jetjam Posted November 10, 2014 at 03:22 AM Report Share Posted November 10, 2014 at 03:22 AM Pushing the button on the side of the transmission selector puts it in downhill mode. What exactly does that do? It seems to coast less, is it simply engaging the regen braking? Does it generate more power than simply coasting? Quote Link to comment Share on other sites More sharing options...
murphy Posted November 10, 2014 at 10:40 AM Report Share Posted November 10, 2014 at 10:40 AM It provides regen while going down hill without having to use the brake pedal. It usually prevents the car from picking up speed during the descent. Hybridbear 1 Quote Link to comment Share on other sites More sharing options...
Hybridbear Posted November 10, 2014 at 04:00 PM Report Share Posted November 10, 2014 at 04:00 PM The purpose seems to be to prevent the car from gaining speed while going downhill. If it hits the max regen limit it will turn on the ICE for engine braking. Rexracer 1 Quote Link to comment Share on other sites More sharing options...
Rexracer Posted November 10, 2014 at 04:09 PM Report Share Posted November 10, 2014 at 04:09 PM If the battery is fully (just unplugged) it will turn the gas motor on to achieve down hill braking as it doesn't have anywhere to put the regen'ed power. Quote Link to comment Share on other sites More sharing options...
jetjam Posted November 10, 2014 at 07:24 PM Author Report Share Posted November 10, 2014 at 07:24 PM Ok, so it's badsically the same as engaging regen braking and does generate more power than simply coasting in normal mode. But if the ICE engages when the battery is full because there is no place to put the excess power, how come the ICE doesn't come on when you have a full battery and lightly depress the brake pedal to engage regen braking? HotLap 1 Quote Link to comment Share on other sites More sharing options...
HotLap Posted November 10, 2014 at 07:39 PM Report Share Posted November 10, 2014 at 07:39 PM jetjam, that's a good question and something I've been wondering about as well. Quote Link to comment Share on other sites More sharing options...
Russael Posted November 10, 2014 at 08:01 PM Report Share Posted November 10, 2014 at 08:01 PM Probably because the car engages the normal friction brakes instead. The ICE will kick on if you try it while driving in L since you're telling the car to use engine braking instead of friction. Quote Link to comment Share on other sites More sharing options...
stevedebi Posted November 10, 2014 at 09:32 PM Report Share Posted November 10, 2014 at 09:32 PM Ok, so it's badsically the same as engaging regen braking and does generate more power than simply coasting in normal mode. But if the ICE engages when the battery is full because there is no place to put the excess power, how come the ICE doesn't come on when you have a full battery and lightly depress the brake pedal to engage regen braking? In negative split mode, the energy goes back into the generator if possible. How do you know there is no place to store the excess power? Do you have a SG II hooked up? But in any case, brakes are normally a short term occurrance, and in my opinion it would be distracting to have the ICE spin up and down for short periods based on the brakes. Shifting to L or hitting the downhill mode indicates to the vehicle that the driver is on a down slope. Quote Link to comment Share on other sites More sharing options...
jetjam Posted November 11, 2014 at 03:04 PM Author Report Share Posted November 11, 2014 at 03:04 PM Probably because the car engages the normal friction brakes instead. The ICE will kick on if you try it while driving in L since you're telling the car to use engine braking instead of friction.Ok, so you're saying if the battery is full, and I lightly press on the brake pedal, the friction brake engages and no regen braking occurs. But when I stop my braking score is 100%, and as I roll to a stop I hear the whir of the regen motors that you usually hear when regen braking indicating to me that the friction brakes have not engaged. Plus, you can feel a difference between the friction brakes and regen. I'm just not sure I buy the notion that electricity needs some place to go. Excess power must be disipated somehow. In my garage I have a cheap constant speed generator that produces 2 KVA. It runs the same whether I plug a light bulb into it or run a refrigerator off it. Clearly it is turning at the same RPM and running the generator no matter what the load, so the unused electricity must be dissipating some how. Quote Link to comment Share on other sites More sharing options...
