# Safe to assume an electric motor is dramatically more reliable than



## lkashjdlkasjdlkjaskldjlks (Mar 4, 2015)

than en internal combustion engine? 

it seems that an electric motor has very few parts, and I can't remember the last time I ever through away an electric device due to motor failure. Is this correct? 

Thanks


----------



## dcb (Dec 5, 2009)

I can't seem to find any actual data on it, and given a lot of systems are newer and still working out some of the kinks, it kinda depends. But generally it is assumed so, and AC even more-so. There are probably some hydroelectric generators that have been running for decades (which is basically a motor).


----------



## Duncan (Dec 8, 2008)

I would say - NO - it is NOT safe to assume

Modern IC engines are very reliable
And you are not comparing apples with apples

With a modern car you are comparing a fully developed product that has been made in the hundreds of thousands with a home made one off

I would expect your reliability to be over 1000 times worse


----------



## Vanquizor (Nov 17, 2009)

Duncan said:


> I would say - NO - it is NOT safe to assume
> 
> Modern IC engines are very reliable
> And you are not comparing apples with apples
> ...


I think you just made a leap from the motor itself to the entire vehicle which is pretty different than the original question.

I haven't owned an ICE that didn't require scheduled maintenance a couple times a year, and I'm pretty sure that the AC-35 has no scheduled maintenance ever so I'd say on that fact alone its more reliable.


----------



## Duncan (Dec 8, 2008)

Vanquizor said:


> I think you just made a leap from the motor itself to the entire vehicle which is pretty different than the original question.
> 
> I haven't owned an ICE that didn't require scheduled maintenance a couple times a year, and I'm pretty sure that the AC-35 has no scheduled maintenance ever so I'd say on that fact alone its more reliable.


Hi Van
Reliability and scheduled maintenance are two entirely separate things,

Yes an IC engine will require more maintenance

Reliability is about time to fail -
And on that the installation is the key
In a forklift installed in a decent manufacturing establishment an electric motor could be more reliable

In practice unless that forklift manufacturer is operating on automotive volumes it will NOT be as reliable

A modern automotive operation talks in repairs per million
(When I was at Cummins we got the highest volume plant to 42 repairs/million)

Lower volume plants - even for MUCH more expensive machinery 
($250,000/engine) were struggling to get below 1 repair/hundred

1:100 = 10,000/million - 238 times worse than 42/million 

So NO a home installed electric motor will NOT be as reliable as a factory installed IC engine


----------



## Vanquizor (Nov 17, 2009)

Again you are comparing bringing install into the question when its not. If you want electric to ice compare Nissan Leaf motor failure rates to Nissan Versa motor Failure rates.

Or since we are on the DIY forum compare ev conversions motor failure rates to backyard swapped motor failure rates...lots of civics head to the bone yard during or shortly after their B series swap.

It is my position that if equal care is given to install and operating conditions that an electric motor will remain in service far longer than an ICE.


----------



## dougingraham (Jul 26, 2011)

In general the electric motor will be more reliable than an internal combustion engine. In the life of an ICE motor the motor might run 150000 miles. Assume all these were highway miles and you average 60mph making the total run time of the motor 2500 hours. If the average speed is 30 mph this is still only 5000 hours. Long haul trucks probably operate twice that many miles before a rebuild is needed but that is still only 5000 hours because their average speed is higher than a car.

The only wear items on an AC motor are the bearings and 10000 hour bearing life would be considered short and 100000 hour bearings are readily available. A brushed motor additionally has brushes which wear. Those are going to limit the time between overhauls to probably quite a lot less than the overhaul time of an ICE but changing brushes is more like changing the oil and filters than even replacing a timing belt would be on an ICE. In our cars the normal loads are axial which means the bearings are lightly loaded in an electric motor. If you use a belt or chain drive then you are adding in radial loads and this could cause bearings to wear faster.

There are hundreds of times the wear points on an ICE. It is reasonably safe to say that the electric motor itself will be more reliable.


----------



## Duncan (Dec 8, 2008)

Doug and Van
You are both right the theoretical reliability of an electric motor is much higher than the theoretical reliability of an IC engine

Unfortunately in the real world a modern IC engine is very very reliable and the unreliability of the conversion process totally trumps any reliability of either type of motors

So in answer to the original question (paraphrasing it slightly) 
"Will a conversion using an electric motor be more reliable than buying a car"
NO NO NO
Not on your nellie

To change it slightly
"Will a conversion using an electric motor be more reliable than replacing the engine in my car"

No - definitely NOT

To change it slightly
"Will a conversion using an electric motor be more reliable than sticking another radically different (IC) engine in my car"

Probably not as there is much more knowledge and experience about doing that than there is about converting to electric

To change it slightly
"Will a factory built electric car be more reliable than a factory built IC car"

That will depend on the factories involved


----------



## dcb (Dec 5, 2009)

Maintenance items affect reliability as well, humans skip a lot of that in practice if we are evaluating the imperfect.

