Note that there is a third water/glycol cooling system in the Clarity. This is for the inverter. This is also independent of the separate ICE and battery cooling systems. This is the cooling system that uses the small radiator located behind the driver's side of the front grill just in front of the left front wheel. One can see the grill in the wheel well for the exit air.
Honda Service Express Bulletins for 2018 Clarity PHEV
- Thread starter AnthonyW
- Start date
- Replies 185
- Views 79K
KentuckyKen
Well-Known Member
OK, so now I’m even more confused than usual. If there are 3 cooling systems and only 2 radiators (plus the AC condenser), then how does that work without two of them being connected? Would the Clarity Brain Trust please explain this in terms a cave man can understand?
I can find 2 radiators and 1 AC condenser up front and 3 cooling fluid caps/expansion tanks (radiator, inverter, HV battery per p 480) under the hood. How does all that work?
There are three air cooled heat exchangers radiators in front of the ICE (and the electric fan). First is the battery cooling system radiator, then the air conditioning condenser, and then the ICE radiator. The fourth heat exchanger is the aluminum inverter radiator which can be seen by looking into the open area just below the horizontal portion of the running light.
Atkinson is correct (thanks). The small radiator, low and off the left side, is the transmission cooler. It appears from a closer look that the inverter and battery cooling systems share a common radiator assembly (the first radiator behind the front grill) with separate water/glycol circuits (two cores). So, there are five air cooled heat exchangers in the Clarity PHEV and six if you count the cabin heater core. Quite complicated.
Mea Culpa.
Mea Culpa.
JFon101231
Active Member
So then I guess color me confused. If the ICE can't warm the battery b/c the coolant loops are separate, then the question in posts 149/153 remain unanswered (in my simpleton eyes) - why does the ICE sometimes run in low temps if SOC is high and motion/heating demands are "low"? I live in New England and car is parked outside but connected to L2. I've had it happen for sure in some cases and also *think* it has happened other times but car says EV still so can't say for sure as I didn't pull over but sounded like it.
Perhaps our view of low demands isn't the way the algorithm looks at it? I know for me it isn't a case of the ICE not running in a long period as generally in these temps it runs at the end of leg of my 40 mi one-way commute.
Perhaps our view of low demands isn't the way the algorithm looks at it? I know for me it isn't a case of the ICE not running in a long period as generally in these temps it runs at the end of leg of my 40 mi one-way commute.
Last edited:
MPower
Well-Known Member
I have the same experience.
MNSteve
Well-Known Member
This is my theory. My experience suggests that below some outside temperature, the ICE will run to provide cabin heat if there is ANY demand for cabin heat. I assume that the algorithm is coded such that at those low temperatures (less than 10-15°F) it simply wants to use the battery charge to move the car. At those temperatures the battery is already providing much less EV range than "usual".
I think your theory is about right. It is in the best interest of Honda to ensure that these batteries work in a pretty narrow range of parameters to ensure that six or seven years from now they are not replacing millions and millions of dollars of batteries.
Resistive heat is essentially dumping a hugh amount of current through a load (usually some kind of mesh or coil). Heavy discharge of Li-ion batteries causes dendrites to form and while chemistry has evolved to help delay dendrite formation, in the end, this is what most likely will kill the cell. If it was just the cold and the only demand was energy to drive the heater and the car at very low speeds, the drain on the battery would probably not be that high, but accelerating to go on to the highway when the temp knob is turned up to high an the resestive element in the seats are running is probably a pretty high current draw, and as we know, if you draw a lot of current under most conditions, the ICE comes on to supplement the battery output.
Anyway, I think the theory is probably about right. Honda wants the battery to last the full warranty period and if the owner dislikes it that the ICE is started every now and then for various reasons, well, they should have bought a regular car or a full electric. I think that Honda has probably really noodled the best way to get the least warranty exposure possible, and there is nothing wrong with that. Considering the incredible value offered by the Clarity price, I can't get upset about some of the quirks associated with the design.
