Insane MPG

[cjp2k20]

Just a warning about that. If you leave the A/C off for an extended period (over the winter months, say) the pipework seals will dry out and fail, the refrigerant will leak out, and you’ve got a very expensive repair bill. As I know to my cost from a previous car. It’s much cheaper in the long run to leave it running; personally I’ve never noticed any difference in mpg with/without it anyway. Even in winter A/C is essential to keep the screen demisted.

Sorry I should clarify, I'm not sure of the effect of ECON on the performance of AC since the weather is so cool already, I don't plan on turning it off. Your advice is correct, it's definitely worth leaving it on to keep the system healthy.

[JazzMusic]

Just a warning about that. If you leave the A/C off for an extended period (over the winter months, say) the pipework seals will dry out and fail, the refrigerant will leak out, and you’ve got a very expensive repair bill. As I know to my cost from a previous car. It’s much cheaper in the long run to leave it running; personally I’ve never noticed any difference in mpg with/without it anyway. Even in winter A/C is essential to keep the screen demisted.

Yes, I know about that. Not using the A/C for a longer time can have ill effects. Using it every 2-4 weeks is sufficient to keep the system ok.
If you recharge it every 2 years you'll notice a growing leak and replace an o-ring is necessary.

[John Ratsey]

I've used Econ since I got my Crosstar. Even if there's reduced performance it's still plenty good enough.

My interpretation of the handbook is that enabling Econ increases the allowable difference between target and cabin temperature. It's likely to mean less running of the engine to provide heating and possibly air conditioning. The latter is powered by the HV battery but a situation could arise when the battery gets low while the vehicle isn't moving. When the weather turns colder we'll get a better understanding of how much the engine gets run purely to provide heating when power isn't otherwise needed (eg in slow traffic with the battery not needing to be charged).

[JazzMusic]

I've let the car sit overnight with 5 bars and the combustion engine decided to fill the battery to the top from the start. I guess that that is its strategy. BTW: A/C was off and temp to min. That was a big hit on mpg on the very first miles.

It's quite a big engine with 1.5 l. I think that warming it up quite fast will be the best strategy.

Not sure what to expect in winter. Mpg will be worse but by how much?
Does it has an additional electric heater for the cabin like a Diesel has?

[John Ratsey]

I've let the car sit overnight with 5 bars and the combustion engine decided to fill the battery to the top from the start. I guess that that is its strategy. BTW: A/C was off and temp to min. That was a big hit on mpg on the very first miles.

It's quite a big engine with 1.5 l. I think that warming it up quite fast will be the best strategy.

Not sure what to expect in winter. Mpg will be worse but by how much?
Does it has an additional electric heater for the cabin like a Diesel has?

My observations reported here https://clubjazz.org/forum/index.php?topic=12352.0 suggest that the car likes to get the engine temperature up to 40C as quickly as possible by revving it at 1600 rpm and using the surplus power to charge the battery.

It's thought that the cabin heating gets the warmth from the engine cooling system. However, if I were designing the vehicle I would take advantage of the possibility to use the electrically-powered airconditioner as a heat pump https://www.newair.com/blogs/learn/can-an-air-conditioner-can-be-a-heater , perhaps in combination with excess heat from the engine when it's available. This is about four time more energy-efficient than using a resistive electrical heater. There's also potential to utilise the heat generated when the battery is charged / discharged but this would add another complexity. We should get a better understanding of the heating arrangements when the weather gets colder.

[culzean]

Problem with air source to air heat pumps is when you need them most they are least efficient - below 10deg C ambient they are about 1.5x  more efficient than electric resistance heating, are far heavier and more complicated.  The engine has to warm up sometime, and may as well get heat from it, maybe a water jacket around exhaust pipe pumping warmed water into engine would warm it up quicker.

[John Ratsey]

I think you'll find that modern inverter driven heat pumps tend to be more efficient than you indicate. Nissan decided it was worthwhile putting one in the Leaf https://www.nissan-global.com/EN/TECHNOLOGY/OVERVIEW/heat_pump_cabin_heater.html .

