Post by: peteo48 on April 19, 2021, 03:35:04 PM
Is this the case? I'm someone who likes to set Climate Control up to my requirements and then leave it to do its job but if this means the petrol engine is always ticking over I don't think I would be tempted by the Mk4.
Post by: Kremmen on April 19, 2021, 04:03:26 PM
Post by: IanG on April 19, 2021, 04:50:18 PM
If climate control switched on prevents EV mode, does the ‘Econ’ switch allow EV mode to function when the climate control switched on?
Post by: Expatman on April 19, 2021, 05:01:35 PM
However, if the compressor gets it’s power direct from the charge motor and not from the battery then the ICE will have to run to power it. In which case MPG in the summer is going to nosedive if you use the A/C. Fundamental question - anyone technically up on this to provide categorical answer?
Post by: John Ratsey on April 19, 2021, 08:50:53 PM
Pressing the Econ button increases the allowable difference between target and actual cabin temperature and thus reduces the amount of time the engine / aircon operate to provide heating / cooling.
Post by: Bristol_Crosstar on April 19, 2021, 09:53:14 PM
Post by: peteo48 on April 20, 2021, 11:23:24 AM
There are a lot of Toyotas near me as the main dealer is only 5 minutes away. The Hybrids do seem to operate in EV mode automatically when moving from a standing start. Have they all got the climate control off? Is it possible to use residual heat rather than turning the engine on. My feeling is that, if I bought a Mk4 Jazz, the engine would rarely be off except, say, when the ambient temperature is higher than the setting chosen.
Having said that, I guess the petrol engine would only be idling so I may be overthinking this!
Post by: ColinB on April 20, 2021, 11:52:08 AM
Having said that, I guess the petrol engine would only be idling so I may be overthinking this!
Wouldn't the ICE, if running, always be running at it's most efficient speed? The notion of "idling" (ie engine running under no-load conditions) might not apply to a hybrid like the Jazz, because if there's no load from the generator, heating demand or direct drive then the engine won't be running?
Post by: Bristol_Crosstar on April 20, 2021, 11:53:26 AM
Thanks for the replies which all make sound sense. I can see that, if heat is required, the engine will need to be on. One thing that has occurred to me is observing Toyota Hybrids. The new range claim that they can (as opposed to will) run for up to 4 miles in pure EV mode and can reach 70 mph.If you just want heat then the heated seats are an alternative to using climate
There are a lot of Toyotas near me as the main dealer is only 5 minutes away. The Hybrids do seem to operate in EV mode automatically when moving from a standing start. Have they all got the climate control off? Is it possible to use residual heat rather than turning the engine on. My feeling is that, if I bought a Mk4 Jazz, the engine would rarely be off except, say, when the ambient temperature is higher than the setting chosen.
Having said that, I guess the petrol engine would only be idling so I may be overthinking this!
Post by: Downsizer on April 20, 2021, 12:05:15 PM
My feeling is that, if I bought a Mk4 Jazz, the engine would rarely be off except, say, when the ambient temperature is higher than the setting chosen.Sunlight warms the car well above the ambient air temperature. I needed air-conditioning in my Mk3 in yesterday's sunshine although the air temperature was only around 14 C. I rarely need heat in East Anglia between April and September, but I suppose it depends on where you live.
Post by: Expatman on April 20, 2021, 01:32:35 PM
It is the air conditioning that is really the question here, is it (compressor) driven solely by the generator/engine or can it be driven by the EV battery? If only driven by the engine/generator then in the summer the engine will be running most of the time to cool the cabin. I would think that the compressor is driven by the EV battery then the engine will only fire up when the battery is exhausted by the electric motor driving the wheels and/or the compressor. Really need a definitive answer from a Honda technical expert?My feeling is that, if I bought a Mk4 Jazz, the engine would rarely be off except, say, when the ambient temperature is higher than the setting chosen.Sunlight warms the car well above the ambient air temperature. I needed air-conditioning in my Mk3 in yesterday's sunshine although the air temperature was only around 14 C. I rarely need heat in East Anglia between April and September, but I suppose it depends on where you live.
