HannahWCU Posted September 4, 2014 Report Share Posted September 4, 2014 This isn't a problem as much as an operational find. Let me explain... As you might have read, I am in the process of attempting an 800 mile tank of fuel. So I have been attempting new ways of improving my MPG and I stumbled across something I don't think anyone had documented (if it has, then I apologize :worship: ) . When cold (i.e, engine it at or near ambient temperature), I cannot exceed 35 MPH strictly in EV mode. It doesn't matter how much charge is in the battery, when the speedometer hits 35MPH the ICE kicks in. It does this even when my foot is completely off the accelerator pedal. When I leave work in the afternoons, the terrain is slightly downhill for more than 1/2 a mile. Usually, when pulling out, I will give it enough throttle to kick the ICE on and allow the ICE to warm while descending this small hill. The other day I had an almost full battery when leaving, so I thought I would run out some juice before the ICE kicks in and charges. Halfway down the hill the ICE kicked in. I thought maybe I had pressed the accelerator pedal a little too much. So the next day, I tried it without touching the pedal. Sure enough, at 35MPH the ICE kicks in. I have repeated this 3 times, so I am pretty sure it is in the programming of the car. Anyone else see this? Or tried it? Or is my CMax more unique than I thought? :clapping: hybridbear and MomsHugs 2 Quote Link to comment Share on other sites More sharing options...
fotomoto Posted September 4, 2014 Report Share Posted September 4, 2014 Hmm, I can't replicate because I don't have hills here. What are your ambient temps now? Quote Link to comment Share on other sites More sharing options...
HannahWCU Posted September 4, 2014 Author Report Share Posted September 4, 2014 Afternoon temps are between 85-95F. So I don't think it is temperature dependent. I know when it's cold (cold for NC not ND! ;) ) the EV threshold is lower. But this seems to be Speed dependant, although, I guess it could be trying to keep things cool rather than warm. But again with the small distance driven (<1/2 mile) I would think heat would not be an issue either. Quote Link to comment Share on other sites More sharing options...
fotomoto Posted September 4, 2014 Report Share Posted September 4, 2014 Yes, the battery temp is most likely too high for the SOC so the ICE comes on to take some of the load off the EV system. We can run into this in the Energi world too. See if the speed limit changes (goes up) on your downhill run as the temps get cooler in the fall. I suspect it will. Quote Link to comment Share on other sites More sharing options...
ptjones Posted September 4, 2014 Report Share Posted September 4, 2014 I will have to try that for sure, but I have gotten on the Fwy in EV and gotten over 50mph with ICE cold. Will do more testing. :) Paul Quote Link to comment Share on other sites More sharing options...
HannahWCU Posted September 4, 2014 Author Report Share Posted September 4, 2014 I will have to try that for sure, but I have gotten on the Fwy in EV and gotten over 50mph with ICE cold. Will do more testing. :) Paul Just a note, the ICE in my scenario has not run at all. So I used all EV from Start to 35MPH. So the ICE isn't just cold, it has not run yet. Just trying to clarify. Quote Link to comment Share on other sites More sharing options...
HannahWCU Posted September 4, 2014 Author Report Share Posted September 4, 2014 Yes, the battery temp is most likely too high for the SOC so the ICE comes on to take some of the load off the EV system. We can run into this in the Energi world too. See if the speed limit changes (goes up) on your downhill run as the temps get cooler in the fall. I suspect it will. I had not thought of the battery being too hot. That is a possibility, I will try that out again when temps fall and see if that does have an affect. Thanks! Quote Link to comment Share on other sites More sharing options...
Wnuk Posted September 5, 2014 Report Share Posted September 5, 2014 I can confirm this. Living on top of a hill, each morning my commute starts with a 1 mile down hill run. Regardless of the battery SOC if the ICE is cold it will always kick in at 35 MPH. The speed limit on that stretch is 50MPH and I've tried many times to hit in from a cold ICE condition and it's the same result. Now if ICE is already warmed I can achieve the posted speed limit on EV alone. Temps don't change the result. It's happened if the temps are in the 50's or the 80's MomsHugs 1 Quote Link to comment Share on other sites More sharing options...
drdiesel1 Posted September 5, 2014 Report Share Posted September 5, 2014 (edited) They don't want the ICE coming on cold at high speeds because of possible engine damage.You exceed the threshold of 35 and it will come on to warm up before the car can get to a higherspeed. Therefore reducing the possibility of high RPM/ lubrication issues at high RPM's, cold. Just think what could happen if the ICE came on at 70 mph, cold :cry: Edited September 5, 2014 by drdiesel1 MomsHugs 1 Quote Link to comment Share on other sites More sharing options...
