How should I drive from a cold start?

I have a similar problem with a 1km dirt driveway where I must limit my speed to 20-30 km/h. The engine is in warm up mode and not driving the wheels (it's essentally in EV mode) so using lots of fuel for the distance travelled. The engine is programmed to fast idle until it reaches about 60 deg C. The only way to economise is to drive fast enough so that EV no longer operates and the ICE is forced to drive the wheels. However that isn't possible for either of us.

 

Buy rally wheels and go for it!

 

Starting from cold is the same as any other ICE vehicle: with gentle throttle. The gentlest you can drive with the ICE is slightly past the halfway point on the HSI.


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The engine will not go into EV mode until the coolant temp is around 110F, and then it will not be consistently available. Above about 130F, glide will work pretty much on demand. The engine is driving the wheels and charging the battery during warm-up, as you can see with an OBD device. There are a lot of threads on warm-up...you can try a search to see what comes up.

 

Get the block heater?

It won't eliminate warm-up, but will get you through it faster. A couple of hours plug-in will bring your coolant up to about 35 deg C. And subsequent warm-up is very fast, as the coolant circulates, evens out.

 

I just punch it when I start out in the morning(staying out of PWR on the HSI). But I have a roughly 950 foot descent from my house to my job site in the morning, so lots of regen while the electric motor drains the battery during ICE warmup.

How far is your commute?

 

You could always just let your car "warm up" like they did in the 70's/80's

 

I know many people who still do this. Although in some cases they like to have the cabin warm, literally, during cold weather. Still a tremendous waste.

 

That isn't actually the case, though it seems a reasonable assessment.

Heavier on the throttle won't burn up gas the same way. You'll get heavier draw from the battery-pack instead, something not possible from a non-hybrid or even one lacking a power-split-device.

Remember, the system is working hard to optimize both fuels. That allows for some flexibility we demand changes.

 

If your question is specifically about driving, then I suspect you will find little measurable difference between techniques in this scenario (if any, they will be overwhelmed by other variables).

This is because you are effectively asking about how best to drive in Stage 1 of the warmup cycle at up to 20 MPH. I also live in a 20 MPH zone in the UK. In S1 at low speed you are effectively driving in EV, although you may not realise it. ICE RPM is typically fixed at 1280 and will only rise above that if you demand more power than the traction battery has been programmed to deliver. On the flat below 20 MPH this is unlikely. Your best driving strategy is to conserve as much energy as possible in forward momentum, therefore, this means anticipating or avoiding traffic and avoiding stops.

Getting to S2 is extremely predictable and, as others have posted, is the moment the coolant temperature hits 40C. At this point, you will experience the first ICE shutdown. After this, you can start P&G , etc.

Therefore, I expend most of my efforts getting to S2 as quickly as possible. These are mostly non-driving strategies. Starting at a higher initial temperature works (e.g. car in garage with heater, as engine block heaters are rarely used in the UK). Keeping all unnecessary electrics off until S2, including any demand for cabin heating (I keep this off till S3).

My logic is that if ICE is on in S1 primarily to get the coolant temp to 40C, then let the car do its job and avoid drawing any energy away from that aim!


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Forgot to add that I also use grill block. Monitoring coolant and inverter temps using SGII I have found no problems keeping the lower grill block all year in London. Even in mid summer, I can complete my 30 min commute to work without coolant temp exceeding 55C, therefore still in S2.


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My logic is that if ICE is on in S1 primarily to get the coolant temp to 40C, then let the car do its job and avoid drawing any energy away from that aim!

This is my strategy as well. I figure the car knows what it's doing. I usually hit the power button first thing in the morning, let it idle for about a minute, then go. A warm engine is more efficient. The oil thins out and actually lubricates, the parts swell and fit better. I haven't noticed any drop in mph by doing this. Your probably not gaining much by driving a dead cold engine except wear.

 

So you always accelerate to maximum speed?

 

No I just drive it like I normally. By the time I get rolling good the ICE is already shutting off and I'm in that normal running mode. By the time I'm at the end of my street I'm usually in the mode where the only red arrow is charging the battery and, as far as I know, I'm gliding with no ICE showing going to the wheels.

Don't get me wrong here anyone. I'm still a newbie and take Rob and the other Gurus Advice to heart. I'm just experimenting with what works best with my particular driving emvironment which maybe why I haven't hit 60mpg on a tank yet.

 

Sorry I was just joking about mph instead of mpg in your post.

 

I know. I posted a wry smiley face but it didn't work with my iPhone. No worries I got the joke.

 

This is an idea that gets a lot of posting time, but is not correct. My ScanGauge says that the battery is being charged during S1, not discharged. If someone has a different experience, please post it. The engine has to run during this part of the warmup, and rather than waste the energy, the Synergy system uses it to charge the battery.

 

S1 does charge the battery, but very slowly. I think typically, I might see about 6 Amps into the battery in S1; at S2, when it starts really charging the battery, it'll do more like 20A. If you have the HSI more than about 1/3 of the EV half of the bar, then it's probably drawing from the battery rather than charging it.

My personal recommendation would be a combination of many things;
1. If you need to get out of your driveway/garage, and your car is warm enough (~68°F), start off in EV. Driving at 20 mph is slow enough that S1 will provide enough power so that you don't discharge your battery too much. You can either let it kick you out of EV when you pass 10 mph, or turn it off yourself when you start down the road. Don't start off in EV if you need to accelerate a lot (e.g. 35 mph or more), because for the first minute, the engine produces very little power, and you're mostly running off the battery.
2. Accelerate fairly slowly, if there's no traffic around. Maybe 1/4 of the HSI or so, if you can stand it, for about the first minute.
3. After the first minute, do whatever you need to. When the engine coolant gets to 40°C, the car is VERY enthusiastic about turning off the engine if you let off the accelerator, so if you can glide for a while (e.g. if there's a nice long downhill), you might get lucky and catch it at that temperature. (By glide, I mean nothing lighting up the HSI - so a very light touch on the accelerator to cancel out the small regen from coasting.) Once it starts up again, though, it's not very likely to turn off again until it reaches 68°C. You could always buy a Scangauge or some other tool to watch the coolant temperature, but the gas you save will almost certainly never pay off the cost of whatever you buy - it's more just a gadget for you to enjoy, if you wanted it for some other reason too. On a warm day, I'll hit 40°C in as little as a half a mile from a cold start.
4. If you do get the engine to turn off while moving, you might consider using EV - the EV button won't work at 20 mph yet, but you can keep the HSI below the halfway point and avoid turning the engine back on. If you need to accelerate or go up a hill, though, it's better to use the engine instead - use the battery power only if you have a very low power demand during this time. The idea here is to use battery power, and let the engine warm up later, when it would have to be on for you to accelerate and drive at higher speeds anyway.
5. If you're trying to get the engine off with #3, leave the cabin heat off. It'll slow you from reaching warm operating temperatures, and below a certain temperature, it will run the engine ONLY to provide heat, even if it has no other reason to run the engine.

 

I think the OP might have the same problem I have that due to the slow drive in, the vehicle EVs and there is little battery charge left to EV out with. So you are left with the situation where on the out (warm up) trip the Ice is both charging and warming up. If you do have enough charge to EV out the ICE is using a lot of fuel to warm up but still not directly propelling the vehicle.