Post by: Bristol_Crosstar on April 20, 2021, 01:51:16 PM
The Aircon is driven by one of the batteries, the engine is used to charge up the EV battery when the power level is low. The 12v battery is charged from the EV battery, not the engine.It is the air conditioning that is really the question here, is it (compressor) driven solely by the generator/engine or can it be driven by the EV battery? If only driven by the engine/generator then in the summer the engine will be running most of the time to cool the cabin. I would think that the compressor is driven by the EV battery then the engine will only fire up when the battery is exhausted by the electric motor driving the wheels and/or the compressor. Really need a definitive answer from a Honda technical expert?My feeling is that, if I bought a Mk4 Jazz, the engine would rarely be off except, say, when the ambient temperature is higher than the setting chosen.Sunlight warms the car well above the ambient air temperature. I needed air-conditioning in my Mk3 in yesterday's sunshine although the air temperature was only around 14 C. I rarely need heat in East Anglia between April and September, but I suppose it depends on where you live.
Post by: jazzaro on April 20, 2021, 03:06:12 PM
Just watched a You Tube video of a chap in the Czech Republic test driving a Cross Star in Prague. I know we've covered this before but the tester said that you need to turn the climate control off if you want the car to run in EV mode. If the climate control is on the petrol engine is on (although not necessarily powering the car directly).The aim of an hybrid powertrain like Jazz or Toyotas isn't to run the most of the time in EV: i-MMD and HSD are used to keep the petrol engine running in the best conditions or to stay off, that's why the power battery is very small. Who wants to drive in EV mode should buy an EV or a plug-in hybrid.
Is this the case? I'm someone who likes to set Climate Control up to my requirements and then leave it to do its job but if this means the petrol engine is always ticking over I don't think I would be tempted by the Mk4.
Post by: peteo48 on April 20, 2021, 03:12:23 PM
Post by: richardfrost on April 20, 2021, 03:18:10 PM
The aim of an hybrid powertrain like Jazz or Toyotas isn't to run the most of the time in EV: i-MMD and HSD are used to keep the petrol engine running in the best conditions or to stay off, tha's why the power battery is very small. Who wants to drive in EV mode should buy an EV or a plug-in hybrid.Exactly.
Post by: Expatman on April 20, 2021, 03:42:27 PM
Post by: Bristol_Crosstar on April 20, 2021, 03:50:43 PM
You have a point but the question asked was simply whether the A/C runs off the battery or the generator. If the generator then A/C needs engine running to work, if battery then A/C will work without engine running until battery needs recharging. Nothing to do with EV use at all. EV's and plug ins are great if you've got somewhere to charge them and the money to buy them in the first place. Not to mention range anxiety!!The climate control will work off the battery only providing sufficient power in the battery (ie > approx 30%), I can confirm as I've done it in my Crosstar
Post by: peteo48 on April 20, 2021, 05:28:15 PM
Post by: John Ratsey on April 20, 2021, 06:03:45 PM
Providing winter heat is less efficient as once the battery is full then the load on the engine becomes minimal but the best way to get the engine warm is to apply some load. Those heated seats provide some electrical load and I would have included an electrical heating element in the windscreen demister vent to help provide hot air for clearning the windscreen. As I've said several times previously, I would have designed the aircon to run backwards as a heat pump to avoid the problem of cabin heating making it more difficult for the engine to reach optimum temperature under light usage (eg urban traffic).
Post by: richardfrost on April 20, 2021, 06:31:25 PM
You have a point but the question asked was simply whether the A/C runs off the battery or the generator.
Actually, no! Read the original post. It seems as if the OP would be put off a hybrid because the engine might be ticking over to keep the aircon running. I think this worry shows a misunderstanding of the role of hybrids. They are not battery electric vehicles and will therefore have the engine running as needed. So I think the point about the difference between the types of vehicles is relevant.
Post by: Kremmen on April 21, 2021, 08:43:08 AM
My objective is to replace my 8 year old Civic, even though it's problem free, is probably the best car I've ever had, and I'll be sorry to see it go, with a new Jazz because I want to downsize and I 'demand' the latest tech :D
My current driving style and routes returns just over 50mpg on a 1.8 torque converter auto so I should get a good increase anyway.
Not bad for a 1.8 slush box:
(https://i.imgur.com/ApMYNXk.jpg)
My last fillup was better:
(https://i.imgur.com/FeD1R9L.jpg)
Post by: Expatman on April 21, 2021, 11:53:59 AM
Okay, you are right. However these threads always develop so hopefully we have answered both points.You have a point but the question asked was simply whether the A/C runs off the battery or the generator.
