MG ZS Hybrid+ high engine revs

[Bill Mitchinson]

My new MG ZS trophy hybrid is revving very high on some inclines, is this correct. Thanks.

 

[DMeine]

Yeah

 

[Hybrid Ann]

Mine does that too Bill. Most disconcerting don't you think? Good job it only happens on hills. I wonder if this is something that can be corrected.

 

[pdm1]

Hi, mine is the same, it's almost like driving a manual, and suddenly it's jumped out of gear and it revs up.

However, I have noticed when the revs increase, after a few seconds if you watch the screen, the revs drastically drop down. I wondered if this was the engine changing gear, trying to find the right gear, bearing in mind it only has 3 gears.

 

[Hybrid Ann]

I don’t know. I try to avoid the situation that makes it happen. Not always possible I know. I’m lucky that I don’t have many hills. Other wise the car is brilliant I must say.

 

[pdm1]

I suddenly realised while driving up a hill today, and it got louder.

The noise you hear is the generator turning on to charge the battery when the regenerative braking cannot cope, such as going uphill.

The ZS hybrid is a strange, but clever design, but the noise is worrying when you don't realise what causes it.

 

[Coulomb]

The noise you hear is the generator turning on to charge the battery...

My understanding, based on very dated Toyota Prius designs, is that there isn't a separate generator that "turns on", rather, a motor smoothly transitions from power flowing battery to wheels into power flowing from wheels and engine to battery.

Assuming that's still the case, and I expect that it still is, I don't see how a motor transitioning into the generator area of operation would cause any change in noise.

The petrol engine and associated mechanical shafts, gears, etc. suddenly having to work harder would be a much better candidate, I think. But perhaps that's what you meant.

 

[pdm1]

But it's

My understanding, based on very dated Toyota Prius designs, is that there isn't a separate generator that "turns on", rather, a motor smoothly transitions from power flowing battery to wheels into power flowing from wheels and engine to battery.

Assuming that's still the case, and I expect that it still is, I don't see how a motor transitioning into the generator area of operation would cause any change in noise.

The petrol engine and associated mechanical shafts, gears, etc. suddenly having to work harder would be a much better candidate, I think. But perhaps that's what you meant.

But it's not a Toyota, it's an MG.

It's like trying to compare a petrol and diesel engine, they both work in completely different ways to achieve the same outcome.

The generator is mentioned in many of the online reviews.

Below is the link to the MG site which also mentions the generator.

https://www.mg.co.uk/media-centre/mg-motor-uk-reveals-all-new-mg-zs-hybrid

 

[Coulomb]

But it's not a Toyota, it's an MG

Sure. But I didn't think that there has been much change in the fundamental hybrid car design since then. I could well be wrong there. It's since occurred to me that the Prius design obviates the necessity for a multi ratio gearbox, and the MG hybrids clearly have a 3-speed gearbox, so there must be something significantly different between the Prius and the MG hybrids.

Below is the link to the MG site which also mentions the generator.

That "generator" at 45kW sounds a bit like MG1 (Motor Generator 1) in a Prius. I did a quick search for a block diagram for MG hybrids, but found only general diagrams, not specific to MG. I think the problem is that Motor/Generator is a very common term in hybrid powertrain designs, and is commonly abbreviated to MG, the same as Morris Garages. If anyone can find such a diagram, I'd be intetested.

Sometimes one of the motors in a hybrid powertrain is called the Starter Generator, though it also assists with torque production, meaning that it also acts as a motor. Perhaps MG refer to this as the generator.

 

[Hybrid Ann]

You've lost me, well and truly

 

[Noel]

Hi. I must admit that I haven’t actually experienced this, as we haven’t got any steep hills locally. However, I’ll add my tuppence worth .

The petrol engine and the battery/electric motor work together to provide sufficient power under all conditions. When going up a steep hill, the system provides adequate power by utilising the engine, and the energy stored in the battery, When the battery becomes depleted, the system increases the RPM (speed) of the engine, providing maximum power to the front wheels, and to the generator, to recharge the battery. As soon as the battery has sufficient power to assist the engine, the RPM is reduced.

