Hybrids & Heat

hybridbatterysolutions · May 27, 2017

Quite a few people ask me how to best look after their hybrid Battery packs during hot weather.

All Lexus / Toyota Hybrids are equipped with at least 4 thermal sensors, in most cases more, so theoretically if all those & their associated cooling fans / ECU's / wiring / ducting / grills etc are all in good clean working order then the vehicles should 'look after themselves' so to speak so no real great cause for alarm or worry - however - issues arise when any of these fail or become broken or clogged.

Also we are all human so when it's hot we want our AC Air Conditioning on, it is not generally known by hybrid owners, however, that our Air Conditioning compressor motors are not driven by a belt & pulley from the engine as the vast majority of other vehicles are. No! ours are driven by quite a heavy three phase electrical motor directly fed via a converter from our Hybrid Battery.

If our Hybrid Battery &/or system is not in good condition & we are sat in traffic, for instance, the engine not running & the air-con working to cool us - the hybrid Battery will quickly drain & be topped up by our hybrid system resulting in a bit of a see-saw effect (discharge/charge) which in itself is not very good (whatever anyone else says) for the health of our Hybrid Battery in effect it eats away at the capacity of the Battery.

What can we do about it ? Some simple steps like setting our A/C's at a specific normal temperature say 20 degrees & placing it in automatic mode, this will ensure the compressor runs only when absolutely needed, not having windows open while A/C is on as we are then trying to cool the entire planet, other simple things like parking in the shade where possible, keeping all vents & air intake grills clear of detritus.

If you know your Hybrid Battery is a bit weak you are probably better off not using the AC at all.

Hope this helps

tonyricha · May 27, 2017

Suppose this means I should not ride about with moon roof open and air con on! Shame as I do like a bit of extravagants!

NemesisUK · May 27, 2017

I'm surprised the Lexus system doesn't know the windows/sunroof are open and moderate the a/c performance automatically? Certainly the case with Mercedes-Benz..

hybridbatterysolutions · May 27, 2017

42 minutes ago, tonyricha said:

Suppose this means I should not ride about with moon roof open and air con on! Shame as I do like a bit of extravagants!

Yeah not ideal really. Sorry

Britprius · May 27, 2017

I have often thought that the hybrid Battery cooling systems use the wrong criteria for turning on the cooling fans. As things stand the fan or fans are turned on by Battery temperature, but this is a bit of shutting the stable door after the horse has bolted. The fans not coming on till the Battery is already warm or hot, and even then they turn on running slowly increasing speed as the temperature goes up. The Battery cell core temperature will be much higher than the outer shell.

Surely it would be better if the fans were turned on by ambient temperature cooling the batteries before they get warm. The sensors are fitted on the under side of the modules meaning the core temperature can have risen considerably before they turn on the fans. On certain models of the Toyota/Lexus hybrids "the Prius, the CT and possibly more" it could be argued that using the AC helps cool the Battery as the air intake is in the passenger cabin meaning cooler air is used when the AC is on. Of course the energy being drawn by the AC must offset this to an unknown degree.

Of course the Battery temperatures should be taken into consideration, but early intervention when ambient temperatures are high must help in keeping temperatures down.

I think we are lucky in the UK that our climate is reasonably moderate compared to parts of Europe, and the US where heat is a major factor in early Battery deterioration.

John.

mrdoofa · May 27, 2017

Yeah, I'm not gonna worry about it too much for the 2 really hot days we get per year in the UK lol 😂😂😂

tonyricha · May 27, 2017

Gotta say my last 450h (with often open moonroof) managed 200 K with no Battery issues so they aint too fragile !

hybridbatterysolutions · May 28, 2017

19 hours ago, Britprius said:

I have often thought that the hybrid battery cooling systems use the wrong criteria for turning on the cooling fans. As things stand the fan or fans are turned on by battery temperature, but this is a bit of shutting the stable door after the horse has bolted. The fans not coming on till the battery is already warm or hot, and even then they turn on running slowly increasing speed as the temperature goes up. The battery cell core temperature will be much higher than the outer shell.

Surely it would be better if the fans were turned on by ambient temperature cooling the batteries before they get warm. The sensors are fitted on the under side of the modules meaning the core temperature can have risen considerably before they turn on the fans. On certain models of the Toyota/Lexus hybrids "the Prius, the CT and possibly more" it could be argued that using the AC helps cool the battery as the air intake is in the passenger cabin meaning cooler air is used when the AC is on. Of course the energy being drawn by the AC must offset this to an unknown degree.

Of course the battery temperatures should be taken into consideration, but early intervention when ambient temperatures are high must help in keeping temperatures down.

I think we are lucky in the UK that our climate is reasonably moderate compared to parts of Europe, and the US where heat is a major factor in early battery deterioration.

John.

Yes John that has occurred to me too, - given the reliability & low power consumption (relatively) of the Battery cooling fans I believe it would be better to cool them via an ambient temperature control - I guess I could construct a device to do that alongside the safety roll of the existing sensors, theoretically this could be quite an easy plug in device which would fool the existing systems into running the cooling fans more or less constantly in temps exceeding something like 12 degrees or even at the temp where the manufacturers say they perform best mmmm thats got me thinking!!!!

hybridbatterysolutions · May 28, 2017

18 hours ago, tonyricha said:

Gotta say my last 450h (with often open moonroof) managed 200 K with no battery issues so they aint too fragile !

