We could power you off the 9v used for heating using a 5v lin reg. <br>At 32 mA the 5v regulator will burn off 1/8 W as heat, which we could use to keep the battery warm.<br><br><div class="gmail_quote">On Fri, Mar 19, 2010 at 10:15 AM, Christie Dudley <span dir="ltr"><<a href="mailto:longobord@gmail.com">longobord@gmail.com</a>></span> wrote:<br>
<blockquote class="gmail_quote" style="border-left: 1px solid rgb(204, 204, 204); margin: 0pt 0pt 0pt 0.8ex; padding-left: 1ex;">That's good to know! I was reading somewhere about good low-temperature performance of lithiums, which confused me. Now the tricky part is I think I need between 5 and 7 V, but less than 0.2 Ah. That would require 4 AA batteries... That would be about 4 times the size and weight of this tiny little board I'm wanting to add.<div>
<br></div><div>I'll look into watch batteries... Thanks for the heads up on the lithium, though.</div><div><br></div><div><div class="im">Christie<br clear="all">_______<br>"We also briefly discussed having officers replaced by very small shell scripts." -- Noisebridge meeting notes 2008-06-17<br>
<br>The outer bounds is only the beginning. <a href="http://www.flickr.com/photos/genriel/sets/72157623376093724/" target="_blank">http://www.flickr.com/photos/genriel/sets/72157623376093724/</a><br>
<br><br></div><div><div></div><div class="h5"><div class="gmail_quote">On Fri, Mar 19, 2010 at 1:47 AM, Adam Greig <span dir="ltr"><<a href="mailto:random@randomskk.net" target="_blank">random@randomskk.net</a>></span> wrote:<br>
<blockquote class="gmail_quote" style="border-left: 1px solid rgb(204, 204, 204); margin: 0pt 0pt 0pt 0.8ex; padding-left: 1ex;">
Hi Christie, Noisebridge,<br>
<br>
We've found lithium batteries very reliable for high altitude projects<br>
-- plain lithium, as opposed to any of the rechargeable types. You can<br>
typically pick them up in a shop in AA format for a bit more than<br>
alkaline batteries, and they get 3Ah and approximately 1.8V per cell,<br>
so two are enough for a 3v3 system, or we have used four to feed a 5V<br>
linear regulator. They last for a very long time (3Ah!) and are not<br>
very affected by the cold. AA form factors have the additional<br>
advantage that battery boxes are readily available, including built in<br>
on/off switches.<br>
<br>
Rechargeable batteries obviously have some advantages but for the<br>
cost, weight and energy storage lithiums tend to work very well. If<br>
you do go the rechargeable route, LiPo batteries tend to fair well at<br>
high altitudes.<br>
<br>
Cheers,<br>
<br>
Adam Greig<br>
CU Spaceflight<br>
<div><div></div><div><br>
On 19 March 2010 08:33, Christie Dudley <<a href="mailto:longobord@gmail.com" target="_blank">longobord@gmail.com</a>> wrote:<br>
> It seems my boss feels like I need more toys. So I have in my grubby little<br>
> hands a tiny little board from Sparkfun - the package tracker I'd mentioned<br>
> earlier. I'd like to see what kind of data we can collect from it and see<br>
> how that data compares to what we're pulling from the G1.<br>
> This nifty little device could also be used to actually log the coordinates<br>
> from the "good" GPS. I'm looking at the protocol now to see what it'd take<br>
> to splice this into the output of that. I also need to come up with a<br>
> battery, but since the thing only averages 31.7mA, meaning for a 5 hour<br>
> flight, it'll eat up only about 159 milliamp-hours. I vaguely remember<br>
> people mentioning the best battery type to use, but since it's not written<br>
> down anywhere... I'm really curious about which types were researched.<br>
><br>
> Christie<br>
> _______<br>
> "We also briefly discussed having officers replaced by very small shell<br>
> scripts." -- Noisebridge meeting notes 2008-06-17<br>
><br>
> The outer bounds is only the beginning.<br>
> <a href="http://www.flickr.com/photos/genriel/sets/72157623376093724/" target="_blank">http://www.flickr.com/photos/genriel/sets/72157623376093724/</a><br>
><br>
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