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Discussion Starter · #1 ·
I have yet to fully deplete my battery while driving and let the engine take over. Any time I have been low on battery, I will put the Clarity in HV mode to keep the battery from fully discharging. Is this the best move, or should I just let the Clarity decide when to turn on the engine? My thinking has been that letting the battery drain all the way is probably not what's best for it, though I've heard so many conflicting takes on what's best for long-term battery life.
 

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I have yet to fully deplete my battery while driving and let the engine take over. Any time I have been low on battery, I will put the Clarity in HV mode to keep the battery from fully discharging. Is this the best move, or should I just let the Clarity decide when to turn on the engine? My thinking has been that letting the battery drain all the way is probably not what's best for it, though I've heard so many conflicting takes on what's best for long-term battery life.
Just drive it, and let the vehicle systems figure it all out. That's what my wife does. I manage vehicle "fueling" of our Bolt and Clarity, and like to fiddle with driving efficiencies and settings, but that's my inner engineer sneaking out.
 

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I have yet to fully deplete my battery while driving and let the engine take over. Any time I have been low on battery, I will put the Clarity in HV mode to keep the battery from fully discharging. Is this the best move, or should I just let the Clarity decide when to turn on the engine? My thinking has been that letting the battery drain all the way is probably not what's best for it, though I've heard so many conflicting takes on what's best for long-term battery life.
Don’t worry. Honda has it all thought out already. Your battery hasn’t completely discharged all the way when the Clarity automatically switches over to HV more. It will do everything it can to keep the battery from fully discharging without your intervention.
 

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The only time you need to think about this is when you're going into the mountains. The ICE in the Clarity simply isn't big enough to haul the car up serious inclines.
 

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The only time you need to think about this is when you're going into the mountains. The ICE in the Clarity simply isn't big enough to haul the car up serious inclines.
Good point. I try to make sure the battery is to at least 50% SOC, and engage HV before climbing passes, and even when entering rolling hills.. On the occasions when I forget (it happens), I'll put it in HV+, endure the Clarity's screaming ICE, and join the slow-pokes in the right lane, until the SOC is back up.
 

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Discussion Starter · #6 ·
The only time you need to think about this is when you're going into the mountains. The ICE in the Clarity simply isn't big enough to haul the car up serious inclines.
I figured that there would still be some EV power left when the ICE kicked on, or that the ICE would quickly give the battery enough charge to aid in propulsion. Not so? Seems like 105hp is woefully inadequate to power the 4000+lb vehicle by itself.
 

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I figured that there would still be some EV power left when the ICE kicked on, or that the ICE would quickly give the battery enough charge to aid in propulsion. Not so? Seems like 105hp is woefully inadequate to power the 4000+lb vehicle by itself.
I live in Illinois which is relatively flat although there are some good sized hills here and there. I have found that the ICE has enough power for my needs. However, I’ve not driven it in mountainous areas yet. In fact, for driving around my small town I almost never need the extra power from the ICE. So I find it a little bit amusing that the majority of Claritys were sold in CA which is a mountainous state!
 

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So I took a trip from Long Island NYC to Utah in the clarity, we weren’t able to charge the entire trip except in (I kid you not!) Lancaster PA, Amish county… the car runs ROUGH when it’s got 0 EV range, it constantly runs in generator mode to keep it in the hybrid range, I run hybrid mode on the highway but I don’t turn it on immediately, I run EV till it’s at 10 miles (15 if I have another stop) I give myself 5 miles per city I run it in EV for the city and have a free charger nearby, charge it up to max, drive it home and 110 charge the last 2 miles or so back. Notes from the trip… that gas tank needs to be bigger… and the snow, wind does NOT bother this thing. Awesome car.
 

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So I took a trip from Long Island NYC to Utah in the clarity, we weren’t able to charge the entire trip except in (I kid you not!) Lancaster PA, Amish county… the car runs ROUGH when it’s got 0 EV range, it constantly runs in generator mode to keep it in the hybrid range, I run hybrid mode on the highway but I don’t turn it on immediately, I run EV till it’s at 10 miles (15 if I have another stop) I give myself 5 miles per city I run it in EV for the city and have a free charger nearby, charge it up to max, drive it home and 110 charge the last 2 miles or so back. Notes from the trip… that gas tank needs to be bigger… and the snow, wind does NOT bother this thing. Awesome car.
I haven't made any long trips yet, but when I do my strategy will be to start with a full charge and then try to use as little EV as possible. Even when driving in HV mode, on a long trip there will be some EV "leakage" and I want to make sure that there is as much charge available at all times throughout the trip especially when there will be hills. I will probably even drive in HV when driving on surface streets, it's usually not that noisy in that situation as long as there is plenty of battery charge.

I do not plan to charge during the trip as that would take time that I prefer not to spend while on vacation. After all that's why I bought a PHEV so that I don't have to charge when I go on trips! Sure if there happens to be to an available charger in the parking lot of the restaurant or hotel where I am staying then I probably would use it, but only if it's extremely convenient. As an example last weekend while doing some driving in the mountains I stopped at a small town that is popular with tourists. I parked in a paid parking lot with no attendant just a self-serve kiosk. As I was walking out of the parking lot I noticed a free charger, was surprised no one was using it. Walked all the way back across the parking lot to my car, then moved my car to the charging spot. Got out and plugged in, nothing. Now I know why no one was using it. Drove my car back to my original spot, fortunately no one had taken my spot as the lot was fairly full. Then had to walk all the way across the parking lot again. Suppose I could have just left the car in the charging spot but I didn't think of it at the time, and I'm not sure I would have done that anyway. As I walked past the charger for the second time I thought about how much time that I had just wasted trying to get a free charge, it was near sunset and I had wasted some of the "golden hour" . Reconfirmed my conviction that I don't plan to mess with anything charging related when travelling.

