EV Discussion thread

michaels

https://forums.moneysavingexpert.com/discussion/comment/82026159#Comment_82026159

Interesting. Google says pre 15 leaf and gen 2 leafs have poor 12v charging algorithms whereas the 15 to 17 ones don't have premature 12v issues which explains why ours lasted 8 years and only failed cos we left the lights on. Of our newer leafs we have had a 2019 40 for 4 years without replacing the 12v but perhaps we are just lucky with that one.

JKenH

https://forums.moneysavingexpert.com/discussion/comment/82026206#Comment_82026206

Our 30kWh was February 2017. Your last post crossed with mine so you may not have seen the data I found and sent which is on page 411.

JKenH

https://forums.moneysavingexpert.com/discussion/comment/82026195#Comment_82026195

If the issue is air quality (rather than CO2) then on many of the roads where these speed limits apply (motorways) we are looking at cars with fully warmed up engines running in high gears so the marginal impact on exhaust emissions from a reduction in speed might be minor.

What is, potentially, more significant, though, is emissions from tyre wear.

Pollution From Tyre Wear 1,000 Times Worse Than Exhaust Emissions

“It’s time to consider not just what comes out of a car’s exhaust pipe but particle pollution from tyre and brake wear. Our initial tests reveal that there can be a shocking amount of particle pollution from tyres – 1,000 times worse than emissions from a car’s exhaust. 

“What is even more frightening is that while exhaust emissions have been tightly regulated for many years, tyre wear is totally unregulated – and with the increasing growth in sales of heavier SUVs and battery-powered electric cars, non-exhaust emissions (NEE) are a very serious problem.” 

Press Release: Pollution From Tyre Wear 1,000 Times Worse Than Exhaust Emissions — Emissions Analytics

In practice having different speed limits for EVs to ICE cars is likely to annoy EV drivers as much as an ICE car driver. Imagine, as will almost invariably be the case on a busy motorway there will be someone sitting in the outside lane at an indicated 60mph on the speedo who doesn’t realise the car tailgating is an EV. Or if the driver does realise he may take the view that he doesn’t see why it’s one rule for EVs and one rule for others and just sit there to annoy the EV drivers. And what’s the rule going to be for PHEV drivers?

michaels

https://forums.moneysavingexpert.com/discussion/comment/82026271#Comment_82026271

I just asked google to do some back of the envelope calculations based on a 17 inch wheel tyre losing 6mm of tread (8mm to 2mm) over 30k miles. With a car having 4 wheels, the loss of tyre material is 0.3g/mile so the 6g per mile of that reports suggest tyres only last 900 miles….hmm

However that is not to say the 0.3g per mile of tyres is not 2 orders of magnitude more than exhaust particulates but they are generally much larger particles which means they are much less likely to be airborne and then more likely to be filtered out by the lungs rather than pass into the bloodstream unlike the exhaust particles.

Edit: Apparently tyre wear is less at motorway speeds in general as cornering and braking and acceleration cause most wear until the tyres get really warm at which point the shed more - so noticeably less tyre wear at 60mph than at 70+. For exhaust particulates in general with a warm engine they will be pretty low so motorway speed limits that reduce fuel use seem to be much more about overall efficiency and CO2 and possibly tyre particulates than exhaust particulates…

JKenH

Yes, I thought the figure given by Emissions Analytics seemed a bit high. I have just asked Google to do a similar exercise to what you did with a “typical EV SUV tyre” and a lower mileage of 20,000 miles and the figure it came up with was 0.32 to 0.45 grams per mile driven: so lower but of a similar order of magnitude.

I also came across this from Transport for London:

However, over 75% of road transport particulate emissions

come from tyre- and brake-wear, not exhausts. This

means driving style is an increasingly important determinant of

overall air quality.

https://content.tfl.gov.uk/speed-emissions-and-health.pdf  

Edit: I wasn’t looking to start an argument about whether ICE cars are cleaner or even suggest they were: I am simply responding to a suggestion that on a road where speed limits apply for (local) emissions reasons, they shouldn’t apply to EVs. There probably still is a case but it’s not perhaps as clear cut as it would first appear. The big advantage of EVs is reducing CO2 emissions.

