Keep in mind that the actual electrical range of a "traditional" hybrid car / SUV / van is low (much much less than the 30 miles on your bike). It is great at giving you enough power to keep your speed constant at e.g. 30mph-40mph, but it would have a hard time accelerating from 0 to that speed unless you were very easy on the gas pedal... It still makes quite a difference on mpg, while requiring much less material to make the battery than a plug-in hybrid or electric car...

 

From what I have read, Battery is meant to kick in when:

1. ICE would be inefficient- ex. During Starts, heavy acceleration etc. After start, and at constant speeds, ICE can stay in it's optimum output zone. Battery might help out at constant speeds too if it gets topped off beyond expected possible heavy load usage.
2. On AWDs, rear wheels are dynamically engaged if there is slippage and/or extra battery capacity.

Asking battery to do more than this would exponentially increase battery size and cost. Essentially, battery is Nitro boost that automatically kicks in when it would be more efficient than ICE. It is not meant to carry full load all the time like the scooter.

That's just my 0.02!

 

From what I have read, Battery is meant to kick in when:

1. ICE would be inefficient- ex. During Starts, heavy acceleration etc. After start, and at constant speeds, ICE can stay in it's optimum output zone. Battery might help out at constant speeds too if it gets topped off beyond expected possible heavy load usage.
2. On AWDs, rear wheels are dynamically engaged if there is slippage and/or extra battery capacity.

Asking battery to do more than this would exponentially increase battery size and cost. Essentially, battery is Nitro boost that automatically kicks in when it would be more efficient than ICE. It is not meant to carry full load all the time like the scooter.

That's just my 0.02!

As I see it, the Sienna battery has seven basic functions:
(1) Power MG1 to crank the engine and control engine power output.
(2) Power MG2 to provide high torque to get the vehicle moving from a dead stop.
(3) Power MG2 to supply extra torque and power during higher speed acceleration so the vehicle can function on a 4 cylinder 2.5L engine.
(4) Power MG3 for AWD
(5) Power MG2 for reverse gear.
(6) Provide enough capacity to store energy from regenerative braking.
(7) Provide power for electrical accessories and charge the 12V battery.
The Sienna battery achieves all of these functions.

Only half of the battery capacity is actually utilized since the system keeps the battery charge between 30% and 80% of capacity to extend battery life.

 

If I'm reading the specs right, the Sienna battery is not even triple the size of my ebike battery! 1.9kwhr = 1900whr, right? How in the world can this make any difference in moving a vehicle that weighs over 4600 pounds at speeds much greater than 24 mph???

I've seen it running a mile or more at 50 mph on the battery alone, without draining it much. Under the right circumstances, it's making a huge difference. I've had a couple of (non-hybrid) Pacificas and could average 23.5 mpg, well above the EPA rating of 19 mpg city. I haven't reset my computer over the last couple of tanks and the Sienna is showing 40.0 mpg. So far, my calcs have come in better than the computer two out of three times and it's always close. The range on this tank is working out to almost 700 miles in city driving.

One caveat is that I've noticed when passing a radar speed limit sign that the digital and analog speedometers are optimistic. With the radar showing my speed at 45 mph, the digital speedometer shows 47 and the analog speedometer shows about 48. It could be that the odometer and computer are off by the same ratio and our fuel economy is really 3% or more, lower. I may take a look at that this Sunday. I have a trip planned that is 200 miles according to Google maps. I'm interested to see what the odometer shows.

Regardless of some minor inaccuracies, the Sienna is capable of incredible fuel efficiency. I don't feel like I'm giving up a thing to get this kind of range.

 

I wouldn't put any weight in those signs to calibrate speed against. They are notoriously poorly calibrated. I've gone past them at 55+ and they think I'm doing 40.

 

Someone posted

in another thread if you want the detailed teardown of how the eCVT works. The battery is big enough to get the van moving up to a few mph and then acts more like a big capacitor. It is big enough to easily absorb the regenerative braking energy when stopping or for a decent of 1500ft or so in elevation. During normal driving it can be used to overcome aerodynamic drag on a low incline with the ICE off. More importantly when the ICE kicks on the battery ensures that all of the power produced by the engine goes somewhere. The eCVT lets the engine provide power to the wheels while also generating electricity which ends up in the battery. Sure there are losses at every step in that process but its way better than losing all the power that isn't needed to move the vehicle.

I do wish it had a slightly larger battery. I take our AWD skiing and I go from 10% to 100% on the downhill home in the first few miles. That said, I also averaged 34mpg over 3 140mi round trips with a 4000ft elevation gain and then loss on each trip.

Also the "EV Mode" is sort of pointless. I'm not sure why the button is even there beyond marketing.

 

Also the "EV Mode" is sort of pointless. I'm not sure why the button is even there beyond marketing.

Duh! Everyone knows that EV Mode is for sneaking into the garage late at night so that the wife doesn't hear you.

From the 2021 Sienna owners manual: This mode allows you to drive in residential areas early in the morning and late at night, or in indoor parking lots etc. without concern for noises and gas emissions.

 

Not that I've found. What is worse for my with doing it skiing is the car also kicks on the ICE for cabin heat. I sort of worked around that by taking a small 800W space heater with me and using the inverter to run that to heat the cabin via consuming some of the power from the HV battery.

