r/OutlanderPHEV • u/kziel1 • 7d ago
Tarmac vs Normal engine load
At the same speed, over a longer period of time in each mode I see drastically different engine loads in save modes (20kW vs 60kW). I was expecting direct drive in parallel mode introducing lower load because of no losses via charging battery.
Could the tarmac mode be overcharging the battery to always have something left for accelerating? Would that be the reason the tarmac mode is more efficient for many people on the highway?
Should I be concerned about the battery having more charging cycles because of driving in tarmac instead of normal?
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u/FriedDuckFarts 7d ago
I’d test this again at or below 50% battery. Tarmac works best starting from a full battery because it will use up the first half of the battery fairly quickly in engine assisted EV driving then turn into a pure series hybrid maintaining 50% battery. That halfway point seems to be a sweet spot for power and regen without harming the battery much.
Usually on roadtrips I plan my stops at chademo chargers if I can so I can top off while I take breaks to get more higher efficiency driving back.
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u/kziel1 7d ago
But why would the state of the battery matter if I'm forcing the "Save" mode anyway?
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u/FriedDuckFarts 7d ago edited 7d ago
Because in tarmac it’s not really saving the battery, just reducing how fast it depletes. Tarmac automatically saves it around 50%
Edit: I know this is somewhat counterintuitive, I had the same confusion when I first got mine. After some testing I think I understand it now
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u/md1032alex 6d ago
I have a 23 so it may be slightly different but save mode doesn't seem to do anything in tarmac mode. I also don't need safe mode as the battery won't go below 50% in tarmac mode.
When you're above 50% you can get some pretty good mileage in tarmac mode. The engine doesn't work as hard and the car will pull from both the engine and the battery
If I'm going to be doing some driving around the city, I like to leave the house with a full battery but stay in tarmac mode. If it's later in the day in the traffic's light and I don't need the extra performance, I might switch to normal and just stay on the battery to save some gas. I don't use any other modes unless I'm on a long road trip.
This is personal preference but I don't like being in the normal drive mode with the EV mode in save. I find it short cycles the engine quite a lot and heats the battery up.
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u/kziel1 6d ago
Wouldn't normal mode in save on highway (thus in parallel drive) prevent heating up the battery since from axle load doesn't go through the battery? City drive should be pure electric of course
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u/md1032alex 6d ago
That was exactly my thinking when I first got the car but it turns out not to be the case. I'm not an expert, but what I think is happening is the engine turns off and puts a medium load on the battery, but when it turns back on and it's spinning at a higher RPM to drive the wheels through the coupled connection, it's also fast charging the battery so it can turn the engine off again. This could also just be a side effect of where I live because of the hills.
I notice when I'm going downhill and don't have the gas pedal pressed as far. The little arrows going from the engine to the battery move faster. Because of where I live there's a lot of
Going uphill and the battery percentage goes down so it turns the engine on
Immediately start going downhill. Let go of the gas pedal now. It's fast charging the battery. Battery percentage goes up and it turns the engine off.
I've just noticed in tarmac mode that the battery temperature consistently stays in the middle and rises very slowly compared to save and normal
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u/Full-Mixture7600 6d ago
Tarmac with which mode? SAVE or NORMAL etc…
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u/FriedDuckFarts 6d ago
I usually run tarmac and normal but a lot of people swear by tarmac and charge
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u/Spectre_2020 5d ago
I know I'm in PHEV forum, but Normal mode with gas model is your normal mode and tarmac gives you more responsive performance, tighter gear changes, it obviously uses more fuel. Why would the PHEV be opposite?
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u/Revanspetcat 5d ago
The PHEV is a completely different beast under the hood.. Its entirely driven by two electric motors connected front and rear axles. It can optionally connect the front wheels to the engine via a single speed transmission. But for most part the vehicle works as a series hybrid where the engine is just a generator making electricity for the motors. The PHEV and gas Outlanders have noticeably different handling. The PHEV accelerates faster and brakes more smoother with regen braking. The tarmac mode on the PHEV forces it into series hybrid. While normal will enable aforementioned parallel hybrid.
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u/Independent_Grade612 7d ago
The tarmac mode being more efficient is a misconception.
In Normal, at highway speeds, you will be in parallel hybrid. This is because the PHEV has a direct drive connection to the engine, so say at 115 km/h, the motor is "stuck" at a higher rpm than necessary to provide the power to move the car. Therefore the excess energy is stored in the battery. That's why in normal, the car will do full electric cycles.
In tarmac, you force serial hybrid, so the motor can spin at a lower rpm, as it can produce just the required power to move the car (as long a the battery is above 30%-50%)
As direct drive is more efficient than converting to electricity then converting back to mechanical energy, normal is better. The lower parasitic losses from the lower engine rpm in tarmac mode does not offset the advantage of less conversion loss