rev up your engines, today I'm going to
talk about that modern auto stop-start system that some cars have, where your driving down the road and when you come to a stop and you're sitting, it turns the engine off,
and then when you step on the gas it starts back up and runs, now these auto
stop and start systems are made to save gasoline and they really started
full-time in modern hybrid cars like the Toyota Prius, now auto start-stop works
great in hybrid cars, because they were designed that way, to begin with, a hybrid
car doesn't have a tiny little starter like a normal car that runs on
12 volts, it uses the generators inside the car to actually start the engine
using a five hundred volt battery, so it's no problem for that giant battery
that's in the trunk of the Prius to start your car up and down and up and
down, it's got a lot of power, but most cars still have these lead acid
batteries they're smaller they're not made for continually starting and
stopping the car, for these kind of apps you need a deep cycle battery, most cars
still use a lead acid, they're not really deep cycle, lithium ion like in the
Prius are, but when you think about it they're making cars cheaper and cheaper,
they're not going to be putting more and more expensive batteries in the cars
just for this, and as I've already said in hybrid cars, they use these giant motor
generators to start themselves up, on a regular car they're using these tiny
little starters, they're not made to be used over and over and over again, now
granted some of these auto stop start cars do a more robust starter, but
it's nothing compared to the generators that they use in the Priuses or any
hybrid vehicle, these things are tiny compared to those huge things, and you
might not think about possible engine damage from starting and stopping all the
time, but I'm a mechanic and I think about it, realize that your crank and
your rod bearings get worn the most upon startups, and in a normal car, they
usually good for a hundred thousand starts and stops before they start to wear out,
and that's fine for a normal car that you start up driving around then later
when you shut it off you start it up, but with these things, you're going to be
starting and stopping a lot more often so you'd need bearings that were good to
300 or 400 thousand of these cycles, so if you have start/stop in a normal
engine, hey it's going to wear the rod bearings and the crank bearings, and then
you're going to have to rebuild the engine it's something that a lot of people
aren't going to think about, but being a mechanic, I think about that stuff and
when I see damage that shouldn't occur I'm not for that system, and then let's
get down to the nitty-gritty, how much better gas mileage do you actually with
one of these Auto stop-start systems well they advertise that they get
between 3 and 10 percent better gas, much but you're only going to get 10 percent
under very limited conditions, the temperature outside has to be moderate,
between 40 and 85 degrees, higher or lower you're not going to get much, and if
you run the AC, you're generally going to get less than 3% better gas mileage,
because air conditioning uses a lot of power, this isn't like you're turning
your whole car off by turning your ignition key off, it shuts the engine off
but other systems are still operating, so if it's hot outside after a very short
period of time, it's going to have to turn the engine back on to run the air
conditioner, now like I said previously these systems work fine in hybrids like
the Prius, because the Prius's use electronic air conditioners and they got
that big old five hundred volt battery in the back. so even when the engines not
running. it can run the compressor with that 500 volt battery and you still feel
nice and cool. inside but a normal car doesn't work that way, now truth be told,
there are a whole bunch of different auto stop start systems out there, some
of them that I've seen in Europe heck they use the alternator to start and
stop the car the alternators in those cars just spin the
serpentine belt and instead of the car driving the alternator, the alternator is
spinning to make the engine go, and some of them have electronic water pumps like
BMWs, so the engine won't overheat if the car isn't running while it's sitting there,
because realized when you shut an engine off, it's got a lot of heat in it,
it's what's called heat soaking, it's just sitting there heat soaking it
actually gets hotter, so the cooling system still has to be doing stuff even
though the engine is shut off, and sure engineers can bypass these
problems with some really high-tech technology, but really when you
think about it, all this technology that's going to break down the line and be
really hard to fix, do you really want that to get a little bit less than 3%
better gas mileage if you run an air conditioner, it doesn't intrigue me, and
for many people there's just the annoyance factor of, your driving and
when you stopped on the engine shuts itself off, now they all do have a button
you can push that turns the system off every time you start the car, if it
drives you nuts, you can push that button and turn it off, and me I find it rather
annoying, every time I get a rental car or I'm road test in a car that has that
system on, first thing I do is push that button off so it runs like a normal car,
because if you want really good gas mileage and all these technology
features, heck go out and get a hybrid like a Toyota Prius, they were designed
for that, because really when you think about it, these auto stop start systems
they're kind of like a halfway measure, you know, they work fine in the hybrid cars, but
in a gasoline car, it's trying to turn them into something that they really
weren't meant for, since I'm a mechanic and these systems have been out a little
while now, they're starting to break, I have to fix them, let me tell you they're
no fun to fix, and you're not going to be happy when you get this giant bill for
fixing them right, so if you never want to miss another one
of my new car repair videos, remember to ring that Bell!
