Tweet
Hello all! I am making a portable evaporative cooler for camping purposes. What I have currently is a submersible battery operated water pump that sits in an ice chest full of ice water. The pump sends cold water up to copper tubing coiled around a battery operated fan. The problem is that the pump runs on 3- D batteries for up to 5 hours. The fan uses 8- D batteries in 10 hours. That means that they're different voltages. I need for the pump to run all night and preferably for them both to have a single battery with solar charging capability. Any help would be appreciated as I am completely new to all this.
-
-
3xD@1.5V = 4.5V
So you could use a 12V battery with an adjustable voltage regulator circuit (cheap on ebay) set to 4.5V.
The issue is knowing the current used by the device. Have a look at the rating of the unit (especially if there is a DC jack) to choose the right size battery/circuit.
Then a solar panel/charge regulator can be chosen. -
That's the problem, the pump has no rating anywhere other than the runs for "up to 5 hours" label. I even opened it up and looked at the motor itself. The fan is 12 volts and .5 amps.Comment
-
Let's say upto 5 hours relates to a typical good alkaline D being 8000mAh (8Ah)
8Ah / 5hrs = 1.6A usage per hour
So a voltage regulator that can handle 4.5V @ 2A should allow a little leeway.
Then you can choose a battery based on preference over size/weight vs hours required between charges.Comment
-
Thanks for your help. So I have a 7.2 watt pump and 6 watt fan. I want them to run for 10 hours for two days. That's 265, then figure for loss and call it 400 watts. That's 33 Ah. Does this sound right or do I need to account for any battery discharge?Comment
-
40Ah battery? It'll be a little heavier than the Ds!
I'd always go above the capacity your calcs say as a minimum as all sorts of factors will affect the usable capacity of the battery. Also the voltage regulator circuit will not 100% efficient so there will be a small amount of loss there also.
Or go smaller with a panel/reg to keep it topped up.Comment
Comment