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Inverter Cooling


Kawaman
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Hi Everyone, 

The past few weeks have been extremely hot ūüĒ• and I had concerns of how hot the Inverter was getting, reaching temperature of 60c plus.¬†

Decided to connect two industrial extraction fans on either of the upper vents, this has brought the temp down to just below 40c. 

My other concern is the Lithium battery in these hot ūüĒ• conditions, perhaps rest the battery on Aluminum heatsink, there are no ventilation holes at all on the battery and for good reason too.¬†

Thought I would share this with the forum who may have the same worry as I. 

The fans will be connected to a timer only for daytime hours. 

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4 hours ago, Kawaman said:

extraction fans

I assume that they are not extracting but are in fact pushing air in?  To my knowledge these inverters have air inlet at the top and air outlet at the bottom - unless you have reversed the fans.

On my inverters (Kings) I have revered the fans, which has helped with cooling (mainly due to the hot air from the outlets not being recirculated after rising to the intakes).  The real change is however not nearly as dramatic as the data from the inverter indicates.  This is probably due to the temperature sensors' mounting position - once air flow is revered a sensor that was on the hot (downwind) side of a heat source is now in fact on the cold side.  The "inverter" temperature on mine now essentially show ambient temperature.

As for the batteries' temperature, heat is the no.1 enemy of LiFePo4 batteries. Well worth the effort to keep below 30C - battery life seriously deteriorates above that.

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Before I had the ceiling insulation in my garage sorted out, my batteries also got hot. I found that adding two whirlybirds in the roof helped a good deal, but got even better results using a low-wattage fan pointed directly on the batteries, initially running only during daylight hours. The batteries themselves seemed to be well-insulated though, so heat build-up from one day carried over to the next, and there was a noticeable temperature reduction when running the fan 24/7. I felt that I needed to point this out because you stated

Quote

only for daytime hours

and I discovered that it works better doing it 24/7, cuts 5-6 degrees.

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10 hours ago, Calvin said:

I assume that they are not extracting but are in fact pushing air in?  To my knowledge these inverters have air inlet at the top and air outlet at the bottom - unless you have reversed the fans.

On my inverters (Kings) I have revered the fans, which has helped with cooling (mainly due to the hot air from the outlets not being recirculated after rising to the intakes).  The real change is however not nearly as dramatic as the data from the inverter indicates.  This is probably due to the temperature sensors' mounting position - once air flow is revered a sensor that was on the hot (downwind) side of a heat source is now in fact on the cold side.  The "inverter" temperature on mine now essentially show ambient temperature.

As for the batteries' temperature, heat is the no.1 enemy of LiFePo4 batteries. Well worth the effort to keep below 30C - battery life seriously deteriorates above that.

Surely a design flaw if it's pulling in cold air from the top and expelling hot air at the bottom?

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Hi Guys,

Thank you for your responses. @Speedster The fans are extracting on either side of the Inverter, my assumption was due to the large Heat-Sink at the top of the Inverter, it would make sense to assist it by pulling out the hot air at both sides. It would be great if someone on the forum could actually pin point where the thermal couple(heat sensor) is placed inside the Inverter, should it be near the fans at the bottom then it does make sense to reverse the fans.

@YellowTapemeasure I only have the one LiFePo4 battery resting on top of my old metal Lead acid battery stand, there is some heat escaping onto the top surface of the stand sort of like a Heat-Sink. The Solar system is in my garage which as no ventilation apart from me leaving the access door to the house open most of the time. I would have to purchase a cheapie fan and mount it in such a way to continually blow on top of the battery pretty much like you have.

 

 

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2 hours ago, Speedster said:

Surely a design flaw if it's pulling in cold air from the top and expelling hot air at the bottom?

It is certainly an unusual design decision - who knows what (if?) they were thinkingūü§™

It works well once the fans are reversed.  The only issue is that, to reverse the fans, you have to remove the seal, which has warrantee implications (unless you use a heat gun or hair dryer to remove it very carefully...)

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1 hour ago, Kawaman said:

The fans are extracting on either side of the Inverter

You really need to check this - it sounds as if your extraction fans are opposing the built-in fans.  If the new fans are strong enough to reverse the direction of the air flow that will explain your lower temperature readings.

