most efficient charging speed

[Titan]

OK, with all this chat about Charge Mode (CM) and Save Mode (SM), battery capacities, graphs, etc., I'm still non the wiser as to whether there is a "best speed" at which to engage and run CM. Has one of the boffins on here been able to interpret the data and graphs to arrive at a speed (or range) one should travel at if using CM. I'm less concerned about SM, being more interested in what speed I should travel at to get best mpg while on the fast sections of road with CM. I'm presuming it's not 70+ but can't fathom whether I should be driving at 40 / 50 / 60 in parallel or series mode.

Thanks muchly.

 

[jaapv]

The car works that out for itself. The only things you need to tell it whether you ar going to cruise over 60 MPH or the motorway (AKA "save" ) or will need maximum charge in the future (AKA "charge").
Leave the strategies to the experienced last drop savers, I would say.

The concept of the car is to be driven with as little user input as possible.

 

[jdsx]

The car works that out for itself. The only things you need to tell it whether you ar going to cruise over 60 MPH or the motorway (AKA "save" ) or will need maximum charge in the future (AKA "charge").
Leave the strategies to the experienced last drop savers, I would say.

The concept of the car is to be driven with as little user input as possible.

But it would be interesting to know/speculate, would it not :?: I think that's what forums are for

 

[Titan]

But that's the point of tho thread. If I'm going to be traveling on the motorway and I need to charge, what speed should I travel at for maximum efficiency?

 

[maby]

But that's the point of tho thread. If I'm going to be traveling on the motorway and I need to charge, what speed should I travel at for maximum efficiency?

Do you need to charge? Recharging the battery significantly on petrol rarely makes much sense in terms of overall running costs. If you are going to be doing a lot of hill climbing, or are going to enter a zero emissions zone, you will need charge in your battery, but it is generally better to use Save to retain the charge you got from the mains than it is to burn petrol to charge the car. Since there are few if any zero emissions zones around here at the moment and Britain is a relatively flat country, there are few occasions when you actually need to charge while on the road.

 

[Titan]

But that's the point of tho thread. If I'm going to be traveling on the motorway and I need to charge, what speed should I travel at for maximum efficiency?

Do you need to charge?

In preparation for towing a caravan. I appreciate that just letting the battery run flat and then have the car do its thing is the standard practice but if towing a 'van I'm going to need grunt. Now obviously in UK, max speed towing is 60 / 50 but there will be times when having parked up the 'van I'll be driving around and I just wondered what to do about recharge.

 

[jaapv]

But that's the point of tho thread. If I'm going to be traveling on the motorway and I need to charge, what speed should I travel at for maximum efficiency?

In general? The lowest speed compatible with safety, like any other car.

 

[anko]

The question is not "what is the most efficient speed to drive at", but "what is the most efficient speed to charge at" Given the fact that your driving speed is somewhat dictated by circumstances, it translates to "what is the best moment to charge".

Although it may be true for the PHEV (in spring or autumn time) I doubt that normal cars have their best efficiency at the lowest possible speed. At very low speed / engine load, the engine becomes so inefficient in producing mechanical output that this may nullify the gain of reduced air resistance. Compare driving 100 km at 1 km/h versus at 100 km/h. The first will take the amount of fuel needed to let your engine idle for 100 hours plus a little bit. My guess is that this is way more than what you need to drive 100 km/h during 1 hour. Just imagine the amount of heat produced in 4 days and 4 hours!

I know Jaap said "in general" and my example is about extremes, but I still think that even in general, cars are configured / designed to have their best efficiency at a higher than the lowest possible speed.

Why did I say "(in spring or autumn time)"? When you request heat or cooling, trip duration has an impact on the amount of energy needed to travel a specific distance. Where waiting for traffic lights is killing for the efficiency of normal cars (without S&G system), it is not for the efficiency of the PHEV. Unless you run the heater or air conditioner.

On the counter side, I would like to think that a PHEV with a depleted battery is more efficient at 65 km/h (in parallel mode) than it is at 63 km/h (in serial mode).

 

[Titan]

I would like to think that a PHEV with a depleted battery is more efficient at 65 km/h (in parallel mode) than it is at 63 km/h (in serial mode).

I think, after reading around the subject a bit more, that is the conclusion I have come to. Parallel mode seems to make more sense although not so fast that all the energy is going to drive.

 

[user 258]

I doubt that normal cars have their best efficiency at the lowest possible speed.

I know Jaap said "in general" and my example is about extremes, but I still think that even in general, cars are configured / designed to have their best efficiency at a higher than the lowest possible speed.

Hi,
In my opinion normal cars give their best fuel economy when driving at the lowest speed they can comfortable manage in top gear. This is so the engine rpm's can be as low as possible and the lowest rpm a particular car can pull varies on many factors. Diesel engines are usually best around 1500rpm ish.
Kind regards,
Mark

 

[duplo]

If the ICE isn't driving the wheels then I'd assume it was running at its most efficient charging RPM automatically, therefore isn't the key thing to drive at the most efficient speed for the electric motors so they drain the least power so charging will be as quick as possible and transmission losses minimised?

From what I have read that is theoretically around 40mph/60kph which is the peak torque point for the electric motors.