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How much were we at risk

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Old 08-26-2012, 04:50 PM
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GarySS
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Default How much were we at risk

Flying with a buddy, I noticed only 4.6 volts on his TX (Spectrum 5x?) He had 4 1.5V rating NIMH batteries. I'm not familiar with Spectrum or even 2.4 radios, I only use 72 MH 8 cell TX NIMH/NICADs. But, old worrywart me, I suggested he change batteries and the new dry cells 1.2 volts read out 6.5V on the TX. I used his transmitter and flew about a 6 minute flight. So, were we at risk of a crash during this short flight with the original batteries? Thanks!
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Old 08-26-2012, 08:02 PM
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Default RE: How much were we at risk

That was a very good move on your part as quite possibly your action saved his plane as 5.0 volts is the recommended minimum Tx voltage for alkaline batteries.

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Old 08-27-2012, 03:10 AM
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Rodney
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Default RE: How much were we at risk

That transmitter will work very safely down to 4.4 volts. At that point you would still have plenty of time to safely land your plane. At 1.1 volts/cell a Nixx battery still has about 20% or its useable power left.
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Old 08-27-2012, 10:58 AM
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GarySS
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Default RE: How much were we at risk

Thanks, So at least a Spektum TX can throw out a sufficient signal only using 4 cells down to 4.4 volts. Is that basically due to the 2.4 technology over the old 72 MH tx technology?
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Old 08-27-2012, 11:29 AM
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AndyKunz
 
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Default RE: How much were we at risk

It's due to the fact that modern electronics run on 3V instead of 5V or 9V.

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Old 08-27-2012, 05:45 PM
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Default RE: How much were we at risk

Nimh batteries are rated nominal 1.2 volts per cell and considered drained at .8 volts per cell. Normally you would stop flying at anything below 4.8 volts with a good margin for safety. 4.6v should not have been an issue for short flight. Disposable batteries are rated ar 1.5 volts per cell.
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Old 08-27-2012, 07:05 PM
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Default RE: How much were we at risk

My DX8 runs off a 4 cell Nimh, and it normally reads below 5v, and has an alarm when the voltage drops to a low level with enough time for you to land.  What is freaky is at full charge the meter on the TX is only at half bar.  The TX can take a Lipo instead and it will show a full bar. I am considering it, but get enough time out of the pack for a night of flying with plenty left over.
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Old 08-28-2012, 03:14 AM
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Default RE: How much were we at risk

ORIGINAL: acdii

My DX8 runs off a 4 cell Nimh, and it normally reads below 5v, and has an alarm when the voltage drops to a low level with enough time for you to land. What is freaky is at full charge the meter on the TX is only at half bar. The TX can take a Lipo instead and it will show a full bar. I am considering it, but get enough time out of the pack for a night of flying with plenty left over.
The DX8 charged to a reading of 5.1 or so- will provide power for 12 hours of ON time
the std battries - NIMH- need occasional charging - when the y finally get to 4.6 or so, 5-8 hours typically fills em up . never a need for field charging
The only problem I have seen with these batteries is overcharging -typically by those who think the battery drain is like the old 9.6 tx and want full batts for each flying session- .
As A Kunz noted the electronics run at 3 volts -just a trickle of current .
Typically, users go weeks even months without a recharge. We see lots of DX8's, this is not unusual
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