Cold Weather and Cabin Heater and Traction Battery

[YarisHybrid2016]

Hi,

Is this placebo, or an actual effect?

Went out earlier today (OAT was +5 C and the car was cold-soaked). MPG was rubbish (well, relatively  ) as expected, and the car sluggish.

This persisted for the duration of driving this afternoon.

This evening, I turned up the cabin heater as it was now dark, and rather cold (nuclear heating FTW)! I ran the heater around 23 C, and got the cabin nice and warm. Coincidentally (?) the car seemed to drive better on electric, and MPG was improved.

Does the warm cabin affect the Battery?

When I was driving this afternoon, the HV Battery had good charge, but required more power than usual to maintain 30 MPH. This evening after the car had warmed up, the same roads, but required far less power.

I'm now wondering if the Battery temperature was low earlier, and affected power capability, hence poorer MPG and requirement for more power on electric to hold speed.

I have no other explanation.

Has anyone else noticed anything similar?

I would have thought however, that driving the car and it charging/discharging the HV battery, would alone raise the battery temperature, and allow it to provide more power. 

[YarisHybrid2016]

Interesting...

This is for a NiMH battery:

[YarisHybrid2016]

https://en.globtek.com/nimh-battery-safety-notes/

[Anthony Poli]

On cold starts, if my Battery is full then mpg isn’t as bad as when it’s empty. It is assisting the ice, as opposed to the ice charging as well driving the wheels.
Since the batteries are a chemical device, temperature is a limiting factor.

On the plus side, a normal ice is no better in winter for my typical commute, as the temperature doesn’t get high enough to give good mpg.

My return journey is always much better. 5% v 60% distance in EV, that’s worst compared to the best.


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[Anthony Poli]

If I am clearing the windows. Within 3 minuets the Battery is at 68% and the charging is stopped. With having the heating set to 22c the Battery only rises to 10c. Electric only driving is only available when crawling.


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[YarisHybrid2016]

Hmm. Interesting.

Like some cars have block heaters, maybe get a Battery warmer? 

I need to get an OBDII dongle.

[Anthony Poli]

What’s more interesting is how the ice charges the Battery, it’s not like you would expect, the harder you press the accelerator doesn’t charge any quicker.
One scenario that charges quicker is when you have the cruise control set to 30 and then you come to and short but decent downhill and then uphill.
For the 5-10 seconds downhill the regen is about 1-2%, compared to less than 1% going uphill on the ice. The centre of the eco gives a decent amount of charge and then on the last bit of the eco is the next point of maximum charge.


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[YarisHybrid2016]

The irony of the heater resulting in a higher SoC is that it's harder to drive in EV! 

Interesting comment regarding the point of maximum charge. If I'm driving around 50 MPH, the power is just above the center of ECO, but to drive at 60 MPH it needs to be around one tick mark below POWER, and I had noticed the Battery reaches a higher SoC quicker at this speed (though figured it was speed related, thus more kinetic energy when lifting off for regen, which was the cause; it's hard to tell as the road undulates).

I'm still having a question mark over how start/stop affects the engine life.

Particularly on the return journey from town, I'll spend maybe 10-15 in start/stop traffic getting out of town, at maybe 20-30 MPH.

The car will go into warm-up, as it has probably been sat a couple of hours. It will warm up, then probably spend 60-70% of the time in EV mode. I then reach a dual-carriageway, which is uphill. I'm not sure if hard acceleration up the hill is bad for it or not? I would hope it's up to temperature by then.

[Anthony Poli]

As for engine life, since there are plenty of hybrid taxis, I doubt it’s something to worry about.

I would imagine it’s similar to the modern normal cars where the engine spins while there is no fuel going in.

If they can overcome restarting a rocket engine in space. I think the car makers can deal with stop start. As the hybrids don’t have an old fashioned starter motor.


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[Madasafish]

Taxis as an example are misleading. They are in frequent use so the engine is usually warm . Maximum engine wear occurs when engine is cold.  The stop/start system only works when the engine is warm.

 

The added strain on electrical systems - eg starter  - is catered for by using heavy duty ones.  

 

The higher mileage hybrids seen on sale usually are either taxis or driven long distances on motorways - so stop/start has little wear impact. I would be more concerned about cars driven daily to deliver/collect children.. often stopped in slow moving traffic.. and with all heaters/electrics full on in winter... 

[YarisHybrid2016]

I drive good distances (14+ miles one way) so the car is not chronically cold, but when starting from town there is a lot of start/stop before the car has warmed up, then I'm hitting dual-carriageway at 70 MPH which I don't like (not the speed so much as joining).

The car seems to consider itself warmed up by then, and the heater does produce some heat, but not convinced.

It would seem that less engine wear should occur as the engine spends a period of not operating, but I'm not convinced about the start cycles.

[Anthony Poli]

I drive good distances (14+ miles one way) so the car is not chronically cold, but when starting from town there is a lot of start/stop before the car has warmed up, then I'm hitting dual-carriageway at 70 MPH which I don't like (not the speed so much as joining).
The car seems to consider itself warmed up by then, and the heater does produce some heat, but not convinced.
It would seem that less engine wear should occur as the engine spends a period of not operating, but I'm not convinced about the start cycles.

The start stop cycles are not from cold and that would be more beneficial than repetitive cold starts.



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[Mick F]

Can I ask a question please?

Am I correct in saying that the heater and the aircon are electrically generated?

Thanks, Mick.

[Anthony Poli]

Can I ask a question please?
Am I correct in saying that the heater and the aircon are electrically generated?
Thanks, Mick.

The aircon doesn’t need the ice, but the heater requires the heat from the ice.


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[Mick F]

How does the heater carry on warming the cabin area when in EV or at a standstill without the ICE running?

Cars we've owned in the past don't seem to give much heat out when the engine is switched off.  They cool off quite quickly as the water pump isn't being driven so hot water isn't being circulated through the heater matrix ................ so there must be something different about a hybrid and cabin heating.  Could be an electric water pump?

Mick.

[Mike J.]

Our cars have electric 'everything'! The brake 'servo', the ICE water pump, the aircon compressor. Note also that the car has no belts to break, etc.

[Anthony Poli]

How does the heater carry on warming the cabin area when in EV or at a standstill without the ICE running?
Cars we've owned in the past don't seem to give much heat out when the engine is switched off.  They cool off quite quickly as the water pump isn't being driven so hot water isn't being circulated through the heater matrix ................ so there must be something different about a hybrid and cabin heating.  Could be an electric water pump?
Mick.

I am using Tapatalk and can’t see which car you have. If I am not mistaken, only the new gen 4 Prius have a different way of operating for the heating. The rest rely on the ice for heating and once there is enough heat, it does shut off.


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[Mick F]

2014 Yaris Hybrid.

I see what Mike J is saying, and that makes complete sense to me.  Once the engine is warm, the hot water is circulated through the cabin heater matrix via the electric water pump, and that is why the cabin is kept heated when the ICE is stopped.  Not noticed anything shutting off at all.

Mick.