Controlling 4 Servos With 6AA Battery holder

Before I ask my question, here are the references you may need for any of the components I am about to mention: - Servo Motor: Tower Pro Micro Servo 9g SG90 Datasheet: http://www.ee.ic.ac.uk/pcheung/teaching/DE1_EE/stores/sg90_datasheet.pdf - 6 AA Battery Holder: http://a.co/gnoSyRJ (Amazon link)

Question:

I am planning on building a robotic arm which will use 4-5 servos, with an operating voltage of 4.8-6V, but I don't want (and probably cannot) to power these directly from the 5V pin of the Arduino. I've heard how 9V batteries are bad, so I bought a 6 AA battery holder (linked above), and am going to connect it to one side of the breadboard (directly to the power rails). Now since 6 AA batteries are going to produce 9 Volts, I am unsure if just connecting the servos directly to these rails would be safe. Of the many Youtube videos I have seen for a robotic arm, most people just directly connect a 9V battery to the micro servos. But this doesn't make sense to me, since the operating voltage is 4.8-6V. So should I directly connect the servos or not? Or would I need a 5V regulator of some sort. (I don't have one, but I know where to find one).

A pack of 6 x AA alkaline cells will produce 9v which is much too high for a 6v servo. 4 x AA alkaline cells will produce 6v and a pack of 3 x AA alkaline cells will produce 4.5 volts which could be used to power the servos and the Arduino. But don't power the servos through the Arduino.

However it is probably better to power the Arduino separately from the servos.

...R

Yea, I wasn’t going to power them through the Arduino. But suppose I wanted to use 6 AA batteries. How would I reduce the voltage from 9V to 5V (Or could I just put 3-4 batteries in my holder)?

It seems a complete waste of energy to reduce 9v from 6 cells to 6v or 4.5v when you can just use fewer cells. You can get battery holders for 3 or 4 cells. And you may be able to modify your 6-cell holder to draw power from fewer cells - depends on your skill with a soldering iron.

...R

For the time being (I know this isn't a good idea), would it damage my servos if I actually used all six batteries? (Only temporarily, and only for a short time).

Robin2: You can get battery holders for 3 or 4 cells.

And I've seen an adapter to fit a 5th one to a 4-cell holder. Reason for that was 4x1.5 is 6V which was fine with throw-aways. But if you switch to rechargeables of nominal 1.2V, then you need a 5th cell, else you drop to under 5V.

arnavb12: For the time being (I know this isn't a good idea), would it damage my servos if I actually used all six batteries? (Only temporarily, and only for a short time).

Nobody's going to tell you that it won't do any damage. Components have ratings published for a reason.

I have used pieces of aluminum rod near the diameter of AAs and cut to proper length then wrapped with tape for "dummy" cells when you don't need all 6, also I have used 2 1N4003 type diodes in series to cut 6V down to 4.75 to power Arduino from 6V.

arnavb12: For the time being (I know this isn't a good idea), would it damage my servos if I actually used all six batteries?

The safe answer is YES, it would destroy the servos.

...R

bloodnok_vc: And I've seen an adapter to fit a 5th one to a 4-cell holder. Reason for that was 4x1.5 is 6V which was fine with throw-aways. But if you switch to rechargeables of nominal 1.2V, then you need a 5th cell, else you drop to under 5V.

Every Arduino I've tried will happily run on 4 x AA NiMH cells provided you recharge them every so often. Despite the nominal voltage they will sit at around 5V for most the charge life and they drop less voltage with servo-type high currents too. Five fully charged NiMH cells will be around 7V and that's a bit high.

Steve