[obermd]

Mountain mode in the Volt predates Hold Mode by two model years. It allows you to tell the car to shift to hybrid before the battery is depleted. The Volt's hold mode tells the car to switch to hybrid immediately. Honda missed the mark with their HV Charge mode by not allowing the driver to set it early and running electric down to that point before it switches to hybrid mode.

 

[obermd]

No question the Volt set the gold standard for how a PHEV should operate. Although I think even the Volt would have benefited from having an option for Blended Mode.

As soon as you put the Volt in Hold Mode you're in what Honda calls Blended or HV mode. The Volt's Hold Mode and Clarity's HV Mode sets a target State of Charge (SOC) and attempts to keep the battery at that level, just like putting the Clarity in HV Mode. If you exceed the target SOC by descending a mountain both the Volt and Clarity will turn the injectors off to the ICE and let the engine continue turning via wheel spin until the battery is depleted back to the target SOC. In the Volt there are a couple of displays via a power meter on the driver information center (dashboard display behind the steering wheel) and a power source graphic in the infotainment area (main radio display). The Clarity can shows the power source graphic in the driver information center and on the infotainment display.

You can tell when the Volt is in hybrid or EV mode by looking at the fuel gauges. The grayed out fuel gauge is the one not being used.

 

[obermd]

Ah but wait... a Blended mode would mix well with a Recharge mode for going up and down mountains. Except that the Recharge mode would need to be a bit less brain-dead and actually recharge when going downhill.

So I really don't get it.

The Clarity will remain in HV recharge until the HV target state of charge is reached. After this the ICE injectors are turned off and the car uses regenerative braking to continue feeding power into the battery. I tested this driving down the south side of Grand Mesa in Colorado. The only real flaw I see in how Honda implemented HV Charge is the fact that you can't tell the car to use it when you start if there is too much battery left.

 

[obermd]

Is that documented somewhere? That is absolutely insane. Why would it throw away perfectly good electricity just because you happen to be above the SOC level that it was at when you pressed the HV button? Literally throwing away electricity that could be used later. I understand when the battery is full it cannot regen because there is no place to store the excess electricity, so it is forced to convert the kinetic energy to waste heat either through spinning the cold engine or by using the friction brakes. That makes perfect sense. Or on a long downhill there might be a limitation on regen to avoid excessive heat from what would essentially be a very fast charge. But what possible reason could there be for someone to not want to increase their SOC if the battery is not full, just because they are in HV mode? Pressing the HV mode button means you want to sustain the charge at the current level, i.e. keep it from dropping. Never in a million years could I have imagined that anyone would not want it to increase SOC above that level if there is room in the battery and the electricity is literally free. Or even worse throwing it away as you are saying it does if it is over the target SOC.

Both cars will continue to use regenerative braking to fill the battery until it hits 100% usable SOC. HV/Hold are identical in that they instruct the car to attempt to maintain the current SOC using the gas (ICE) generator/engine. Regenerative braking isn't constrained by this and will fully charge the battery if possible. The car will remain in EV mode until it reaches the HV/Hold SOC point again. As long as the SOC is above the HV/Hold set point the car will operate as an EV. The ICE is still turning via wheel spin; ICE water and oil pumps are pumping to maintain engine temperature and lubrication; and the fuel injectors are turned off. At any time the car is below the HV/Hold SOC the car will use both regenerative braking and ICE to recharge the battery.

Mountain/HV Charge instructs the car to use all available resources (ICE and potential/kinetic energy) to recharge the battery to a pre-programmed SOC.

Okay there is a separate topic that some people advocate to not charge to 100% to prolong battery life, and stop at say 80%, which makes sense if you are wall charging or otherwise paying for the electricity because if you stop at 80% you also stop being charged for it. But if you have free charging at work or wherever I question whether it makes sense to not just go ahead and charge to full. To each his own on that one I guess. But in this case we're not talking about 80%, if what you are saying is true then let's say you press the HV button at 40% SOC, then you are saying it will not regen past 40% as long as you remain in HV mode and it will just throw away the energy as waste heat?

The Clarity and Volt batteries are both larger than the usable KWh. The car shuts off charging when it reaches the 100% usable SOC point. Likewise it won't regenerate above this point. Both cars also keep a small buffer at the bottom to protect the battery from being completely drained. Bottom line is that the worst thing you can do to a LiOn battery is fully charge it. The second worst is to fully discharge it. Tesla recommends no more than 90% charge and actually has a user setting to control this. The Bolt has a buffer at the top but has a Mountain Top setting to increase the size of the buffer with respect to EVSE (wall or station) charging to allow a driver who starts their daily drive with a long descent to avoid wasting "free" energy.

 

[obermd]

Not real clear, was I. The engine is kept spinning to enable significantly faster restart. It's a trick auto makers developed called Deceleration Fuel Cut Off and it keeps the ICE engine turning without burning any fuel. In this mode you can start/stop an ICE engine in roughly every half second. The amount of friction in a modern automotive gas engine is very, very tiny. There's actually an order of magnitude friction from the flex in the tires as they roll. You want to keep the engine warm - it doesn't have to be hot, but anywhere above about 50F will do and the oil and coolant circulating to avoid jarring the engine when the car needs to switch back to gas. If you don't do this you're looking at up to a full minute to restart the ICE engine to avoid excessive stress and wear on the engine.

 

[obermd]

In a separate but similar topic, I have often wondered about true cold engine starts in the Clarity, meaning switching to HV when the engine has not run since yesterday (or longer) and is truly cold and dry. From my observation when I press the HV button in that situation while on the freeway for example, the engine starts but it basically just idles for the first minute or so, which agrees with what you are saying at least in a true cold start situation.

