EV general discussion

ICDP said:
Are you seriously saying it is impossible to place bags of cement into a caravan? Is there a law I have missed, either legal or scientific that states a caravan cannot hold some bags of cement?
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I assume he means structurally it can't hold the weight.

Its a bad example. you'd have have a van where there is no change in aerodynamics drag, or height of the vehicle then you'd see the difference.

Its all moot though as no one is driving a van and a van has the aerodynamics of a brick in the first place.

I'd guess EV drivers aren't trying to squeeze an extra 10% of range out by being lighter or driving really slowly. They'll just hit a charger for a top up, and add so much charge weight becomes irrelevant. Stopping for a few minutes on a long journey is mostly more practical.
 
b0rn2sk8 said:
Well a typically single axel caravan normally only has a payload of 150kg when empty regardless of size. That would take it up to it’s maximum weight per its chassis plate which it’s legal maximum weight. I think mines only 125kg.

So yes, you could put 150kg of cement in if you really want.

I’m not sure how that differs from the stuff you’d usually take when caravanning like gas bottles, food clothing, awning etc. You also have to account for any fitted accessories like a motor mover which is ~30kg, oh and a battery.
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Fair enough if you are being pedantic.

Replace the caravan with trailer. If the trailer is empty versus full of cement, which one will have the biggest impact on EV efficiency?
 
OspreyO said:
I assume he means structurally it can't hold the weight.

Its a bad example. you'd have have a van where there is no change in aerodynamics drag, or height of the vehicle then you'd see the difference.

Its all moot though as no one is driving a van and a van has the aerodynamics of a brick in the first place.

I'd guess EV drivers aren't trying to squeeze an extra 10% of range out by being lighter or driving really slowly. They'll just hit a charger for a top up, and add so much charge weight becomes irrelevant. Stopping for a few minutes on a long journey is mostly more practical.
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Yes and the same applies to any EV. Fill the same EV with people and luggage and the efficiency will be impacted.

We can see this with similar EVs with smaller batteries having higher efficiency.
 
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Weight - pulling a heavier car/caravan slowly up a hill uses more energy than aero benefits.
Aero - this has more benefit for efficiency when moving at speed along a normal road, than weight saving does.

Ride a heavy aero bike, in an aero position, Vs a light weight bike and the above is obvious.
 
SDK^ said:
Weight - pulling a heavier car/caravan slowly up a hill uses more energy than aero benefits.
Aero - this has more benefit for efficiency when moving at speed along a normal road, than weight saving does.

Ride a heavy aero bike, in an aero position, Vs a light weight bike and the above is obvious.
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But that was never in question. All things being equal, same EV, same road same driving style and conditions but adding more weight = overall decreased efficiency.
 
I just made the point the guy had a car full of stuff and a dog and seemed to suggest it actually made a difference in a steady speed motorway journey.

Not sure how we got into caravans and cement :)
 
Source ChatGPT:

“ Summary

The actual efficiency loss due to extra weight in an EV will depend on various factors, but a general estimate is around 1-2% increase in energy consumption per 100 kg of additional weight. This results in a corresponding decrease in miles per kWh (or increase in kWh per mile). For a more precise figure, specific testing under controlled conditions would be required.”

Don’t know how accurate it is but seems extremely low tbh.
 
Why does it seem low?

Once the wheels are moving your biggest enemy is the air and always has been. It only gets worse the faster you go.

If you are in stop start traffic the impact will be bigger but as we all know efficiency/range around town is almost irrelevant.

Realistically, long range towing is usually with a big trailer that had a huge impact on aero. Think horse box, caravan, car trailer, boat etc. even a bike rack with bikes materially impacts efficiency.

I can’t think of any realistic reason why you’d fill a trailer with bags of cement and tow it 150 miles other than for the YouTube clicks. You can get cement in almost any town.
 
z10m said:
Source ChatGPT:

“ Summary

The actual efficiency loss due to extra weight in an EV will depend on various factors, but a general estimate is around 1-2% increase in energy consumption per 100 kg of additional weight. This results in a corresponding decrease in miles per kWh (or increase in kWh per mile). For a more precise figure, specific testing under controlled conditions would be required.”

Don’t know how accurate it is but seems extremely low tbh.
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That’s what I said. Although I didn’t need to use chatGBT
 
b0rn2sk8 said:
Why does it seem low?

Once the wheels are moving your biggest enemy is the air and always has been. It only gets worse the faster you go.
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Indeed and with increasing weight you have more kinetic energy and therefore more regen when slowing down.

Air resistance is everything, especially if on a motorway journey.
 
So how much efficiency would I gain by swapping front number plate with a sticker on my model 3.?

Edit: ChatGPT tells me 1-2% so probably not worth it.
 
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Guys can we leave it now please. Let me just say that in the same vehicle under the same test conditions, the energy required to maintain the same speed, is higher with more weight. In physics nothing is free.
 
ICDP said:
Guys can we leave it now please. Let me just say that in the same vehicle under the same test conditions, the energy required to maintain the same speed, is higher with more weight. In physics nothing is free.
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of course it will be higher due to increased rolling resistance but 1-2% is negligible.
I guess you can reduce friction by overinflating tyres when carrying heavier loads to make up for it somewhat.
 
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z10m said:
of course it will be higher due to increased rolling resistance but 1-2% is negligible.
I guess you can reduce friction by overinflating tyres when carrying heavier loads to make up for it somewhat.
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Exactly. It’s not like the car gets bigger cause it’s heavier. Tiny diff due to tyres. But hey this is the EV thread where everyone is hyper focused on efficiency. Usually backed up by google searches or such like.
 
Simon said:
Exactly. It’s not like the car gets bigger cause it’s heavier. Tiny diff due to tyres. But hey this is the EV thread where everyone is hyper focused on efficiency. Usually backed up by google searches or such like.
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I have an I-Pace, I am in no way obsessed with efficiency. What I will do though is correct misconceptions such as weight has no impact on EV efficiency.
 
z10m said:
So how much efficiency would I gain by swapping front number plate with a sticker on my model 3.?

Edit: ChatGPT tells me 1-2% so probably not worth it.
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But it means you can get rid of those number place holders which let’s be honest, are not the best, especially the older ones.

The alternative is to take the plate holders off and tape the standard plate directly to the mount underneath.
 
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