What happens when you go to zero bars?

[Aaron]

In all my driving I have never gone below 2 bars until.............I was driving home from work and going up a very slight hill and all the sudden I was at 1 bar and the engine did not sound happy at all. Happily I had a full tank however it made me wonder....
Has anyone gone to zero bars? How did you get there? What was the result?

 

[Boston_Pilot]

In all my driving I have never gone below 2 bars until.............I was driving home from work and going up a very slight hill and all the sudden I was at 1 bar and the engine did not sound happy at all. Happily I had a full tank however it made me wonder....
Has anyone gone to zero bars? How did you get there? What was the result?

Yea, 2 bars remaining is “empty” as the car reserves some battery so that you’re never really empty.

 

[Landshark]

There was a thread awhile back where an owner ran the battery down to zero bars AND ran it out of gas, twice, if I recall on the same trip. No fatalities were reported, so it may just result in a minor inconvenience.

The reason the engine was hard at work, is because it can only produce 60hp worth of electricity. With the battery at 1 or 2 bars there is little to no support from that energy source to provide additional power.

 

[ClarityBill]

Zero bars is an artificial marker, and the battery will actually continue to operate into 'negative' bars. The gas engine goes to high rpm to try and bring the charge up.

I have gone to zero bars several times. Driving up a hill at highway speed with heater running.

1 bar is about 2% SOC on the meter. 0 bars is 0%.

I have continued up the hill at zero bars, and it keeps going... Only once, the hill was long enough that I actually started to lose speed due to no battery power to supplement gas engine. (Speed dropped from 78 mph to 72 mph, but then I got to top of hill, and battery started to charge.)

It does not seem to do serious damage to the battery: I have 97,000 miles on the car, and my battery still displays 48 aH.

 

[Aaron]

Zero bars is an artificial marker, and the battery will actually continue to operate into 'negative' bars. The gas engine goes to high rpm to try and bring the charge up.

I have gone to zero bars several times. Driving up a hill at highway speed with heater running.

1 bar is about 2% SOC on the meter. 0 bars is 0%.

I have continued up the hill at zero bars, and it keeps going... Only once, the hill was long enough that I actually started to lose speed due to no battery power to supplement gas engine. (Speed dropped from 78 mph to 72 mph, but then I got to top of hill, and battery started to charge.)

It does not seem to do serious damage to the battery: I have 97,000 miles on the car, and my battery still displays 48 aH.

Thank you! This is the information I was looking for. Real world experience.
I have 35k miles and roughly 48 AH......

 

[Landshark]

 

[Dislin]

Yeah, for optimal battery longevity purposes, the full battery capacity is limited, both off of the top and off of the bottom. Therefore, once you hit two bars, the Clarity switches to a full hybrid model. At sub-highway speeds, it'll run off the battery and the gas engine will serve as a generator to charge the battery. Once you go fast enough, the gas engine clutches in. There are situation of high demand (going up a hill at high speeds, plus using the heater etc) which can continue to drain the battery over time. The car tries to maintain that 2-bar battery charge level if at all possible, so it swaps to high revs to generate as much electricity for the battery as it can. It's generally recommended in these types of cars to use the HV charge mode before going up high mountain passes to prevent it from happening. I believe it's called "Mountain Mode" in the Volt.

 

[Aaron]

I recently changed my hud to display the vehicle and the battery with the blue lines and the green lines and the gear in the middle. It is interesting to watch when the gear gets engaged and try and determine under what conditions that tends to happen.

 

[Landshark]

It is interesting to watch when the gear gets engaged and try and determine under what conditions that tends to happen.

Over 45mph is one condition. I’ve seen it as high as 85mph. Another is light to moderate load or acceleration. Goose the throttle and it will disengage. I’ve also had it re-engage on a fairly consistent basis by easing off the throttle, until a tick of regen shows, and then easing back on the throttle.

 

[Landshark]

It's generally recommended in these types of cars to use the HV charge mode before going up high mountain passes to prevent it from happening. I believe it's called "Mountain Mode" in the Volt.

My limited understanding of the Volt is that Mountain Mode is essentially the same as HV Mode on the Clarity, which is also referred to as Charge Sustaining Mode. I’m not aware of the Volt having the ability to actually charge the battery in the same manner as the Clarity in HV Charge.

I believe in either car, it would enhance the driving experience if the battery SOC was somewhere north of depleted prior to entering mountainous terrain.

 

[insightman]

I recently changed my hud to display the vehicle and the battery with the blue lines and the green lines and the gear in the middle. It is interesting to watch when the gear gets engaged and try and determine under what conditions that tends to happen.

I wish our Clarity PHEVs had a real HUD like the Clarity Fuel Cell (which also has a better sound system).

 

[Clarity_Newbie]

I recently changed my hud to display the vehicle and the battery with the blue lines and the green lines and the gear in the middle. It is interesting to watch when the gear gets engaged and try and determine under what conditions that tends to happen.

Aaron

Gear mode engagement is directly proportional to a given speed and RPM's.

Data collected off multiple Clarity's demonstrates...for example...at 45 mph gear mode will occur when RPM's are ~1625 +/- 2%. Outside of these parameters gear mode will not likely engage at 45 mph.

Data collected on these same Clarity's at 50, 55, 60, and 65 mph show the same relationship albeit higher RPMs.

Several threads from 2 years ago discuss this issue in detail. The link below is to one of these.

https://insideevsforum.com/community/index.php?threads/the-elusive-gear-icon.4112/

Hope this helps.

 

[Landshark]

Data collected off multiple Clarity's demonstrates...for example...at 45 mph gear mode will occur when RPM's are ~1625 +/- 2%. Outside of these parameters gear mode will not likely engage at 45 mph.

Data collected on these same Clarity's at 50, 55, 60, and 65 mph show the same relationship albeit higher RPMs.

It makes sense that engine speed and vehicle speed would need to be synchronized in order for Engine Drive Mode to engage. I’ve attached a graph that is part of the Honda Powertrain Development document which displays the narrow band of torque within which EDM operates. It doesn’t provide numbers for speed, however, the document, and owner’s manual, state that EDM will engage at speeds above 45mph.

What you’ve described, explains, to my mind, why my method of easing off the throttle after EDM has disengaged, often results in EDM re-engaging. It allows the engine RPM’s to decrease from the variable RPM’s while operating as a generator, and presents an opportunity for all the stars to align for EDM to engage.