Increase Power Supply

[Ibaeni]

Hello I'm working on a maze solving robot that also allows user control over Bluetooth and an arduino UNO. I am driving it with two continuous servos. It works when connected to a computer through USB or the wall using a wall wart but a 9V battery is unable to power it consistently. I was wondering what options I have to power it without it being wired. The UNO has a max of 12V in. I was thinking it may be possible to wire two 9v's in parallel or use an alternate power supply to power just the servos. Any advice is appreciated.

[Kohanbash]

Hi
When you say it does not power consistently are you referring to the power dropping in and out? Is it only dropping out when you are driving?

If you want to avoid adding a second battery you can try adding a capacitor to help handle the transient surges.

[jwatte]

You could get a 2-cell LiPo battery (nominal 7.4V) or a 7-cell NiMH (nominal 8.4V) or perhaps six regular alkaline AA batteries (nominal 9.0V.)
You can buy carriers for AA batteries in various combinations (three, four, six, etc) from Radio Shack and various online hobby stores.

[Ibaeni]

Hi
When you say it does not power consistently are you referring to the power dropping in and out? Is it only dropping out when you are driving?

If you want to avoid adding a second battery you can try adding a capacitor to help handle the transient surges.

When powered by a battery it will only go for a very short amount of time then the servos will sort of sputter around.

[bdeuell]

It sounds like the 9 volt does not have enough capacity to power your robot for a sufficient length of time. The sputtering is likely caused by the battery voltage dropping too low to power the servos. Any of the battery packs suggested will probably solve your problem. You can compare the capacity (mAh) rating of the various batteries to get an idea of your robots run time.

If you are powering the motors directly from the battery be cautious of not selecting a battery that will over-volt the motors.
If you are powering devices with linear regulators be aware that they become less efficient at larger input voltages (will produce more heat under the same current load).