... and it can't be 'cold' like it would be in a car in winter pretty much anywhere?

A built-in battery header would serve as a workaround in many circumstances, and is already being worked on.[0] The heater would draw power when the car is charging to either keep the electrolyte above room temperature or preheat prior to expected use. You could even run the heater off standard 110v or 220v outlets, for instances where the car is parked but doesn't need to actually be charged (a garage might not be willing to deal with EV charging, but be fine with the relatively minor draw of a car's built-in battery heater in comparison). And when that doesn't work, you could probably run the heaters off the battery if you keep it from dropping too far, or a secondary battery as suggested by the grandparent.

There aren't really any perfect solutions, but cold temperatures are a problem we've dealt from the beginning with both batteries and internal combustion engines. My dad used to tell me stories about his time in Alaska as a teenager, and a bush pilot who would talk about when he'd have to pull the drain the oil from his plane, pull the battery, and take both inside overnight to keep them from freezing.

0. http://popularmechanics.com/cars/hybrid-electric/a21999984/e...

> standard 110v or 220v outlets

That isn't the standard, at least not in North America (120V/240V) or Europe (230V):

https://en.wikipedia.org/wiki/Mains_electricity_by_country

Those are nominal rms values, the range is plus or minus 10%.

I am not sure where it comes from but in the US it's not uncommon for supplies to be referred to as 220/110 rather than 240/120. They're generally understood to be the same thing.

"110" or "220" are legacy terms for mains voltages in the US, they are still in common use.

i believe that's the case with current batteries too. Car batteries, such as Tesla's, require both heating and cooling elements to keep them in an acceptable temperature range. Unsure what the exact temperature range is, but my guess is it's not too far off of those ranges.

Interesting fact: Tesla achieves their ludicrous mode (2.3 seconds 0-100kph) by pre-heating their batteries so that more power can be drawn. During my test drive, it took an estimated 40 minutes to heat the batteries to do this...

Do capacitors have the same problem? I know they’d take longer to charge than discharge, but I don’t know temperature requirements.

Capacitors are blindingly fast in both charging and discharging compared to chemical batteries, and are much less susceptible to thermal variance in performance to boot. Their downsides are greater mechanical fragility, greater self-discharge, and comparatively terrible energy density.

I believe it would depend on the type of capacitor. A metal foil capacitor would have no problem, but an electrolytic might. The rate for capacitors is so much larger than batteries I doubt it's actually a problem.

Perhaps the solid cells could be warmed up via some cheap coils powered by some bootstrapping liquid cells?

So like a diesel, it may need a heater circuit.