Under normal conditions, the battery/motor combination is employed as the primary source of power, the engine being employed, as necessary, to assist, and to recharge the battery.
The display has a screen which graphically shows how the system works, and instantaneously shows where the power is coming from, and where it’s going to.
The car has automatic braking, but please don’t glance down for too long .
Cheers Noel

 

[wiggles]

Sure. But I didn't think that there has been much change in the fundamental hybrid car design since then. I could well be wrong there. It's since occurred to me that the Prius design obviates the necessity for a multi ratio gearbox, and the MG hybrids clearly have a 3-speed gearbox, so there must be something significantly different between the Prius and the MG hybrids.


That "generator" at 45kW sounds a bit like MG1 (Motor Generator 1) in a Prius. I did a quick search for a block diagram for MG hybrids, but found only general diagrams, not specific to MG. I think the problem is that Motor/Generator is a very common term in hybrid powertrain designs, and is commonly abbreviated to MG, the same as Morris Garages. If anyone can find such a diagram, I'd be intetested.

Sometimes one of the motors in a hybrid powertrain is called the Starter Generator, though it also assists with torque production, meaning that it also acts as a motor. Perhaps MG refer to this as the generator.

The ZS Hybrid + and MG3 Hybrid + use the same base drive train It has the standard Petrol ICE alongside a 100kW electric motor for drive. Additionally, it has a 45kW electric generator that charges the hybrid battery as needed twinned with regenerative braking.

The way it works depends on the demand, the below is taken from the press pack with my added findings in brackets.

EV Mode

Running on electric-only power for as long as charge allows. (low/Med demand up to 40MPH in my testing)

HYBRID

Series
The engine runs the generator, which powers the electric motor
for driving. (low demand 30MPH in my testing)

Series & Charge
Series driving, plus topping up the battery when under low load. (low to Med demand Up to 40MPH in my testing

Drive & Charge
The engine drives the wheels while charging the battery through the generator.
(medium demand 40-60MPH in my testing)

Parallel
Both the engine and electric motor power the wheels.
(High demand 60MPH+)

You can see the power flow by navigating with the right-hand menu toggle on the wheel. When you see your current journey stats (distance, time, average speed, fuel economy), navigate down 3 or 4 times, and you will see the Hybrid battery charge and the energy flow.

The comments about it revving high when going uphill or close to a gear change, I have experienced this and it will be something that MG can and SHOULD fix in a software update, as it is only a 3-speed drivetrain when using the petrol ICE for drive it has to cycle across and it's not as smooth, remember the MG3 Hybrid is a smaller car that this one is based off.

 

[MGerized]

Hi!, first of all I'm not english speaking fluent, sorry to all users. I'm driving an MG ZS hybrid+ since december 27th, my daily route is arround 27 km of hilly terrain with slope values arround 6% to 23%. Driving down from home i'm getting comsumes close to 0,3 l to 0,8 l/100km, the worst case was 1,9l. Driving to home, the first week i've suffered punctual 4400 revs and 5200 climbing on Highway, of course was scaring, and forced me to Drive on low speeds. Thanks to this forum i did several tests, specially thanks to Coulomb and DMeine who gave me the basic keys to Drive this car. These are my solutions:

For flat and urban areas: Drive in eco/normal mode, get speed in recharging mode 1 and change to 2, this lets car recharge, i preffer eco after getting speed and mode 2.

In hill change to sport Mode and recharge 2, Mode 3 slows the car without chance to glide, Drive at 60 kmh in 12% slope, your motor keeps 2200 revs to 2500, maybe you can refine, and get the 80 kmh climbing at 2700 revs.

Now i have a drivable car, not the faster, but remmember it's an hybrid car, the way you drive needs to be reviewed, at least uphill. It's a magnific car by it's price.

Seems we have to manage two motors instead one system, eco Mode consumes less gasoline and promotes electric use extending battery but gives low power too, if you use recharge 2, energy produced overpass the requirements at least in glide. Sport Mode promotes gasoline use and a reinforcement from the electric engine, ideally the recharge Mode should be better in level 3, but this recharge forces to use more energy due to regen brake ressistence.


Quote

 

[Graydo]

I suddenly realised while driving up a hill today, and it got louder.

The noise you hear is the generator turning on to charge the battery when the regenerative braking cannot cope, such as going uphill.

The ZS hybrid is a strange, but clever design, but the noise is worrying when you don't realise what causes it.

Its not the generator, it's defintely the engine revving hard as the rev counter jumps to 3600 revs, maybe its because the engine is now having to run the generator AND the car to get it up hill but it's definitely the engine.

