My servo controler drains batteries too fast
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"Parallax uses the Futaba S-148 servo which draws around 125mA to 1amp depending on the torque that is applied."
Dave
I have a board (using a B2SX module)·that receives PULSIN commands from 1 servo to constantly control another servo with PULSOUT. No matter what batteries I use (6v 0r 7.2v w/400 to 500watts), they drain very fast. In fact they drain so fast, it makes my servo controller unusable for my application.
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I am only using PAUSE 25 between program loops that continually update the servo. Is this a programming·or possibly a "Duty Cycle" issue that is causing my batteries to drain so fast??
TY
Dave
I have a board (using a B2SX module)·that receives PULSIN commands from 1 servo to constantly control another servo with PULSOUT. No matter what batteries I use (6v 0r 7.2v w/400 to 500watts), they drain very fast. In fact they drain so fast, it makes my servo controller unusable for my application.
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I am only using PAUSE 25 between program loops that continually update the servo. Is this a programming·or possibly a "Duty Cycle" issue that is causing my batteries to drain so fast??
TY
Comments
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·· Where did you get those battery ratings from?· Also, are you powering the BS2sx from the same supply as you’re powering the servos from?
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Chris Savage
Parallax Tech Support
It is also sensitive to the size of battery packs it uses, 6v and 7.2v packs I know are proper for a B2SX. But it will only operate with small·"park flyer" battery packs around 400 to 600 mAH (not watts, SRY). I have a new 6v·1800 mAH "JR" battery pack and for some reason, it will not work with it.
The board itself was designed by an engineer in the UAV field, it also has 2 servo outputs, 2 thermocouples and 2 hall sensors for multiple engines and many expensive chips.·I have been finishing up the programming and converting it for use in our nitro methane powered Giant scale pylon racers, but right now it will go thru a batterey pack before the end of a 6 min race.
Can you put an amp meter on the battery input line to see at idle what the amp draw is, with and without the servos connected,
it's probbly not the servos, I suspect a voltage regulator and something should be getting hot is you are draining that much amperage that fast.
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Think outside the BOX!
For this particular application, you really need/"must have" two seperate battery packs that share a common ground.
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Beau Schwabe
IC Layout Engineer
Parallax, Inc.
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But what I don't understand is, why it drains so fast within my board? That same battery pack would have powered a gear reduced 280-size park-flyer motor, a·speed control, 2 servos and the receiver for about 6 minutes and not loose servo control. My setup is the BS2sx, 2 egt's, 1 hall effect sensor, a pulsin from a servo connected to the transmitter, 1 180' servo and it won't operate a servo for·more than a couple minutes straight.
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If my program sends a single pulsout, will the servo hold that position indefinitely until a +/- pulsout value is sent? And will it draw less current while it's stationary? (My program loops over and over sending out the same pulsout value, about 40 times a second).
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Or does the current draw effect the certain parts of the stamp, more than others when the power supply reaches a certain point?
TY
A servo requires a periodic pulse (about once every 20ms) for proper functioning although its current consumption should not increase if the pulse occurs less often than that. It will draw more current when the position changes (because the motor moves), but the current should decrease again once the motor reaches the new position.
The Stamp will not work as well when the power supply voltage (Vin) drops below 6V, but its current draw should not increase significantly and it should operate certainly down to maybe 5V and, at some point, will go into reset state.
"...But what I don't understand is, why it drains so fast within my board? That same battery pack would have powered a gear reduced 280-size park-flyer motor..."
It might be possible that the Stamp is being held in "reset" mode, or starts to go into reset mode because the "gear reduced 280-size park-flyer motor" could be pulling
the voltage down enough that the brown-out circuitry of the Stamp·engages.
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Beau Schwabe
IC Layout Engineer
Parallax, Inc.
Before applying power to any circuit I make, I check to see how much resistance the circuit has, if it's too low then there may be a short, solder bridge or something amis. You should be able to calculate the current draw and should for battery operated devices.
You need to breakdown the circuit, disconnect components and test it, if you have a schematic you can figure out what the current should be and then test it. Shooting in the dark 2 min vs 6 min, like I said, just hold your hand on some components something has to be getting hot.
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Think outside the BOX!