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Best Practices for Reliable Electronic Deployment
#21
(03-21-2013, 09:32 AM)jderimig link Wrote:I ordered a bag of 500, I'll give them away to anyone who wants some.

Let me know if they fit into the MARSA4 jacks. If so, I would be interested in some.
Thanks John
Greg Young - L3
NAR #42065
TRA #00234
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#22
Got the ferrules and the 22ga EASILY fit the MARSA connectors.  I am guessing the 20ga will fit also.

Anyone that wants some just PM me with your address, how many you want and I will send by first class mail.

I crimped using a standard molex terminal gage crimper.

I will upload pics later.
John Derimiggio
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#23
Now lets turn our attention to batteries, our source of energy for a successful deployment.

What battery should you use in your rocket.

This one.
[Image: media.nl?id=1787&c=288557&h=3febf271b11aaab495a1]

This is an 8-cell (9.6 volt nominal) 230mah rechargeable NiMH battery with internally welded tabs.  It will supply 5A into a dead short

You will need this charger.  Its compact and comes with an 12v car adapter so you can recharge or top-off your battery at the field.
[Image: media.nl?id=1567&c=288557&h=88c1afbef1497359f5c8]

Forget about 9v alkalines and throwing away perfectly good batteries after a flight or two.  That is a strong indicator of an IQ less than 77.
Do not substitute "regular" 9V rechargeables.  They are only 6 cell and have a nominal voltage of 8.6v.  Probably good enough but why run your 9v designed electronics on low voltage?

Forget Lipo's.  There are only downsides to them, no upsides.
John Derimiggio
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#24
Quote:Forget Lipo's.  There are only downsides to them, no upsides.

Build me a 29mm coupler based altimeter bay that is 2.5" in length with a 9V
Build me a 38mm coupler based altimeter bay that is 3" in length with a 9V

If dead short current is a measure of quality, Lithium Polymer battery technology is impressive, check it out.  :atf:

What are the outputs on the new MARSA altimeters rated for? 

N
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#25
(03-25-2013, 04:15 PM)jderimig link Wrote:Forget Lipo's.  There are only downsides to them, no upsides.

Upsides: Only require charging once in a blue moon, available in multiple sizes / weights,etc.

Downsides: Occasionally are more "toasty" than a sparky motor if you abuse them. ;D

David
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#26
Repeat: There are no upsides for a LiPo in a rocket other than tiny size for tiny rockets.

If you can't fit a 9v battery in your altimeter bay your rocket is too damn small and needs to be designed better.

Current capacity is meaningless when just less than one ampere is needed to fire an ematch.
Excess current capacity will fry your altimeters when (not if) you accidentally short your outputs.  9V batteries are current limited to about 5A, they cannot deliver more.  Most altimeters use outputs good for at least 5A which means you have a protected situation.

Lipos with current protection circuits provide an additional point of failure.
John Derimiggio
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#27
(03-25-2013, 10:43 PM)Nat Kinsey link Wrote:
Quote:Forget Lipo's.  There are only downsides to them, no upsides.

What are the outputs on the new MARSA altimeters rated for? 

N

Infinity.  They are PWM'd to keep the average current under 5A regardless of the load. Another MARSA exclusive feature.
John Derimiggio
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#28
(03-26-2013, 07:44 AM)jderimig link Wrote:If you can't fit a 9v battery in your altimeter bay your rocket is too damn small and needs to be designed better.

John discriminates against small rockets! The MARSA4 creator is rocket racist!  ;D
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#29
(03-26-2013, 07:49 PM)Dave Riedel link Wrote:John discriminates against small rockets! The MARSA4 creator is rocket racist!  ;D

Well of course he does.  You only have to look at the size of a MARSA4 altimeter to know he discriminates against tiny rockets. ;D 

There is also the fact that they are $12 each vs. $2.25 for a Duracell.  Gets expensive if you fly like Bill Clune and never get the battery back.

Dale
Dale Stoyer - L3
NAR #91256
TRA #13499
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#30
To quote John from the early development days of the MARSA4: " There are already a number of small altimeters sitting in huge rockets. I'll make a larger altimeter with many more features" or something like that. Good strategy, based on his results / sales.

Now we just need John to make a "micro altimeter" with his nice features that fit in a 1" body tube. Can it be done? Wink

David
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