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Comment by megraf | Hacker News Reader

>operating temperatures ranging from -20 C to 45 C.

I'm curious to see how thermal management is done. 45 C is not _that_ hot for a black box in the [insert warm place] heat during summer.

I'm also curious if they were able to use the casement as a heatsink in itself

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Then don't use it in the [insert warm place] ?

-20 C to 45 C might not cover every place on earth, but they cover a significant portion. If you had to design a first version of a product, in order to gauge interest of the market, wouldn't you have enough data point with these ? If the number one complaint is "operating temperatures are too narrow, I can't use it", I am pretty sure V2 will cover you.

On top of that, it's pretty safe to say that the true operating marking of the product are wider than that, but that significant safety margins are taken just to be sure a unit does not explode.

> 45 C is not _that_ hot for a black box in the [insert warm place] heat during summer

I've been in a major city that would benefit from power backups like this. The hottest day the all-time heatwave was 45.2 C. So yes it's provably a reachable temperature, one where you _really_ want the aircon to work, and not lose the power.

Toyota's vehicles there have a reputation for being affordable, rugged and long-lived. And mass-produced. So the Tesla Powerwall may be a nice Proof of Concept - if you can afford it, if you can get one, but if Toyota is also in that market, well that's a different ballgame. Far more people will pay attention. All the same, I would wait a couple of years, see if the V2 is much of an upgrade.

It’s worse. A black box can be significantly hotter than the reported temperature.

https://www.nist.gov/how-do-you-measure-it/how-do-you-measur...:

“To measure outdoor air temperature on land, the setup is simple. A thermometer is placed inside an enclosure […]. Regardless of the shape, the enclosure is white in color to reflect solar radiation, which heats the thermometer and keeps it from getting an accurate air temperature reading. The enclosure also typically has slatted sides to allow air flow, and a double roof (a roof and a raised roof over that) to protect the thermometer from rain and further resist the influence of the Sun.”

So, they measure temperature in the shade, away from the ground, under a roof that’s painted white.

In the sun things can get hotter. 45 C water for a few seconds isn’t painful, but touching the hood of a black car or the asphalt on a road surface on a 40 C day immediately is.

I expect that a responsible owner would put the battery unit in the shade of some roof or awning. But YMMV, it might get sun at just the wrong moment.

If it's indoors or in the shade, I don't think there are many places regularly hitting >45C temperatures. Obviously placing it in the sun wouldn't be wise.

The -20C limit could hit more areas, but if placed indoors I guess most should also be fine with that.

And -20 C isn't that cold for outside and close to the floor either. There are places that occasionally reach both. But none of them would be anywhere close to a sea, so perhaps they simply didn't mind extending the temperature range because they start with their domestic market? And then there's the question of what happens beyond that range: will it shut down? Will it go up in flames? Or will or perhaps just age a little faster than rated? If it's the latter, a few dozen hours a year certainly wouldn't matter a lot.

I definitely reach -20 every single year and 45C on a hot day in an enclosed space with sunshine on it isn't unheard of either.

But it's not too much to ask to just create a space for it that's slightly insulated. Making a small space in the garage be within say -10..45 even though outside temps vary -30..30 like they do where I live, is cheap and easy.

Also -20 isn’t unheard of in some places, upper Midwest USA and north….i wonder if it could warm itself if needed?

Lots of people with electric cars have no idea their batteries have heating and cooling packages. I would assume this does as well.

it's always puzzled me when my prius prime asks for permission to use AC while charging, like what are you asking me for bro do what you gotta do

I suppose if you don't want it to for whatever reason it'll shut off if it gets too hot (perhaps short of where it would otherwise start cooling) instead?

Or charge slower.

It is warming up the exterior of the car (pumping heat out of the battery).

If you have a garage integrated into the home, I guess it might be undesirable.

It would be weird if the manufacturer rated it for that temperature range without considering that.

Upper Midwest here. Our power doesn't go out often, but of the times that it has, I think only twice was above -30 degrees.

It really varies a lot by your utility company though; our coop is quite good for the most part. On the other side of the same state, my brother is in an area more prone to bad storms and tornados, so he's had to deal with several multi-day blackouts. It gets hot here, but not above 40c in the shade, so he'd probably be fine if it can handle direct sunlight. If not, a gasoline / nat gas / propane generator would be far more reliable.

Seems to be the best place may be indoors, in a garage or basement

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