HannahWCU Posted September 5, 2014 Author Report Share Posted September 5, 2014 They don't want the ICE coming on cold at high speeds because of possible engine damage.You exceed the threshold of 35 and it will come on to warm up before the car can get to a higherspeed. Therefore reducing the possibility of high RPM/ lubrication issues at high RPM's, cold. Just think what could happen if the ICE came on at 70 mph, cold :cry: Never thought of that. It makes sense though. Thanks for the insight. Quote Link to comment Share on other sites More sharing options...
fotomoto Posted September 5, 2014 Report Share Posted September 5, 2014 Just think what could happen if the ICE came on at 70 mph, cold :cry: I do that quite often in my NRG. :shift: As a fellow NRG owner, you are probably aware the computer initially idles the ICE and blends it in with the EV motor until it warms up a bit before taking completely over. So why the 35mph difference in the hybrid? Since wnuk says ambient temps don't seem to matter, I'm now leaning to a transmission lubrication issue on a cold drive train. Thoughts anyone? Quote Link to comment Share on other sites More sharing options...
nsteblay Posted September 5, 2014 Report Share Posted September 5, 2014 I've experienced the same but never determined the speed threshold. My understanding has been the catalytic converter needs to be at a certain temperature. The engine will kick on to get it to that temperature, apparently once 35 MPH is hit. Not sure why 35 MPH. This is one of the major reasons mileage goes down in cold weather. From the manual ... Engine idle speed after startingThe speed at which the engine idlesimmediately after starting will varydepending on the engine temperature.The idle speed is automatically increasedwhen the engine is cold this is to heat thecatalytic converter. This keeps the vehicleemissions to an absolute minimum.The idle speed will slowly decrease to thenormal level as the catalytic converterwarms up. MomsHugs 1 Quote Link to comment Share on other sites More sharing options...
Wnuk Posted September 5, 2014 Report Share Posted September 5, 2014 Wouldn't the vehicle produce zero emissions if it stayed in EV mode? Fotomoto may be on to something with transmission fluids needing to be warm. Quote Link to comment Share on other sites More sharing options...
ptjones Posted September 6, 2014 Report Share Posted September 6, 2014 I got home early this evening with the HVB at 80% and 1 1/2hr later I left to go into town on the FWY. WT was at 145*F and sure enough when I hit 35mph in EV the ICE came on WOW. Went about 3/4mi and then returned to EV. Then entered the FWY and was able to get to 55mph in EV and 53mpg for the 7mi. trip. Very interesting. :) Paul MomsHugs 1 Quote Link to comment Share on other sites More sharing options...
drdiesel1 Posted September 6, 2014 Report Share Posted September 6, 2014 (edited) The engine isn't going to warm the trans fluid directly. The bigger issue is, the hybrid isn't equipped with the trans fluid pump for extended EV. So they probably active the ICE to circulate the trans fluid for proper lubrication and limit the RPM's to help lubricate the ICE before it hits a high load demand, when cold. Only the engineers know the control strategy behind it. Edited September 6, 2014 by drdiesel1 hybridbear, MomsHugs and ptjones 3 Quote Link to comment Share on other sites More sharing options...
hybridbear Posted September 7, 2014 Report Share Posted September 7, 2014 I had not thought of the battery being too hot. That is a possibility, I will try that out again when temps fall and see if that does have an affect. Thanks!Don't you have a ScanGauge? With it you can see the HVB temp. But I'm thinking that the thought that this happens for transmission lubrication purposes is likely right. As drdiesel mentions, the Energi has an electric transmission fluid pump, the hybrid does not. That means that the fluid inside the eCVT isn't flowing unless the ICE is on. Quote Link to comment Share on other sites More sharing options...
ptjones Posted September 7, 2014 Report Share Posted September 7, 2014 Don't you have a ScanGauge? With it you can see the HVB temp. But I'm thinking that the thought that this happens for transmission lubrication purposes is likely right. As drdiesel mentions, the Energi has an electric transmission fluid pump, the hybrid does not. That means that the fluid inside the eCVT isn't flowing unless the ICE is on.I think this makes scents, because I've been hot or cold and It still comes on at 35mph. I can go along way if I keep it below 35mph in EV, but now you got me thinking that may not be a good idea. ;) Paul Quote Link to comment Share on other sites More sharing options...
HannahWCU Posted September 9, 2014 Author Report Share Posted September 9, 2014 Don't you have a ScanGauge? With it you can see the HVB temp. But I'm thinking that the thought that this happens for transmission lubrication purposes is likely right. As drdiesel mentions, the Energi has an electric transmission fluid pump, the hybrid does not. That means that the fluid inside the eCVT isn't flowing unless the ICE is on. I do have a scangauge but an not using it at the moment. I have it in another vehicle. :doh: Quote Link to comment Share on other sites More sharing options...
ptjones Posted September 11, 2014 Report Share Posted September 11, 2014 I do have a scangauge but an not using it at the moment. I have it in another vehicle. :doh:Make sure it is one that will work with Hybrid. :) Paul Quote Link to comment Share on other sites More sharing options...
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