I hope this is highly technical enough. I am thinking about building a solar battery to power an array of high intensity LEDs. It will be somewhat intelligent, and will only switch on the LEDs with the light levels drop below some yet to be determined point, meaning it should charge up during the day and discharge at night. However, I have been having problems with finding a way to store up the power from the solar cell. I live in Alaska, and the city I am in has an all time low temperature of -40C. This limits the type of battery which I can use. While it is very unlikely that the temperature will reach that low again in the useful lifetime of the solar battery, I want to design it for that temperature extreme.
I found some cheap industrial solar panels, and from what I understand industrial means that it can take down to -40C. Also, I found industrial versions of all the integrated circuits, so that should not be a problem.
However, I need some way of storing the energy I get from the solar cells, and I can't find any way of doing it at -40C. I have found a few options, but none of them can operate in cold enough temperatures. Below is the what I think the options might be:
NiCd
Pros: Cheap
Can discharge at -40C
Easy to charge
Cons: Not that environmentally friendly
Can't recharge below 0C
LiPo
Pros: Can charge/discharge at -25C
Cons: Expensive
Requires IC to charge
Supercapacitor
Pros: Can charge/discharge at -25C
Cons: Expensive ($20 for a 50F aerogel capacitor)
Low power density
Anyways, from what I have found out I can't charge anything below -25C. Are there any battery technologies that I am missing that might work for this application? If no other technologies exist, would it be possible to heat the battery using some of the energy from the solar panel? (The solar panel gives around 450mA at 7-10 volts, I am going to start small to test it out before spending very much). Does anyone have any ideas for storing energy at low temperatures?
Edit: I don't need that high of a capacity battery. Around 500mAh at 3.6V is plenty.
Edit: While I am on this topic, will small motors be ok at really low temperatures?
I found some cheap industrial solar panels, and from what I understand industrial means that it can take down to -40C. Also, I found industrial versions of all the integrated circuits, so that should not be a problem.
However, I need some way of storing the energy I get from the solar cells, and I can't find any way of doing it at -40C. I have found a few options, but none of them can operate in cold enough temperatures. Below is the what I think the options might be:
NiCd
Pros: Cheap
Can discharge at -40C
Easy to charge
Cons: Not that environmentally friendly
Can't recharge below 0C
LiPo
Pros: Can charge/discharge at -25C
Cons: Expensive
Requires IC to charge
Supercapacitor
Pros: Can charge/discharge at -25C
Cons: Expensive ($20 for a 50F aerogel capacitor)
Low power density
Anyways, from what I have found out I can't charge anything below -25C. Are there any battery technologies that I am missing that might work for this application? If no other technologies exist, would it be possible to heat the battery using some of the energy from the solar panel? (The solar panel gives around 450mA at 7-10 volts, I am going to start small to test it out before spending very much). Does anyone have any ideas for storing energy at low temperatures?
Edit: I don't need that high of a capacity battery. Around 500mAh at 3.6V is plenty.
Edit: While I am on this topic, will small motors be ok at really low temperatures?
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