[aprssig] Balloon warmth
kc6ete at gmail.com
Wed Mar 24 11:18:53 CDT 2010
I have lots of discharge tests on these if you want it.. 0.7a, 1.5a, and 2.2a. Titanium powpower cells were significantly better than anything else I found.. -
Sanyo and tenergy sucked big time.
-- Sent from my Palm Prē
On Mar 24, 2010 9:27, Scott Miller <scott at opentrac.org> wrote:
The sodium acetate ones are heavy, though.
If I can find board space for the traces, I'm thinking of scattering a
few big flat SMT resistors around the board. The CR123A cells can put
out 1500 mA continuously, so I could easily get a few watts of heat as
needed. I wish metal core PCBs were a little cheaper - that might help
spread the heat around better.
Steve Noskowicz wrote:
> The sealed plastic pouch versions don't use air. It is a reversible exothermic chemical reaction. This is the ones with the metal popple disk.
> I think they have a super saturated solution of an acetate salt, perhaps sodium acetate. There's several YouTube videos showing the process - ad nausium...
> at fractions of an inch of mercury the Iron compound versions will die.
> -- 73, Steve, K9DCI
> --- On Wed, 3/24/10, Scott Miller <scott at opentrac.org> wrote:
>> About a dozen people have suggested
>> this, but I'm not convinced the oxygen level is
>> sufficient. I do happen to have a vacuum chamber in
>> the shop, so once I get a functioning payload again I'll
>> have to throw a few of those in there and compare the heat
>> generated to a control at 1 atmosphere.
>> AD4BL wrote:
>> > An alternative to keeping equipment warm on a balloon
>> flight is to use the hand warmers. They
>> last about
>> > 8 hours and provide enough heat to keep equipment
>> operating in a cold environment.
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