During normal chatter between CACOR members within the privacy of a Google Group, this exchange between four members on Electric Vehicles should be of interest to a wider audience.
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Very important research at U of Toronto based on 2 years of data collection suggests that vulnerable population such as children (schools near roads) and seniors (in retirement homes ditto) are at health risk
National air pollution report calls out rush-hour traffic, diesel truck emissions as major areas of concern
Main culprits? heavy trucks and large SUVs for emissions but tire and brake ware are as important as tail pipe emissions and these come from all vehicles (even the electric ones)
for more (with data on Ottawa’s schools etc) see:
Brake wear on Electric Vehicles is not zero but sharply reduced. Braking is done with regenerative braking most of the time and the brake pads rarely rub against the brake resistive surface. In my EV, I use the most advanced regenerative braking so it is termed “single pedal driving”. When I slightly lift my foot off the accelerator, it starts to slow the vehicle with regenerative braking. The more I remove pressure from the accelerator, the greater the regenerative braking. I often never have to move my foot to activate brake pad rubbing at all. When I am travelling about 5 km/h approaching a red light, I am occasionally forced into standard braking. My brake pads will likely outlive the vehicle. Emergency braking is a very rare event that happens as often as ICE vehicle driving. I do notice that I start regenerative braking far earlier than ICE vehicles when approaching a STOP sign which is annoying to those who like to rush to be the first to the mandatory stop. Perhaps there is a driver age factor here. I don’t care very much if I annoy the high speed crowd.
Tire wear on an EV is the same as an ICE vehicle with one exception. I have not tried but I doubt it is possible to “smoke” the tires at full acceleration. When entering the 417 or any other 400 highway, I do get instant torque when I press the petal sharply to the floor and acceleration is impressive, but smoke and high pitched noise from spinning tires on asphalt has never happened. Perhaps I am not trying hard enough to accelerate to the full capacity of the drivetrain.
Point taken Art
But in heavy traffic with frequent stops and starts, is regenerative braking as effective as it is when you are cruising at highway speeds and gentle braking?
There are two main problems:
Heavy trucks and buses that travel within the urban core
And two, why is near road air pollution not measured – the city pre Watson had two roadside monitors but they were discarded in 2012 and the province only sees large scale regional pollution as their mandate so that unlike Vancouver or Montreal we have little data to counter the siting of schools and retirement homes near busy roads.
And that is why over 500 people in ottawa die prematurely each year (Ont Med Assoc -Illness Costs of Air Pollution) and the city has over 500,000 registered (polluting ) vehicles
My comments were for heavy traffic with many stops and starts. The friction brake is only used at 5 km/h or less. Coasting down with regenerative braking to a near stop is the normal way I drive. The speed I am travelling at when I commence this action makes no difference, so the regenerative braking is the same from 100 km/h or from 20 km/h. I use the brake pads when at 5 km/h to full stop. Single pedal driving takes about 2 minutes to learn and it is fantastic. A variation on it is to gently put some pressure on the brake pedal as this action increases the regenerative braking without brake pads.
I drove a Camry Hybrid for seven years, with much a smaller battery and electric motor than Art’s, but quickly learned to drive the way Art describes. I still do that when driving an ICE (and get better fuel consumption than another driver!)
I seem to remember that Phil Reilly had to replace the brakes early on his EV because he did not use them enough and they rusted prematurely.
I should add one more reality to this thread.
In my EV I have three gearshift choices in how aggressive the regenerative braking will be in single pedal driving. I use the most aggressive which means you are certainly aware braking action is happening when you lift your foot totally off the accelerator. Your body is rocked forward and pressure from your shoulder strap to retain you is felt when starting full regenerative braking at about 50 km/h and above. Of course, one avoids this “bang – full regressive braking ON now” to “bang – full regressive braking OFF now” by partial lifting of the foot pedal pressure on the accelerator. This is what takes 2 minutes to learn. You have control of how strong this deceleration is at any moment just as in an ICE vehicle it depends on how hard you press the brake pedal. Depending on traffic patterns you rapidly learn to be less annoying to those who are rushing to the stop sign and just avoiding four skid marks on the road to stop just-in-time. But, I am annoying to some drivers even when I am driving an ICE vehicle as I don’t drive this way. But in an EV I start regenerative braking earlier and soon learn how to get my timing right through mental integration of acceleration, to velocity to distance. The objective is to avoid any brake pad wear using a “slow and go” tactic. You do the same mental integration in an ICE vehicle with two pedals in what one could call road sense and planning ahead but you do this in an EV with one pedal and have the option to not add any wear to the brake pads. Getting the timing right becomes easier with more experience and soon is an automatic response to changing busy traffic patterns including multiple stops and normal “slow and go” situations.
In conversations with new EV owners, this one pedal driving is the first thing they want to talk about as it is “different” and adds some joy to the driving experience.
John Hollins, you are right about my having to undergo more brake maintenance on our EV’s. Again, last month, I had to have front rotors and brake pads replaced after less than two years of driving. In installing my winter tires myself a couple of weeks ago, I did see rust buildup on both vehicles’ rotors and was not unhappy with having the suggested repairs. In combination, for both cars, my costs will have exceeded about $1,000.00 (taxes included). Before accepting the replacements I did ask “why not resurface the routers and prolong their utility?” His response … “the rotors are being manufactured thinner on EV’s to reduce vehicle weigh. They are not in a condition to resurface.” I don’t know whether to believe this or not. However, when asked, I was told that the work billing would be about the same whether having resurfacing or installation of new rotors.
It was interesting that the Kia dealer’s desk clerk suggested extra winter car washing (when air temperatures are above minus 10 C.) at commercial drive-through car washes. He highlighted that road salt deposits are removed in these facilities and thus reduces corrosion of the brakes’ metal components. As for using regenerative braking or not, I was told that at least once per outing (no matter the braking option selected) we undertake a forceful/aggressive stop to activate the brakes moving parts (thus lubricating them) and bringing the brake pads in complete contact with the rotors and creating enough friction to remove grit on the entire surface of the pads and rotors.
Thanks Phil and Art for your comments and insights on regenerative braking
A whole new aspect of EVs for me
After two years of ownership/driving I went to the Mitsubishi dealer for servicing. The Maintenance desk fellow said to me “Your brake pads are showing 10% wear and need to be replaced.” I responded “Did you hear what you just said? At this rate I have another 18 years of brake service life. I will not replace them.” He put down on the invoice “customer refused brake pad replacement.” Then last autumn I took the EV in for annual servicing and was told “Your brakes are seized and need to be replaced.” I declined and had a similar note on the invoice. I have very good emergency braking capacity, can see no signs of oxidation and consider the words as another gross exaggeration. I don’t trust these people. Post sales servicing is a big money grab for the company. I will take the EV into a mechanic I trust here in Manotick and let them tell me about the brakes state of health. In fact, Tom will even let me see the brakes once everything is exposed. The dealership would never let a customer actually see what the mechanic sees.
Having seen the rotors’ conditions when changing tires, and expecting repairs, I was expecting a repair/replacement recommendation. I was surprised that refacing the rotors was going to amount to about (within $100’s) the same cost as installing new parts. Having the repair done, I immediately noted the improved braking on my drive home. So my posting was more about the structure of the rotors rather than the advice I was given. The convenience of having the brake repairs done while I sat (for three hours) at the dealers rather than having had to await delivery of parts to an independent garage was acceptable under my time restraints. I had taken a lunch and my computer to undertake review and re-familiarization of my presentation, on gardens of Sicily seen four years ago, to the Carleton Place Horticultural Society this coming Wednesday eve.