Servo Power Supply

I want to build a robotic arm that has 4 servos. The servos are “SG90 9G”. My biggest challenge though is getting an appropriate power supply. I first thought of buying 4 “9V NiMH Battery, 250mAh” and use a buck converter to lower the voltage to about 5-6 volts on each battery.

Then I did some further research and thought if it was a better idea to instead get a “7.2 NiMH 3000mAh Tenergy” battery to power all four servos.

I’m still very undecided, if you have any suggestions, I would like to know. Thanks

How much current do 6x of that motor use and for how long time do You want Your project to run?

The current per servo is about 550mA. I wouldn’t keep the project running for a long time. Maybe 30 or 40 minutes

9V batteries are useless. But what made you decide on a 7.2V battery? That's too much for those servos.

Personally I'd use a simple 4.8V 4-cell NiMH battery. There are plenty available in AA size or even larger sub-C cells depending on how much room you have for the battery and how long you need to run before having to recharge. Even NiMH AA cells should easily run 4 x SG90s.

Steve

Ok, thanks. Would it be ok if i bought 4 AAA batteries and connect them in series? I’d rather get AAA since I have a battery holder already.

You can always try them but they're much lower capacity and I think 4 x SG90s might be too much for AAAs. I've never tried using AAAs with servos.

NOTE: NiMH is important. Standard 1.5V alkaline batteries are nowhere near as good for this purpose.

Steve