Better hybrid performance in really hot weather-

[MakinDoForNow]

I don't know how hybrids work but in an ice vehicle, when you enter a hot car you put the a/c on regular, not max. That draws in fresh air that's not as hot as the inside air. Once the cabin cools down you switch to max which recirculate the cold air and stops the hot outside air from entering.

Maybe a hybrid is different.

I believe the hybrid will use outside or inside return air whichever is is cooler when max cool is selected. Note that "LO" IS BELOW 60°F, the lowest selectable setting. It will keep cooling until you say "I'm happy with 60°F don't shoot for lower (50°F?)!

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[inline_five]

The AC works exactly the same in both drivetrain variants, with the exception that the compressor is run by the engine in the EB model and a 400V electric motor in the hybrid in order to provide cooling when the ICE is not running.

No, the hybrid uses a variable speed compressor. On the EcoBoost it’s belt driven so rpm is determined by engine rpm.

 

[Vaportrail]

Ahhhh-

Finally starting to cool off around here...

 

[The Real Maverick]

I don't doubt you but I am still trying to figure out how the two cooling systems - ICE engine and hybrid battery - benefit from this. Does the hybrid system stay on longer or at a higher pump volume? Dunno and still scratching my head.

I think I can shed some light here.

Battery Energy Control Module (BECM)

The BECM manages the condition of the high voltage battery to control its charging and discharging. The BECM controls the high voltage battery coolant pump in conjunction with BCMC controlling the diverter valve. When additional high voltage battery cooling is needed (high ambient temperatures and/ or during high current flow demand) the coolant diverter valve is energized to allow coolant to be diverted through the high voltage battery chiller. The high voltage battery chiller is part of the HVAC system to chill the coolant prior to being returned to the high voltage battery.

Now, in 19 years, almost 20 years of driving Ford Hybrids I can describe the operating strategy in previous Ford Hybrids. If the hybrid battery internal temperature was borderline, the vehicle would "opportunity cool". That is, if the driver has the A/C controls set to "ON" it would take that opportunity to chill the battery at the same time. If the driver's controls were set to "OFF" it would not. There was a 10°F band for "opportunity" cooling.

Once the battery internal temperature exceeded a threshold, the A/C would turn on automatically to chill the battery with no driver input. There would also be no indicator light illuminated of any kind to let the driver know the A/C was on.

In the Maverick:

Battery liquid coolant pump can be on or off at any time (and I expect it is variable speed but I'm not sure)

Battery liquid coolant can be:
Artificially warmed
Circulated at ambient
Artificially chilled

It is almost always circulated, to a radiator, at ambient. "Water" has great heat absorbing characteristics, is much denser than air, and can carry away much more heat than air can.

You will find a 78°F pool chilly.
You will find a 78°F room warm.

The battery, most often, except for the most extreme cases, does not need refrigerant chilling. It only needs the fluid to circulate to avoid stagnant HEAT BUILD UP.

UP TO ABOUT 113°F (maybe more) running the loop at ambient is deemed sufficient. Here, or slightly above here, a valve can open, and now air conditioning refrigerant can help chill the water. This may occur while idling for example when there is little air flow over the radiators.

If OP observed by running the A/C in the cabin, he seemed to get better battery performance, it is possibly due to "opportunity cooling". It may trigger active cooling sooner, like 10 degrees lower/sooner than if the cabin A/C is off.

This is my theory, but it has a lot of supporting evidence.

Hope that helps.

 

[The Real Maverick]

The HV battery is cooled via a separate radiator ("high voltage battery radiator", #11 in the pic below), the a/c compressor does not loop into it at all.

On pure electric cars the a/c compressor is used to cool the coolant flowing into the battery, however.

The A/C freon is looped in at #19.

DOH!

 

[Oscarcat]

I think I can shed some light here.

Battery Energy Control Module (BECM)

The BECM manages the condition of the high voltage battery to control its charging and discharging. The BECM controls the high voltage battery coolant pump in conjunction with BCMC controlling the diverter valve. When additional high voltage battery cooling is needed (high ambient temperatures and/ or during high current flow demand) the coolant diverter valve is energized to allow coolant to be diverted through the high voltage battery chiller. The high voltage battery chiller is part of the HVAC system to chill the coolant prior to being returned to the high voltage battery.

Now, in 19 years, almost 20 years of driving Ford Hybrids I can describe the operating strategy in previous Ford Hybrids. If the hybrid battery internal temperature was borderline, the vehicle would "opportunity cool". That is, if the driver has the A/C controls set to "ON" it would take that opportunity to chill the battery at the same time. If the driver's controls were set to "OFF" it would not. There was a 10°F band for "opportunity" cooling.

Once the battery internal temperature exceeded a threshold, the A/C would turn on automatically to chill the battery with no driver input. There would also be no indicator light illuminated of any kind to let the driver know the A/C was on.

In the Maverick:

Battery liquid coolant pump can be on or off at any time (and I expect it is variable speed but I'm not sure)

Battery liquid coolant can be:
Artificially warmed
Circulated at ambient
Artificially chilled

It is almost always circulated, to a radiator, at ambient. "Water" has great heat absorbing characteristics, is much denser than air, and can carry away much more heat than air can.

You will find a 78°F pool chilly.
You will find a 78°F room warm.

The battery, most often, except for the most extreme cases, does not need refrigerant chilling. It only needs the fluid to circulate to avoid stagnant HEAT BUILD UP.