If my battery charge goes down too much through EV leakage or (more likely) by me forgetting to turn HV back on when leaving a stop, I will probably use HV Charge which at least will bring it up to about a half a charge. Using HV Charge when cruising on a level highway usually doesn't make that much additional noise.

But yes I can understand being in your situation, a really long trip and if your charge gets low on a trip like yours with lot of mountains, HV Charge doesn't always cut it so I can understand trying to find a place to fill the battery hopefully without too much inconvenience.
 

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Dropping to zero EV while driving at freeway speeds or in hilly areas will result in the engine starting up and depending on weather temperatures the ICE will rev up to 3000-4000rpms as it struggles to supply amps to power the car and charge the battery back to 0%.

On long trips I’ll use HV mode once my battery reaches around 50%. This seams to be the best battery capacity for the car to charge and deplete as the car does its switching from ice, ice direct drive, ice charging and battery assist.

Since I know when I want to select HV. About 5 miles before this I would press the pedal to the floor, briefly, just to trick the IcE to turn on. It will run at 1500rpms as it warms up to 160-180deg. Otherwise HV mode has a delay on a cold engine until it warms up to around 120. Then the ice can rev way up and be under high loads while it still not fully warmed up.

does it matter. Yes and no. The ice will last well beyond my years of use regardless of how you drive.
 

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Dropping to zero EV while driving at freeway speeds or in hilly areas will result in the engine starting up and depending on weather temperatures the ICE will rev up to 3000-4000rpms as it struggles to supply amps to power the car and charge the battery back to 0%.

On long trips I’ll use HV mode once my battery reaches around 50%. This seams to be the best battery capacity for the car to charge and deplete as the car does its switching from ice, ice direct drive, ice charging and battery assist.

Since I know when I want to select HV. About 5 miles before this I would press the pedal to the floor, briefly, just to trick the IcE to turn on. It will run at 1500rpms as it warms up to 160-180deg. Otherwise HV mode has a delay on a cold engine until it warms up to around 120. Then the ice can rev way up and be under high loads while it still not fully warmed up.

does it matter. Yes and no. The ice will last well beyond my years of use regardless of how you drive.
That's interesting about the temperature. When there is a brief startup, like your example of pressing the pedal to the floor momentarily, the engine always goes through a warmup cycle as you indicated, even though the gas engine is no longer needed, or let's say no longer being called upon by the driver as it is still in EV mode. The reason for the full warmup from what I understand is that it's really about warming up the catalytic converter, because apparently it's not good for a cold catalytic converter to have unburnt fuel left in it because it can shorten its life.

So based on your observations, my guess is that 160-180 degrees is the required temperature for cat warmup. So after a brief gas engine demand by the driver which has now concluded (i.e. the driver essentially tells the system I want to go back to EV mode), it stops using ICE other than just idling the engine until it gets to that temperature then shuts off.

However HV mode is different, in this case you are telling the system that you want to keep your battery capacity as close to the set point as possible (what the SOC level was when you activated HV). So it fires up ICE, but idles it initially until it reaches an "engine healthy" temperature to start putting a load on it, which based on your observations would be around 120 degrees. It then starts using ICE for power, but by then the SOC has dropped quite a bit from the set point so it starts working harder to get the SOC back up, while also propelling the car, so it can get noisy.

Seems like another approach to avoid the noise would be to simply turn off HV when you start hearing the engine get louder (or see the RPM increase if you are monitoring it), and then after a few seconds turn HV back on again which resets the set point to a lower level. This technique actually can be used any time the engine seems to be getting a little noisy due to having fallen too far below the set point, which can happen especially when driving in hills.

Other than noise though there would be no real reason to do any of this, as I don't think you could kill these engines if you tried, other than by neglecting oil maintenance.
 

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My wife and I have done one road trip in her Clarity. What I learned is to keep the battery at half full using the HV Charge mode. Unfortunately you can't select this mode until the battery is already depleted to this point.
 

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Discussion Starter · #13 ·
My wife and I have done one road trip in her Clarity. What I learned is to keep the battery at half full using the HV Charge mode. Unfortunately you can't select this mode until the battery is already depleted to this point.
Standard HV Mode should maintain SOC, so if you're at half EV bars putting the Clarity in HV should keep you at half. HV Charge would just be used to gain EV range (up to 57.7% according to Honda) for when you're in town/city after getting off the highway.
 

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Standard HV Mode should maintain SOC, so if you're at half EV bars putting the Clarity in HV should keep you at half. HV Charge would just be used to gain EV range (up to 57.7% according to Honda) for when you're in town/city after getting off the highway.
Similar to what Chevy said about the Volt. The problem is that driving across Kansas always involves a 30 to 40 MPH headwind, which combined with the 75 MPH speed limit puts the car above it's top speed relative to the air mass it has to push out of the way. This translates into both the battery and ICE having to provide so much power that there is no available ICE power to recharge the battery.
 

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Standard HV Mode should maintain SOC, so if you're at half EV bars putting the Clarity in HV should keep you at half. HV Charge would just be used to gain EV range (up to 57.7% according to Honda) for when you're in town/city after getting off the highway.
Since I replied previously, I realized that I've tried to use HV mode to burn old gas out of my wife's Clarity. The car uses battery even in HV mode.
 
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