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Protecting External Batteries During Cold Imaging Sessions

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#1 nickkohrn  Happy Birthday!

nickkohrn

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Posted 24 January 2021 - 11:44 AM

I have been reading Beginner's Guide to DSLR Astrophotography by Jerry Lodriguss, and I recently read a section in which he displayed a photo of his imaging setup. In the setup, his 12v deep-cycle battery is housed within a cooler to protect the batter from the cold. Is this a common practice?

 

I ask because that is the first time that I have seen such a setup. If this is a standard practice, would it be beneficial to throw a heat pack or another safe source of radiant heat into the cooler with the battery in order to maintain a warmer temperature as the cold air enters the cooler through cutouts that cords pass through?



#2 Apagador

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Posted 24 January 2021 - 12:36 PM

I live at the arctic circle and when it's clear outside it's also usually -20°C to -30°C (-4F to -22F). I use a cooler with a jug of warm water in it keeping company to my power packs. Works wonders.
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#3 SteveL42

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Posted 24 January 2021 - 01:04 PM

I haven't done it, I guess it depends how cold it gets when you image, and how much capacity you can afford to lose.  I use a 100AH AGM battery that can run my scope (mount, Raspberry Pi, cameras, etc) for days.  At about 15F, I loose about 25% capacity, and I haven't been imaging in much colder weather. And when I bring the battey outside and start, it's at room temp, not cold soaked. 

 

If you have very little reserve in your power budget, and extreme temps, I can see this buying you some.  But might just be easier to have a bigger battery.


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#4 SteveL42

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Posted 24 January 2021 - 02:16 PM

There is one other factor to consider.  A fully charged battery won't freeze until about -70C (bacause of the amount of acid in the electrolyte), and I don't plan on imaging in temps anywhere near that.  However, a fully discharged battey's electrolyte has little acid in the solution, so it can freeze much closer to the freezing temp of water.  SO... if you are imaging in sub zero (F) temps, and you use an appreciable amount of your batteries capacity - freezing might become an issue.  There are charts on this of you do a google search.  Again, a bigger battery (left with a 50% or better State of Charge at the end of a session) will do better in the cold.


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#5 nickkohrn  Happy Birthday!

nickkohrn

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Posted 24 January 2021 - 02:19 PM

I appreciate the information provided here. I live in Ohio, USA, at which winter temperatures have reached -40ºF (-40ºC), and it's not a temperature that I am willing to endure. I suppose I will opt for a larger battery when the time comes.

 

Thanks!



#6 dx_ron

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Posted 24 January 2021 - 02:46 PM

Columbus doesn't go below 0F all that often, so it's pretty tropical - compared to that one 1899 day in Perry County :)

https://www.currentr...temperature.php




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