The Author's Quest to Build a Self-Heating Chamber for Solar Batteries

As I sat in my cold German garage, surrounded by the chill of winter, I couldn't help but think about the limitations of my solar battery system. You see, these batteries can only safely charge up when it's above 0 degrees Celsius, and my PV system wants to play it even safer by only charging above 5 degrees Celsius. This is a problem because the batteries are placed inside my concrete garage that comes with forced ventilation, which will definitely get colder than that during winter time.

There do exist self-heating batteries that avoid this problem, but they're quite expensive and when you want a truly massive energy storage, I haven't seen a solution yet. However, I decided to take matters into my own hands and build a self-heating chamber for my solar batteries.

The Project Begins

I started by designing the basic structure of the heat chamber. It would need to be insulated well to retain heat and protect the batteries from freezing temperatures. I chose to use mineral wool insulation, which is a great conductor of heat. I also added some reinforcement beams for extra support and installed an OSB floor at the bottom.

Next, I moved on to building the inner walls of the chamber using plywood. This was a bit tricky, as I had to figure out how to mount it securely without compromising the structural integrity of the chamber. Luckily, my new band saw came in handy, making it easier to cut and shape the plywood to fit.

The Insulation Process

With the basic structure complete, it was time to add the insulation. I cut the mineral wool to size and pushed it into the cavities of the chamber. This was a bit messy, as you can imagine, so I wore gloves and respiratory protection to avoid inhaling the stuff.

Once the insulation was in place, I closed everything up with another layer of OSB on the outside. The result was a cozy, warm space that should keep my batteries nice and toasty even in the coldest temperatures.

Adding the Door

Now that the chamber was mostly built, it was time to add a door. This wasn't too difficult, as I just had to mount some hinges and install a handle. I also added some snapping thingies to keep the door closed for good measure.

However, upon closer inspection, I realized that there was a bit of a gap between the door and the chamber. Not a huge problem, but it meant that I needed to add an inner and outer sealing line to make sure everything stayed warm and cozy.

The Control Electronics

With the chamber mostly built, it was time to think about the control electronics. I wanted something simple and reliable that could monitor the temperature and turn on or off my heater as needed.

Luckily, I had all these components lying around in my lab, so I didn't need to go out and buy anything new. I hooked everything up together, connected a light bulb as a load, and fine-tuned the temperature thresholds until it worked perfectly.

The First Test

Finally, the day arrived when I was ready to test my self-heating chamber. I set the thermostat for 20 degrees Celsius and closed everything up. Then, I waited...

As expected, it took only 20 minutes for the chamber to reach that temperature. The system drew around 32 watts of power and required a total of 0.012 kWh, which costs me nothing.

But what really impressed me was how well the insulation did its job. After an hour, the chamber dropped down to not even 15 degrees Celsius without heating, proving that my DIY self-heating chamber is working like a charm.

Of course, with the batteries inside, the energy requirements and heat-up times will change over time, so I'll have to see how it all plays out in the long run. But for now, everything seems perfect, and I'm excited to share this project with you all.

Conclusion

Building a self-heating chamber for solar batteries was a fun and rewarding experience that taught me a lot about insulation, structural integrity, and control electronics. If you're thinking of doing something similar, I highly recommend it – just be prepared for the mess and the learning curve. And if you do decide to take on this project, don't forget to share your own experiences and tips in the comments below.

And as always, thank you for watching, liking, sharing, subscribing, and hitting that notification bell. Stay creative, and I'll see you next time!

