dc motor questions

[Christian Keith]

https://blog.adafruit.com/2012/05/25/new-product-waterproof-2xaa-battery-holder/

http://www.amazon.com/Magnetic-Vibr...453659505&sr=1-19&keywords=dc+vibration+motor

I want to use this 2 AA battery holder to power this vibration motor. Will this work? (i've provided the links above)
Does anyone have a prediction on how long these batteries would last with this application?
Can I use a resistor to slow this motor down and prolong battery life? I don't necessarily need it to run at 3200 RPM.
Thanks

 

[Anon_LG]

The motor in question is listed here. It is claimed to run at a minimum of 3 volts, whether it could drive any usable load is questionable. The motor draws 35 ma apparently. Let us assume that the average AA current capacity is 1500 mah. 1500mah/35ma = 42 hours (approx). This assumes that the battery holds nominal voltage will be held for the entire discharge run, which it will not. So, the motor might run for about 2 hours (at most) on those AA's. But it will probably only run properly for 30 minutes.

I hope this helps,

 

[Minder]

A one cell LiPo may be a better choice, and at the lower voltage also rechargable.
M.

 

[Christian Keith]

I have a project where I need to run a small vibration motor for an extended period of time. The motor doesn't need to be any bigger than around 1"x1" and I'd like to run it off non rechargeable batteries. I'd like to keep the battery pack pretty small as well, maybe a few aa's or a 9v. The vibration motor does not have to run full speed. I was thinking about using a resistor to slow the motor down to prolong battery life, but I'm pretty clueless, and i'm not finding much help. Could anyone give me a set up that might work? Any help would be much appreciated. Thanks!

 

[Colin Mitchell]

"But it will probably only run properly for 30 minutes."
Where do you get these absurd predictions for a 35mA load ?????

 

[hevans1944]

Your requirements are too vague. You need to be much more specific. How fast does the motor revolve (RPM)? What is the mass of the offset weight that causes vibration? What is the radius of gyration of the offset weight? How is the motor vibration coupled to a load, and what is the mass of that load? How is the vibration energy dissipated? How much current does the motor draw and what voltage is applied to it at that current? The voltage and current measurements must be made with the motor attached to whatever load it is vibrating.

If you use a resistor to slow the motor down, the power dissipated in the resistor will decrease battery life. if you are pretty clueless, please provide a list of places you have looked to find help. Here at Electronics Point, most of us love to help those who help themselves.

 

[davenn]

I have merged the 2 threads since they are about the same motor

 

[Anon_LG]

"But it will probably only run properly for 30 minutes."
Where do you get these absurd predictions for a 35mA load ?????

Have you ever viewed the voltage curve for an alkaline battery?

The motor is quoted to run at a minimum of 3 volts, I should not imagine with the curve of your typical alkaline battery that the motor may even run for this long. I have run this type of motor before, very common model here, when I tried to run one a while ago, it only lasted about half an hour continuously with alkaline batteries and the only load was a small fan.

 

[BobK]

"But it will probably only run properly for 30 minutes."
Where do you get these absurd predictions for a 35mA load ?????

Yep, looking at an Energizer datasheet I get 60Hrs to discharge to 1.2V.

http://data.energizer.com/PDFs/E91.pdf

Bob

 

[Anon_LG]

I must of used some rather terrible batteries.
Which type of battery are you thinking of using Keith?

 

[Colin Mitchell]

"If you use a resistor to slow the motor down, the power dissipated in the resistor will decrease battery life."

Where do you get this gobbledygook from?