In the Volt you can actually see how much power is being generated by the ICE and the Electric motors. For the first 65 seconds at highway speed the ICE contributes less than 5KW to the powertrain. Definitely nerve racking the first time I saw this at 75 MPH going up a slight hill out of Denver on I-76.

It's quite different however if you do pedal to the floor acceleration on a cold engine. I did that as a test and to my surprise the engine roared to life. I have no way to know how much power it was contributing, but based on the noise probably something. It's probably not all that great for the engine to have to provide instantaneous power after being woken up for the first time that day (or week or month) but then again for most people it's very rare that you put the pedal to the floor, so probably the engineers decided that if you do then you probably have a real need for it (avoiding an oncoming train as just one example), so wearing the engine down a little is an accepted tradeoff, if it only occurs infrequently it will have little effect on overall engine life. But I don't recommend someone who is a leadfoot to do this every morning, just like you shouldn't do that with any gasoline engine. Then again people with a lead foot aren't always prone to thinking beyond the moment.

I've done the pedal to the metal with a cold ICE in my wife's Clarity and yes, the ICE revs really high, but it provided zero to the car's acceleration. Once the ICE is warm it provides acceleration during these high revs. As for how rare, consider what you have to do when getting on a short uphill freeway on ramp where traffic is moving at 55-70 MPH. You really need to be moving with the flow of traffic when you reach the start of the merge area to give yourself room to adjust. This is a weakness in the Clarity that it requires both the electric and gas motors to get full power.

 

[obermd]

Figurately, but it definitely not what the Clarity's ICE provides when warmed up already.

I've driven all over the country and have found that really old on-ramps and newer on-ramps are decent. It's the on-ramps that were built during the double nickel (55 National MPH) era (1972 - late 90s) that are way too short for today's highway speeds and also on-ramps in dense urban areas. There are a lot of these on-ramps.

Passing on two lane roads, especially in mountains, is also best done pedal to the floor. You want to accelerate hard and complete the pass and then get back in your lane. This has the additional side effect of discouraging the driver you're passing from accelerating with you because they aren't paying attention to their speed.

 

[obermd]

I agree there are different opinions on passing, but here're my thoughts:

- I was taught in drivers' ed to accelerate and get back into my lane as quickly as possible. This doesn't always require full throttle acceleration but on occasion it does, especially on twisty mountain roads where passing zones are infrequent and relatively short. Don't start the pass if there's any risk of completing it.

- Put your car on cruise control (used to ensure a steady speed) at 1 or 2 MPH faster than another car on the interstate. About two thirds of the drivers you pass will accelerate to match your speed because they have no clue how fast they're going and unconsciously accelerate because they see you in their peripheral vision. Once you pass them they slow back down. I've noticed that about a quarter of the drivers will accelerate as much as 5 MPH, and a few even more, when you do this unless you accelerate during the pass. Invariably these drivers actually slow down to below the speed they were doing before you passed them - another sure sign they had no clue as to how fast they're actually going. More proof that most drivers have no clue to their speed - I was on cruise control at 75 MPH (posted speed limit) near Burlington, Colorado about 15 years ago. There was a long line of traffic (turns out it was close to a quarter mile of cars) doing just under the speed limit in the right lane and no one in the left lane. No indications of construction on a bright sunny day with dry roads and no wind. I pulled into the left lane and remained at 75 MPH. As I reached the head of the line there was a Colorado State Patrol cruiser running just under the posted speed limit. Not a single one of those drivers behind him knew how fast they were going and/or what the road's posted speed limit was.

- I drive in an environment where the average passing zone is about a half mile. When you commit to a pass you really need to commit to completing it quickly, leading to harder accelerations at the start of the pass. In addition I generally don't start the pass from right behind the other vehicle either, preferring to stay back a ways for better visibility of the road ahead of them. This also leads to harder accelerations during the pass to ensure it's safely completed. I've found Sport mode in the Clarity to be the only operating mode that really allows for this. When I drive on open, flat roads, I don't need to accelerate or if I do, it's not a full out acceleration.

 

[obermd]

As an experiment, next time you are at a stoplight and there is someone next to you, when the light turns green don't go just sit there. It's surprising how many people won't go until the car next to them goes. Of course you should only do this when no one is behind you. Probably in some cases they weren't looking at the light, but it happens too often for that to be the only explanation.

One time I was on the freeway and traffic was heavy but moving at good speed, but then I came up on a mass of cars in all lanes that were going under the speed limit. Hard to see from that far back but there was what looked like a police car in the front row with lights on the roof, lane number three out of five lanes. Occasionally a car in the fast lane would slowly move up to the front, but once they were there they would shoot off at least 10 mph over the speed limit which I thought was strange. So I got in the fast lane and waited my turn to get up to the front, sure enough it was just a security car, the driver oblivious to the traffic jam he was creating.

I've done both of these - this is so common it's proof that most people shouldn't be driving simply because they're not paying attention.

 

[obermd]

Hi! I recently passed my driver's license and I want to share my experience in visiting a driving school. Many people say that this is a waste of time and they will not teach you anything there, but who will force you to teach? If you do not want to learn a theory that will be useful to you in the future, then no one will force and cause your mother to go into shock. For example, I really liked my auto school, as I approached its choice with great responsibility. After reviewing a lot of information on the Internet, I found https://www.anewdriver.ie/ and I did not regret that I got to them. My wonderful instructor James helped me learn how to drive a car from 0 and I am very grateful to him for his patience and excellent pedagogical individual approach to each person.

Off topic, but a good driving school is a very good investment. Good beginner schools will include things like low speed skid pad training.