batteries

[nachi]

I need to operate two high torque servo motors : HITEC HSR 5995TG using single battery pack.
Also I need to drive two low torque motors : HITEC HS322-HD using another battery pack.

Anybody having experience using these servos , plz help me find the suitable battery pack.

What exactly should I look  for in selecting a battery for driving servos?

[HDL_CinC_Dragon]

Control System: +Pulse Width Control 1500usec Neutral
Required Pulse: 3.3-7.4 Volt Peak to Peak Square Wave
Operating Voltage Range: 4.8-7.4 Volts
Operating Temperature Range: -20 to +60 Degree C (-68F to +140F)
Operating Speed (6.0V): 0.15 sec/60? at no load
Operating Speed (7.4V): 0.12sec/60? at no load
Stall Torque (6.0V): 333.29 oz-in. (24kg.cm)
Stall Torque (7.4V): 416.61 oz-in. (30kg.cm)
Standing Torque (6.0V): 433.27 oz-in. (31.2kg.cm) 5 degree deflection
Standing Torque (7.4V): 541.59 oz-in. (39kg.cm) 5 degree deflection
Operating Angle: 90 Deg. one side pulse traveling 400usec
360 Modifiable: Yes
Direction: Clockwise/Pulse Traveling 1500 to 1900usec
Idle Current Drain (6.0V): 3mA at stophttp://www.servocity.com/assets/images/autogen/HSR-5995TG_Ultra_Torque_NWhite_Page_Banner.jpg
HSR-5995TG Ultra Torque
Idle Current Drain (7.4V): 3mA at stop
Current Drain (6.0V): 300mA/idle and 4.2 amps at lock/stall
Current Drain (7.4V): 380mA/idle and 5.2 amps at lock/stall
Dead Band Width: 2usec
Motor Type: Coreless Metal Brush
Potentiometer Drive: 6 Slider Indirect Drive
Bearing Type: Dual Ball Bearing MR106
Gear Type: 4 Titanium Gears
Connector Wire Length: 11.81" (300mm)
Dimensions: 1.57" x 0.78"x 1.45" (40 x 20 x 37mm)
Weight: 2.18oz (62g)

Based on this, I would suggest the maximum battery to use would be an 8v NiMH battery pack for the HSR-5995TG. Not sure on this one but you might need something like 4 or 5 Amp hours...

Control System: +Pulse Width Control 1500usec Neutral
Required Pulse: 3-5 Volt Peak to Peak Square Wave
Operating Voltage: 4.8-6.0 Volts
Operating Temperature Range: -20 to +60 Degree C
Operating Speed (4.8V): 0.19sec/60? at no load
Operating Speed (6.0V): 0.15sec/60? at no load
Stall Torque (4.8V): 42 oz/in (3.0 kg/cm)
Stall Torque (6.0V): 51 oz/in (3.7 kg/cm)
Current Drain (4.8V): 7.4mA/idle and 160mA no load operating
Current Drain (6.0V): 7.7mA/idle and 180mA no load operating
Dead Band Width: 5usec
Operating Angle: 40 Deg. one side pulse traveling 400usec
Direction: Clockwise/Pulse Traveling 1500 to 1900usec
Motor Type: Cored Metal Brush
Potentiometer Drive: 4 Slider/Direct Drive
Bearing Type: Top/Resin Bushing
Gear Type: Heavy Duty Resin
360 Modifiable: Yes
Connector Wire Length: 11.81" (300mm)
Dimensions: 1.57" x 0.79"x 1.44" (40 x 20 x 36.5mm)
Weight: 1.52oz (43g)

a NiMH battery pack of 6 or 7 volts and 1500+ mAh should be sufficient.

[Admin]

I often use both of those servos . . .

For the 5995, expect between .2A and .7A of current, depending on how much torque they apply.

For the 322, expect between .2A and .5A of cucrrent.

To calculate how long your battery will last, use this battery calculator:
http://www.societyofrobots.com/battery_calculator.shtml

Enter in ~.4A for Expected Current Draw and 4 for # of Motors to get a good estimate.

[nachi]

hi...
for torque requirement of 2.12 Nm I have bought HSR5995 TG and for 0.41 Nm I am using HS 322HD.
Now I am searching for a good battery pack to drive these servos.
 According to the specs.  I need a battery pack having 7.4 V and max of 5 AH supply for 5995 servo. Am i right?
 So If I use two such servos I will be needing a single battery pack of 7.4V and max. of 10 amp suppy.
searching through the net i found that this motor need a current supply of 2500 mAh.
I am getting confused  a little over here.
 same is the case with 322HD servo.
Plz help me clear my basics about batteries and suggest a suitable NiMH battery pack to two servos of each type.
 Thank you.

[HDL_CinC_Dragon]

Batteries in series meaning:
---|i|i--|i|i---
Give more voltage but the same amount of amperage. Batteries in parallel meaning:
    ---|i|i---
---|         |---
    ---|i|i---
Give the same amount of voltage but they will supply more mAh (MilliAmp hours) so they can run longer at higher loads.

Thats the basics on batteries.

[Admin]

According to the specs.  I need a battery pack having 7.4 V and max of 5 AH supply for 5995 servo. Am i right?
 So If I use two such servos I will be needing a single battery pack of 7.4V and max. of 10 amp suppy.
searching through the net i found that this motor need a current supply of 2500 mAh.

First, 10 amps and 10Ah are two different things. 10Ah means if a battery is drained at a constant 10 amps, it will take 1 hour before it dies. 10Ah also means that if it is drained at a constant 5 amps, it will take 2 hours before it dies, etc.

So 2500mAh means it will take 1 hour for it to die if you drain it at 2.5A constant. So if you have two servos that each drain 1A (for 2 amps constant), then it will last 2.5Ah/2A = 1.25 hours.

As for 7.4V, thats its maximum rating. You can always use a 6V or 7.2V battery, no problem.