Factory Service Manual?
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KentuckyKen
Well-Known Member
OK, I’ll be the first to admit I’m a bio guy and not a physics guy, but I just don’t get the reasoning here. Isn’t it the same thing happening, i.e. work being performed/exerted in both cases?
First possibility: Starter-generator takes regen power and turns the non running/non firing ICE which exerts force against inertia, friction and cylinder compression. And ICE fires up after excess regen event is over.
Second possibility: Starter-generator takes regen power and exerts force against the direction of the fired up and running ICE.
Third possibility: Starter-generator takes regen power and exerts force to turn the running ICE faster than its already going. (I don’t like this one just on principle)
In all cases work is being performed which must of course produce more heat in the total system, that I would suppose cause one of the cooling loops to be utilized if temps go over a certain limit but probably not since it’s a transient event.
So it’s the same thing either way as far as turning excess regen power into work which is what you are calling “dissipated”. Or am I missing something here?
In any case, I can guarantee that the ICE fires up and burns gas because my exhaust manifold got hot, the engine icon came on, and my inductively powered hour meter coupled to a spark plug incremented. The few times it’s happened to me, it seemed that the ICE fired up immediately with no delay and then stayed on until warmed up. It also ran very quietly. And it’s happened too often to be a coincidental System Check, although all the outward appearances, including the Power Meter turning and staying all white, were the same. I have no good explanation of how it does it but I’m pretty sure of what it does.
I will make the unproven and totally speculative assumption that the ICE is fired up for reasons of engine health and not because it’s absolutely needed to dissipate the excess regen power that’s not allowed into a full battery for reasons of its health. But we really don’t know for sure about anything other than our observations at this point.
First possibility: Starter-generator takes regen power and turns the non running/non firing ICE which exerts force against inertia, friction and cylinder compression. And ICE fires up after excess regen event is over.
Second possibility: Starter-generator takes regen power and exerts force against the direction of the fired up and running ICE.
Third possibility: Starter-generator takes regen power and exerts force to turn the running ICE faster than its already going. (I don’t like this one just on principle)
In all cases work is being performed which must of course produce more heat in the total system, that I would suppose cause one of the cooling loops to be utilized if temps go over a certain limit but probably not since it’s a transient event.
So it’s the same thing either way as far as turning excess regen power into work which is what you are calling “dissipated”. Or am I missing something here?
In any case, I can guarantee that the ICE fires up and burns gas because my exhaust manifold got hot, the engine icon came on, and my inductively powered hour meter coupled to a spark plug incremented. The few times it’s happened to me, it seemed that the ICE fired up immediately with no delay and then stayed on until warmed up. It also ran very quietly. And it’s happened too often to be a coincidental System Check, although all the outward appearances, including the Power Meter turning and staying all white, were the same. I have no good explanation of how it does it but I’m pretty sure of what it does.
I will make the unproven and totally speculative assumption that the ICE is fired up for reasons of engine health and not because it’s absolutely needed to dissipate the excess regen power that’s not allowed into a full battery for reasons of its health. But we really don’t know for sure about anything other than our observations at this point.
KentuckyKen
Well-Known Member
Well, this discussion has just hit home. I charged o/n to full, then left home this morning and at third stop (first two were 15-20 mph) at about 0.2 miles, the ICE came on for what has to be the “full battery can’t accept any regen”. I had clicked for 4 chevron regen and it blinked and only allowed 3 chevrons and then the ICE came on instantly as evidenced by sound and the engine icon (had it already on display). This was from a speed of about 35-40 mph on level road. And the ICE had previously run just 6 days ago, so I don’t think it was a System Check.
IMHO, based on observations, the ICE turns on and burns gas immediately when regen is not allowed to charge a full battery.
IMHO, based on observations, the ICE turns on and burns gas immediately when regen is not allowed to charge a full battery.
The Gadgeteer
Well-Known Member
It only burns a minimal amount of gas when this happens presumably to warm up the engine and circulate oil. It makes sense once the engine is warmed up any spinning of the engine for "engine braking" would be done with the fuel injectors shut down much like a regular ICE car does.
KentuckyKen
Well-Known Member
I agree that any time the ICE comes on that it stays on until it reaches an operating temperature in order to take care of such things as condensation and be kind to the engine. The braking/regen event is short lived so I see your point that it could be occurring with gas/spark off and then the engine is turned on not for braking, but for engine protection. However, it seems to come on immediately, but admittedly, this is hard to determine for sure with such a short transient braking/regen event.