As well, if your starter motor or alternator dies, or a fuel pump? does that go in the failed ICE category? It is part of owning an ICE. 

So from that perspective, an equally well designed and tested AC EV will undoubtedly be more reliable. No starter or alternator or ICE, just a big motor and a solid state controller. 

Solid state has a peculiar failure rate, they pretty much fail early or not at all, so some manufacturers use a burn-in period to max out the reliability there:
http://www.weibull.com/hotwire/issue21/hottopics21.htm


----------



## Duncan (Dec 8, 2008)

_an equally well designed and tested AC EV will undoubtedly be more reliable._

Almost 
_an equally well designed *built* and tested AC EV will undoubtedly be more reliable._

And that's not easy - its only when you are building LOTS (hundreds of thousands) that you can develop the build process to those levels

There is another way to get to those levels, the aerospace way - just multiply the costs by 10


----------



## dcb (Dec 5, 2009)

yah, and if the manufacturers can keep out the competition via bureurocracy then there's sure to be planned obsolescence, lines around the block for icar3 :/ Sorry you need a network connection to start your car, and your "old" car doesn't support bla bla bla, your gas pedal algorithm subscription has expired.


----------



## Duncan (Dec 8, 2008)

_then there's sure to be planned obsolescence_

Yes we did get a lot of 
"those bits last too long - can't you cut the cost and reduce the life"

Trouble is it's difficult to make something last long enough - then fail
What we normally found was it either failed in warranty (bad idea) or it just kept going!
Making it last "just long enough" was nearly impossible (for "mechanical bits" electronics are a whole other ball game)


----------



## dcb (Dec 5, 2009)

there was a guy bought a salvage tesla and got it working again, and tesla disabled it wirelessly. I give 'em a zero for reliability if they keep a button around just to kill your car.


----------



## Duncan (Dec 8, 2008)

dcb said:


> there was a guy bought a salvage tesla and got it working again, and tesla disabled it wirelessly. I give 'em a zero for reliability if they keep a button around just to kill your car.


Is that true? - or just an urban legend?

There are times that I think having a remote disable function could be a really good idea

Stolen car..
Police chase..
That would mean that you would have to have a trustworthy police force 

Also
Not paid road tax
Warrant of fitness out of date

I'm not fully convinced that it's a good idea but it's worth arguing

How many lives would be saved if the cops could just shut down a speeding car?

It's probably over 10 lives a year just here in NZ


----------



## dcb (Dec 5, 2009)

It was reported by rickard fwiw. https://www.google.com/search?q=tes...57.8178j0j8&sourceid=chrome&es_sm=93&ie=UTF-8

It is pretty clear to me they want to control the aftermarket. and safety is a convenient excuse.


----------



## Sunking (Aug 10, 2009)

I have not read through all the replies, nor will I. But IMO as a whole ICE is more reliable, and a very mature technology.

Electric motors come in many forms. Just from experience golf carts using DC brushed motor is it rare to find one more than 5 to 6 years old without burning up the windings or brushes worn out. 

The big weakness of electric motors is heat, especially in continuous duty use like a long haul trip through hilly or mountain terrain. Couple that with controllers that can force up to 4 times the rated continuous power compounds the problem like ascending up a mountain.

Granted modern EV's use Lithium batteries so watering PM is thus removed, but you had better be on top of your game monitoring battery connections and cleaning. Otherwise you might have a good electrical fire while climbing that hill from just a single loose battery connection somewhere. 

In my short 55 years on this earth I have seen first hand golf carts catch fire from bad battery connection and countless destroyed battery post melted away. 

So IMO you are just trading out potential problems. In that respect I give the good ole ICE an advantage. From what I have seen and witnessed is EV's problems tend to be very expensive problems like a burned out motor, controller, or batteries the majority of times. ICE on the other hand tend to be less expensive issues the majority of times.

I see EV's like VCR's when they first came out. Promising, but still have a long way to go to become mainstream


----------



## major (Apr 4, 2008)

Sunking said:


> ... IMO as a whole ICE is more reliable, and a very mature technology.


Actually I think electric motors may predate the internal combustion engine by a few years, but I'd say, maturity, in time, is about equal. And the topic is about the EM vs ICE, not the vehicles or supporting equipment. Sure, you can find cheap EM and compare it to a validated automotive engine. But show me an ICE that can run at rated load for 20 years continuously in a hostile environment without service like required for pump motors in nuclear power plants. If reliability is the objective, the electric motor wins out dramatically over the ICE.


----------



## Moltenmetal (Mar 20, 2014)

An EV with an AC motor has far fewer systems to fail than an IC engine does. None of them require substantial maintenance. Simplicity has to win in the end, and I'm confident it will. Batteries are and will remain the weak link though, as they fail as a result of mechanisms which can be reduced but not eliminated. Until they're a great deal cheaper, and better, the EV will remain a bit player, despite its elegance and simplicity- and vastly better environmental performance.


----------



## Sunking (Aug 10, 2009)

major said:


> But show me an ICE that can run at rated load for 20 years continuously in a hostile environment without service like required for pump motors in nuclear power plants.


