ICE auto on???

[Ohliuw]

I know that it’s normal for the ICE to turn on by itself if not used for a while.

However, lately it started happening every couple of days. I noticed it’s been turning on shortly after I leave home on the highway While my battery is FULL and there is no way to turn it of. After about 10kms, it would switch back to EV.

not sure if this is normal or maybe due to the cold?

 

[cokeb5]

If the battery is already full and the car is attempting to charge it more (e.g. from going down a hill, braking, etc.) then ICE will turn on. You should be able to test this and see if that's what's causing it to turn on in these cases.

 

[PHEV Newbie]

When the battery is close to full, even moderate braking can turn the ICE on (too much regen for a full battery will harm it). This can be infuriating because, like the OP said, the running ICE will run for a few minutes, which will charge to battery back to full, shut off after a few minutes and then it can turn on again if I go downhill or have to brake hard! I charge to full only once a month or so for cell balancing. Otherwise, I charge to no more than 80% (sometimes just to 60%, if I know I'll charge again after a short errand). There's a dramatic effect on battery longevity if you can keep the SOC hovering as close to 50% as possible. And the bonus is that the ICE doesn't turn on in normal driving, unlike when it is full.

 

[KentuckyKen]

Some have posted that they’ve been able to avoid this by turning on the heater, defrosters, or maybe even just seat heat immediately after starting. Seems like it doesn’t take much of a load drawing down the full charge to prevent this. Mine did this when new and I’ve not even got much of a downhill from my house. The good news is that after a year or so, it quit doing this.

My Charge Point EVSE doesn’t allow charging to a specific % SOC and I’m too lazy to try and time it, so I always charge to 100%. This does not cause my ICE to come on in EV except for the very occasional and short System Checks. So I don’t think a full battery causes ICE operation.

 

[weave]

My Charge Point EVSE doesn’t allow charging to a specific % SOC and I’m too lazy to try and time it

I just set a timer on my watch for 30 or 60 minutes and when it goes off I just open the app and stop the charge. I generally try to avoid going to 100% unless planning on a long trip. Maybe a bit silly consider it's supposed to manage that all for you, but it's not THAT much effort. (Most of my miles are within a small town so I only do about 5-10 miles a day)

 

[Sandroad]

Is this your first winter with the Clarity, or is this a change from last winter? I see a few bars low on the HV battery scale, so it's not completely full. No one really knows what's normal for each specific circumstance/use, but I wouldn't worry at all about it from what you describe.

 

[Ohliuw]

First winter, the pic was taken few minutes after it started.

the braking at full battery makes sense - I usually pre warm the car with the L2 turned on, then I leave my parking and now I recall that it turned on when I pressed the brakes at the stop sign at the T-intersection 300 meters down my street.

So is this a bug? Is there a patch for it?

Is this your first winter with the Clarity, or is this a change from last winter? I see a few bars low on the HV battery scale, so it's not completely full. No one really knows what's normal for each specific circumstance/use, but I wouldn't worry at all about it from what you describe.

Is this your first winter with the Clarity, or is this a change from last winter? I see a few bars low on the HV battery scale, so it's not completely full. No one really knows what's normal for each specific circumstance/use, but I wouldn't worry at all about it from what you describe.

 

[Ohliuw]

If the battery is already full and the car is attempting to charge it more (e.g. from going down a hill, braking, etc.) then ICE will turn on. You should be able to test this and see if that's what's causing it to turn on in these cases.

yes, if I look back, it makes sense - it happens either at the stop sign 300m from my parking or downhill on the highway 1km away from my house.

but how this make sense? It is soooo counterintuitive???

 

[KentuckyKen]

but how this make sense? It is soooo counterintuitive???

All of us and especially @insightman would part with a considerable amount of money to know this. Yes, it’s totally counterintuitive, but is so well documented that it has to be taken as fact. And as @PHEV Newbie posted, it’s doubly counterintuitive to then see the ICE start feeding charge into the supposedly too full to allow regen traction battery.

I just set a timer on my watch for 30 or 60 minutes and when it goes off I just open the app and stop the charge...but it's not THAT much effort.

PS: @weave , you seriously underestimate my degree of laziness!
My lawyers will be in touch with you shortly.

 

[Ohliuw]

When the battery is close to full, even moderate braking can turn the ICE on (too much regen for a full battery will harm it). This can be infuriating because, like the OP said, the running ICE will run for a few minutes, which will charge to battery back to full, shut off after a few minutes and then it can turn on again if I go downhill or have to brake hard! I charge to full only once a month or so for cell balancing. Otherwise, I charge to no more than 80% (sometimes just to 60%, if I know I'll charge again after a short errand). There's a dramatic effect on battery longevity if you can keep the SOC hovering as close to 50% as possible. And the bonus is that the ICE doesn't turn on in normal driving, unlike when it is full.

the actual capacity of the battery is 17kwh, but my JB reports 13kwh from 0 to full.

My guess is Honda has implemented battery management not to allow 100% charge and shuffle the cell use to even it out.

Also, the car dramatically reduces the amperage after it gets 80% full to prevent fast charging at the last 20%

Also, 100% is bad only if you leave it fully charged for long periods. Think of it like having you muscles fully engaged - you are ok for short period, but obviously you will hurt them.

bottom line, as long as you don’t leave it at 100% for days and weeks, you shouldn’t worry about longevity.

 

[insightman]

but how this make sense? It is soooo counterintuitive???

Yes, as @KentuckyKen says, I would part with a considerable amount of money to know this. My belief is that the starter motor/generator is being used in an attempt to SLOW the running ICE to burn off the excess power than cannot go to the fully charged battery. The non-plug-in Honda hybrids don't start their engines in this situation, they force the starter motor/generator to turn the ICE with no power to the spark plugs.

 

[The Gadgeteer]

How cold was it? Below 15F the engine may start.