Question about self charging hybrids

Stubod

I was very, (very) sceptical about self charging hybrids, and thought they were just a gimmick...but then I ended up getting one as it was the only car that met my needs when it became time to change cars. After much deliberation I ended up with a Kia Niro, and since I have had it I have averaged around 65mpg (actual). I would not buy a full electric vehicle, but would not hesitate to get another self charge hybrid as and when the time comes. (Tank range is a rather irrelevant as it obviously depends on the size of the tank, but for info I get 500+ miles per tank according to the on board computer).

poppy12345

I have a Toyota Corolla 2022 plate. During the warmer months I get about 65mpg. Colder months it drops down to about 50mpg. Fuel tank holds 43 litres. 

I wouldn't hesitate in getting another self charging hybrid.

Petriix

'Self charging' isn't meaningless, it's blatant false advertising. Many people genuinely believe that they magic energy out of the air. Ultimately it's a limitation not a benefit: you can't plug it in so you can't benefit from the incredibly cheap and efficient grid electricity to power your car; instead you need expensive fossil fuels and waste most of the energy.

They're pretty pointless because the marginal gains in efficiency over a regular diesel car will never make up for the added complexity and expense. My last diesel car averaged around 50mpg.

WellKnownSid

Petriix said:

They're pretty pointless because the marginal gains in efficiency over a regular diesel car will never make up for the added complexity and expense. My last diesel car averaged around 50mpg.

Yes, it's very true that 'self charging' is just marketing bull - however I wouldn't say it's 'marginal gains in efficiency'.

My last 7 seat diesel got 44mpg
My current - larger, boxier - 7 seat HEV gets 60+mpg - using petrol which is cheaper (and less energy per litre).

Diesel car: 15.5 pence per mile
Hybrid: 10.5 pence per mile
= saving a third.

Yes, our EV gets 2 pence per mile and blows everything else away, but compared to our old diesel our 'complex hybrid' has: no clutch, much simpler timing system, no drive belt, no VVT, no alternator, no starter motor, no DMF, no DPF, no high pressure fuel pump, simpler indirect injection, no glow plugs, etc, etc.

Goudy

Self Charging might not be the most accurate term, which is why they are often referred to as HEV's, but they do work, in a fashion if you compare them to an straight petrol or diesel.

Take your average petrol or diesel vehicle.
It burns fuel to move but quite a lot of that fuel is wasted in the process, 70% or more.

It's turns into heat that the car needs to dissipate by the cooling system and oil, it turns it into noise, you have pumping losses and engine friction.

It also wastes energy when braking, you use friction to brake and that turns the energy from combusting fuel into heat, wasting it.

A "Self Charging" hybrid tries to steal some of those losses back so doesn't waste as much fuel.

Instead of wasting all that energy via the braking system, it uses a generator to help slow the vehicle down and as a result, store electrical energy in a battery to help power the car later.

The engine doesn't need to run all the time and when it does it's not under the same high load as a straight petrol or diesel. So heat, friction and noise wastages are less.
When it is running it is usually only helping to move or just running to generate electricity, not solely moving a tonne and a half of metal and plastic from the traffic lights.

As they don't use the combustion engine as a sole source of power, they can run a different combustion cycle.
A normal petrol or diesel will run an Otto cycle, what you know has even strokes of suck, squeeze, bang, blow which suffers pumping losses.
These pumping losses are effectively the effort the engine uses on the suck stroke to draw in air.

On a normal car, these losses do help slow you down but a HEV doesn't want this remember, it wants to use that energy to generate electricity.

A HEV doesn't have as much pumping losses as they don't run an Otto cycle, they run an Atkinson cycle.
The suck and squeeze stokes are effectively shorter than the bang and blow strokes which reduces these pumping losses.
(it's not actually shorter, they use different valve timings that holds the valves open longer to reduce these pumping losses)

Engines running an Atkinson cycle don't produce a lot of torque, but your HEV's engine isn't it's only source of torque, it has the electrical motor which as EV drivers will tell you, has lots and it's powered by energy saved from braking.

OK, it's still not as efficient as an EV, there are obviously still more losses with a HEV than an EV.
There's little heat loss with an EV (but they then need to use some power to heat the cabin), they can also generate energy from braking and there's just a small loss in pouring electricity into the battery and sending it to the motor.

There are plenty of losses suffered generating electricity, like heat, even a nuclear power station produces heat and that heat is generally wasted energy.
But that tends to be away from the car, so out of sight, out of mind.

A few years ago your average HEV was able to return similar mpg figures to a similar sized diesel.
These days they have moved on a bit and generally beat a diesel for mpg. (and murder them when it comes to tailpipe emissions)

The systems they use are better at reclaiming wasted energy, batteries are slightly bigger because of that, so can use more electrical energy and the engines and gearboxes have advanced as well so they waste less fuel.

Car_54

Petriix said:

'Self charging' isn't meaningless, it's blatant false advertising. Many people genuinely believe that they magic energy out of the air.

That’s not false advertising - it’s stupidity on the part of “many people”.

Grumpy_chap

hollie.weimeraner said:

Too many variables (like asking what mpg does everyone get without specifying a make and model)  but I used to have a 1.8 Toyota Auris Tourer that used to get 50mpg around Sheffield and up to mid 60's on a long journey.

That seems to be about right for that car.
I had one for two years and 25k miles - overall fuel consumption was 53 mpg. 
For comparison, my subsequent (and simpler) petrol Focus achieved 52 mpg overall.

Martyn1981

Petriix said:

'Self charging' isn't meaningless, it's blatant false advertising. Many people genuinely believe that they magic energy out of the air. Ultimately it's a limitation not a benefit: you can't plug it in so you can't benefit from the incredibly cheap and efficient grid electricity to power your car; instead you need expensive fossil fuels and waste most of the energy.

They're pretty pointless because the marginal gains in efficiency over a regular diesel car will never make up for the added complexity and expense. My last diesel car averaged around 50mpg.

Yep, Toyota created the term, but has been banned from using 'self charging hybrid' in many countries, stretching back as far as 2020 (Norway). Still allowed in the UK I think. A few years earlier they were trialling - "we choose not to plug in".

ididgetwhereiamtoday

Imagine if Toyota had of put full EV tech into their Prius's many years ago. Those EVs would be all over the place now. A Prius EV would be as efficient as a Tesla Model 3 and the company would be in much better shape, probably as big as Tesla. Kia and Hyundai where successful in making EVs along side Hybrids so it could have been done.
Toyota have seriosly got it wrong. Their Hybrids are good but their EV Prius would have blown the market away, they would easily achieve 5 MPKW with this aerodynamics. Instead they have their over priced BZX4 about 5 years too late, its almost as if they don't want to make EVs.

Veteransaver

grahamgoo said:

Veteransaver said:

Self charging hybrid is just a meaningless marketing word. It doesn't mean anything other than it charges its very small battery by running a petrol engine, which is actually very inefficient.
The car uses a tiny battery to either crawl.at.very.low speed for a few hundred yards or give a small boost to acceleration.
You get slightly better fuel economy than an equivalent non hybrid petrol car.
A mild hybrid offers even more marginal fuel efficiency gains.

How is it meaningless?  It distinguishes it from plug-in and conventional full petrol/diesel.  What term would you suggest describes it better?  

They can also use energy recovery from braking to charge the battery (although I guess that isn't a huge amount)

The term "hybrid" or HEV is sufficient. "Self charging" suggests it magics the charge out of thin air. It doesn't, it gets all its electric charge from the petrol put in.