler’s actual costs range from $200 to $400, so $6k for an extra 12 kWh would guarantee a fat profit.  The upgrade would be directly comparable to Tesla which would score some points in the cheering section.
  • Higher power limit on motor/generator A.  Right now this thing can deliver 125 N-m of torque, which is only used to start the engine.  It is power limited to 63 kW.  During full-throttle acceleration runs, during which MG A is in generator mode the whole time, the power limit on MG A causes the computer to run the engine slower than its maximum power peak.  With a more powerful inverter and more coolant flow (but no changes to the rotor and magnets and so on), MG A could have its power limit increased to 110 kW.  That won’t do much on a FWD car (as there’s nowhere else to put the power), but a 4WD car can route the extra power to the rear axle.
  • Let the driver get rid of the full-throttle stopped-launch transient by giving him or her a way to force an engine start.  This is a software change that ideally they could roll out to existing Pacificas.  Put your left foot on the brake.  Floor the accelerator.  The engine should start and rev to 1500 rpm and something like 80 N*m torque.  Motor/generator A will put 12 kW into the battery and you will hear that the engine is under some load, just like if he did this in a normal automatic.  Release the brake.  Now there is no need to start the engine while at full acceleration, so there is no transient, just constant acceleration to 24 mph and smoothly decreasing acceleration from there to full speed.  The engine can switch to wide-open throttle and build revs fast enough to keep A generating power, so it should be possible to get a full-speed run even with a depleted battery.
  • $0: Ludicrous mode.  Tesla has made head-snapping acceleration part of the brand of electric cars.  That’s because at anything like legal speeds, acceleration is about torque and not power.  The current Pacifica has whiners complaining about the drivetrain, which is actually really well designed.  4WD, the 28 kWh battery, and the MG A changes are the preparation needed to utterly invert the perception of reviewers at C&D and get Chrysler on board with Tesla fans (which are provably legion).  Frankly, the combination in a minivan will make for very loud PR that leads to lots of sales and market disruption.  Here’s how:
    • The existing hybrid drivetrain delivers constant acceleration of 0.38 G until it gets power limited at 24 mph, and holds on reasonably well to get a 7.8 second 0-60 time.  Amazingly, the existing hybrid drivetrain (with software changes) needs just 22 kW from the battery while doing this, and that’s only because of the MG A power limits mentioned earlier.
    • The existing 16 kWh battery is limited to 85 kW output.  A 28 kWh battery could put out 150 kW with the same strain.
    • On the back axle, I want a 170 kW motor with a corner speed of 30 mph.  This is a no-screwing-around motor but there is no deal-breaking reason not to install something this large.  It will weigh 525 pounds, just like a Tesla’s rear unit.  If there is a problem with stow&go, increase the wheelbase a few inches to make it fit.  The standard Tesla Model X uses a slightly higher power motor on the rear axle.  With this motor the vehicle will accelerate at over 1 G off the line and will reach 60 mph in 4 seconds, curb stomping the long-range Model X and Porsche Cayenne S.
    • The resulting vehicle will steal most Model X sales.  Ludicrous mode acceleration (2.7 sec 0-60) is not practically achievable since it requires a much larger battery or substantial and expensive changes to the hybrid front end.
    • I understand that any sane product manager will insist on a derated ~80 kW rear end as an option, because you can sell the super-go-fast stuff for an extra $20k.  I’d strongly suggest no derated version, since Chrysler really needs something disruptive to grab a lot of electric car sales.
  • Limited slip front differential.  There is no limited slip, and both my wife and I spin the inside right tire frequently while pulling out and turning sharp right into traffic.  We’ve obviously both gotten sloppy about having lots of torque right off the line, but the car could manage it better.  The rear end should have electronic limited slip since it should have one motor for each wheel.
  • Better weight distribution.  I expect electric rear wheel drive and a larger batter pack to move more weight to the back and get a better weight distribution for the common case of 1-2 adult occupants and no cargo.
  • Higher pressure tires.  The hybrid weighs more than the base model and needs higher pressure tires to handle the higher loads, especially in front.  This is just a stupid oversight on Chrysler’s part.
  • $4k option: 4 inch lift option with metal belly pans.  (5.1 inch normal ground clearance, 9.0 inch with the option.)  My sister lives in the mountains.  We were talking about why she wants a new massive SUV rather than a minivan, and it comes down to ground clearance.  She regularly has to drive through roads that are not plowed.  Snow tires are not enough, she simply cannot have that snow pouring over the hood and windshield.  And you know that a jacked minivan with 20 inch rims will look fantastic.  For $6k, swap to air springs on all four corners and dynamically lift the car while driving.