Resistive heat is essentially dumping a hugh amount of current through a load (usually some kind of mesh or coil). Heavy discharge of Li-ion batteries causes dendrites to form and while chemistry has evolved to help delay dendrite formation, in the end, this is what most likely will kill the cell. If it was just the cold and the only demand was energy to drive the heater and the car at very low speeds, the drain on the battery would probably not be that high, but accelerating to go on to the highway when the temp knob is turned up to high an the resestive element in the seats are running is probably a pretty high current draw, and as we know, if you draw a lot of current under most conditions, the ICE comes on to supplement the battery output.
Anyway, I think the theory is probably about right. Honda wants the battery to last the full warranty period and if the owner dislikes it that the ICE is started every now and then for various reasons, well, they should have bought a regular car or a full electric. I think that Honda has probably really noodled the best way to get the least warranty exposure possible, and there is nothing wrong with that. Considering the incredible value offered by the Clarity price, I can't get upset about some of the quirks associated with the design.
JFon101231
Active Member
I'm still having the car run ICE with no heat demands, no seat heater/defroster, and temps in the 50's. It happens when I first leave home, and I usually notice it after my first stop sign or 2. It will then run for a while unless I cycle the key to force it. SOOO frustrating I can't make the car act like an EV sometimes. Haven't bothered to bring it to dealer b/c I assume I'll be sent home with a "we don't see anything unusual"...
If you halt charging before the battery is fully charged, then your ICE won't have to start up to use up the excess energy that can't go to the fully-charged battery when slowing down creates regenerated energy. Alternatively, you can run the electric resistance heater to use up some of the battery charge before you start out.
Here's the most recent thread of many that cover the topic of the ICE starting up when the battery is fully charged and regen braking occurs.
Here's the most recent thread of many that cover the topic of the ICE starting up when the battery is fully charged and regen braking occurs.
MNSteve
Well-Known Member
Does this happen when you first leave home but with the car not 100% charged?
JFon101231
Active Member
thanks I'll go check out that other thread to avoid clogging this one. The idea I should guess how much to not fully charge by to avoid that is ridiculous. It should just not regen, just like my Fit EV didn't regen much/at all if battery was full.
@MNSteve - first leave home, fully charged at 99-100% SOC
@insightman, not sure how this is physically possible, ICE doesn't 'use up' electrical power AFAIK?
"ICE won't have to start up to use up the excess energyIt should just not regen."
@MNSteve - first leave home, fully charged at 99-100% SOC
@insightman, not sure how this is physically possible, ICE doesn't 'use up' electrical power AFAIK?
"ICE won't have to start up to use up the excess energyIt should just not regen."
KentuckyKen
Well-Known Member
Well, the Clarity is not a true EV, it’s a PHEV. Also, there is no way to select “pure” or 100% EV (battery only) driving. It is, however, quite possible to drive it like a virtual EV with almost all (but not quite all) your miles on the battery for the first 50 to 60 miles in the summer, and 30 to 45 miles in the winter. YMMV depending on how far north you live and how aggressive you drive.
For me in KY, with on passengers or luggage, on no more than rolling hills, and obeying they speed limits, I get mid 60s EV range Spring to Fall and mid 40s in winter without the ICE inning on except as noted below. Note that ceramic tint, preconditioning, garaging, and non-extreme climate help a lot to stay EV vs gas, along with moderate driving and local speeds limited to under 60 mph.
So I’ve been able to go 14 months and 9,200 miles on 15 gal of gas since I’ve only taken about 700 miles of out of town trips. I do have the ICE come on very occasionally and for short periods of time. That’s normal and to be expected. The engine has to exercise itself to make sure it’s always willing and ready to instantly come on when you call for it. It’s just keeping everything lubricated and stays on until it reaches operating temperature which gets rid of any condensation in the oil and in the exhaust system. You are just defeating this benefit and not helping your engine by trying to turn off the ICE before it warms up. Also, it doesn’t burn an appreciable amount of gas. I haven’t used HV in 10 months and haven’t even lost a bar in the fuel gauge from the occasional and short System Checks.