Actually, no! Read the original post. It seems as if the OP would be put off a hybrid because the engine might be ticking over to keep the aircon running. I think this worry shows a misunderstanding of the role of hybrids. They are not battery electric vehicles and will therefore have the engine running as needed. So I think the point about the difference between the types of vehicles is relevant.
Post by: Bazzzer on April 21, 2021, 01:32:23 PM
My last fillup was better:
(https://i.imgur.com/FeD1R9L.jpg)
Doesn't the 54.7mpg refer to your last trip? "Single trip" shows the trip in progress and the previous one.
Fill ups are displayed on the other tab
Post by: Kremmen on April 21, 2021, 01:57:27 PM
Still, 54mpg is better than I thought for my last journey.
Post by: jazzaro on April 21, 2021, 03:10:41 PM
As I answered before, what you suggest would be nice but very expensive, it would mean to deeply change the aircon-heating system of the car. The heating mode of the heat pump (remember that the traditional aircon is still a heat pump, even if a single mode) would be added to the standard liquid heater, I don't know if people would be happy to pay 500-1000$ or more for this feature, to be used only in particular moments.
Providing winter heat is less efficient as once the battery is full then the load on the engine becomes minimal but the best way to get the engine warm is to apply some load. Those heated seats provide some electrical load and I would have included an electrical heating element in the windscreen demister vent to help provide hot air for clearning the windscreen. As I've said several times previously, I would have designed the aircon to run backwards as a heat pump to avoid the problem of cabin heating making it more difficult for the engine to reach optimum temperature under light usage (eg urban traffic).
A dual mode heat pump would be like the Renault Zoe one: the aircon cannot run backwards, they must add valves and heat exchangers. Consider that in first Nissan LEAF EVs the dual mode heat pump was optional, standard trims had a traditional aircon cooling system and a PTC heater.
Ah, last but not least, with a heat pump in heat mode, you cannot have the demist function: the device cannot extract humidity from the air as a traditional aircon.
Post by: Kenneve on April 21, 2021, 05:12:14 PM
Post by: peteo48 on April 22, 2021, 10:42:12 AM
I've got over 18 months before I need to decide. I am hoping that a suitable EV will be available then.
Post by: Bristol_Crosstar on April 22, 2021, 02:19:18 PM
Some excellent points made above and I get the point about not fully understanding how the hybrid system is meant to work. That said I think there is an issue with air pollution especially in built up areas like where I live. I quite like the stop start system (even allowing for it being somewhat temperamental) which reduces pollution when stopped, at say, traffic lights. The boon of a hybrid, as I understand it, is that it almost always cuts the engine at a stop and then moves off in pure EV mode even if only for a short distance. That's how all the Prius taxis that I have used seem to work. I wouldn't be happy with the engine idling at traffic lights - it would annoy the hell out of me.If you have the climate control on all the time on an EV it can significantly reduce the range so there's still a price to be paid, it is rare for the engine to be running when stationary on the Jazz but it does happen occasionally
I've got over 18 months before I need to decide. I am hoping that a suitable EV will be available then.
Post by: Kremmen on April 22, 2021, 03:12:19 PM
Post by: Kenneve on April 22, 2021, 03:16:59 PM
Post by: Kremmen on April 22, 2021, 03:21:04 PM
Time v Cost
Post by: Jocko on April 22, 2021, 03:35:37 PM
Post by: Expatman on April 22, 2021, 04:37:52 PM
Post by: peteo48 on April 23, 2021, 10:33:34 AM
How very true, a friend has a Jag i-Pace and he gets nowhere near the quoted 250 mile range in summer. He reckons nearer to 150.
Yes - even the new WLTP figures, although much less "optimistic" than NEDC, still tend to exaggerate the range. I read somewhere than WLTP is attainable but would require extraordinary discipline to attain and only then in summer. The other factor to bear in mind is that, for reasons of preserving the battery, not all the kwhs quoted are available. In the case of the Honda E only 28 of the 35 are useable although that is probably a reflection of Honda's conservative approach.