 

I just hit the Fan Off button for both front and rear and that seems to do it. Often the ICE turns off immediately after I hit the Off button if I'm just sitting.

 

If you turn the HVAC off before you start the car so it doesn't default to heat in colder temps you may be able to get some minimal time out of your battery before the engine cranks up, assuming you have over 3 bars on the meter. If it is trying to run heat the ICE will be running.

 

When the engine is cold (below about 50 degrees or so), the ICE will start regardless of whether the HVAC is on or off.

 

You have to put your foot on the brake while moving the shifter, after you've pressed the start button 2x with foot off brake. You'll also have to make sure the parking brake is disengaged before it will roll.

Did you do that? Sorry if I wasn't clear.

 

The battery isn't big enough to run in EV mode above 20mph or for any real distance.

We climbed I-70 going up into the rockies (Grand Junction to Vail) with a HEAVILY loaded van (4 people, full roof box, back of the van COMPLETELY FULL) with zero issue holding 70mph the entire way.

The van will vary the engine speed and battery usage based on moment to moment power demand. If the incline lessens its going to keep the engine running the same speed and dump excess power into the battery, when it gets steeper it will pull power from the battery to augment the engine.

The only case I know of where you run into an issue is if you are driving up something steep enough, long enough, with enough load that you are constantly using 100% of the max possible ICE output to drive the wheels in which case you'd end up not getting any help from the battery. My personal/anecdotal experience is that even with a heavily loaded van, in the winter, at freeway speeds, doing a steep climb, the van always had headroom to periodically put power back into the battery.

My gripe on battery size is actually more about long descents. I ran into this again driving from Seattle to Yosemite and back. We "waste" a huge amount of potential energy on long downhills because the battery fully charges and then we are stuck engine braking or using the actual brakes to keep the speed down. This is vs a true EV with a big battery where you'd just charge the pack the entire long downhill and retain MUCH more of that energy for later use.

 

I’ve flat towed a 2200lbs with my awd 21 limited then had two other buddies and about ~200lbs of gear in the back.
No issues going up an 8% grade and passing big rigs.
Also averaged 20mpg for that trip!

As for the main topic mentioned in op, I think it’s a rather neat feat Toyota was able to pull off getting a Sienna to get 30+ mpg with a hybrid battery its size.

From research I did on a paper on hydrogen cars in college, I found some documentation from Toyota of their approach to building their current hybrid models. Their angle was to maximize the potential a battery can provide and have clear guidelines of what the car should be capable of. The goal was to minimize the amount of battery material each car is needed and to be able to make more cars from a limited battery supply. Then also from an environmental angle as battery material extraction is not the most environmental friendly thing. Less battery material needed, less impact on environment.

 

Thanks for sharing your experience, as I anticipate I will be using the van the way you did. It seems that the current configuration will be sufficient.
Initially, I was going to hold off and wait to see if they put a bigger engine (V-6) or bigger capacity battery in the upcoming year models.

Do you have the AWD version? Do you know if that rear motor will kick in to aid traction at any speed (when driving over ice or snow covered roads, especially on turns)?

 

Thanks for sharing your experience, as I anticipate I will be using the van the way you did. It seems that the current configuration will be sufficient.
Initially, I was going to hold off and wait to see if they put a bigger engine (V-6) or bigger capacity battery in the upcoming year models.

Do you have the AWD version? Do you know if that rear motor will kick in to aid traction at any speed (when driving over ice or snow covered roads, especially on turns)?

I have the awd model. But the power display thing showed all power going to the front wheels during the climb and hard accelerating.

I don’t have any experience on ice yet, but there are some pretty goood yt videos out there.
@3:45

@3:30 has a good view of all wheels slipping while going up an icy driveway

 

Can it be assumed that AWD versions charge the HV battery faster and can drain it faster too compared to the FWD versions ? If so, does anyone know by how much ?

 

Based on HP ratings being the same for FWD/AWD, it would seem like the computer divides the required electric power between the front and rear in an AWD, resulting in the same electric power for both versions. I expect that the same is done for regenerative braking, since charging causes braking force. The required braking force computed is probably split between the front and rear in an AWD.

By the way, I have an AWD. One thing that I notice is when the battery shows 7 out of 8 bars and I am going downhill with the brakes applied, the engine starts spinning up to provide braking power. I have seen the engine as high as 4000 rpm. The use of the engine braking when the battery is not full seems to indicate that when the battery get close to 8 bars, it no longer can take the amount of charge that could be available with regenerative braking.

 

There is speculation that the battery itself is the limiter in charge/discharge current. I have an ODBII data logger and can get the charge/discharge current for my battery if someone with a FWD can do the same we could compare

 

I have OBD2 also using app called Dr Prius (used it to monitor battery health/charging/etc). What app are you using ? Perhaps we should use another thread for that purpose.

 

Out of pure curiosity I would love to be able to get the AWD and FWD versions of the van onto a dyno and see what the actual wheel power is in all these cases

 

What app do you use when capturing amp charge/discharge rates. i use dr prius / dr hybrid but it does not get engine rpm and vehicle speed. EricD I would love to compare my FWD.