That's great - very good, but in my own personal opinion & experience I think that is more likely the exception rather than the rule! - so many different factors affect the condition & lifespan of a Battery no matter what type, it is pretty impossible without exceptional testing in a Lab & real on-road extensive long term testing to predict. All we do know & can say with certainty is that temperature has a significant negative effect on cell condition, lifespan & performance.

NemesisUK · May 28, 2017

Does one see significantly more Battery failure/unreliability in countries with hotter climates, compared say with Northern Europe?

hybridbatterysolutions · May 28, 2017

1 hour ago, NemesisUK said:

Does one see significantly more battery failure/unreliability in countries with hotter climates, compared say with Northern Europe?

A good question - I had one from Malaysia which was pretty nearly scrap but not sure?

NemesisUK · May 28, 2017

Well Japan (Tokyo) has much higher average temperatures than we do here, so I'd guess Lexus would have designed with that in mind?

In the recent 'heat-wave' we've experienced here lately I've felt the car has performed much better as a hybrid than during the winter months.

Britprius · May 28, 2017

4 hours ago, hybridbatterysolutions said:

Yes John that has occurred to me too, - given the reliability & low power consumption (relatively) of the battery cooling fans I believe it would be better to cool them via an ambient temperature control - I guess I could construct a device to do that alongside the safety roll of the existing sensors, theoretically this could be quite an easy plug in device which would fool the existing systems into running the cooling fans more or less constantly in temps exceeding something like 12 degrees or even at the temp where the manufacturers say they perform best mmmm thats got me thinking!!!!

The actual single fan motor loading at full fan power is 1.4 amps or 18 to 20 watts less load than a stop light. Running the fan at say 10 watts would give efficient cooling with little fan noise. This when the theoretical GS450H Battery capacity is around 2000 watt hours.

Connecting an adjustable stat in series with suitable resistor across the existing Battery sensors would turn the fan/s on at a predetermined ambient temperature without upsetting the existing Battery temperature monitoring. The resistor could be adjustable allowing for fan speed to be set as well as temperature turn on point.

John.

Farqui · June 4, 2019

On 5/27/2017 at 3:07 PM, Britprius said:

I have often thought that the hybrid battery cooling systems use the wrong criteria for turning on the cooling fans. As things stand the fan or fans are turned on by battery temperature, but this is a bit of shutting the stable door after the horse has bolted. The fans not coming on till the battery is already warm or hot, and even then they turn on running slowly increasing speed as the temperature goes up. The battery cell core temperature will be much higher than the outer shell.

Surely it would be better if the fans were turned on by ambient temperature cooling the batteries before they get warm. The sensors are fitted on the under side of the modules meaning the core temperature can have risen considerably before they turn on the fans. On certain models of the Toyota/Lexus hybrids "the Prius, the CT and possibly more" it could be argued that using the AC helps cool the battery as the air intake is in the passenger cabin meaning cooler air is used when the AC is on. Of course the energy being drawn by the AC must offset this to an unknown degree.

Of course the battery temperatures should be taken into consideration, but early intervention when ambient temperatures are high must help in keeping temperatures down.

I think we are lucky in the UK that our climate is reasonably moderate compared to parts of Europe, and the US where heat is a major factor in early battery deterioration.

John.

John, that's an interesting idea.

The hybrid cooling fan can be controlled via the Hybrid Assistance app; https://hybridassistant.blogspot.com/2017/12/fan-assistant.html

Quote... "The Fan icon is now a 3-state toggle; every tap will rotate between:
OFF - fan controlled by the car
MANUAL - forced ventilation
AUTO - Hybrid Assistant will turn on or off according to temperature"

I've only briefly tried this function and it did kick my cooling fan in to what seemed like overdrive.

hybridbatterysolutions · June 4, 2019

On first impression that looks pretty good, there would also be a way we could "fool" the ecu to constantly run the fan unit on different stages of speed by adding fixed value resistors across the thermistor terminals, in Techstream there is actually a 6 speed graduation on the test function. The fans are very robust on our GS's.

Looking out the window we definately don't need it today !

royoftherovers · June 4, 2019

2 hours ago, hybridbatterysolutions said:

On first impression that looks pretty good, there would also be a way we could "fool" the ecu to constantly run the fan unit on different stages of speed by adding fixed value resistors across the thermistor terminals, in Techstream there is actually a 6 speed graduation on the test function. The fans are very robust on our GS's.

Looking out the window we definately don't need it today !

DefinItely, Richard.

Are you able to tell us members how many ACTUAL Hybrid Battery failures you have diagnosed?

We keep referring members queries to you,but have no feedback on outcomes.

hybridbatterysolutions · June 5, 2019

Oh really? I didn’t realize thanks chaps! I’ve usually got 2 or 3 in but it can go in fits & starts - extremes of temperature sees more in though definitely!

i hesitate to post about their results without they’re permission & it could be seen as advertising.

What I would say is keep an eye on my sites as prices of my new ones are dropping a fair bit as soon as I finish publishing them that is!!

i did ask Steve about advertising on here but prices were very too high for a one man workshop!!!

all the best

Richard

Herbie · June 5, 2019

15 hours ago, hybridbatterysolutions said:

i did ask Steve about advertising on here but prices were very too high for a one man workshop!!!

That surprises me and is rather disappointing to hear. Although in a different field of work, I too am a one-man band and the places where I advertise either have sliding scales or give substantial discounts to sole traders.

Actually, thinking about it, I don't think I've seen any adverts on here so maybe it's not that advantageous anyway. Is there a special section for member's adverts that I've just never visited?