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Discussion Starter · #1 ·
I just installed a Level 2 charger at home (JuiceBox) and it has been great...2 hours to a full charge (approx. 44 miles). A new issue has arisen after a full charge that I just don't understand. Within the first 1/4 mile of driving, the EV mode shuts off! I have been watching it over the past few days and have attributed it to pushing on the brake when the battery is fully charged...it apparently doesn't like additional charge from the regeneration and disables the EV mode. The only way to reset it is to turn the car off and then back on. I have tried driving a different way out of my house to avoid using the brakes in the first 1/2 mile or so and it stayed in EV mode. Anyone know why it does this and how to avoid it going forward?
 

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I just installed a Level 2 charger at home (JuiceBox) and it has been great...2 hours to a full charge (approx. 44 miles). A new issue has arisen after a full charge that I just don't understand. Within the first 1/4 mile of driving, the EV mode shuts off! I have been watching it over the past few days and have attributed it to pushing on the brake when the battery is fully charged...it apparently doesn't like additional charge from the regeneration and disables the EV mode. The only way to reset it is to turn the car off and then back on. I have tried driving a different way out of my house to avoid using the brakes in the first 1/2 mile or so and it stayed in EV mode. Anyone know why it does this and how to avoid it going forward?
This is a known "feature" with the Clarity although no one knows for sure why it does it. Although obviously if the battery is full there is no place for it to put the electricity produced by regen. But it seems like it could simply use just the friction brakes in that case and not do regen if the battery is full. But for some reason it does regen even with a full battery and it uses the excess electricity to spin ICE, and for some reason if ICE is spinning they feel it is necessary to start it up. Some people speculate it's to circulate the oil, but I would think the oil would circulate just from the motion of the engine. But whatever the reason, if ICE starts up then it will want to go through its full warmup cycle, and as mentioned recently on another thread it's probably best to just simply let it run its course rather than turning the car off and back on.

Also this doesn't seem to happen to everyone. I have a fairly steep although short downhill about a hundred yards from my house, with a stop sign at the bottom. But it never seems to trigger ICE when I leave home with a full charge. Now I tend to go down the hill fairly slowly, about 15 mph, and I notice from the needle that regen is really not active at that speed it is using the friction brakes. But I have tried going down the hill faster a couple of times but I did not trigger ICE.

In your case the only solution is to not charge to 100%, however since there isn't a way to specify a maximum charge SOC in the settings, you would have to use scheduled charging and estimate when to stop charging to keep it below 100%. Some people do that anyway as there is a commonly held belief that there might be some benefit to battery life by not charging to full (albeit possibly little or no benefit), and with a little practice it's entirely possible to charge to say 90% when you don't need a full charge. But when you do need 100% then I guess you have to live with the possibility of the engine running for a few minutes, although it will only be idling during that time so very little gas will be used.
 

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I've not experienced anything like this in my '21 PHEV Touring, and I drive it while full all the time. I'm quite familiar with the issue, though, as GM added "Hilltop Reserve" to charge to only 90-ish% on early Bolts, so those that live at the top of a hill would still get regen like normal when leaving the house. It can be quite disconcerting to not have regen when you're expecting it. Regen on the Bolt can be very aggressive when in "L" mode and doing one-pedal driving.

I've heard some call driving in Sport on the Clarity as "One-pedal driving". That's laughable, after experiencing "L" mode on a Bolt while using the paddle. In a Bolt, you can drive for miles in the 'burbs without once touching the brake pedal. I still do, though, once stopped, to illuminate the brake lights.

Edit: I changed my post to reflect what 2002 was writing at the same time I was.
 

