I need some options for 12V battery supply

I've done a lot of searching here and with Google but haven't found the answer yet. I'm developing a project that uses a stepper motor purchased from SparkFun (the ROB-09238). It needs 12V.

On my development Uno I currently have a 12V wall-wart power supply plugged into it and am powering the motor with a lead from Vin. The current draw should be low as the motor will be slowly moving a wheeled or slider platform about 3' max on a horizontal surface.

When I move the project to a portable platform I'll need 12V battery power. I could probably buy something like a 12V motorcycle battery and have some long leads. But that is big, heavy, expensive and overkill. If I could wire up some lithium ion or other batteries in series to get 12V that may work. The lithium ions I'm seeing for sale ar 3.7V, so three in series would only give me 11.1 at a full charge. Maybe use 4 in series? They can also be expensive.

Suggestions on a portable and prefereably inexpensive ( less than $30) 12V battery supply would be appreciated. Small and light if possible would be great too. I'm willing to make my own by rigging up batteries in series.

Thanks, Jake

p.s. the project is a DIY motorized camera slider for time-lapse photography.

I use this one,(6800mhA actually) but there are many others like this for less. 12V Super Battery

They also last for a [u]VERY[/u] long time (charge wise).

If you have a stepper driver board such as an Easydriver or a Pololu A4988 you can drive that motor with a much higher voltage.

The current draw in a stepper motor doesn't vary much with speed - it draws pretty much the full current even when stationary in order not to lose position,

For how long do you want the motor to operate from your battery?

...R

Thanks Robin.

I am using an EasyDriver board :slight_smile:

It needs to run for one hour minimum. 90 minutes would be more than enough.

Jake

I recently bought this holder for 2 18650 batteries. I liked it because it was reasonably small, had built-in plugs for recharging in the USA, and provided multiple power outputs.

It has 3 plugs for USB 5v power (2 with 2.1 amps, 1 with 1 amp) , and one for 5v (2.1 amps), 9v (1.2 amps), or 12v (800mA) output. I bought the 18650 batteries from a USA seller. I haven’t done a test of how long I can run things: http://www.ebay.com/itm/5V-9V-12V-2A-Dual-USB-18650-Battery-Mobile-Power-Charger-Box-For-iphone-ipod-MP4-/390851148875?pt=Laptop_Adapters_Chargers&var=&hash=item5b008b3c4b

I was originally thinking of this unit which comes with 6 batteries (so presumably longer run time), and it can do 1 amp of 12v power: http://www.ebay.com/itm/24000mAh-5V-9v-12v-USB-Power-Bank-Charger-Box-6x-18650-Battery-for-Cellphone-/301064928798?pt=US_Cell_Phone_PDA_Batteries&hash=item4618de3e1e

If you only need 12v, look in sites that cater towards security cameras, as a lot of those cameras use 12v.

Thanks Michael. Those look like what I need.

Jake