I've got an inverter driven aircon / heat pump for my conservatory (the equipment does both functions depending on whether the Heat or Cool button has been pressed) and on a cold day it draws about 600W and is more effective than a 2kW electric heater. Heating a car should require somewhat less than 600W.

[culzean]

I think you'll find that modern inverter driven heat pumps tend to be more efficient than you indicate. Nissan decided it was worthwhile putting one in the Leaf https://www.nissan-global.com/EN/TECHNOLOGY/OVERVIEW/heat_pump_cabin_heater.html .

I've got an inverter driven aircon / heat pump for my conservatory (the equipment does both functions depending on whether the Heat or Cool button has been pressed) and on a cold day it draws about 600W and is more effective than a 2kW electric heater. Heating a car should require somewhat less than 600W.

The leaf needs the heat pump anyway to provide cooling aircon, so makes sense to use it for reverse cycle heating as well. Cars are getting more expensive and complex every year, which is a worry for second hand buyers who may well get hit by huge bills for repairs and routine maintenance.

[John Ratsey]

The leaf needs the heat pump anyway to provide cooling aircon, so makes sense to use it for reverse cycle heating as well.

That's my point: Honda have put an electrically powered aircon in the Mk 4 Jazz so why not also use it for heating?

[JazzMusic]

I've noticed that there are two coolant caps, so two systems I assume. 

[madasafish]

Excellent mpg. Height from start to finish can make a big difference. I use a particular route regularly because it gives great mpg. 6.3 miles with plenty DFCO and I have registered 108 mpg on my ScanGauge start to finish. In the opposite direction, I would be lucky to get half that.

My 2012 Jazz started from cold gives 39mpg  for the first mile on the display if I turn right out of our drive.

It gives 13-16mpg for the first mile if I turn left.

Guess which way comprises a 100 meter climb or a 50 meter drop!

[JimSh]

The leaf needs the heat pump anyway to provide cooling aircon, so makes sense to use it for reverse cycle heating as well.

That's my point: Honda have put an electrically powered aircon in the Mk 4 Jazz so why not also use it for heating?

It's set up as an air conditioning system. removing heat from the cabin and heating up the atmosphere in the same way as your fridge removes heat from the interior and heats up your kitchen.
You can't just throw a switch and run them in reverse.

[Jocko]

I've noticed that there are two coolant caps, so two systems I assume.

There is a cap for the radiator and one for the reserve tank, but both are the same system. All Jazz models have two caps. On the Mk 1, the lid of the reserve tank is the second method of topping up,

[Muldoon]

It will be interesting to see how these new Jazz models operate in winter, the petrol engine may be needed even more to heat up the cabin and help defrost the windscreen plus the impact on MPG.

The new jazz appears a very expensive car to buy and run compared to the claimed savings from slightly higher MPG of 60 to 70 in real world driving. The purchase price and insurance group seems very high plus all the technology and batteries to keep maintained as it gets older. I think road tax is still £140 due to it running on petrol not full EV.  It would take a long time to recoup the extra £10k purchase costs compared to buying an ordinary petrol car with an efficient engine that can get near to 60MPG giving similar figures. It also depends on your driving if you do lots of low speed local journeys but motorway driving has no benefit over normal cars.

[culzean]

The leaf needs the heat pump anyway to provide cooling aircon, so makes sense to use it for reverse cycle heating as well.

That's my point: Honda have put an electrically powered aircon in the Mk 4 Jazz so why not also use it for heating?

It's set up as an air conditioning system. removing heat from the cabin and heating up the atmosphere in the same way as your fridge removes heat from the interior and heats up your kitchen.
You can't just throw a switch and run them in reverse.

John  is just saying that reverse cycle air conditioning is widely available ( and has been for a long, long time ) and in the Leaf they use the system for both heating and cooling, and wondering why Honda fitted an electric cooling system on latest Jazz but didn't make it reverse cycle,  well the truth is they will have to on their BEV vehicles.