Speak EV - Electric Car Forums banner

1 - 20 of 23 Posts

·
Registered
Joined
·
379 Posts
Discussion Starter #1
I make a 700 mile round trip about 4 times per year and am currently making 4 rapid charge stops per 350 mile run. The longest leg between charges is about 88 miles but generally the are about 70 mile legs at a speed of 55 to 60 miles per hour.

I was thinking about increasing the average speed to around 60 to 65 and increasing the number of stops to account for the loss in distance because of the average speed.

I'd be interested to hear from anybody who has done trips at 60 to 65 miles per hour and how this affected the number of charging stops and total journey time.
 

·
Registered
Joined
·
771 Posts
I would be thinking the correct speed is the one that gets you to the next charger at zero charge. There can be no such thing as average as the wind direction will have a particular bearing. In a 10 mph wind then 70mph down wind has the same drag as 50mph up wind. You need to build this into your thinking and this may result in you going faster down wind to save time but it could if possible allow to use one less stop. Conversely you may have to go slower to not increase the charging stops. The other biggy is whether the journey is in winter or summer as the range could be 20% different before the heater.
If i was really into a very strong headwind i would tuck in behind a lorry (not one thats come off a building site or tip -too much risk of cracked windscreen) at least your min speed is the 56mph.

The answer is probably to start a leg at say 56mph and see if the GOM is above the distance required and then increase the speed to 60mph to see what you have then and if it stays consistent and above the distance required. Only increase the speed further when you get nearer the charging point and you can stay relaxed.

You say 4 charge stops so does that mean 5 amounts of full charges are being used. I would be looking to reduce that by 1 . 350mls/5charges = 75mls 350/4 = 87.5 mls
 

·
Registered
Joined
·
44 Posts
I can easily get 4 miles/kWh at 60-65 on motorways. I use cruise control, others use speed limiter. For me it's more relaxing with cruise. I'd say you would be able to increase your speed to 60-65 without impacting on those charges. One good trick is to watch the miles/kWh display, and slow down if the average starts to drop. How you drive makes a real difference..
 

·
Registered
Joined
·
2,220 Posts
The answer is probably to start a leg at say 56mph and see if the GOM is above the distance required and then increase the speed to 60mph to see what you have then and if it stays consistent and above the distance required.
Remember to take into account any uphill or downhill sections of route you have still to travel as they can impact on the available range over that section. From experience with my 24kWh Leaf, I don't trust the GOM, but instead note how far I am getting for each 10% reduction in the State of Charge and calculate my remaining range accordingly.

If you are doing the route regularly, you will probably have an idea of the %SOC normally used on each section of route, and have in mind minimum %SOC targets for each waypoint. If on reaching a particular waypoint you have more %SOC than your target you can speed up, and if your %SOC is below your target you know you will need to slow down.

It would be interesting to find out if the time saved by travelling faster exceeds the extra time spent adding an extra charging stop.
 

·
Registered
Joined
·
379 Posts
Discussion Starter #5
It would be interesting to find out if the time saved by travelling faster exceeds the extra time spent adding an extra charging stop.
This is what I wanted to find out - can I gain a time advantage by upping my speed and will this be negated or improved by shorter charge stops. I can do a test run at 60 - 65 and see what % decrease I get over a measured distance, then try and calculate it out over the current 4 stops.
 

·
Watford FC Supporter
Joined
·
103 Posts
This is similar to Maths questions when I was at school so one should be able to work it out in theory assuming a given charge rate. Of course there were no EVs then apart from milk floats and it was a long time ago otherwise would give you a quick answer.

Having done long trips in a much lower range EV had presumed the slower you drove the quicker you get to the end destination but perhaps that is wrong.
 

·
Registered
Joined
·
109 Posts
It seems logical that even with the time needed to slow down, find the charger, set it going, do the charge, unplug, drive off; then the speed of a rapid charge is quite a bit faster than you can legally drive and so frequent charging and fast driving would be quicker than slow driving and infrequent charging over a distance. Whether that is true in practice is the crux of your question. I think the crucial thing would be to go as fast as you can to get to a charger as close to 0 SOC as you can. A non-working charger would really spoil your journey though!
 

