Hi,

I want to power a 6V 300mA water pump for a bonsai/terrarium display for a stream/waterfall.

Preferably I would like to have it run on rechargeable batteries (built into the base of the terrarium - so it's portable) and have a power supply plug in to recharge/power the pump when the batteries are dead.

I've been trying to find a "simple" solution but with no luck. I think I will have to construct my own circuit board but do not know the schematics that I will need. Or only have a single power source (battery or AC power).

The terrarium will have limited space so the smaller the battery unit the better.

Any help would be appreciated!

Thanks!

Art

Specifications on pump (http://www.amazon.com/gp/product/B004HHW0FU/ref=ox_sc_act_title_2?ie=UTF8&smid=AGJOB9QIKR6CC):

Input: DC 5~6V
Output: 1.0L/min or 0.264 gallon/min
Range: 1M (3ft horizon) @6V
Current: 300mA@6V
Intake: 9mm Dia.
Outlet: 7mm Dia.
Life span: > <FONT color=#ff9900>20,000hrs</FONT> @ 1600rpm~4200rpm
Noise: << 20dB
Working Temp: 100'C (non-submersed)
Size(L*W*D): 32mmx22mmx36mm (1.26" X 0.87" X 1.42")
Weight (net): 2.0oz​

 

How long must motor run? Four, AA, NiMH 2400 mAh batteries, 5V, woukld give about 8 hrs. Should have low V disconnect ckt. Do you need a timer, or other control? How much space is available? Want to throw in a LED light display?

 

The outer dimensions of the container is:

12.5 inches by 7.25 inches by 3 inches high​

I want to keep .5-1 inches available on top so things don't spill over, so have safely 2 inches to work with for the height. I'm not too concerned about the rest (as long as it doesn't take the entire bottom).

I was thinking about being able to put on 2 LED lights for miniature spot lights, but didn't want to get ahead of myself

I didn't really think about a timer, but that would be a nice addition to control the water flow/lights, but not really necessary.

As for the battery run time, the longer the better. The main reason for the battery run time is to be able to move it to areas that don't have a power outlet (inside & outside) or have it on display during the day/afternoon in a window. So 8+ hours would be preferred.

Thanks!

 

Your motor takes 300mA, so for say 10 hrs running thats a 3AH battery or 3000mAH, if its running in the daytime near an outside window, why not add a solar panel to charge it up as well.

 

I think I'd look for a sealed lead acid (SLA) battery of that capacity, because the SLA is easier to safely charge. The "charger" circuit could just be a voltage regulator. The downside is cost, rechargeable AAs are so common and easier to find.

You still need a low-voltage cutout with any battery chemistry, although I guess nicad is often used without a cutout.