My Nissan Leaf owning pal (a 2014 24 kwh model with 22 kwh useable) reckons about 3.2 miles per kwh is a useful yardstick for his winter range so little more than 70 miles. In the summer about 3.9 is realistic so high 80's. He reckons he got 100 once but it was squeaky bum time towards the end.
You need an enormous battery to get close to ICE ranges. The VW ID4 is available with a choice of batteries including a 70 plus kwh unit but even then 250 miles or less is about the most you'll get.
Post by: Downsizer on April 23, 2021, 11:27:39 AM
How very true, a friend has a Jag i-Pace and he gets nowhere near the quoted 250 mile range in summer. He reckons nearer to 150.If the UK is to be successful in banning new ICE vehicles from 2030, we will need major progress in EV range and rapid recharging widely available. My car is parked 30 yards away from my home, so home charging is impossible, as it is for many others. If I’m still allowed to drive I think I’ll buy a hybrid in 2029!
Post by: Kremmen on April 23, 2021, 12:27:10 PM
Hopefully technology will move on or they will be forced to delay full electric.
Post by: peteo48 on April 23, 2021, 04:35:55 PM
Post by: Expatman on April 23, 2021, 05:58:58 PM
You wonder just how much thought went into the decision to adopt 2030 as a cut off date.
Post by: John Ratsey on April 23, 2021, 06:02:05 PM
How is anyone going to tow a caravan?By keeping an old gas-guzzling filth-producing diesel until anything non-EV has been banned from the roads. It might then be necessary to exploit a loophole by having a vintage diesel vehicle.
Post by: Expatman on April 23, 2021, 06:21:49 PM
That's exactly what I think. But what is it going to do to the caravan building industry? Employs thousands in UK and without any assurances on towing vehicles potential buyers are going to be put off. So a few more thousand jobs sacrificed on the altar of virtue signalling by government.How is anyone going to tow a caravan?By keeping an old gas-guzzling filth-producing diesel until anything non-EV has been banned from the roads. It might then be necessary to exploit a loophole by having a vintage diesel vehicle.
Post by: Jazzik on April 23, 2021, 06:41:07 PM
https://www.youtube.com/channel/UCW5OzRikwv1HRRsLSu79_HQ
(https://pbs.twimg.com/media/ETPZ9gsWAAATGw1.jpg)
Post by: culzean on April 23, 2021, 06:50:54 PM
How is anyone going to tow a caravan, stop every 100 miles to re-charge?
You wonder just how much thought went into the decision to adopt 2030 as a cut off date.
One gallon of petrol has over 25 kilowatt hours of energy, that is as much as an original Nissan Leaf battery - added to that both solar and wind are very weak energy streams that need an awful lot of equipment to extract meaningful amounts of energy.
Post by: Jocko on April 23, 2021, 07:04:20 PM
Post by: culzean on April 23, 2021, 07:41:34 PM
How is anyone going to tow a caravan, stop every 100 miles to re-charge?
You wonder just how much thought went into the decision to adopt 2030 as a cut off date.
I agree - here are the figures from the video - and max speed was 50mph - conditions damn near perfect - no wind, dry road, and sunny. Range without caravan was pretty much 2.5x
The car used is a Tesla Model 3, long range, all wheel drive from 2019.
Here are the statistics from the drive:
Distance travelled: 201 km (125 miles)
Total elevation change: 974 m (3196 feet)
Energy used: 70kWh
Speed: 80km/h (50mph)
Consumption with the caravan: 374Wh/km (558Wh/mile)
Consumption without the caravan: 145Wh/km (233Wh/mile)
Added consumption by the caravan: +202Wh/km (+325Wh/mile) or +140%
Range: 216 km (134 miles)
Endurance: 2.5 hours
This test was done under the following conditions: Calm winds, sunny, dry road, 5C, studless winter tires.
Post by: Downsizer on April 23, 2021, 09:59:39 PM
One gallon of petrol has over 25 kilowatt hours of energy, that is as much as an original Nissan Leaf battery - added to that both solar and wind are very weak energy streams that need an awful lot of equipment to extract meaningful amounts of energy.I think it’s more like 45 kWh per gallon of petrol, so using 45 mpg as a typical consumption, this means 1 mile/kWh. However, there are a lot of thermal losses in an ICE, so 3-4 miles/kWh is realistic for an EV. I think 2 watts/sq m, or 2MW per sq km, is a realistic norm for a wind farm (assuming the wind is blowing!).