Major I understand your point, but no manufacture is going to use industrial grade motor in a consumer grade product. Few could afford it. 

Would be nice if auto manufactures installed the same grade of engines they put in 18-wheel tractors made to go 1,000,000 miles between overhauls. They could if they thought the public is willing to pay for it. No one wants to keep a vehicle for 30 to 50 years. Would not be good for business if you think about it.


----------



## MightyAA (Nov 19, 2014)

I’ve always kind of questioned this myself. There are things about most EV motors that bug my engineering head. With ICE, there is a whole cooling and oiling system to keep that motor within set parameters and prolong wear items like bearings and keeping things "slick" instead of gumming up. It’s a sealed system where environmental contaminates can’t easily get into the works. They’ve also developed over the years in a variety of ways.

Most EV motors have no such things. How long will the bearings last without an oiling system or way to keep the temps down? How long will a spinning thing last when the housing is slotted allowing any dust and road debris to get in there? How long before the heat, cold, dust, road salts, etc. adversely affects the various components and connections in a non-sealed motor? I can't imagine asphalt and tire dust can be 'good' for it and no amount of fair weather driving can avoid.. How long before it starts affecting the motor? 

It just looks like most EV motors on the market were built to be placed in an environmentally controlled space versus ‘out there’ free range exposed to the elements. Basically, the ICE lawn mower engine being converted to work with a motor vehicle; it can work, but not as well or reliably as something designed around the specific application. The ‘tech’ of most EV motors on the market just doesn’t seem to be any more developed than my electric pool pump, so I question the reliability 'adapting' it to another use. The theory is sound, but the housing and design solutions to 'real world' exposures just don't appear to be highly considered which I'd tend to think would lead to more failures than should be.


----------



## dcb (Dec 5, 2009)

well, the bearings are as reliable as wheel bearings. And can be overengineered as such, or made to be easily replaced/maintained as a wear item.


----------



## major (Apr 4, 2008)

MightyAA said:


> .....
> It just looks like most EV motors on the market were built to be placed in an environmentally controlled space versus ‘out there’ free range exposed to the elements. ....


You must be talking about the Warp motors for DIY. Go take a look at the motors in automotive OEM BEVs by Nissan, GM, Mercedes, etc. Those are built to withstand the same environments and rigors as the ICEs they displace. Thinking about it, since EMs don't need to breath (air intake and exhaust), the EV would be more capable of adverse environment like say underwater


----------



## Sunking (Aug 10, 2009)

major said:


> You must be talking about the Warp motors for DIY. Go take a look at the motors in automotive OEM BEVs by Nissan, GM, Mercedes, etc. Those are built to withstand the same environments and rigors as the ICEs they displace. Thinking about it, since EMs don't need to breath (air intake and exhaust), the EV would be more capable of adverse environment like say underwater


I understand your point Major. Good examples are Train Locomotives, Submarines, any ship, large scale mining cranes, and the list goes on. However this is a DIY site, and DIY's don't use commercial or industrial grade motors. They use motors like Warp motors, or even HPEV AC motors. Not certain but I think HPEV finally came out with a Marine grade motor but have no idea how proud they are of it.


----------



## dcb (Dec 5, 2009)

Of course the problem is one of comparisons, like a DIY ICE is likely to use an oem engine vs a briggs and stratton. The highest mileage popular OEM electric motors are found in priuses, if either motor fails the car basically stops. And even as of a year ago, folks were reporting over half a million trouble free miles (except for ICE maintenance):
http://www.mercurynews.com/ci_23057096/prius-goes-530-000-miles-same-battery

They die because of the ICE limitations. Indeed a few folks have DIY converted them to all electric (and this was made in 2008), or have found DIY uses for other hybrid motors, again designed to work, and to last.
https://www.youtube.com/watch?v=FqAzMzT_0qg

and figured out 70mph: 
https://www.youtube.com/watch?v=tywkJ8DKhis

So, again, it depends.


----------



## DIY eddy (Apr 19, 2015)

Of course electric motors are extremely reliable,I have seen many ac motors from the 1950's that are still running today after 50 years or more of extreme duty on heavily loaded conveyor belts,Operating 24hrs a day.How many 2-3 year old ice cars have you seen dead on the side of the road.Ford has several ice truck engines that are lucky to make 60k miles without a rebuild,on the other hand some models will last 2-300,00 miles! Most ev motor failures are caused by diy guys overloading the motors or over powering them.The weak point in all ev's are the battery's and controller.Production ev's and hybrid's are very reliable compared to ice engines.Diy conversions not so much unless they are built to oem quality standards.Forklifts are a good example,the electric ones seem to last forever with no maintenance,were as the ice ones are in need of maintenance often.I know of a electric lift from the 70's that looks like a pile of scrap,all kinds of diy repairs of questionable integrity,old battery's,engine bay full of dirt,oil and 40 odd years of crud and it works just fine,If this is not reliable ????


----------