WEBVTTKind: captionsLanguage: enIt is getting cold here in Germany; so I thoughtwhy not build a well insulated chamber thatI can heat up electrically and in which Ithen can sit inside to warm up.And yes; that was a joke, because this heatingchamber will of course not be for me but insteadmy 4 solar system batteries.You see the problem is, that those can onlysafely get charged up when it is over 0 degreeCelsius; and my PV system wants to play iteven safer by only charging above 5 degreeCelsius.That is of course a problem because the batteriesare placed inside my concrete garage thatcomes with forced ventilation which will definitelyget colder than that during winter time.Now there do exist self heating batteriesthat avoid this problem, but those are quitea bit more expensive and when you want a trulymassive energy storage, then I have not yetseen a self heating one.So in this video I will try my best to buildsuch a heating chamber that will hopefullynot require too much energy in order to findout whether such a solution could be scaledup for a possibly bigger battery later one.Let's get started!This video is sponsored by PVcase; your goto Photovoltaic design software that can beused for ground mount installations and roofmount installations.PVcase will speed up your design process;increasing your pipeline up to 50% for largecommercial PV systems and utility scale plants.Key features include 3D modeling in complexterrain, slope analysis, shading calculationand intelligent algorithms that makes planningfast and accurate.So click the link in the video descriptionbelow and start your free trial now!Now to make this big project easy to understand,let's divide it into these 3 segments: howto create heat, building the actual chamberand finally the control electronics.And let's start off with creating heat becausethat initially sounds simple; but it is actuallyquite complicated.The reason is that I wanted a big surfacethat can only heat up to a maximum of around50 degree Celsius for safety reasons.And I also wanted to power this heater directlywith mains voltage to keep it all as simpleand efficient as possible so that I do nothave to worry about a separate power supply.So the simplest solution of grabbing a bigpower resistor, slapping that onto a metalsurface and powering that, is pretty muchout of the question because it uses a lowervoltage and it also gets too hot.Instead I searched for a heater you can buyfrom the internet, in this case from AliExpressto be specific and I think I found 4 differentones that could to the job.But long story short, the resistance of thesilicon covered one as well as the heatingwire was way too low and of course a low resistancemeans a high power output when hooking upmains voltage.The result is, as you can see, a super quickheating up time as well as a too high temperature.But luckily for me I also ordered this bigterrarium heat pad which comes with a higherresistance and thus after hooking it up tomains voltage, it heated up slowly and onlyup to 40 degrees Celsius, perfect.Sadly though the size of this thing was inthe end too big for my heat chamber and thusI had to switch over to my last ordered productwhich was a plastic enclosed heating pad thatis usually used for floor heating.And luckily for me this thing performed prettymuch the same way as the terrarium heatermeaning it is definitely suitable for my application.Only difference here is that I had to addmains voltage wires by myself and at thispoint I also have to warn you that workingwith mains voltage should only be done byprofessionals.Ok; and with that out of the way, the heatingproblem was solved and it was time to buildthe actual chamberFor that I firstly measured the dimensionsof my batteries and checked what lumber Istill had lying around.And I think these pretty generic wood lathesin combination with some plywood and OSBsshould do the trick just fine.And in case you are wondering here are theirdimensions.But of course just using wood does not holdthe heat that well which is why I made a tripto my attic where I still got lots of mineralwool lying around.Now this one is 5cm thick and my idea hereis to basically double it up and thus hopefullyget a good heat insulation.And luckily for me two wood laths stackedon top of one another are the perfect heightfor this insulation.So after making a truly rough sketch of howthe wood construction should look like inthe end; I started cutting wood lathes tosize with the miter saw, stacked them up andthus created the sides for my first wood rectanglewhich I then put together with more screws.After repeating this complete process to createa second rectangle for the top and bottom,I then cut more wood lathes to size and combinedthem to make the connection pieces for therectangles.With the help of some wood dowels and glueI then put this all together and thus gotmyself the basic structure of my heat chamber.So next I put in some reinforcement beamsfor the middle section as well as the lowersection and used that in order to firstlyinstall the lower OSB floor.At this point I also scrapped my initial buildingplans and went freestyle in order to somehowmount plywood to create the inner walls forthe batteries.And by the way using my new band saw was ahuge help here.But anyway after this was finally done; Imoved on to the middle or upper section whereI pretty much repeated all the steps fromthe lower section.And with that complete I got all the innerwalls done, meaning it was time to cut themineral wool to size, push it into the cavitiesand close it all up on the outside with anotherOSB.If you want to do something similar then Iwould highly recommend wearing gloves anda respiratory protection because you do notwant to touch or breath in this stuff.But anyway as soon as all insulation was inplace and wheels got added to the bottom;I got to say that I was very happy with thechamber so far.All that was missing now was a door, but thatwas pretty easy to create at this point becauseit was basically the same building techniqueI used before.Except that this time I also added a handle,hinges to mount the door to the chamber andfinally these snapping thingies that keepthe door closed.And there you have it, my lovely crafted heatingchamber which was still not done though becauseat this point I realized that there was away too big gap between the door and chamber.So to fix that I added an inner and outersealing line and with this part finally complete,we can move on to the control electronicsNow all we need here is basically a temperaturesensor, a relay to turn on or off our heaterand a microcontroller that monitors the temperatureand then turns on the relay.And yes I had all these components lying aroundin my lab; but I wanted to be lazy this timeand thus got myself this premade commercialsolution.After hooking it up to mains voltage, it seemsto measure the temperature accurately enoughwith its sensor and after connecting a lightbulb as a load and fine adjusting the temperatureon and off thresholds, this system works perfectlyfine and is suitable for my application.That means it was time to finish this allwhich I did by mounting the control circuitto the top, cutting my heater to size, addingwires, securing it to the inner door of mychamber, guiding the wires to the top forwhich I previously drilled some holes andfinally doing all the mains voltage wiringinside a distribution box and securing thetemperature sensor inside.And just like that my project was more orless done and it was time for a first propertest at a room temperature of 13 degrees Celsiusthat I wanted to increase up to 20C.So I closed everything up and did a time-lapse;but sadly the only analog clock I have, failedpretty much at the start.So you have to believe me that it only took20 minutes to reach that temperature and whiledoing that the system drew around 32W andrequired a total of 0.012 kWh which costsme like nothing.And best of all the chamber dropped down tonot even 15C after one hour without heatingmeaning the insulation seems to do its jobjust fine.Of course with the batteries inside the heatup time and energy required will change andI will actually have to see overtime how wellthis works with the batteries and whethernew problems arise with this setup.But with the new battery poles on top fornow, everything works perfectly fine and Ihope you enjoyed the show and maybe got inspiredto make something on your own.If so consider supporting this show on Patreonso that I can keep making videosAnd as always don't forget to like, share,subscribe and hit the notification bell.Stay creative and I will see you next time.