·
Registered
Joined
·
244 Posts
Remember at 60mph you cover 1 mile every minute so to up your speed from 55 to 60 means you arrive 5 minutes earlier, not a huge gain.

I do a trip with 2 stops both around 70 miles apart and travel at an indicated 66mph so probably a true 60 and arrive with plenty of range. I normaly charge fo 30 minutes at each stop. As others have said just watch the range especially in a head wind.
 

·
Registered
Joined
·
848 Posts
Assuming the chargers exist, one will always get a higher average speed by driving faster and charging more often. Of course this also costs you more cash. But it's not a huge difference in the Leaf, you might see your average speed (including charging) rise from high 30's to low 40's mph. This is because of the large penalty in efficiency going from, say, 50 to 70mph- roughly 50% more energy per mile.
Maybe it feels like you're better off driving more slowly even when you're not, because you spend much more time in the car!
 

·
Registered
Joined
·
2,220 Posts
This is what I wanted to find out - can I gain a time advantage by upping my speed and will this be negated or improved by shorter charge stops.
This can probably only be sorted out by trial and error - you have your current four stop schedule, and probably know the fastest speed you can use between each stop to arrive at the next stop with just a reasonable safety margin left in the battery (and the overall time for this journey). Now work out a five stop schedule, which will allow you to drive faster between the stops, and see if you get to your destination any quicker. (You may have to watch battery temperature with more Rapid charges and faster discharging).

For the 24kWh Leaf there is also the question of how full you should let the battery get, as its charging speed reduces as it gets towards full charge, but I understand this is not such a problem with the 30kWh Leaf
 

·
Lettuce Leaf early to be sure of arriving on time.
Joined
·
918 Posts
I don't think it would make a lot of odds. Our long journeys are all done at 65-75mph (displayed - 60-65 actual) and we do legs of 60-70 miles between charges. That's what we are comfortable with: driving slower could be inconsiderate/dangerous, we think, and we like to keep a margin for plan B charging, diversions, etc. Rule of thumb: drive for an hour, charge for half an hour.

Having said that, you could make a case that the more often you charge, the more you will be delayed: more visits to MSAs mean more waiting at occupied chargers, more faffing about with stupid apps, more logging on to wifi, more calls to helplines, more chats to interested coach passengers and so on.

I reckon that an MSA stop costs you 10 minutes extra, besides whatever time you charge for, compared to flying past with a fullish tank of petrol.
 

·
Registered
Ion, Kona, 16 + 18 + 2020 Soul EV
Joined
·
2,712 Posts
From experience over our last few long trips the trick seems to be that 3 short stints at 3 rapids while you are drawing a high rate is quicker than 2 long stints on 2 rapids. Assuming you have the rapids on route. Speed of 65mph wherever possible.
 

·
Registered
Joined
·
279 Posts
you can answer this question mathematically, but in reality it's the distance between rapids which determines if travelling faster or slower on any given journey is faster
 

·
Registered
Joined
·
848 Posts
you can answer this question mathematically, but in reality it's the distance between rapids which determines if travelling faster or slower on any given journey is faster
Thats true if the rapids are far apart compared to your range, however on most motorways there's enough Chademo rapids that a Leaf30 doesn't need every one.
 

