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Old Feb 02, 2013, 10:39 PM
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Razorback Flyer's Avatar
United States, AZ, Mesa
Joined May 2012
54 Posts
Question
645 MG Servos

Ok I was told that Im asking for trouble With the 645mg servos with a 5 cell NIMH battery, because when charged up, and when I get to the flying field, my voltages are around 6.75 volts. The Hitec specs are given for 4.8 and 6v. So am I over a safe voltage for these servos? Should I be running a BEC or like a BATshare unit?

Thx, Terry
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Old Feb 02, 2013, 11:54 PM
Registered User
Joined Aug 2002
5,696 Posts
Quote:
Originally Posted by Razorback Flyer View Post
Ok I was told that Im asking for trouble With the 645mg servos with a 5 cell NIMH battery, because when charged up,
and when I get to the flying field, my voltages are around 6.75 volts.
The Hitec specs are given for 4.8 and 6v. So am I over a safe voltage for these servos? Should I be running a BEC or like a BATshare unit? Thx, Terry
"The Hitec specs are given for 4.8 and 6v."
= Nominal voltages of standard 4 and 5 cell NiMH/NiCD battery packs, refer:
. Servo - Operating Voltage Range - (Hitec) usage with NiMH, Lipol & A123 batteries.

A 5 cell NiMH battery could be a problem if high capacity AA cells above say 1500 MAh as they do not
withstand the current draw of several 645MG servo and become the frequent cause of jitters.
Users may resort to/ recommend a 5V 10A switchmode regulator to reduce voltage thus reduce the higher
current draw which their battery packs could not otherwise withstand.
The higher the voltage, the higher the current draw and faster wear & tear on the servo.
. Dual Batteries - Multiple Batteries may be installed for redundancy or even one for each servo.

Much more information available e.g.

. Servo - FAQ : Metal Gear Servos - DIY Repair & Extend MG Servo Gear Life

under sub sections
"Battery Care, Performance & DIY Battery Packs."
"Glitches & Jitter in Receiver, Servo & ESC - Causes and Cures"
below
"Radio Systems, Accessories, Alterations and FAQ" at
Alan's Hobby, Model & RC FAQ Web Links

Alan T.
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