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Topic: power supply trouble with 6 x 1.2V AA accus (Read 2314 times) previous topic - next topic

wolpertinger

i built a robot powered by 2 servos SM-S4303R. Before i used a 9V battery for supplying the arduino and servos via the external power supply. all went well and as expected, only battery life was not that long.
Today i changed to a 6 x 1.2V rechargable AA battery powerpack with 2500 mAh each.
Now, connected to the external arduino supply it does not work, servos turn but in reverse direction and not as programmed. Connecting the usb and all is ok at once. i measured the powerpack output voltage as 8.4 V.
btw all AA´s are freshly recharged.

MarkT

The servo seems to be rated upto 6V only.  It may be pulling excess current with that battery pack and becoming unstable.  The 9V battery probably limited the current and thus reduced the loop gain of the servo.   Could you run the Arduino and the servo from 4 cells (4.8V)?
[ I won't respond to messages, use the forum please ]

wolpertinger

MarkT> thanks your input.
justed tryed to run on 4 cells. now only one servo turns, randomly starting foreward or backward direction.


retrolefty

Sadly you may have damaged your servos as they are typically rated as requireing 4.5 to 6 volts, with 6 volts as a maximum. 7.5vdc may have been too much.

Lefty


smeezekitty

#4
Jan 20, 2011, 09:29 am Last Edit: Jan 20, 2011, 09:29 am by smeezekitty Reason: 1
Are you using the servos with or without the regulator?
Avoid throwing electronics out as you or someone else might need them for parts or use.
Solid state rectifiers are the only REAL rectifiers.
Resistors for LEDS!

wolpertinger

i never have supplied anything more than the 5 Volts from the arduino board 5 V outlet, so i think that the servose are fine. They are working perfectly when i power the arduino board with the USB.

regarding regulator - i have connected both servos directly on pins 9 and 10 of the arduino uno board.

AWOL

#6
Jan 20, 2011, 11:58 am Last Edit: Jan 20, 2011, 11:59 am by AWOL Reason: 1
Are you saying you powered the servos from the Arduino's 5V regulator?
Are these special low current servos?
"Pete, it's a fool looks for logic in the chambers of the human heart." Ulysses Everett McGill.
Do not send technical questions via personal messaging - they will be ignored.

AWOL

#7
Jan 20, 2011, 12:14 pm Last Edit: Jan 20, 2011, 12:15 pm by AWOL Reason: 1
You shouldn't ever run servos from the Arduino's regulator; it is only rated at 500mA.
(Another sticky thread candidate)
"Pete, it's a fool looks for logic in the chambers of the human heart." Ulysses Everett McGill.
Do not send technical questions via personal messaging - they will be ignored.

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