Post by: jazzaro on April 23, 2021, 11:41:05 PM
Post by: Kenneve on April 24, 2021, 07:55:04 PM
I'm running with the Climate Control permanently On, set to 20c, and can confirm that the EV mode does work for a significant amount of time, Only had the car for 3 days and about 35 miles covered, current average consumption of 63.7Mpg. local motoring. I will be doing my first long distance run on Saturday circa 250 miles and will report back.
Did my first long distance trip today, taking in M42/M1/M18/M180, plus a few miles of local roads, making a total of 335 miles since delivery. Speed on the motorways was kept at 60 Mph using ACC
Climate control set as previously stated.
I can confirm that EV mode did work for many miles (perhaps a mile or so each time, but not really sure how many) and returned 66.8 MPG over the 335 miles total, with 315 miles remaining as per attached photo
Similar trips in the past, with the Mk3 EX have returned around 55 MPG, so quite pleased with results so far.
I think I saw an article recently on the Tesla EV, which claimed a difference in range of only 5 miles with and without Climate Control, so if that is case here, then I'm not concerned.
Post by: Jocko on April 24, 2021, 08:07:08 PM
I think I saw an article recently on the Tesla EV, which claimed a difference in range of only 5 miles with and without Climate Control, so if that is case here, then I'm not concerned.That is born out by jazzaro's link to Peugeot
Post by: peteo48 on April 25, 2021, 10:49:53 AM
Post by: Jocko on April 25, 2021, 11:02:47 AM
Post by: Expatman on April 25, 2021, 01:52:30 PM
Thanks for the information. I would be most interested what MPG you achieve on that journey if you increased your speed on motorways to 70’ish - because that’s the speed I drive on motorways! Any idea when you are making the same journey again so you can do a direct comparison between 60 and 70 on motorway driving?I'm running with the Climate Control permanently On, set to 20c, and can confirm that the EV mode does work for a significant amount of time, Only had the car for 3 days and about 35 miles covered, current average consumption of 63.7Mpg. local motoring. I will be doing my first long distance run on Saturday circa 250 miles and will report back.
Did my first long distance trip today, taking in M42/M1/M18/M180, plus a few miles of local roads, making a total of 335 miles since delivery. Speed on the motorways was kept at 60 Mph using ACC
Climate control set as previously stated.
I can confirm that EV mode did work for many miles (perhaps a mile or so each time, but not really sure how many) and returned 66.8 MPG over the 335 miles total, with 315 miles remaining as per attached photo
Post by: Kenneve on April 25, 2021, 04:15:15 PM
My only reason for 60mph was, as an old school driver, was to run it in a bit.
I know it’s not supposed to necessary nowadays, but I still think it makes a difference.
Post by: Expatman on April 25, 2021, 05:08:05 PM
Might be some weeks before I do the same trip again, but will let you know when I do.Thought so, I've always felt it better to run new cars in a bit as well and I'm of that vintage when it was considered essential!
My only reason for 60mph was, as an old school driver, was to run it in a bit.
I know it’s not supposed to necessary nowadays, but I still think it makes a difference.
Post by: John Ratsey on April 25, 2021, 07:09:05 PM
Thanks for the information. I would be most interested what MPG you achieve on that journey if you increased your speed on motorways to 70’ish - because that’s the speed I drive on motorways! Any idea when you are making the same journey again so you can do a direct comparison between 60 and 70 on motorway driving?You can figure this out by looking at the components of the WLTP test cycle https://en.wikipedia.org/wiki/Worldwide_Harmonised_Light_Vehicles_Test_Procedure. The extra high phase is representative of cruising at up to 80mph and the results (see attached extract from Jazz Mk 4 brochures with columns the 4 grades of Jazz) show that the fuel economy falls through the floor at the motorway speed limit.
Drag losses are roughly proportional to speed squared and the Jazz, being relatively short and high, has a higher drag factor than cars which are more streamlined. At 60mph or over the hybrid system brings minimal fuel economy benefit although the Atkinson cycle engine helps a bit. However, when there's a problem and the motorway traffic changes to stop-start-crawl mode then the hybrid system provides a very obvious benefit.
