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518 posts

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  # 1706140 20-Jan-2017 00:10
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RUKI:

 

...that nonsense feature - "start-stop". My friend has it in Polo and he switched it permanently off.

 

Real start-stops works perfectly well in hybrid car - engine is usually off at the intersections but you immediately start moving in Electric Drive (as in EV).

 

 

 

 

Stop start is quite nice for driving situations where you are going to be stationary at the traffic lights for 3+ minutes. It just sucks when you are at the front of the queue of a roundabout/ give way sign / stop sign with poor sight lines / small gaps where you want acceleration immediately (normally a pulse on the break gets the running), or when the car doesn't restart for some reason (happened to me twice, you just break again, and then accelerate again...). Other time it is annoying is when you are in a pulsing queue (i.e. roundabout /ramp signal), but this is more about excessive wear on the drivetrain.

I wonder how many cycles the stop-start starter motors are rated for... in city traffic you can see a lot of cycles in not many KM.

It takes a lot of fuel savings to pay for one expensive part like a $750 battery or stop-start starter motor (not sure what they are worth)...


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  # 1706207 20-Jan-2017 08:58
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Well I just dropped my wifes CX5 (2.5 Petrol) into the shop to get them to look at why the istop is turning itself off at random times (warning sign and istop in amber flashing on the dash)....I suspect they are going to call back and say the battery needs to be replaced....this is 3.5 years old too.....coincidence? :\

 

I will come back here with what they say. 


 
 
 
 


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  # 1706210 20-Jan-2017 09:01
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How long does the AC keep blowing cold when the stop start has stopped?





Richard rich.ms



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  # 1706219 20-Jan-2017 09:16
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richms:

 

How long does the AC keep blowing cold when the stop start has stopped?

 

 

TBH, I've always had the sense the temperature warms a bit as soon as iStop engages on my car.

 

Essentially iStop doesn't work (and the iStop light goes out) if the aircon is needing to blow cold air.

 

However, some Mazdas including my own have a capacitor that stores otherwise wasted braking energy to power the electrics (called iELoop) - this includes the AC, so while there energy stored there and iStop is engaged the AC will continue to function. But once that energy is used the engine starts back up again.


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Ultimate Geek
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  # 1706690 20-Jan-2017 22:28
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richms:

 

How long does the AC keep blowing cold when the stop start has stopped?

 

 

 

 

All the conventional stop start car's I have driven the air conditioning compressor is driven of the engine itself, so the chiller itself is off whenever the engine is off. The fan part of the air conditioner keeps running though. There is some thermal mass in the evaporator coil, so the air stays cold for 30 seconds or so. As long as the cabin is already cool, I don't remember not having the air con being an issue for the say 3 minutes you are stopped.

 

The 12V battery isn't really big enough to run the air conditioning compressor.

Generally "Max-AC" setting will disable stop start (along with a heap of other parameters such as Towing (trailer lights connected), Battery voltage low, Engine too hot/cold etc)

 

 

 

Electric vehicles & most hybrids are different though. They have the air con compressor driven off the high voltage traction battery, so in the case of hybrids it can run without the engine.

 

On the i3 you can tell it to leave the Climate control on when you park (It's really nice if you park in the sun for 15 - 20 mins in the sun on a really hot day to get back into a really cold car), or start it remotely from a button on the fob, or set a timer. In other markets (not NZ) with the leaf you can turn on the climate control from your smartphone via the internet.

 

 


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  # 1706692 20-Jan-2017 22:33
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Scott3:

 

......

 

Why is temperature monitoring even needed for a 12V battery, and given it is only for accessory loads, shouldn't a tiny battery do fine.

 

 

Same can be found in Nissan Leaf EV. Leaf's 12V battery also has temperature sensor.

 

My educated guess - it is because those cars use electronic chargers and properly designed electronic chargers use temperature sensors.

 

For example: serious UPS use lead acid batteries and those UPS are equipped with temperature sensors.

 

My High Voltage Battery Analysers (I've designed) are capable of testing any chemistry. I also use temperature sensors alongside other alarm triggers.


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  # 1706693 20-Jan-2017 22:34
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E3xtc:

 

Well I just dropped my wifes CX5 (2.5 Petrol) into the shop to get them to look at why the istop is turning itself off at random times (warning sign and istop in amber flashing on the dash)....I suspect they are going to call back and say the battery needs to be replaced....this is 3.5 years old too.....coincidence? :\

 

I will come back here with what they say. 

