So I went to Norway for the holidays, with my tiny RV as vehicle, but did not sleep in it.
And it got to -19C overnight.
And it seems my solar mppt controler broke, ended up with a burst capacitor. Upon returning, the MPPT was dead with a few drops of electrolyte still seen dripped out when I dismounted it and likely held it at new angles. And yes, it is electrolyte, not water. Horrible smell, even worse taste (I should not have tasted that). Manufacturer lists -30C for the MPPT device as a whole, but I am not sure what the capacitors by themselves would be.
As you may imagine, there is not a whole lot of solar load in the Norway winter, so we can ignore cooking or frying the capacitor. Even if there was a single sunny moment, it would get nowhere near the specs (in fact, it would not even get near the voltage specs if I was in Spain in Summer).
Someone mentioned condensation, but while condensation can short or rot stuff, I do not see how external water, freezing or not, can cause a capacitor to burst from within. Also, apart from the exact place where the stuff dripped, everything else, above, below, to the side of the device, was very dry with no visible hints of past water. No drying lines nor blackness on the untreated wood.
And of course, condensation is actually more of a summer or spring problem. The air is actually pretty dry in winter.
Can they freeze? Anyoney has had such a thing before?
Or am I completely chasing phantoms with this freeze theory?
Would it have to have been a bad batch to freeze (like the famous Dell capacitors of early 2000)?
Photo for ambiance