Although there are some conditions that will call for the ICE (see p 13 of the manual), it is very easy to achieve virtually the same economic and environmental benefits of a BEV during local driving. As a PHEV, the Clarity the gives you all that plus the added benefit of unlimited range at 40 to 50 mpg in semi-luxury. So I say don’t obsess about the ICE running very occasionally when you are in “EV mode” because it’s normal expected behavior and has no discernible cost.
But there is always a fly in the ointment so to speak. Although not mentioned anywhere by Honda, it is well documented on this forum that the Clarity has one unusual quirk about its ICE. When the battery is fully charged it cannot accept any more charge by regeneration and so to protect the battery, the ICE will start and in some not fully understood way keep the battery from being overcharged. This is most often seen on a down hill after a full charge or with hard braking or 4 chevron regen. Others have posted that drawing down the battery with cabin heat/defrost at start up can help mitigate this, but I’d your hill is very steep it may not be enough. Then some have tried not charging to 100% but that takes some effort. FWIW, mine did this for a while and I’m not on a hill. I found that not calling for 4 chevron regen and braking gently the first 5 miles or so eliminated it for me. Or it could have been just that my car and battery ages a little bit. I just know it’s stopped except for one time I had to panic brake right after a full charge and the ICE came on.
If it’s only happening when you leave home on a full charge, the it’s probably the no regen on full charge to protect the battery by ICE start thing. (Wish we had a name for that!)
Hope this helps and hope you enjoy your Clarity as much as I do.
Last edited:
MNSteve
Well-Known Member
It should be warm in MN in the Winter.
As KentuckyKen points out, nothing is perfect. At least I haven't found the perfect car yet. I love my Clarity, but it has traits that drive me a bit crazy, like a mind of its own for engaging the gear icon.
I don't think any of us understand why the ICE triggers when the battery cannot accept the output of regenerative braking. But it is what it is. I don't agree with the decision that the engineers made to trigger the ICE in this case, but it's a well-documented fact based on the experience of several folks here. I am sorry that your driving configuration is such that you need to use regenerative braking immediately after fully charging. I don't have this issue, but that's because I don't need to use my brakes until I've sucked a bit of charge out of the battery.
Your alternatives seem pretty clear cut. My suggestion would be to just accept this as one of the quirks of the car; it's not really that big a deal. You could charge to less than 100% if it really bothers you that much. Or move to a different location where you climb a hill on departure instead of descending one.
See my detailed (harebrained?) theory about fighting in the Clarity's engine compartment in this post in another thread today.
Kerbe
Well-Known Member
Thanks for all the Service Bulletins and other downloads. One question: I've heard that the Clarity has its own DPI (Dealer Prep Instructions) that's distinct from the standard Honda DPI, including such items as installing frame plugs, etc. Has anyone seen a copy of this document and, if so, could it be posted? TIA!
Texas22Step
Well-Known Member
Not 100% sure this copy of SB 17-093 v3 is what you want/need. (This is the latest version I have in my file, so there may be some updates after this one. This should still provide some useful info to you, however.)
Teslawannabe
Active Member
Just a possible explanation: Spinning the engine with the engine generator/starter uses electricity (energy). This can in effect dump some juice. A spinning ICE will sound just like a running ICE even if it is off (no fuel injectors turned on). Ford uses this on Fusion and Cmax Energy's to dump excess juice. In fact in Ford Hybrid school the techs had to diagnose a fault based on a diagnostic trouble shooting chart. The first question was " does the engine start?". Well that was the bug. The injectors were disabled but the engine was in essence running/(pumping air) but just spinning. Sounded the same. Just a thought.