Post by: Expatman on April 25, 2021, 10:49:12 PM
I can see that but I would rather have real world figures to compare against. Wouldn’t you?Thanks for the information. I would be most interested what MPG you achieve on that journey if you increased your speed on motorways to 70’ish - because that’s the speed I drive on motorways! Any idea when you are making the same journey again so you can do a direct comparison between 60 and 70 on motorway driving?You can figure this out by looking at the components of the WLTP test cycle https://en.wikipedia.org/wiki/Worldwide_Harmonised_Light_Vehicles_Test_Procedure. The extra high phase is representative of cruising at up to 80mph and the results (see attached extract from Jazz Mk 4 brochures with columns the 4 grades of Jazz) show that the fuel economy falls through the floor at the motorway speed limit.
Drag losses are roughly proportional to speed squared and the Jazz, being relatively short and high, has a higher drag factor than cars which are more streamlined. At 60mph or over the hybrid system brings minimal fuel economy benefit although the Atkinson cycle engine helps a bit. However, when there's a problem and the motorway traffic changes to stop-start-crawl mode then the hybrid system provides a very obvious benefit.
Post by: Kremmen on April 26, 2021, 03:57:32 AM
The one thing that keeps popping up is, even if we keep a hybrid long after 2030, will the oil companies still supply the UK when other countries will be more profitable until/if they ban fuel.
Post by: John Ratsey on April 26, 2021, 08:56:21 AM
I can see that but I would rather have real world figures to compare against. Wouldn’t you?Yes, but the real world figures can be distorted by real world factors, particularly the wind and temperature. For example, yesterday I did a round trip 46 miles each way, 94 minutes outbound and 84 minutes return and the car reported 77.8 mpg for the outbound leg and 70.8 mpg for the return. The difference, is I think, largely due to a tailwind going out and a headwind on the way home.
At motorway speeds the wind effect is even more noticeable. A 20 mph wind would give wind drag appropriate for anything between 50 mph and 90 mph depending on the wind direction (and I reckon that the turbulance caused by crosswinds add significantly to the drag losses.
As for 90+ mpg, this might be achievable by pottering along very slowly so that the drag losses are minimal or the end being much lower than the start. I've seen over 80 mpg on some short trips after a brief stop (so the engine is still warm) with the battery starting at the higher end of its charge range.
BTW, yesterday I noticed for the first time the car doing engine braking towards the bottom of a long hill after the battery reached 100% charge. I think I'd previously not noticed this happening because it's necessary to listen carefully for the change in vehicle sound as the engine was very quiet.
Post by: Expatman on April 26, 2021, 10:44:08 AM
When Which? had a MK4 on test they were getting 91mpg but I don't know exactly what their test routes were.There will be millions of ICE vehicles on UK roads after 2030, and for many years after that. Drivers regularly doing long journeys for which EV's are unsuitable, second hand car drivers who can't afford an EV or have the space to charge it, first time young country drivers who need a car to get round but can't afford anything newish, cars towing caravans, not to mention trucks etc. The change to full EV ownership will take years, if ever.
The one thing that keeps popping up is, even if we keep a hybrid long after 2030, will the oil companies still supply the UK when other countries will be more profitable until/if they ban fuel.
Petrol and diesel will remain easily available because demand will be there.
Post by: peteo48 on April 26, 2021, 11:24:57 AM
Post by: Jazzik on April 26, 2021, 11:49:45 AM
Petrol and diesel will remain easily available because demand will be there.
Even if a ban on gasoline is announced, we will have no problem. Our hybrids use so little of it that when we fill our bathtub at home, we can keep driving for years and years, right? (https://www.cheesebuerger.de/images/midi/froehlich/a068.gif)
Post by: peteo48 on April 26, 2021, 12:33:51 PM
Post by: Downsizer on April 26, 2021, 04:46:32 PM
What about the coal in your bathtub?Petrol and diesel will remain easily available because demand will be there.
Even if a ban on gasoline is announced, we will have no problem. Our hybrids use so little of it that when we fill our bathtub at home, we can keep driving for years and years, right? (https://www.cheesebuerger.de/images/midi/froehlich/a068.gif)
Post by: Mellorshark on April 26, 2021, 06:15:46 PM
When Which? had a MK4 on test they were getting 91mpg but I don't know exactly what their test routes were.