 

 

 

 

Will be really interested to see what they say. If they say it's the battery, that isn't long for that to last. Maybe it would help to give the car a big long drive to charge up the battery?

 

 

 

I am tempted now not to invoke istart at all, and either disable it on each drive (which is a hassle), or use the tricks so it doesn't engage. I doubt it is really saving me much on fuel, and if there are savings, I doubt it would cover the cost of replacing the battery. 


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  # 1706786 21-Jan-2017 01:46
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Lead acid batteries hate sitting partially or fully discharged. So a car used for lots of short trips will often not be able to charge its battery fully. On some cars the manufacturer will on purpose undersize the wire running between the alternator and battery. This is so if someone drains an otherwise good condition battery completely flat, gets a jumpstart, then immediately drives away. The battery will draw a massive charge current. The car company doesn't want to pay out for new alternators under warranty. And a smaller piece of wire is far cheaper than a much larger alternator. But this means that often at idle with a discharged battery and large electrical load. Charge voltage will be low. So very easy to kill a car battery in just 3.5 years. As well as leaving the interior light on, Faulty glovebox or boot light not turning off is a common one as well.

 

In saying that, occasionally the internal connections can go open circuit. Meaning battery will go instantly from working fine to completely dead and open circuit. If this happens then I would try for a CGA claim.

 

Even on modern cars without stop/start. The alternator charge voltage is often controlled by the engine computer. As varying it is a way of reducing alternator load on the engine therefore better fuel economy. But of course this affects battery life. As voltage control is optimised for best fuel economy not battery life. Common trick is increase voltage when engine braking, even if this runs the risk of overcharging the battery. And reduce battery voltage when car computer detects emissions test conditions.

 

Ideal float voltage for lead acid batteries varies with temperature. (voltage to keep battery charged but without overcharging it). More voltage needed with lower temperatures. And as the battery nears full charge, more of the charge current gets turned into heat. So a battery temp sensor is part of a smart charging system.

 

Then there are people who put modern sealed for life batteries in old cars with mechanical voltage regulators. Which are simply a voltage sensing relay with a resistor or 2 to vary the alternator field current, therefore the charge voltage. Found a 94 Nissan Navara Ute that had this. (was surprised for something comparatively modern) Those older cars need batteries with the removable caps so you can top up the acid level. Only use deminerialised water for this - not tap water.

 

And calcium batteries need slightly more charge voltage than non calcium types. So yet another trap if the alternator was designed for a non calcium and you fit a calcium battery.

 

 

 

 






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  # 1706876 21-Jan-2017 12:10
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Aredwood:

On some cars the manufacturer will on purpose undersize the wire running between the alternator and battery. This is so if someone drains an otherwise good condition battery completely flat, gets a jumpstart, then immediately drives away. The battery will draw a massive charge current. The car company doesn't want to pay out for new alternators under warranty. And a smaller piece of wire is far cheaper than a much larger alternator.



Which manufacturers and which cars?




BlinkyBill

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  # 1706919 21-Jan-2017 13:23
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MikeAqua:

 

My tyre guy's eyes lit up when he saw our Mazda 3 SP25.  Based on the size of his grin, I shudder to think what they will cost to replace. 

 

 

Hah! I found this out on boxing day of all days... drove from Welly to Palmy with a flat rear. Went to tyre shop $180-ish each.


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Ultimate Geek
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  # 1707044 21-Jan-2017 17:11

Aredwood:

 

On some cars the manufacturer will on purpose undersize the wire running between the alternator and battery. This is so if someone drains an otherwise good condition battery completely flat, gets a jumpstart, then immediately drives away. The battery will draw a massive charge current. The car company doesn't want to pay out for new alternators under warranty. And a smaller piece of wire is far cheaper than a much larger alternator.

 

 

 

 

I have never heard this one before. What car manufacturers do this?

 

Cable size is more likely to be the minimum size that they can get away with to save cost and weight.




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  # 1707295 22-Jan-2017 09:19
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mattwnz:

 

Will be really interested to see what they say. If they say it's the battery, that isn't long for that to last. Maybe it would help to give the car a big long drive to charge up the battery?

