Keeping LiFePO4 Battery Banks cool in Australia

[mcart117]

I've done a quick search on cooling and many solutions posted here seem heavily engineered and expensive. My offgrid solar system saves me about $2 a day from my electricity bills, so I have opted for using a cheap domestic evaporative cooler:



That works quite well on its own, but I can improve the airflow by placing a light linen cover over the top.



Without the cooler, my batteries rise to about 5 degrees above the ambient temperature. With the cooler I can reduce the battery temperature to about 5 degrees below the ambient temperature.

I am not sure how well this Gerry-rigged system sits with the philosophy of the forum, but if anyone has any constructive thoughts, I’d be happy to receive them

 

[Substrate]

I'd do this regardless - but maybe make sure you've got clean busbars / terminals, and light amount of anti-oxidant paste like no-alox, penetrox etc on the flat surfaces.

 

[meetyg]

I wouldn't use an evaporative cooler in any electronics environment.
These put out a light mist of water, which will quickly cause corrosion and possibly shorts.

Can your cooler work in fan-only mode? If so, I would try that to see if it's still effective.

 

[toms]

I built a “shed” out of coolroom panels on s concrete slab, situated 300mm away from the exterior wall of our games room.

I have a 100mm PVC duct connecting the enclosure to the house, with an extraction fan connected to an inkbird temperature switch that switches on at 30°C and draws cool air from the games room through the enclosure.

I have a reverse cycle aircon cooling the games room, in summer i have plenty of PV (as most of Australia does) to cover the cooling. Batteries stay cool, games room stays cool - cost less than 1k and electronics are secure and sealed from dust and bugs as well as keeping cool.

 

[mcart117]

I'd do this regardless - but maybe make sure you've got clean busbars / terminals, and light amount of anti-oxidant paste like no-alox, penetrox etc on the flat surfaces.

Everything is clean right now because it is new, but the anti-oxident paste is a good idea so thanks for that.

 

[mcart117]

Can your cooler work in fan-only mode? If so, I would try that to see if it's still effective.

The cooler does have a fan only mode, but if it is blowing 35° air, it won't do much good. And my gut feeling is that at that temperature and hotter any "droplets" will vaporise.

We have a phenomenon called virga rain, which falls from the clouds as regular rain but evaporates before reaching the ground.

I could be wrong, but time will tell.

Maybe I'll look out for a a cheap stand alone refigerative air con, but again as that cold air mixes with the moist summer air there could be droplets forming albeit briefly.

 

[mcart117]

I have a reverse cycle aircon cooling the games room, in summer i have plenty of PV (as most of Australia does) to cover the cooling. Batteries stay cool, games room stays cool - cost less than 1k and electronics are secure and sealed from dust and bugs as well as keeping cool.

That sounds like a really good system. My shed is just a shed, and the whole thing is just an experiment really, but it is nice to hear what other people are doing.

 

[Leeds]

What is your temperature goal here?

How hot would you allow them to get before cooling? When cooling them how cold do you consider cold enough?

 

[Quattrohead]

Sounds like a very bad idea. Just blow air, that is way better than nothing or mist.

 

[wattmatters]

I'm with the others, blowing humidified air over electronics is not a good idea, unless it is a particularly arid part of Australia and it is just bringing humidity up to more normal levels. Americans calls these things "swamp coolers" for a reason.

Other than simply using convective cooling (i.e. fans), I don't have a solution for you though if the system can't be housed in a cooler space, or a space which can be cooled.

 

[toms]

The cooler does have a fan only mode, but if it is blowing 35° air, it won't do much good. And my gut feeling is that at that temperature and hotter any "droplets" will vaporise.

We have a phenomenon called virga rain, which falls from the clouds as regular rain but evaporates before reaching the ground.

I could be wrong, but time will tell.

Maybe I'll look out for a a cheap stand alone refigerative air con, but again as that cold air mixes with the moist summer air there could be droplets forming albeit briefly.

I initially had my power room cooled by a little kelvinator RC aircon. It worked really well, never noticed condensation in the room (we do live in a desert though).

The kelvinator window units are quite efficient and come up for sale 2nd hand for around $200.

 

[mcart117]

What is your temperature goal here?

How hot would you allow them to get before cooling? When cooling them how cold do you consider cold enough?

I get a warning at 35°c and the battery cuts out at 36°. The aim of the cooler is to get the battery temperature back to the mid to late 20s.