·
Registered
Joined
·
758 Posts
This is what I wanted to find out - can I gain a time advantage by upping my speed and will this be negated or improved by shorter charge stops. I can do a test run at 60 - 65 and see what % decrease I get over a measured distance, then try and calculate it out over the current 4 stops.
Assuming the chargers exist, one will always get a higher average speed by driving faster and charging more often. Of course this also costs you more cash. But it's not a huge difference in the Leaf, you might see your average speed (including charging) rise from high 30's to low 40's mph. This is because of the large penalty in efficiency going from, say, 50 to 70mph- roughly 50% more energy per mile.
Maybe it feels like you're better off driving more slowly even when you're not, because you spend much more time in the car!
you can answer this question mathematically, but in reality it's the distance between rapids which determines if travelling faster or slower on any given journey is faster
Thats true if the rapids are far apart compared to your range, however on most motorways there's enough Chademo rapids that a Leaf30 doesn't need every one.
The biggest factor is the location and availability of the charges - you clearly have a set pattern you use for that journey, presumably with some contingency. So if stop 2 is 70 miles away, but contingency is 85 miles away then you have a plan B - but plan B only works if its available, and stop 3 now works out at a favourable distance rather than using you original stop 3 with a shorter leg.

If there were reliable Chademos every 20 miles than you probably could speed up/slow down to suit the day of travel.

My longest regular journey is 135 miles, involves one stop but i only have an option of two rapids, one at 80 miles and one at 95 miles - i try to use the latter, as its free vend, but always have that risk that i could be turning back to the first if there's a problem ! Yes there are 3kW within 5 miles of the furthest charger but who uses those unless you are parked up all day
 

·
Registered
Joined
·
44 Posts
I went to Lancaster today, 64.1 miles. I drove at 70 indicated wherever possible on cruise/eco B. Twice I cut out of eco and steamed away from bunching traffic(expensive but fun). Got there with 20% remaining (from 100%). Came back down after topping up to 80% at Lancaster south (60 miles) cruising mostly 60 indicated with some spells of 65 and had about 30% left. I'm sure you could do your 70 mile legs at 65 no problem. The 88 mile leg might be touchy..
 

·
Registered
Joined
·
848 Posts
The biggest factor is the location and availability of the charges - you clearly have a set pattern you use for that journey, presumably with some contingency. So if stop 2 is 70 miles away, but contingency is 85 miles away then you have a plan B - but plan B only works if its available, and stop 3 now works out at a favourable distance rather than using you original stop 3 with a shorter leg.

If there were reliable Chademos every 20 miles than you probably could speed up/slow down to suit the day of travel.

My longest regular journey is 135 miles, involves one stop but i only have an option of two rapids, one at 80 miles and one at 95 miles - i try to use the latter, as its free vend, but always have that risk that i could be turning back to the first if there's a problem ! Yes there are 3kW within 5 miles of the furthest charger but who uses those unless you are parked up all day
Many areas have much better coverage than that already. For example there are now 20 Chademo chargers on or very close to the M4 from Heston to Swansea - a distance of less than 200 miles. I realise not all motorways are as well served, I recently came across a CCS-free zone on the M5.
ZapMap is consistently reporting around 10 rapid installs a day so far in 2018 so we're much better off than we might think for rapids in the UK in key corridors. There's almost as many non-rapids going in too.
Reliability, contactless payment, CCS and AC provision do need to be addressed of course, as well as greater numbers of rapids at each location, as demand picks up.
 

·
Registered
Joined
·
379 Posts
Discussion Starter #19
I have just managed to do two 10 mile runs at 60 - 65 miles per hour and both used 1% of the battery capacity per mile. I will now be able to work out which approach will best suit me on my 350 mile journeys.
 

·
Registered
2020 Vauxall Corsa E
Joined
·
873 Posts
Personally I keep one eye on the SOC %age and the other on the Sat-Nav miles-to-go (and my third on the road ;)), estimating the %age I expect to have left and my next charge point. Ballpark being 1% per mile. I normally aim for about 20%, enough to get me to the next MSA if the charger is knackered/has a queue. If the estimate is higher, then I speed up. I don't usually pay much attention to the GOM. I believe it estimates based on yesterday's driving conditions, which are usually completely different.

But I know from experience, for example, that approaching Tibshelf from the north will cost me about an extra 5%, because its uphill for quite a distance.
 
1 - 20 of 23 Posts
Top