murphy Posted November 11, 2014 at 03:32 PM Report Share Posted November 11, 2014 at 03:32 PM (edited) In my garage I have a cheap constant speed generator that produces 2 KVA. It runs the same whether I plug a light bulb into it or run a refrigerator off it. Clearly it is turning at the same RPM and running the generator no matter what the load, so the unused electricity must be dissipating some how. There is no unused electricity. When you increase the load on the alternator the force required to turn the alternator increases. At the current fuel flow rate the engine can't provide that force so the engine starts to slow down. That causes the governor to increase the fuel flow to the engine so it can match the required force and return to the required RPM. If you remove a load from the alternator the force required to turn the alternator is reduced. This causes the engine to start to speed up. The governor reduces the fuel flow to the engine so it can match the reduced force and maintain the required RPM. Viewing the engine and alternator as a system when the electrical load is increased the fuel flow increases to provide the required additional energy. Back on topic: electricity can only flow if there is a complete circuit. If regen is generating electricity it has to be in a complete circuit. That normally is to the battery charger to charge the battery. If the battery is full it can't go there. They could have provided a BIG resistor to turn the electricity into heat but I don't think that they did. Instead of generating electricity the ICE is spun up but no gasoline is fed to the cylinders. In effect the ICE becomes an air pump and the force used to turn that air pump is the back pressure that holds the car back from accelerating. Edited November 11, 2014 at 03:33 PM by murphy Hybridbear and HotLap 2 Quote Link to comment Share on other sites More sharing options...
jetjam Posted November 11, 2014 at 03:40 PM Author Report Share Posted November 11, 2014 at 03:40 PM There is no unused electricity. When you increase the load on the alternator the force required to turn the alternator increases. At the current fuel flow rate the engine can't provide that force so the engine starts to slow down. That causes the governor to increase the fuel flow to the engine so it can match the required force and return to the required RPM. If you remove a load from the alternator the force required to turn the alternator is reduced. This causes the engine to start to speed up. The governor reduces the fuel flow to the engine so it can match the reduced force and maintain the required RPM. Viewing the engine and alternator as a system when the electrical load is increased the fuel flow increases to provide the required additional energy. Back on topic: electricity can only flow if there is a complete circuit. If regen is generating electricity it has to be in a complete circuit. That normally is to the battery charger to charge the battery. If the battery is full it can't go there. They could have provided a BIG resistor to turn the electricity into heat but I don't think that they did. Instead of generating electricity the ICE is spun up but no gasoline is fed to the cylinders. In effect the ICE becomes an air pump and the force used to turn that air pump is the back pressure that holds the car back from accelerating.Ok, that makes sense, thanks for the excellent explaination!! The amount of complexity in this car is amazing. Quote Link to comment Share on other sites More sharing options...
HotLap Posted November 14, 2014 at 11:21 PM Report Share Posted November 14, 2014 at 11:21 PM Murphy, great explanation and JJ I completely agree, it's amazing the technology in a $40K car. This MUST be a loser for Ford (profit wise) and sold to maintain/increase their CAFE fuel avgs! Quote Link to comment Share on other sites More sharing options...
jetjam Posted November 15, 2014 at 01:54 AM Author Report Share Posted November 15, 2014 at 01:54 AM Murphy, great explanation and JJ I completely agree, it's amazing the technology in a $40K car. This MUST be a loser for Ford (profit wise) and sold to maintain/increase their CAFE fuel avgs! I'm sure they're losing money on them, mine for sure since the sticker was 38K and they sold it to me for 31K The more I drive it the more I like it, but there's a lot to learn about these cars! Quote Link to comment Share on other sites More sharing options...
stevedebi Posted November 17, 2014 at 05:48 PM Report Share Posted November 17, 2014 at 05:48 PM (edited) Murphy, great explanation and JJ I completely agree, it's amazing the technology in a $40K car. This MUST be a loser for Ford (profit wise) and sold to maintain/increase their CAFE fuel avgs! I think it is more to meet the CARB requirements that a certain number of vehicles be of a certain zero emissions level. Here is CA, there is a requirement for that, and I think a couple of other states may have followed suit. Otherwise the car doesn't make any financial sense. If it were CAFE, they could simply push smaller ICE cars that get pretty good MPG. That is also the reason for the recent FFE price drop. Edited November 17, 2014 at 05:49 PM by stevedebi Quote Link to comment Share on other sites More sharing options...
bruc2y Posted November 19, 2014 at 02:58 AM Report Share Posted November 19, 2014 at 02:58 AM Someone just please tell me what ICE is. I just joined. Lot of terminology to learn. Yes, I just love this car. I will not get used to it, which makes each drive unique. Quote Link to comment Share on other sites More sharing options...
Rhynri Posted November 19, 2014 at 05:34 AM Report Share Posted November 19, 2014 at 05:34 AM ICE = Internal Combustion Engine. The boom-boom-splody bang-bang noisemaker heat-waster under the hood. (Sorry, couldn't resist.) Quote Link to comment Share on other sites More sharing options...
bruc2y Posted November 21, 2014 at 01:52 AM Report Share Posted November 21, 2014 at 01:52 AM LOL! Rhynri, Thanks. I can tell this forum is going to be a lot of fun. Quote Link to comment Share on other sites More sharing options...
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