Angry Bees Test, Result, Theories

Very interesting, @Bbeardb - thanks for the test and the details.

Not that I don't appreciate all the effort and description, but it is too bad you didn't have a way to log the data during the test as it would have been really interesting to parse through the whole test and see the SoC of the battery, the current values, the engine RPMs, etc.

If anyone plans to repeat this kind of test with any cheap bluetooth OBD-II scanner, the 'Car Scanner' app (Android) seems to have a lot more data available for the Clarity than Torque Pro.

Thanks again for the detailed story...

 

There's an easier way to get the bees, without exhausting the battery by killing the reserve bars. Put it in HV, drive somewhere, and sit there stopped with the A/C on max. Once the EV range has dropped by a few miles (this works faster when it's 100°F+ in Texas), drive back home. For the first several minutes, you'll have the bees as it attempts to get the EV range back to where it was before you stopped by running a max RPM.

 

Yes, I concur with this... I stumbled on this 'technique' a couple of months ago. You don't even need to have a low SOC for this to happen. I agree with @Ray B , it would be nice to capture this scenario with an OBD-II log.

 

Interesting observations. BTW you can drive 2000' elevation 9 mile grade using about 40% of the battery in EV mode. But it is good to know that with zero bars and 11000 ft elevation the 1.5 engine can still manage it, although barely. I think Honda should have used the 2.0 engine from Accord hybrid for this car. But an easy software fix to improve car performance in this situation is to add a mountain mode, where the car uses the engine at for example 4500 rpm, and supplements it with battery power. This way you should be able to climb over any mountain with good performance.

 

Do you not know what "HV mode" means with a Clarity? The engine will run to keep EV mileage as close to when you turned HV on as it can. A "mountain mode" is meaningless.

 

That is exactly a mountain mode is useful. When I go over a mountain range with a full battery, I don't want to maintain EV mileage. I want to use the battery to have better performance and reduce engine RPMs, but don't want to climb in EV mode because the battery will be depleted before I cross over the top. A mountain mode will use for example 2/3 from the engine and 1/3 from the battery, so you can drive about 100 miles and go over even the largest mountain range. Then you can use HV charge on the downhill to restore battery charge.

 

That's not "an easy software fix". You're asking for magic. The car cannot know the length of the incline without a locally stored complete topographical map, cannot calculate how much power is required to get to the top, and there is no way it can optimize for X% battery usage on X mountain. It also doesn't know if you're going to stop at an overlook along the way.

 

The Chevy Volt has a "Mountain Mode". I don't think @Agzand was asking for something that was anticipatory, just something that uses the ICE some. Not enough to 'hold' the charge like HV, but enough to augment EV, allowing it to deplete but at a slower rate.

The "Mountain Mode" in the Volt is different than this... It is more like an HV mode with a preset goal of 45% SOC. Here is the description from the Volt Wiki:

"The mountain mode, which is expected to be required only under unusual power demand conditions, increases minimum battery state of charge (SOC) to around 45%, thus maintaining performance on steep and long grades. The driver hears more engine noise due to the higher rate of power generation required to maintain this mode."

 

Actually, it is an easy software fix to have an HV type mode that does not try to maintain the battery SOC. It just needs to be a manually selected mode, not a computer controlled mode (but with a safety option that cuts it out when the battery SOC gets too low). One might think of this as the reverse of the HV Charge mode. I have wished many times to have a battery boosted hybrid option on my ICE only vehicle for times when I would rather not have the automatic transmission down shift to climb an interstate grade at speed. BTW, such an hybrid mode is available on hybrid race cars (F1) and will be even more so in the future (IndyCar).

Leop

 

Let's call it an "HV Deplete" mode !!

 

Exactly as described above, it is HV deplete mode. It doesn't have to be smart. They can just calibrate it for something like 150 mile range on flat terrain (e.g. 2/3 from engine, 1/3 from battery). I doubt there is any mountain range that needs more than that, even if you stop at a few lookouts.

 

The Clarity has a 103 HP 1.5 liter engine, but the generator that it drives can only produce 60 HP equivalent electricity. The engine can also directly couple to the drive train at certain speeds. This means that once the battery is completely depleted, there can be as little as 60 HP trying to power a 2 ton car + payload up the mountain incline. The obvious solution on trips through the mountains is to put the car into HV mode so that there is plenty of battery reserve. The car will then have an additional 121 HP from the battery at the ready when needed. Once on level ground or going back down, the Clarity will automatically put back into the battery approximately the amount "borrowed" to get up the mountain.

 

I think all of this discussion demonstrates that the transition into the EV 'era' will require some driver education.

Drivers will need to be more knowledgeable about their specific vehicle and take into consideration the vehicle attributes in combination with the expected terrain, temperature, etc. for their trip. This will be true with any vehicle that has electric content (PHEV, or BEV). The days of just hopping in your car and going without thinking twice will be gone.

I think Honda did an excellent job of making the Clarity drive and feel just like a conventional vehicle. Anyone can drive it and it does not feel odd in any way (until you push it into an extreme state where it looses its ability to act like an ordinary vehicle).

 

DaleL,

Can you please provide the reference that specifies that the main generator on the Honda Clarity PHEV is only capable of a 45 KW (60 HP) output? Also, do you have a reference to the output specification for the traction motor/generator? Thanks,

LeoP

 

I have driven the Clarity with a zero bar battery, it doesn't drive like a 60 hp car. I think the generator output is similar to the engine (around 100 hp).

 

Absolutely agreed. This is one of Honda's best features, the "normalness" that the EV powertrain feels "normal'.

 

I got this bright idea to write an email to one of the powertrain engineers of the Clarity and request the mountain or HV Deplete mode. Unfortunately I didn't get any answer.

 

Well, I'm just surprised that you were able to identify an email that seemed appropriate !
I'm not holding my breath for ANY updates. Honda seems to keep everything constant (except for a very few service bulletins early on).
Never any performance or convenience updates.

 

It's already in there -- the Clarity's "HV Charge" mode does the same thing as the Volt's "Mountain Mode" to the best of my knowledge, just at 58% SOC.

This is an awesome report, OP, great detail and info. I'd argue that *any* car's performance while climbing very long steep grades at 11,000 ft elevation is an edge case. The engine loses ~1/3 of it's HP, and at ~70 HP is definitely going to have trouble keeping a continuous climb. That would explain why in the OP it kept using the battery buffer that would otherwise only be needed for short acceleration bursts, until it hit another harder limit and stopped using the battery's power, then had to limp along with only the engine's low HP providing power. There are many underpowered cars that would struggle to maintain 40 MPH in the same place, and they do so the entire climb.

As another data point, I did a climbing experiment starting at 0 EV (2 bars) going from sea level to 4000 feet over ~35 miles with some pretty steep sections, in EV mode (but of course actually operating like HV). I deliberately pushed it hard, accelerating up the steepest parts etc. No loss of power, and the SOC never went below 2 bars. Engine audible at ~5500 RPM of course during the climb, but I choose to call them busy bees rather than angry . Similar on a 7000+ foot elevation trip, but we started with more SOC then. I'm looking forward to taking a drive through Monitor Pass (8300 ft) when the air clears up, will do some experiments then too.

So I'd agree that for very steep very high elevation climbs it's worth planning ahead and keeping or getting a good HV SOC (including use of "HV Charge"). However, in most other daily driving situations, I don't worry about "rules" that sometimes get put out here (never letting EV go to 0, always HV for highway, etc). Just drive the car and take advantage of all the EV miles it'll give you.