Crash: battery at fault?  
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All Forums >> RC Airplanes >> Crash & Rebuild >> Crash: battery at fault?
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Crash: battery at fault? - 2/29/2008 8:57:18 AM   
LeeHop



Posts: 211
Joined: 4/5/2005
From: Aurora, OR, USA
Status: offline 		A friend crashed today - total loss of control after about 15 min of perfect flight.
4-cell nicad receiver battery measured 4.9V on meter which includes a load about 10 min after.
Individual cells all measured 1.30 V about 30 min after that. (Battery connector straps removed.)

Do the voltages tell us anything?

This was the only plane in the air at the time and we are at a loss to explain the crash...

Tnx - LeeH
       Post #: 1

RE: Crash: battery at fault? - 2/29/2008 9:57:42 AM   
Mr67Stang



Posts: 2266
Joined: 4/26/2006
From: , NC, USA
Status: offline 		Check for power through the ON/OFF switch as well. Unfortunately after a crash you will not know if the crash damaged the switch or not though. 4.9V is fair under a load. and you state that they rose to 1.3V per cell after 30 min (5.2v total). This looks like a strong battery pack. I would charge a pack at 4.9V under a load before flying. After 15 min of flight your freinds battery may have dipped lower than 4.9V as well. How far out was the plane when the loss of control occured?

_____________________________

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(in reply to LeeHop)
       Post #: 2

RE: Crash: battery at fault? - 2/29/2008 11:43:37 AM   
Flyboy Dave



Posts: 13448
Joined: 3/20/2002
From: San Bernardino County, CA, USA
Status: online 		....true. The voltage was satisfactory, although getting low. More than likely the system
lost power due to a weak connection in the switch. Years ago I had problems with some
new Futaba switches....they were"soft" when you switched them on and off, they were not
crisp and precise. The vibration of the engine makes the switch eventually lose contact.

FBD.

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(in reply to Mr67Stang)
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RE: Crash: battery at fault? - 2/29/2008 1:07:10 PM   
Insanemoondoggie


 

Posts: 1656
Joined: 11/29/2006
From: Somewhere, MN, USA
Status: offline 		If he was using Spektrum , at 4.9 volts , he could of had a brown-out.

(in reply to Flyboy Dave)
       Post #: 4

RE: Crash: battery at fault? - 2/29/2008 4:05:54 PM   
LeeHop



Posts: 211
Joined: 4/5/2005
From: Aurora, OR, USA
Status: offline 		Ahh so...
The plane was less than 100 yards away when it went down. He was not using Spectrum/2.4GHz.

The switch was found to be off after the crash but we all assumed it was a result of the crash because it couldn't have flown without switch on. You have given us a likely reason, I think: the switch may not have been all the way on to start out with and vibrated off. The switch was autopsied and looked fine inside (no arcing, etc) but we never thought or knew of this problem. It was a Futaba switch by the way.

Thanks - this is a great newsgroup!

-Lee

< Message edited by LeeHop -- 2/29/2008 4:08:42 PM >

(in reply to Insanemoondoggie)
       Post #: 5

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