 

[mcart117]

I'm with the others, blowing humidified air over electronics is not a good idea, unless it is a particularly arid part of Australia and it is just bringing humidity up to more normal levels. Americans calls these things "swamp coolers" for a reason.

I would be exaggerating to say we are on the edge of the Great Sandy Desert, but it is usually pretty dry here.

Sometimes we get a “heat trough” over us, and my intention is not to attempt cooling in those conditions, but rather to turn everything off until the weather improves.

 

[Aussie]

I've done a quick search on cooling and many solutions posted here seem heavily engineered and expensive. My offgrid solar system saves me about $2 a day from my electricity bills, so I have opted for using a cheap domestic evaporative cooler:

View attachment 119489

That works quite well on its own, but I can improve the airflow by placing a light linen cover over the top.

View attachment 119490

Without the cooler, my batteries rise to about 5 degrees above the ambient temperature. With the cooler I can reduce the battery temperature to about 5 degrees below the ambient temperature.

I am not sure how well this Gerry-rigged system sits with the philosophy of the forum, but if anyone has any constructive thoughts, I’d be happy to receive them

If you got some ply, or even cardboard, and lined the tin behind the batteries, if should stop some radiant heat. If the wall behind is exposed to the sun

 

[mcart117]

I initially had my power room cooled by a little kelvinator RC aircon. It worked really well, never noticed condensation in the room (we do live in a desert though).

The kelvinator window units are quite efficient and come up for sale 2nd hand for around $200.

I like your idea of using coolroom panels to construct a dedicated space for the battery; and using a second hand air con unit to cool that also sounds like a good idea. As you said we are not short of solar energy here, and hot days are mostly sunny, so the energy absorbed by the cooler would be justified by being able to keep charging and using the battery.

 

[mcart117]

If you got some ply, or even cardboard, and lined the tin behind the batteries, if should stop some radiant heat. If the wall behind is exposed to the sun

Thanks, that sounds like another good idea.

This is all a learning process for me.

 

[wattmatters]

I would be exaggerating to say we are on the edge of the Great Sandy Desert, but it is usually pretty dry here.

Still, often pretty dry over that way.

Good to experiment, hope it works out!

 

[octal_ip]

I have a similar problem to deal with. My batteries will be located in workshop that's exposed to pretty high temperatures. I've picked up a large aluminum toolbox that I'll line with fireproof blankets as thermal insulation and a safety measure. I'm hoping to pick up an office style water cooler with built-in refrigeration circuit that I can adapt to cool the interior of the box.
Still on the drawing board, but as my cells arrived today I'd better get to work on it soon. I'll post my experience and results.

 

[Frick]

I've done a quick search on cooling and many solutions posted here seem heavily engineered and expensive. My offgrid solar system saves me about $2 a day from my electricity bills, so I have opted for using a cheap domestic evaporative cooler:

View attachment 119489

That works quite well on its own, but I can improve the airflow by placing a light linen cover over the top.

View attachment 119490

Without the cooler, my batteries rise to about 5 degrees above the ambient temperature. With the cooler I can reduce the battery temperature to about 5 degrees below the ambient temperature.

I am not sure how well this Gerry-rigged system sits with the philosophy of the forum, but if anyone has any constructive thoughts, I’d be happy to receive them

So, where you are sounds hot and dry, and while it may nearly simultaneously evaporate, you could get corrosion which is a world of issues. swamp coolers need constant air from outside, in a sealed room they swamp it up amd stop working so make surre it’s ventilated.

here’s an option, point the cooler elsewhere, put a small water circulation pump in its tank ( that water ends up cold) and pump it into 5 meters of small pexpipe that is wrapped around the batteries ( no metal, those batteries are live under a thin blue film). Insulate them somehow with foam box.
now they will be dry and likely very much below ambient.
I have used a custom built larger version of this to cool rooms in desert environments, works really well as a low power AC.

 

[littleharbor2]

Being that my battery is in a box I have installed a mini refrigeration unit and digital thermostat. It runs off it's own dedicated 12 volt panel and battery. I only run it in the hot summer months and it does help keep the batteries cooler than ambient outside air temp. There's no chance of getting the batteries too cold being that this tiny unit isn't that powerful, plus the programable thermostat works really well. I did have to create a drain chute to get the dripping condensation out of the enclosure.

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