 

I am tempted now not to invoke istart at all, and either disable it on each drive (which is a hassle), or use the tricks so it doesn't engage. I doubt it is really saving me much on fuel, and if there are savings, I doubt it would cover the cost of replacing the battery. 

 

 

My battery was apparently down to 20-something percent when checked at service; charging brought it up to 70-something. And this is after we'd only recently driven from Chch to Palmerston North. So a long drive may not restore the charge. That said, I'm not sure whether the battery is still charging ok, or if it's dropping back to that lower number over time. 

 

A genuine question: how much fuel does a car use at idle? 

 

If my car has sat at lights etc with its engine off for 49 hours over the 40k km it's done, that's 12.25 hours per 10,000km (a typical distance over a year say). How much fuel would that have used?

 

Anyway, back to my original post: as it so often happens a GZ member (@jeffnz)  has come to the party - he happens to work for the company that brings in these batteries, so has contacted the local dealer on my behalf so hopefully I can get the new battery at a fairly good price. Thanks again, Jeff! 


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  # 1707452 22-Jan-2017 14:49
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trig42:

 

MikeAqua:

 

My tyre guy's eyes lit up when he saw our Mazda 3 SP25.  Based on the size of his grin, I shudder to think what they will cost to replace. 

 

 

I have the Mazda3 MPS, and had to get a couple of new tyres for it (18"). First quote was near $500 each. Shopped around (on the phone). Discount Tyres put a couple of Falkens on it for around $270 each I think.

 

Have to get brakes (pads) done next - they wont be standard either. Any recommendations (North Shore preferably)?

 

 

You can go for "Street Perfomance" pads. I changed my OEM ones on my previous EK4 to some Dixcel Type M pads. Better braking and way less brake dust on the wheels.

 

North Shore Toyota are also official distributor fo Project Mu. Talk to this guy: nick@nst.co.nz

 

Brake pads are usually quite easy to change yourself.


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  # 1707463 22-Jan-2017 15:19
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jonathan18: A genuine question: how much fuel does a car use at idle?

 

Exactly diddly-squat. Consider how long a carb engine will idle with the fuel supply switched off before they no longer have enough in the float bowl to do so. Then consider the affect the float level has on the idle - it doesn't need to be out much to seriously affect the stoichiometric ratio (air:fuel) and make it idle and run badly.

 

I suspect there's nothing to be gained in terms of fuel economy by switching off the engine at idle for under 5 minutes at a time. These systems were implemented for emissions reasons, not economic. They will be a maintenance nightmare for owners once the vehicles have a few miles under their belts further increasing their economic detriment.


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Ultimate Geek
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  # 1707525 22-Jan-2017 16:59
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jonathan18:

 

 

 

A genuine question: how much fuel does a car use at idle? 

 

 

 

 

 

 

USA department of energy did some research in 2015. There results were:

 

 

 

2.0L petrol sedan: 0.61L/h

 

4.6L petrol sedan: 1.47L/h

 

2.0L diesel sedan:0.64L/h

 

 

 

Testing was done under no load (neutral, accessories off). Note that things that having a conventional auto transmission in Drive position while stationary adds load to the engine (torque converter trying to creep the car).

Some people shift their auto's to neutral at traffic lights to save fuel. I don't as I think the additional wear on the gearbox is greater than the value of fuel savings.

 

 

 

cadman:

 

 I suspect there's nothing to be gained in terms of fuel economy by switching off the engine at idle for under 5 minutes at a time. These systems were implemented for emissions reasons, not economic. They will be a maintenance nightmare for owners once the vehicles have a few miles under their belts further increasing their economic detriment.

 

 

 

 

It's small, but better than nothing. Automakers are desperate to do whatever they can to drop an extra 0.1L/100km from the official ratings. The easy wins have be claimed already, so automakers are going to more desperate lengths.

 

In other important jurisdictions tax on car purchases is based on fuel consumption or emission ratings, making it extra important to get good ratings.

Meeting modern emission standards (especially for diesel engines) is really hard. Technologies like the diesel particulate filter, add complexity, capital cost, hurts performance and impacts on reliability. Really they offer minimal advantages to the owner, mostly it is the car following, and people nearby that get the benefit. It will be interesting to see how the current crop of car's are holding up in 15 years. That said, I don't think the automakers care if their cars become uneconomic to run in 10 years. There business is selling new cars...


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