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Discussion Starter · #4 ·
This is a known "feature" with the Clarity although no one knows for sure why it does it. Although obviously if the battery is full there is no place for it to put the electricity produced by regen. But it seems like it could simply use just the friction brakes in that case and not do regen if the battery is full. But for some reason it does regen even with a full battery and it uses the excess electricity to spin ICE, and for some reason if ICE is spinning they feel it is necessary to start it up. Some people speculate it's to circulate the oil, but I would think the oil would circulate just from the motion of the engine. But whatever the reason, if ICE starts up then it will want to go through its full warmup cycle, and as mentioned recently on another thread it's probably best to just simply let it run its course rather than turning the car off and back on.

Also this doesn't seem to happen to everyone. I have a fairly steep although short downhill about a hundred yards from my house, with a stop sign at the bottom. But it never seems to trigger ICE when I leave home with a full charge. Now I tend to go down the hill fairly slowly, about 15 mph, and I notice from the needle that regen is really not active at that speed it is using the friction brakes. But I have tried going down the hill faster a couple of times but I did not trigger ICE.

In your case the only solution is to not charge to 100%, however since there isn't a way to specify a maximum charge SOC in the settings, you would have to use scheduled charging and estimate when to stop charging to keep it below 100%. Some people do that anyway as there is a commonly held belief that there might be some benefit to battery life by not charging to full (albeit possibly little or no benefit), and with a little practice it's entirely possible to charge to say 90% when you don't need a full charge. But when you do need 100% then I guess you have to live with the possibility of the engine running for a few minutes, although it will only be idling during that time so very little gas will be used.
Thank you...so much more information than I would have gotten from a Honda Rep. Very informative. Unfortunate...what's the point of a full charge before my 30 minute commute to work if I have to run the car in HV mode. I can go door to door on a full charge with only about a half mile on HV. One of the main reason I got the Clarity. Thank you for the detailed response!!
 

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Thank you...so much more information than I would have gotten from a Honda Rep. Very informative. Unfortunate...what's the point of a full charge before my 30 minute commute to work if I have to run the car in HV mode. I can go door to door on a full charge with only about a half mile on HV. One of the main reason I got the Clarity. Thank you for the detailed response!!
But you won't be in HV mode during your commute to work, you will be in EV the entire way, using only electricity for propulsion. The engine will only be idling during its few minutes of warmup, it won't be providing any appreciable power to the wheels, then it will shut off.

During winter some people are able to avoid the regen engine startup by cranking up the heater when they leave the house. This seems to give the regen electricity a place to make itself useful rather than annoying the driver by starting up ICE for a few minutes.

Actually if I understand correctly even if regen didn't turn on ICE when you leave the house, you said you have to do a small amount of HV anyway. So maybe when the engine turns on switch to HV and do your HV half-mile then since the engine is already warmed up
 

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I think most dealerships understand that with the more sophisticated vehicles, the potential customer has done a lot more research than they have. It has been on more than one occasion that I have known far more about a product (mostly Priuses) than the dealer's sales team has. I suspect most on this forum have had this experience.
 

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It happens.

My C-Max’s air-cooled HV battery does the same thing: warm weather, fast L2 charging, drive immediately (or soon) after unplugging, use regen + brake pedal=ICE start. Activating HV mode to help lessen the stress on the battery is a good thing in the long run. I had to (re)learn to use D instead of L gear (max regen) in these circumstances and that was enough to avoid ICE starts.

It’s not the best suggestion but you can always shift to N and use the brake pedal for 100% friction braking/no regen for that first mile or so. Secondly, in cooler weather, cranking the heat at startup should burn off enough watts before regen.
 

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I think most dealerships understand that with the more sophisticated vehicles, the potential customer has done a lot more research than they have. It has been on more than one occasion that I have known far more about a product (mostly Priuses) than the dealer's sales team has. I suspect most on this forum have had this experience.
OMG YES! I've schooled a half-dozen sales people (and their managers) on EVs since I started this journey in 1997.
 