Not great when you're trying to keep the revs under 3000 (as per chinglish manual) and it revs its guts out on a modest hill about 40mph..
It doesnt seem to want to either change up or down.
It doesn't rev this highly doing 70 on the motorway!
Most worrying, hope this is normal.

Graydo

 

[MGerized]

Its not the generator, it's defintely the engine revving hard as the rev counter jumps to 3600 revs, maybe its because the engine is now having to run the generator AND the car to get it up hill but it's definitely the engine.

Not great when you're trying to keep the revs under 3000 (as per chinglish manual) and it revs its guts out on a modest hill about 40mph..
It doesnt seem to want to either change up or down.
It doesn't rev this highly doing 70 on the motorway!
Most worrying, hope this is normal.

Graydo

It's normal our MG has a DHT or dedicated hybrid transmisión, this means electric engine runs to recharge battery leaving Thermic motor with a huge work to keep the speed. A simply solution, a second battery and a recharge-discharge alternate cycle, second battery goes to rescue while primary reloads.

 

[DMeine]

It would be enough if the combustion engine only drove the wheels when going uphill with an empty battery and also not charged the battery. It's not rocket science for the software to recognize this. If the car notices that you are accelerating hard, charging the battery should simply be interrupted when the battery is empty and only charged again when the load on the combustion engine is reduced.

 

[MGerized]

It would be enough if the combustion engine only drove the wheels when going uphill with an empty battery and also not charged the battery. It's not rocket science for the software to recognize this. If the car notices that you are accelerating hard, charging the battery should simply be interrupted when the battery is empty and only charged again when the load on the combustion engine is reduced.

Abslutely agree, but this Atkinson cycle motor gives 128Nm Torque at Max, something i've noticed it's the thermical efficiency which it's preferred by the brand.

 

[Graydo]

It would be enough if the combustion engine only drove the wheels when going uphill with an empty battery and also not charged the battery. It's not rocket science for the software to recognize this. If the car notices that you are accelerating hard, charging the battery should simply be interrupted when the battery is empty and only charged again when the load on the combustion engine is reduced.

Sounds like a good solution to me, does it really HAVE to charge the battery on a short incline, surely the car can recognise that it is on a hill and reduce the load on the engine accordingly for a short time.

Hard to run in a new engine and keep it below 3000 revs when the only option is to slow down considerably annoying other drivers behind, who wonder what the hell you are slowing down for.

Should add that the revs do drop to about 1800 rpm eventually, but it takes a few minutes to do so, is the battery really depleted this quickly, I know its not a Tesla and is only 1.83kw battery but wonder how the power is used up and in what ratio's.

I'll try and bring up the power stats mentioned earlier in this thread, would be very interesting to see just how quickly the battery is depleted/charged, and at what stage of the journey.
Also, how.long regenerative braking takes to put meaningful charge back into the battery at different regen states (1,2 or 3 ).

This cold weather will also have an effect.

I know the salesman said drive, and let the car do its thing but I'm curious to know.

Graydo

 

[Busman]

Sounds like a good solution to me, does it really HAVE to charge the battery on a short incline, surely the car can recognise that it is on a hill and reduce the load on the engine accordingly for a short time.

Hard to run in a new engine and keep it below 3000 revs when the only option is to slow down considerably annoying other drivers behind, who wonder what the hell you are slowing down for.

Should add that the revs do drop to about 1800 rpm eventually, but it takes a few minutes to do so, is the battery really depleted this quickly, I know its not a Tesla and is only 1.83kw battery but wonder how the power is used up and in what ratio's.

I'll try and bring up the power stats mentioned earlier in this thread, would be very interesting to see just how quickly the battery is depleted/charged, and at what stage of the journey.
Also, how.long regenerative braking takes to put meaningful charge back into the battery at different regen states (1,2 or 3 ).

This cold weather will also have an effect.

I know the salesman said drive, and let the car do its thing but I'm curious to know.

Graydo

Software PD 052 is now available in UK and Ireland to address this problem.I am getting it on Wednesday. You need to contact your dealership as they will not contact you..

 

[pdm1]

Software PD 052 is now available in UK and Ireland to address this problem.I am getting it on Wednesday. You need to contact your dealership as they will not contact you..

Hey Busman

Please let us know if you manage to get the update, and if it does make a difference.

Am looking forward to your results.