Perhaps, a way to try to prove this one way or the other, would be to get up to highway speed so as to have a longer braking event while a passenger closely monitors the icon and engine sound. I will try this when I can and report back the results. I’m thinking that if the engine didn’t start until the braking/regen was over, then your theory would hold, and if it starts immediately then somehow it’s requiring a running and firing engine and not just a rotating engine.
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David in TN
Well-Known Member
From my observations:
I have a ScanGauge II, with the State-of-charge (SOC) showing on it. When the SOC is > 95(%), then the ICE will kick on if aggressively hitting regen paddle to increase braking and regen. Since there isn't room for regen to take place, then it fires up the ICE for additional engine braking.
Once SOC < 95, then this hasn't occured for me. I can pull the regen paddle to 4 chevrons, and it increases the regen accordingly. Also, the amount of regen available is dependent on the SOC. More regen will occur when SOC is below, say, 80, than at 90.
With the current temps, and my current work location, I have to be careful not to hit the paddle at my first stop light. After that, it's usually ok. In the summer, of course, I have to wait longer as the SOC depletes at a slower rate.
And Ken -- we don't have rotating engines. Mazda used to sell those!
I have a ScanGauge II, with the State-of-charge (SOC) showing on it. When the SOC is > 95(%), then the ICE will kick on if aggressively hitting regen paddle to increase braking and regen. Since there isn't room for regen to take place, then it fires up the ICE for additional engine braking.
Once SOC < 95, then this hasn't occured for me. I can pull the regen paddle to 4 chevrons, and it increases the regen accordingly. Also, the amount of regen available is dependent on the SOC. More regen will occur when SOC is below, say, 80, than at 90.
With the current temps, and my current work location, I have to be careful not to hit the paddle at my first stop light. After that, it's usually ok. In the summer, of course, I have to wait longer as the SOC depletes at a slower rate.
And Ken -- we don't have rotating engines. Mazda used to sell those!
Do you still have those files?
I'm a bit late to the party, but I have to say second option doesn't really make sense from a physics perspective, this is clearer if you consider it from a conservation of energy perspective, now on top of dissipating the kinetic energy of the car itself, the kinetic energy produced by the ICE must also be dissipated--probably as heat. The first and third are really just variations of each other, the regenerative braking energy to convert to kinetic energy in the ICE, if the ICE is burning gas it just means it will spin faster which isn't really a problem is not like it's going to red line or anything. Yes it uses some gas but that's just until the engine warns up enough.
I think I can clear up a couple things. The Clarity does indeed use resistive heaters to dump excess energy, including the cabin heater as well as a coolant heater in the ICE coolant circuit. As far as why does the engine run? It's because the ICE coolant pump is run by the timing chain, and so the engine has to run to avoid overheating the coolant heater, and then completes the warm up cycle.
I am now a bit confused. In 2018 AnthonyW posted a pdf file of pages from the Honda Tech website about the Clarity PHEV heating system:
https://www.insideevsforum.com/comm...-for-2018-clarity-phev.2183/page-2#post-19536
The diagrams in the file (P26A3.pdf) clearly show that the engine cooling water pump (as well as all other water pumps associated with the Clarity PHEV heating/cooling system) are electric pumps. Looking at the parts diagrams, pictures, and listings in the Honda Clarity PHEV parts listings on the Internet also leads me to believe that all the coolant water pumps on the Clarity PHEV are electric and not mechanical. So, SR2K, does the Clarity PHEV ICE engine have a mechanical or an electric water pump for the engine cooling system? Perhaps, there is an additional water pump that is not so easy to find.
LeoP
https://www.insideevsforum.com/comm...-for-2018-clarity-phev.2183/page-2#post-19536
The diagrams in the file (P26A3.pdf) clearly show that the engine cooling water pump (as well as all other water pumps associated with the Clarity PHEV heating/cooling system) are electric pumps. Looking at the parts diagrams, pictures, and listings in the Honda Clarity PHEV parts listings on the Internet also leads me to believe that all the coolant water pumps on the Clarity PHEV are electric and not mechanical. So, SR2K, does the Clarity PHEV ICE engine have a mechanical or an electric water pump for the engine cooling system? Perhaps, there is an additional water pump that is not so easy to find.
LeoP
Except for the camshaft, all the engine accessories under the hood are electric.
You can buy a Clarity electric water pump at Honda Parts Now.