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Topic: power supply trouble with 6 x 1.2V AA accus (Read 2 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!

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