[amsat-bb] High Altitude Balloon micro battery recommendation

[Norm n3ykf]

CR123. Almost everything else will freeze. I used a home made pack to
power the TT4/Garmin lvc18 for my flight. Worked around 8 hours. Long
enough to make it to 78k and into the trees. Recovered a week later
when it fell down.

Norm n3ykf

On Tue, Dec 27, 2016 at 5:49 PM, Ted <k7trkradio at charter.net> wrote:
> Skyler, you may want to look at various li-po batteries at your local hobby
> store. You may find more capacity at the same or close to same weight as
> watch batteries
>
> 73, Ted
> K7TRK
>
> -----Original Message-----
> From: AMSAT-BB [mailto:amsat-bb-bounces at amsat.org] On Behalf Of Skyler F
> Sent: Monday, December 26, 2016 8:21 PM
> To: amsat-bb at amsat.org
> Subject: [amsat-bb] High Altitude Balloon micro battery reccomendation
>
> I am going to send up a few micro beacons (milliwatt HF CW transmitters)
> probably using Walmart balloons and thin wire as the active antenna/payload
> string.
>
> The CW beacon RF module is a really simple oscillator that drifts a certain
> amount with temperature - that way I can tell how cold it is based on the
> received frequency from on the ground. An ATtiny or something similar will
> probably be used to keep the beacon legal and send out CW every 10 mins to
> break the carrier.
>
> So the whole RF module and beacon is extremely light, basic
> transistor/crystal oscillator + ID chip so I don't have to worry about
> recovery. The only consideration is the battery. I will probably have
> something operational between 3 and 7 volts, so I am thinking about just
> stringing a few watch batteries together. Is there a certain recommendation
> for low temperature operation miniature batteries? I need to make this
> payload as light as possible.
>
> The goal is the cheapest Amateur Radio balloon project where recovery is not
> a worry. Signal strength reports across the country as well as wind
> predictions can get a good idea of where the balloon travelled. I can then
> match this data up with the daily National Weather Service launch data to
> determine how high my balloon went based on temperature.
>
>
> 73
> Skyler KD0WHB
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