Speak EV - Electric Car Forums banner

1 - 9 of 9 Posts

·
Registered
2014 Leaf 24Kw
Joined
·
90 Posts
Discussion Starter #1
I mostly drive my Leaf 24 alone. However I am considering driving my folks and aunt to their holiday cottage in The Lakes just beyond Keswick.

It will need two hops and I will be checking Instavolt status prior to leaving at Booths Carnforth (the halfway split, 44 miles each hop) and of course Keswick to get me back! There is a possibility I could granny charge it at the destination if I get a free night accommodation out of it!

However... the car will have 4 adults and luggage...

How will this affect my range?

Cheers!
 

·
Registered
Joined
·
1,984 Posts
It will effect the range but not that much as you might think, the extra power is used accelerating the added mass only. once at speed the consumption will be much as usual. As a bonus regen will be greater due to more mass to slow down.
More power needed to climb hills but more recovered coming down the other side.

A leaf owner will give some figures, the above is generic for EV's
 

·
Registered
Joined
·
7,308 Posts
.......... the car will have 4 adults and luggage...
How will this affect my range?
Apparently not by much.

I use "Abetterrouteplanner" a lot so I entered a fictitious journey by a Leaf 24 from Rufford, near here, to Keswick - a trip of 88 miles. First with just a driver aboard and then with an extra load of 400 Kg. The settings were for a nice mild day driving at a max speed of 65mph - dry roads - no wind - and 10 C temperature. If any are worse than this then the range can reduce a lot as you know - so take care when planning such trips in inclement weather. If the day is at the freezing point, with rain and a headwind you might want to reconsider the use of a Leaf 24.

Assuming a nice day ABRP recommended a stop at the new Polar Hub at Lancaster Park and Ride ( right by J34 of the M6 ) to take on board an extra 15 kWh of electrons and enable the journey to end with a spare 20%.

With just a driver on board, it predicted a car usage of 288 Wh/mile.

Changing the settings to include 400Kg on board but with the same other settings, it then asked for 17kWh's to be added at Lancaster to still end with 20%. Or just load 15 kWh's and end up with 18%.

With an extra 400Kg on board, it would use electrons at a rate of 293 Wh/mile.

So the impression is that you would only lose a couple of kWh's by filling the car with people and luggage. ( In decent weather conditions)

In dreadful weather conditions plan to also stop at the excellent Tebay Service Station. ;)
 

·
Registered
2014 Leaf 24Kw
Joined
·
90 Posts
Discussion Starter #4
Thanks!

Same distance from the top of Southport where I am :)

Was planning to stop at Booth's Carnforth then Keswick as all the Booths supermarkets seem to have InstaVolt. Could even split into 3 and stop for less time at Windemere.

I'm doing A6 instead of M6 as that is their preference which means 50mph tops mostly...
 

·
Registered
Joined
·
1,156 Posts
Given that the unladen weight is well over a tonne - and fast approaching 2 tonnes - the additional weight of 4 people + luggage won't be a huge percentage increase.
 

·
Registered
Joined
·
167 Posts
Ultimately, the only additional losses are a small amount more rolling resistance and the difference between the extra energy used to accelerate the added mass and that which can be recovered by regeneration. Not a massive drop in range, maybe 5-10%.
 

·
Registered
Joined
·
4,408 Posts
In theory the range penalty of adding extra passenger weight should be considerably less per extra Kg in an EV than an ICE, due to regenerative braking.

In an ICE when you add more weight you consume more fuel to accelerate or climb hills, however when you decelerate that extra weight using friction brakes that extra energy is thrown away as additional heat in the brakes (or engine radiator for engine braking), and descending a hill in an ICE where air/rolling resistance isn't enough and you need either brakes or engine braking to keep your speed under control is also throwing away additional energy.

With regenerative braking in an EV slowing down a more heavily loaded car returns more regenerative energy, as does descending a hill at a controlled speed using regeneration.

Of course there's more to it than that - round trip regeneration is at best around 70% efficient, (kinetic energy of the car, rotating the motor acting as a generator, charging the battery, then using that energy to propel the car later) and regeneration only helps when you need to decelerate or descend a hill. Different EV's also have different maximum regeneration limits - if your EV only has relatively weak regeneration then you'll be forced to use the friction brakes more and lose some of the benefit. A car with stronger regeneration can probably still decelerate quickly or hold itself back on steep hills even when more heavily loaded so will be at an advantage here.

If you assume a round trip of efficiency of 70% and assume that you can do most of your braking/deceleration using regeneration (this may be optimistic) then potentially the consumption impact of adding additional weight is only about 1/3rd of what it would be in a vehicle without regeneration like an ICE.

This is actually really important as this helps an EV carry it's own weight efficiently. Batteries are very heavy and one of the criticisms of EV's vs ICE is that the battery makes for a heavier car within a given class of car - and this is generally true at the moment, however the penalty in efficiency is not as bad as it might seem at first as the benefits of regeneration mean that you get significantly less penalty per extra Kg the EV goes beyond the weight of a comparable ICE.

This may be part of the reason why EV efficiency (miles/kWh) doesn't bear such a strong resemblance to the size of the car as it does with ICE where bigger, heavier higher performance ICE cars invariably are less efficient than smaller lighter ones with smaller engines.

I think it's fair to say that extra passenger load has a fairly minor perhaps even insignificant effect on range for an EV - much more important is whether you drive smoothly or aggressively, (aggressive braking will require more friction braking negating some of the benefits of regeneration) maximum speed, and heater use.

I frequently drive my Ion either with just me in the car, two people or three people and I notice very little difference in driving efficiency or range between the three - the effect is smaller than just knocking a few mph off my maximum speed, and doing say 55mph instead of 60mph. So I don't even give a second thought to how many people will be in the car, but I do think about anticipated road speeds and heater use.

Of course if you go adding extra load in the form of roof boxes or trailers you would destroy the range due to aerodynamic changes, but that's a separate issue to weight increase.
 

·
Super Moderator
Joined
·
7,532 Posts
between 1 and 2 miles of range per person, dependant on the weather and their mass.
 
  • Like
Reactions: Woodulike

·
Registered
Joined
·
7,308 Posts
I drove a 7.5T Merc Truck for a while that had a weight sensor built into the rear suspension. If the truck was empty it restricted engine power by its mapping and added power incrementally as loads were added. The effect was that it was much faster when fully loaded than when empty.
 
1 - 9 of 9 Posts
Top