JKenH

https://forums.moneysavingexpert.com/discussion/comment/82026493#Comment_82026493

Although this Guardian article is based on the same research it does suggest that tyre particles can enter the bloodstream.

The tests also revealed that tyres produce more than 1tn ultrafine particles for each kilometre driven, meaning particles smaller than 23 nanometres. These are also emitted from exhausts and are of special concern to health, as their size means they can enter organs via the bloodstream. Particles below 23nm are hard to measure and are not currently regulated in either the EU or US.

 Car tyres produce vastly more particle pollution than exhausts, tests show | Pollution | The Guardian

Grumpy_chap

Is this discussion around the emissions arising from a typical EV tyre without full context if it is not compared to an appropriate baseline that allows an indication as to what good-bad-average would look like?

Would a typical ICE tyre provide that baseline?

Does the consideration of such particulate emissions also need to consider the brake systems?

born_again

https://forums.moneysavingexpert.com/discussion/comment/82026645#Comment_82026645

Found no difference in tyre wear on a EV with previous ICE.

Current tyres on EV std All season are looking good for 30K+ miles.

Goodyear Vector 4Seasons Gen 3 Tyres: 215/55 R17 98W (All Season Tyres, Extra Load, Mountain Snowflake

JKenH

https://forums.moneysavingexpert.com/discussion/comment/82026645#Comment_82026645

I am not sure what you mean by full context. Do you mean how does an EV compare with an ICE car of the same weight, power and tyre size? The differences would be smaller and probably related to how the car was driven. Generally though EVs might be expected to be heavier with larger tyres.

Yes, we do need to consider both tyre particles and brake dust particles and I have acknowledged this. EVs according to Google emit less particles overall. However, one has to bear in mind that in particularly polluted areas modern ICE cars to Euro 6e standard can actually vacuum up particles.

Modern internal combustion engine vehicles carry extensive exhaust aftertreatment systems that have the potential to reduce their tailpipe pollutant emissions to near-zero, or even within the zero levels of measurement equipment in real-world conditions. It has been reported, therefore, that such vehicles have the potential to have tailpipe pollutant levels lower than the air intake of the vehicle – that they are cleaning the ambient air. This study investigates this hypothesis using a range of internal combustion engines and real-world emissions data alongside pollutant (in this case nitrogen dioxideand particulate matter) data from around the world and the accuracy of the instrumentation typically used to measure tailpipe emissions. The results show that it is unlikely that a modern internal combustion engine vehicle will clean ambient air, even at extreme pollution levels, although it is possible. However, where a vehicle inlet is in the plume of a dirtier vehicle or the pollution measured is among the highest values recorded globally, the pollution reduction can be substantial.

A negative emission internal combustion engine vehicle? - ScienceDirect

Remember, I did make it quite clear I wasn't suggesting that ICE cars produce less emissions than EVs. As I said “I wasn’t looking to start an argument about whether ICE cars are cleaner or even suggest they were: I am simply responding to a suggestion that on a road where speed limits apply for (local) emissions reasons, they shouldn’t apply to EVs. There probably still is a case but it’s not perhaps as clear cut as it would first appear. The big advantage of EVs is reducing CO2 emissions.”


JKenH

https://forums.moneysavingexpert.com/discussion/comment/82026654#Comment_82026654

That may be due to the fact that your car runs a similar size tyre (albeit with a higher weight rating) to what an ICE car uses. You didn’t specify what ICE or EV you were comparing so I am speculating. Most EVs run much bigger tyres.

Just out of interest my son fitted some all weather tyres to his Leaf and found that it significantly impacted his range (on a Leaf that matters). He ended up getting a second set of wheels for his OE spec EV tyres for the summer keeping the all season tyres for winter. Have you found the same?