Hi, I recently got some servos online with intention on making a spider bot controlled by an arduino. I've connected them up to a seperate power source (4x AA) to the board and with the first set of 3 no problems. But as i've gone to add more they started acting rather strange. When I apply power to the servos they sometimes all max out try to go beond their limits, if I disconnect the power from the servos and board and restart they sometime works, but only for a short amount of time before going back to maxing out.
I've checked all the servos indevidually on different pins and they all seem to work, it's only when companined with more then 3 that they have issues. It also has happened when the servos not connected to the board at all,just power.
I'm hoping someone on here my have some insights as i'm not sure where to go from here.
What type of batteries are What type of batteries are you using? I would suggest NiMN rechargeable AA, because they can produce more power at a given time than alkaline batteries. Also, being rechargable, they are less expensive overall.
It’s useful to give a lot of information when asking for help because you’ll avoid getting questions like this.
One very useful thing you can do is to take a high resolution picture of your system so we can see the wiring and such.
I’ve attached some photos of the set up (see below). With the power issue, would it be possible to connect a second set 4x AA in parallel? Just trying to think of a temporary solution to test before going all out with LiPos. Another thing I’ve noticed is that if I have all the servos connected, but only send singal to one most twitch, this gets worse the more servos I send a signal to, could this be a noise issue (the servos I’m using are very very cheap)?
I had the same problem like you. I tried to controll 12 servos with NiMH batteries they also started wiggling and doing strange things.
The problem is that the seros need very much current (like Duane and DT said) but the Battery can’t provide such a big amount of current (two of my servos draw 1 A so 12 of them need 6 A my NiMH had just 2300 mAh so that was way too much). You should use a LiPo or if the weight isn’t that important you can use D batteries those have 10.000 mah or more.I can control 12 servos with those.
Going to grab a second 4x AA pack to test today and connect a second leg (3x servos) to it. If that works (which by the sounds of things, it should) i’ll look at a LiPo power pack. If anyone has any sugestions on a LiPo option for powering 12 servos that would be great.
Set up to dual battery packs and it works much better. Two of my servos still wig out when powered, but when switched out with servos from the other leg it’s all good so I think those two might have been damaged (trying to go past min/max limits). Waiting on some new servos, but if all goes well i’ll at lest have two legs working before hittng up the lipos and adding the other legs. Thanks for the help and i’ll be sure to post pictures once there is something more to see.
You can place a capacitor over the servo power + and - lines. Place it as close as possible to servos. Also make sure your wires aren’t too thin or too long.
Been a while since the last update, but have managed to complete the two front legs along with basic coding for the walking cycle. So far 4xAA plus a capacitor for each leg seem to smooth things out and keep thing running (at least till the batteries start to drain).
I’ve been looking at LiPos and regulators and I think I’ve got it covered except for knowing how many amps will be needed and how what a LiPo can put out. I would ideally like to be able to run all the legs (12 9g servos in total) of a single LiPo and regulator but not sure if that’s wishful thinking.
If anyone has suggestions how many amps it would take to run servos like these or how to figure it out it would be muchly appreciated.
