Hybrid Cars and how power is calculated

[NorthDave]

Hi All

Prepare for a stupid question.

I'm looking at a new car at the moment and hybrids seem to be everywhere. On some sites I see the power being quoted as 390 whereas on the manufacturer site it might be 303 + 87. I assume that is engine / battery power.

I assume in the example above it would be the same as driving a 303 powered car unless moving slowly when the battery would take over and use the 87 powered battery. I also assume that the battery power doesn't help the ICE engine at all, it just stops it being required in certain situations. I guess this improves economy.

Have I understood correctly? As a say a daft question probably!

[CanAm]

The electric motor operates on its own at low speed etc and adds to the power of the ICE when necessary.

[Krikkit]

It's symptomatic of the fact that the engine and electric motors won't always supply peak power at the same time.

e.g. Peak for the electric motor might be at 3000RPM on the ICE when it's not producing its full power.

[NorthDave]

So from what you guys are saying the battery does supplement the ICE engine too (although it isn't as simple as adding the figures together as they may peak at different times)?

Thanks!

[Scrump]

[Rich Boy Spanner]

Doesn't it also depend on driving mode? On the Prius there is a 'power' button which (IIRC) uses the motor and ICE together rather than as supplementary?

[Scrump]

Yes there are modes in most hybrids which change the way the two types of power work together such as keeping the internal combustion motor running or keeping that motor off and rely solely on battery.

[Otispunkmeyer]

Rich Boy Spanner said:

Doesn't it also depend on driving mode? On the Prius there is a 'power' button which (IIRC) uses the motor and ICE together rather than as supplementary?

I have a Prius and I think that all those buttons do is change the pedal map. The mk3 Prius seldom runs on just the motors, it’s nearly always using a combination of both motors and engine. Even on the motorway. All accelerations use the motors and engine together regardless of mode.

Might be different in the newer one mind. I know it’s capable of punting itself along at motorway speed using just the motor for a short distance, whereas before this wasn’t possible as the motors couldn’t spin that fast and needed the engine to be turning as well in order to spin.

http://eahart.com/prius/psd/

(View on a pc)

That shows how it works. Its a lovely bit of engineering.

[Chris-S]

I have a C350e and it uses ICE and battery power in pretty much all ways you can imagine, depending on circumstances and to an extent, driver inputs/requests. Power is quoted as x + y for the reason given, the two sources produce peak power at different rotational speeds. Net result is a pretty much seamless transition between power sources most of the time. You can force it to run ICE all the time if you want, so it provides performance or battery charge (different modes), or just battery power unless it runs out of charge or puff.

You can watch a pretty graphic that tells you where the power is coming from and going to as well.

Battery capacity is pretty pathetic on ours, meaning pure EV miles can be an embarrassingly small number, but it does give decent mpg on a long run if driven sensibly.

Does go pretty well when provoked too as the torque from the electric motor is impressive. Combined on ours is 600Nm but you can definitely sense that EV urge dropping off as revs pick up. ICE torque curve is a flat line from 1200rpm to near the red line so it isn’t that.

It’s a setup that’s very sensitive to how you drive as far as overall economy goes and if your driving profile is lots of motorway miles, I’d think a diesel ICE component would make better sense than petrol.

FWIW, if I’d waited a few years before buying, I’d have a Tesla M3 now instead.