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Thank you...so much more information than I would have gotten from a Honda Rep. Very informative. Unfortunate...what's the point of a full charge before my 30 minute commute to work if I have to run the car in HV mode. I can go door to door on a full charge with only about a half mile on HV. One of the main reason I got the Clarity. Thank you for the detailed response!!
robdrumms

In my experience, when the clarity ICE comes on with full battery...it will run 5 to 7 minutes then revert back to EV mode. This happens to me every time after a full charge since I live on a mountain and have a downhill run every day when leaving the house. It's almost like clockwork at this point.
 

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I thought this was the System Test feature, where it fires up the ICE on purpose to move the oil around and make sure the mechanical parts of the ICE are still working. But I have noticed this happening sometimes two drives in a row, and sometimes not for 8+ weeks. I guess it depends on how aggressively I brake after leaving the house with 100% battery.
 

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I thought this was the System Test feature, where it fires up the ICE on purpose to move the oil around and make sure the mechanical parts of the ICE are still working. But I have noticed this happening sometimes two drives in a row, and sometimes not for 8+ weeks. I guess it depends on how aggressively I brake after leaving the house with 100% battery.
@nhdabzr

The Clarity will occasionally run the engine for maintenance if EV is used exclusively as noted by others. You refer to this as system test.

The ICE will activate while in EV mode when battery close to full and brakes are applied or going downhill and Regen tries to kick in. Quick acceleration past a certain point with the throttle will also activate ICE.

When battery is close to full, Regen via the paddle on the steering wheel is also limited or not available.
 

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This is a known "feature" with the Clarity although no one knows for sure why it does it. Although obviously if the battery is full there is no place for it to put the electricity produced by regen. But it seems like it could simply use just the friction brakes in that case and not do regen if the battery is full. But for some reason it does regen even with a full battery and it uses the excess electricity to spin ICE, and for some reason if ICE is spinning they feel it is necessary to start it up. Some people speculate it's to circulate the oil, but I would think the oil would circulate just from the motion of the engine. But whatever the reason, if ICE starts up then it will want to go through its full warmup cycle, and as mentioned recently on another thread it's probably best to just simply let it run its course rather than turning the car off and back on.

Also this doesn't seem to happen to everyone. I have a fairly steep although short downhill about a hundred yards from my house, with a stop sign at the bottom. But it never seems to trigger ICE when I leave home with a full charge. Now I tend to go down the hill fairly slowly, about 15 mph, and I notice from the needle that regen is really not active at that speed it is using the friction brakes. But I have tried going down the hill faster a couple of times but I did not trigger ICE.

In your case the only solution is to not charge to 100%, however since there isn't a way to specify a maximum charge SOC in the settings, you would have to use scheduled charging and estimate when to stop charging to keep it below 100%. Some people do that anyway as there is a commonly held belief that there might be some benefit to battery life by not charging to full (albeit possibly little or no benefit), and with a little practice it's entirely possible to charge to say 90% when you don't need a full charge. But when you do need 100% then I guess you have to live with the possibility of the engine running for a few minutes, although it will only be idling during that time so very little gas will be used.
I also live at the top of a hill. If I turn on the heated seats and defroster (set to above ambient temps) it will take away half a mile or so from the range so that by the time I reach the bottom of the hill the regen gets it back to nearly full. I then turn off the seats and return to auto AC set to a more comfortable setting for the conditions that day. By do this I can avoid the ICE revving up to dissipate the excess charge.
 

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And wouldn't you know it a few days after I made my post it happened to me. I was running a little late and I went down the hill faster than I normally do but still within the speed limit. And I probably braked for the stop sign later than I normally do. About a minute later as I was leaving my subdivision I noticed my engine was on. I'm pretty sure it turned on at the stop sign but for some reason I didn't notice it right away. I was going to do some HV on that trip anyway so when I realized that the engine was on I went ahead and switched to HV so that after the warmup ended it would remain in HV.
 

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that's strange, I always full charge. I live on a hill so when I leave my neighborhood I regen + brake beyond what the car can take but it just stops regenerating and miles never changes up or down. no engine start either.
 
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