UP TO ABOUT 113°F (maybe more) running the loop at ambient is deemed sufficient. Here, or slightly above here, a valve can open, and now air conditioning refrigerant can help chill the water. This may occur while idling for example when there is little air flow over the radiators.

If OP observed by running the A/C in the cabin, he seemed to get better battery performance, it is possibly due to "opportunity cooling". It may trigger active cooling sooner, like 10 degrees lower/sooner than if the cabin A/C is off.

This is my theory, but it has a lot of supporting evidence.

Hope that helps.

Hey Real Mav - thank you - I had no idea how complex the hybrid cooling system and need to cool the battery was. Even if your detailed explaination isn't perfect, it at least gave me an idea of the cooling needs of the battey. In days of yor, I used to hear my wife's Prius making sounds while parked in the garage. My Mav hybrid does the same and I guess it is the coolant circulating to respond to heat buildup. Many thanks!

 

[The Real Maverick]

Hey Real Mav - thank you - I had no idea how complex the hybrid cooling system and need to cool the battery was. Even if your detailed explaination isn't perfect, it at least gave me an idea of the cooling needs of the battey. In days of yor, I used to hear my wife's Prius making sounds while parked in the garage. My Mav hybrid does the same and I guess it is the coolant circulating to respond to heat buildup. Many thanks!

You are welcome.
My thirst for knowledge is high.
I like to know how things work.

While in extreme cases I suppose it is possible to circulate battery coolant "while parked in a garage" however the noises you usually hear are the hydraulic brakes relieving / equalizing pressure.
Other sounds are electrical relays opening and closing. Some may be from the fuel system doing leak tests.

The water pump running would produce a continuous gentle hum or buzz.

 

[Random]

I will say I get much better MPG in hot weather as well. For my 12 mile commute into work I averaged 57mpg in summer and 43mpg in winter.

edit: that’s with AC on

 

[The Real Maverick]

I will say I get much better MPG in hot weather as well. For my 12 mile commute into work I averaged 57mpg in summer and 43mpg in winter.

You have to define hot.

"Optimal" is going to be in the 80's F.

 

[AVC]

Lithium chemistry batteries are most efficient at taking/delivering charge between about 65F and 105F, rapidly deteriorating outside that range. Further the batteries start to suffer significant service life (# of charge cycles) damage at temperatures above 100F or so.

I believe the service lit says active (AC compressor) cooling kicks in when ambient temp exceeds 90F. There is a PID one can monitor for HV battery temp, if curious what temp range the HV battery is kept at.

As for running the AC on MAX; this does force RECIRC mode, which, after the cabin reaches a desired temp, reduces the heat load the AC system must manage as compared to FRESH mode (recirculating 75F ambient, dehumidified air, versus a constant flow of say 100F humid air). This would make available the excess capacity from the AC system for "more" battery cooling.

I also imagine that you wouldn't have to use MAX, but just simply switch to RECIRC mode and gain similar benefit.

Last, would guess to avoid $$$ HV battery damage, the PCM will manipulate the AC compressor and system modes however it needs to, including possibly some compromise to cabin cooling.

 

[The Real Maverick]

I believe the service lit says active (AC compressor) cooling kicks in when ambient temp exceeds 90F. There is a PID one can monitor for HV battery temp, if curious what temp range the HV battery is kept at.

A/C cooling kicks on (in mine) above 110°F.

Below this, battery coolant loop just recirculates to the front radiator and back.

Yes, a little surprising but these are industrial batteries not hoverboard batteries and apparently they are designed to take it. Also there are variances in battery chemistry and precise physical make up, from maker to maker. But yes, I watch those PID's quite often actually.

 

[The Real Maverick]

A/C cooling kicks on (in mine) above 110°F.

Below this, battery coolant loop just recirculates to the front radiator and back.

Yes, a little surprising but these are industrial batteries not hoverboard batteries and apparently they are designed to take it. Also there are variances in battery chemistry and precise physical make up, from maker to maker. But yes, I watch those PID's quite often actually.

My HV battery is above 100°F almost every single drive cycle.

City stop n go heats it up more than highway or towing. I do 75% city.

 

[AVC]

The AC Cooling kicks in a t 110F AMBIENT, or 110F battery temp? As you've monitored (graphed) the temp PID(s), is there an obvious regulation set point or hysteresis temp range?

 

[The Real Maverick]

I don't get really hot very often.

But it would be driven by internal battery temperature not ambient.

Here is today. 20 minutes into a morning commute after a cold soak all night at under 65 degrees. 65°F at time of the photos.

The internal HV battery temperature is already 97°F after 20 minutes & 10 miles on a mild 65 degree morning. Battery coolant is basically ambient.

 

[Vaportrail]

Why do you crack the vents and not open them fully to allow good airflow across the evaporator and into the cabin? You're artificially reducing the capacity of the A/C system; granted it would reduce the power drawn by the compressor but you aren't adequately conditioning the space.

Seems odd.

I was used to electric propulsion simply not working with ambient temperature above 110.

It was about 113 degrees outside driving through town. Wife was in the back seat, complaining she needed more AC.

So, I turned it on max, and pointed an open vent towards her.

I don't like all the cold air blasting on me, so I closed my vents, to barely open and my son did the same with his front passenger vents.

To my surprise, electric propulsion started working again!!!
Regen braking was actually charging the high voltage battery, like normal.

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