The report states that the jazz should post average fuel economy of 62.8mpg. They couldn't match this, achieving 55.4mpg in independent tests. If you drive mostly in town, they achieved 91.1mpg in urban testing.
Post by: Zaier on April 26, 2021, 09:17:06 PM
As other stated, the AC compressor is powered by the high voltage system, so you don't need ICE running as long as there is enough charge in the battery, otherwise ICE will kick in to recharge the battery, but once there is enough charge it will shut down while the AC will continue to run.
The AC will draw approximately 3-4kW of power when started, and then will reduce to 700-500W once it and the car reached it's working temperature.
The AC compressor it's connected in parallel to the engine PCU (inverter converter of the two electric machine) and has it's own inverter, which drives it to the exact amount of rpm needed, so if you fire the AC and stay outside the car, you'll hear a load buzz for the first 20-30 seconds as the compressor runs at full speed, then the noise will reduce gradually as the compressor slows down when the system reaches its working temperature, then it will be almost unnoticeable.
Regarding the heating, it work almost likely all the non hybrid car, ICE coolant is circulated into the heather core, so warm air can then be blown inside the car.
There are two big differences regarding a non hybrid car:
first is that if you ask far warm air, and ICE is not warm enough, then ICE will be started and run on a "warm up" mode, which consists of running it in a quite inefficient way with a slightly retarded ignition timing, this will allow ICE to warm up faster while having the possibility of powering the generator/wheels, but during this phase the battery will not be charged by ICE, because that will increase the load and thus engine efficiency.
Off course if you brake regen will work as usual.
You can recognize this phase without reading data from OBD because ICE will sound louder than usual, and off course because if you shut down the heating, then ICE will immediately turn off.
The second difference is that ICE has an electric water pump, so once the right temperature for heating the cabin is reached, ICE can shut off but you can still heat the cabin, whereas in a conventional car you need to have ICE running to pump hot coolant on the heather core.
The temperature at which ICE can shut down when heating the cabin depends on the combination of outside temperature and the temperature set for the cabin, so one trick is to avoid having ICE running just for heating is set a low temperature first, and then increase it while ICE warms up.
I did several test this winter, and also covered partially the ICE radiator to speed up the warm up process, because my usual commute to bring my daughter to school is very short 8km (5mi), and while I have heated steering and seat, she doesn't.
On cold days with temperature of 2-3°C below zero, cabin temperature set to 17° ICE shut down approximately at 68°C.
With higher temperature of 4-5°C above zero, it shut down approximately at 62°.
With more than 10°C I saw it shut down at 57°C.
Air recirculation helps a lot in warming up ICE faster, so I usually insert it untill ICE shuts off for the first time, then I switch to "auto" so the system can demist automatically if needed.
Then I usually increase the temperature to 18-19° which is what I like on cold morning.
So, you cannot avoid the "warm up" phase of you want a warm cabin unless you drive at certain speed, because ICE is so efficient that if you drive around town it will never warm enough with such cold temperature, but you can help speed up this phase with some "tricks".
If you're worried about fuel consumption, yes there is a big difference between winter and summer on short trips, but it's not only dependant on cabin heat request, you have also to consider the different efficiency and power output of the battery which is quite big with lithium ion.
Some days I had almost 20° of difference between the morning when going to work, and the afternoon when coming back from work, I'll summarize the difference like this, in the morning I was driving and average hybrid car, in the afternoon I was driving a plug-in
.Anyway a side of the trick of keeping the temperature low in the morning when cold and set the recirculation, I'm very happy about Jazz climate, I keep it 99% of the time on auto and just vary the temperature set.
A side of this, I drove a Yaris Hybrid for 8 months before buying the Jazz, and the behaviour is almost the same, the only big difference is that Toyota charges the high voltage battery when ICE is kept running due to cabin heat request.
Post by: John Ratsey on April 26, 2021, 10:09:03 PM
There's a description of the testing at https://www.which.co.uk/reviews/new-and-used-cars/article/how-we-test/how-we-test-mpg-and-emissions-amm4w1M5ytlb.When Which? had a MK4 on test they were getting 91mpg but I don't know exactly what their test routes were.The report states that the jazz should post average fuel economy of 62.8mpg. They couldn't match this, achieving 55.4mpg in independent tests. If you drive mostly in town, they achieved 91.1mpg in urban testing.