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question about need for regulator

Old 04-11-2013, 12:31 PM
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dbeeler
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Default question about need for regulator

simple question; using a servo rated for 4.8 Volts and using a fully charged 4.8 volt battery which reads 5.6 volts when fully charged. does this higher voltage negatively affect 4.8 V servos? same for a 6 volt battey and using servos rated for 6.0 volts. fully charged bettery reads 7.4 volts. can someone please educate me on whether a regulator is needed?
thanks much
Old 04-11-2013, 12:36 PM
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BarracudaHockey
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Default RE: question about need for regulator

No.

4.8v translates to "just fine for a fully charged 4 cell pack"
6.0v means "fine for a fully charged 5 cell pack"
Old 04-11-2013, 07:00 PM
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BuschBarber
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Default RE: question about need for regulator


ORIGINAL: dbeeler

simple question; using a servo rated for 4.8 Volts and using a fully charged 4.8 volt battery which reads 5.6 volts when fully charged. does this higher voltage negatively affect 4.8 V servos? same for a 6 volt battey and using servos rated for 6.0 volts. fully charged bettery reads 7.4 volts. can someone please educate me on whether a regulator is needed?
thanks much
Many use 2cell LiFe/A123 Rx packs with servos rated for 6v, without issue. Typical 5cell NiCad/NiMh Rx packs charge to 6.6v.
4cell 4.8v NiCad/NiMh Rx packs typically charge to 5.5v and still work fine with servos rated at 4.8v.

4.8v and 6v are the Nominal voltages for those battery packs and typically the lower end of the voltages they normally operate at.
Old 04-11-2013, 09:33 PM
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chuckk2
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Default RE: question about need for regulator

There can be a problem using NiCad or NMIH batteries and the newer digital receivers and servos.
Under significant momentary loads (from servos, electric retracts, etc.) The NiCad and NMIH batteries can decrease in voltage,
even enough to cause the digital receiver to reset, go to defaults, or just momentarily hold.
The actual current for this to happen with the common AA cells is somewhere around 2A.
We tested some or the larger E-Flite electric retracts, rated at 900Ma, and found peak currents around twice the rating.
With a less than fully charged 2000NMIH pack, the momentary voltage drop was enough to cause the retracts to hang, get out of sync from one to the other, or just not operate. The retracts have an odd shaped cam slot, and the peak current occurs as a brass "T" cylinder goes over the sharp "hump" in the slot.  Many digital servos may draw a momentary current (per servo) of up to about 1-1/2 A.

Lesson learned was to use a 5-6A,  5 to 6v regulator on a LiPo battery to insure sufficient available current.
With electric retracts, think about using a separate power source or regulator.      

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