See this post by @Coulomb for more details on reversing the fans: http://forums.aeva.asn.au/viewtopic.php?p=60086&sid=3d9e5d756e0de0ea73dee8e1bb2fd2aa#p60086

 

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2 hours ago, Kawaman said:

Hi Guys,

Thank you for your responses. @Speedster The fans are extracting on either side of the Inverter, my assumption was due to the large Heat-Sink at the top of the Inverter, it would make sense to assist it by pulling out the hot air at both sides. It would be great if someone on the forum could actually pin point where the thermal couple(heat sensor) is placed inside the Inverter, should it be near the fans at the bottom then it does make sense to reverse the fans.

@YellowTapemeasure I only have the one LiFePo4 battery resting on top of my old metal Lead acid battery stand, there is some heat escaping onto the top surface of the stand sort of like a Heat-Sink. The Solar system is in my garage which as no ventilation apart from me leaving the access door to the house open most of the time. I would have to purchase a cheapie fan and mount it in such a way to continually blow on top of the battery pretty much like you have.

 

 

I used this on its lowest setting, had it lying around: https://clicks.co.za/safeway_30cm-floor-fan/p/226181

I blow directly towards the batteries, not on top.

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1 hour ago, Calvin said:

You really need to check this - it sounds as if your extraction fans are opposing the built-in fans.  If the new fans are strong enough to reverse the direction of the air flow that will explain your lower temperature readings.

See this post by @Coulomb for more details on reversing the fans: http://forums.aeva.asn.au/viewtopic.php?p=60086&sid=3d9e5d756e0de0ea73dee8e1bb2fd2aa#p60086

 

Thank you @Calvin There is a definite drop in temperature, when placing my hands in front of the new fans I can feel the warm air being extracted quite well. Due to the very fact that there is a heat-sink on top of the unit means it is there to capture the heat rising. I'm not sure if I should go through the trouble of reversing the bottom fans,  just leave it as it is for now perhaps. I will only use the fans when the ambient temperature is 27 degrees and higher. This week in Cape Town there is no need for the fans however I did notice the Inverter temp was sitting at 55 degrees early this morning which is a normal temp, I've seen the the temp rise as high as 63 degrees, I left the fans off. I have owned the Inverter since 2015, just would like to encourage more life out of the inverter

Personally I don't see any harm in what I have done, I'll send a pic of the type of fans I am using when I am back home from work.

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I have a fan (similar to the fans you get on the cooling system of quad bikes - mine is however 110v AC) blowing from the one side pointing at the intake holes of the inverters.  I installed a thermostat switch (bought from ACDC) between my 2 paralleled inverters which switch the fan on as soon as the temp rises above 25c.

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16 minutes ago, Speedster said:

Or a sonoff with temperature probe

@Speedster I suppose the sonoff is similar to these cheap Chinese controllers which I've used to build my wife and daughter-in-law 2 yogurt-makers.  That will make it nice and digital, the thermostat is just analog (if I can put it that way).   I actually thought about replacing the thermostat with one of these Chinese temp controlers once the thermostat stop working in future.

IMG_7535.JPG

IMG_7536.JPG

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3 minutes ago, Cassie said:

@Speedster I suppose the sonoff is similar to these cheap Chinese controllers which I've used to build my wife and daughter-in-law 2 yogurt-makers.  That will make it nice and digital, the thermostat is just analog (if I can put it that way).   I actually thought about replacing the thermostat with one of these Chinese temp controlers once the thermostat stop working in future.

IMG_7535.JPG

IMG_7536.JPG

The sonoff is simply a smart switch to which you attach a temperature probe and set it to turn on/off based upon some criteria.

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4 minutes ago, Speedster said:

The sonoff is simply a smart switch to which you attach a temperature probe and set it to turn on/off based upon some criteria.

Yes I saw the sonoff smart switches but that was too expensive for me to use for this small application. 

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On 2021/03/17 at 8:42 AM, Speedster said:

Yeah, one has to obviously spec for the job at hand. Sonoff TH10 should set you back about R200-ish.

Wow!   I've no experience of the Sonoff brand, but the price you mentioned is below what I paid for the thermostat and the Chinese temp controller.  Definitely going to investigate the Sonoff.

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