How fast – how far!

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This topic contains 25 replies, has 7 voices, and was last updated by  Dexter1979 2 years, 6 months ago.

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  • #13349

    sandy
    Participant

    Generally speaking I drive 6miles to work and the same home each day, speed ranges from 45mph to 60mph over that journey. On a busy day its 45mph or a late finish I can speed home at 60mph.

    So how may this affect my range? I’ve got a fairly equal uphill/downhill drive all on B roads pretty much.

    On a workday there are a couple of free Council charge points at the building next door, so range anxiety won’t really be an issue i’d expect, so I’ll probably slip into the habit of driving to work in as short at time as possible.

    Also say I decide on a Jolly to Edinburgh, that’s about 35miles from my house in Fife, say I was off to the Zoo with the family, chances are I’ll want to zoom through, If I drive at 70mph the whole way will I wipe out most of the charge? Might be an issue if there is a point I can plug into near by but best to know these things up front.

    I don’t mind moderating how I drive to get range when necessary but generally I’d like to think i’ll be zipping around as normal without a care in the world charging at night (generally I do less than 50miles a day at weekend).

    Has anyone done a basic calc of range based on speed for me to look at? I accept it will be rough and ready. But when I see range of up to 120miles I start thinking but at what speed? If I have to limp along at 20mph I’d rather know range at 55mph and 65mph seeing as those are probably more representative of every day driving for anyone that ventures out of the city limits so to speak.

    #13351

    buchanan101
    Participant

    Yes you will wipe out charge at 70mph…

    I think the car uses charge per mile fairly consisently up to between 40mph and 50mph, then aerodynamics take over. Drag is proportional to speed squared, so there is 3 times more drag at 70mph than at 40mph.

    You won’t get 70miles at 70mph; you most probably would at 55mph.

    What you want to keep an eye on when driving is the energy usage in miles per kwH (mpkwh selectable on the right stalk – reset it for a trip and keep an eye on it). If you keep this at 4 you will get 88 miles range. i.e. multiply by 22 (which is the battery capacity in kWh). This is better than looking at the range indicated because this only tells you how you drove BEFORE the most recent charge – it muliplies yesterdays consumption rate in mpkwh by 22 to give today’s estimate. It’s pretty poor really – it doesn’t even take in to account outside temperature today – which it could find from Tomtom..; At this time of year it’s only showing between 60miles and 70 miles range every day for me, but I know if I kept the speed down, I could get over 80miles… I’ve driven mixed roads, with some motorway at around 55mph to 60mph (nice to keep ahead of the lorries) and had 4mpkwh showing, so 88miles range.

    Display goes a lovely reddish purple when you do 70mph…

    You’d probably get to the zoo and back at 55mph in winter. DOn’t know what the aircon does to consumption!

    #13358

    sandy
    Participant

    My plan, not sure if it will be at all possible, would be to drive the car as ICE like as possible, generally speaking in my short commute, and if I was only going say 30miles each way. Happy with a 60mile range with no charge.

    If I was pushing the boat out, and say doing a holiday trip. I.e done Aviemore a few times, might again. I’d probably stop at Pitlochry where there are chargers, probably more of a top up while we are here having a picnic than a top up out of necessity.

    I appreciate if I want to go big miles I’ll have to drive sensibly and fairly slowly. I did a quick guesstimate of the mileage of my current car 100k and how far has been traveled outside of Fife, and its probably less than 10% over 12 years. Furthest the car has ever been was Alton. So the ZOE would be for my normal commute, and occassional 30-ish mile trips to Dundee/Edinburgh. Maybe the odd long haul if i’m feeling brave but more likely we will go holidaying in my partners B-Max with turbo nutter b’stard 1 litre engine.

    #13359

    sandy
    Participant

    Also I plan on garaging the ZOE if I can make enough space in the garage, so it should take a good charge in a modern warm garage in winter…. assuming I can squeeze the old mini up enough for the ZOE to fit.

    #13361

    Big277wave
    Participant

    Take a look for Trevor’s Zoe range predictor app on the Android and Apple app stores. You can enter speeds and state of charge and it gives you a predicted range.

    I drive about 5 miles to work, slight incline to get to work +22 meters altitude difference although there is a small hill in the way. Most of the distance is on the A40 at 50MPH on the way to work. Typically I use 1.2KWH getting to work with 0.1KWH of regen and 1.0KWH on the way home with 0.1KWH of regen, so 1.1KWH and 0.9KWH respectively. As the prevailing wind is from the west, I’m usually heading into the wind on the way to work and it’s a following wind home + home is usually a bit slower. Heating energy varies. When it’s been around 0 C I’ve been using 0.3KWH per trip, when it’s warmer this rapidly drops so usually 0.1 -0.2KWH on the way home. Most of the energy is used warming the car up so the heating energy used on longer trips is proportionately a lot less. For a couple of hour trip on a 3 degree day I used about 1KHW for heating. I usually have the heating set to 21 degrees and use auto.

    On your work trips you will probably only have to charge up a couple of times a week. For best battery life resist charging when you have sufficient range left. The range meter usually gives a reasonable estimate of your range left . Short trip will reduce your predicted range as you use proportionately more energy for heating so you tend to gain range when you go on longer trips.

    #13364

    buchanan101
    Participant

    Not sure how much the temp affects the amount of charge the batteries will take.

    I suspect the charging may be a bit more efficient (and therefore quicker) when warm, but I’m not sure you will squeeze any more in.

    #13369

    Big277wave
    Participant

    You don’t really squeeze any more in when it’s warm the issue is the other way around, when it’s cold the internal resistance of the battery rises so you loose more energy in the battery when discharging it at high rates. The car takes longer to charge the battery when it’s cold. You use more energy for heating and the air is thicker at lower temperatures so there’s more wind resistance. In winter you tend to use the headlights and wipers a bit more but their consumption it relatively small compared to traction. All of these factors reduce the range a little.

    #13378

    buchanan101
    Participant

    Hadn’t appreciated the density of air part. It drops by around 10% from 0°C to 25°C; the reason why the Olympic velodrome was made to run hot! Supposedly a 1.4sec advantage over 4km with raising the temp from 20°C to 25°C.

    #13379

    Big277wave
    Participant

    Pilots are very aware of it, the lift generated by the planes wings drops in high temperatures. Sailors say add a wind speed in winter i.e. a force 6 wind feels like a summer force 7 in low temparatures.

    #13385

    sandy
    Participant

    Great app find. I’ve got a Blackberry Fortunately its the Z10 so can do android apps.

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