Small pond pump battery backup

[bigredball90]

I am looking to add a bigger panel and a battery backup for my small pond pump. It came with a 25w panel that directly connects to the pump, but it only runs when its perfectly clear, and my wife has decided it needs to run 24/7. I have built a small 12v Lifepo4 battery for a van I had but thats the only thing Ive done, and could use some help picking out what I need to make this project work. Battery, and SCC need to be waterproof or in a box.

Pump:10w draw at 18v, at 370gph.
Current list: 24v battery around 500wh, 24v-18v converter, 100-200w of panel, renogy 10a voyager pwm controller.

I dont have any solar panel connection crimpers or connectors so I might need to pick up a few new tools as well.
Thanks

 

[OzSolar]

You had me at "new tools"! lol

10W x 24hr = 240WH. Round it up to 300 Wh for safety to get 24 hours of pumping with no sun. ~600 WH for 2 days, etc

I think I'd try to skip the 24v-18v converter. Have you tried to to run that pump at 12v? That might be the easiest way to do it.

You didn't mention your location but In the shortest days of winter here in Missouri a 200 watt solar panel should be able to make ~600 Wh so I think your right in line with your solar panel sizing.

 

[bigredball90]

You had me at "new tools"! lol

10W x 24hr = 240WH. Round it up to 300 Wh for safety to get 24 hours of pumping with no sun. ~600 WH for 2 days, etc

I think I'd try to skip the 24v-18v converter. Have you tried to to run that pump at 12v? That might be the easiest way to do it.

You didn't mention your location but In the shortest days of winter here in Missouri a 200 watt solar panel should be able to make ~600 Wh so I think your right in line with your solar panel sizing.

I have not tried 12v yet, I do have an adjustable power supply I can try to see if it works. Wife wants max flow and run time so I was thinking 18v would be best. But yea definitely easier to stick to 12v.
Upstate SC, so fair amount of sun usually... just not this week.

Thanks for the response I will test out the 12v theory when it stops raining.

 

[bigredball90]

Pump does work on 12v but at a much lower flow rate. Would definitely like to stay 18v if possible. At 12v it pulled around 4.5 watts.

 

[marionw]

I installed a pond pump as a water fountain (sprays 6 ft. in the air) in a small town south of Charleston SC. One 100 watt panel into a Victron MPPT. I have the pump connected directly to the battery using a 12vdc to 18vdc buck converter via a small automobile type relay. The relay is operated by the "load" output of the MPPT so the buck convert/pump gets turned off when the battery drops to 12vdc and gets turned back on when the battery gets charged back up to 13.5. Been in operation for the last 3 years with no issues.

 

[bigredball90]

This is my current parts list. Would it be better to stick with the 2 panels vs 1 bigger panel from santan? Looks like the 2 panels in series will be around 10v higher than the single 250w panel. Still need a box to put everything in and a 24v battery. Thinking about unistrut to make my mount, whats a good place to get the brackets for the panels?
Looking at these batteries but not sure if they can be wired in series.
Battery 1: Heter 12.8v 20ah 256wh Lifepo4 Battery with BMS – Battery Hookup
Battery 2: Tenergy 12.8v 20ah 256wh Lifepo4 Battery with BMS – Battery Hookup
MPPT: Amazon.com: Victron Energy BlueSolar MPPT 75V 15 amp 12/24-Volt Solar Charge Controller : Patio, Lawn & Garden
Panels: Amazon.com: ECO-WORTHY 2pcs 100 Watt Solar Panels 12 Volt Monocrystalline Solar Panel for RV Marine Boat and Other Off-Grid Applications, 2-Pack 100W… : Patio, Lawn & Garden
Adjustable converter: Amazon.com: DROK DC Buck Converter, 5.3V-32V to 1.2V-32V 12A Adjustable Power Supply, 5v 9v 12v 24V 30V 32V Step Down Voltage Regulator with LCD Display Volt Transformer Reducer CC CV for RV Solar Panel Golf Cart : Electronics

 

[bigredball90]

I installed a pond pump as a water fountain (sprays 6 ft. in the air) in a small town south of Charleston SC. One 100 watt panel into a Victron MPPT. I have the pump connected directly to the battery using a 12vdc to 18vdc buck converter via a small automobile type relay. The relay is operated by the "load" output of the MPPT so the buck convert/pump gets turned off when the battery drops to 12vdc and gets turned back on when the battery gets charged back up to 13.5. Been in operation for the last 3 years with no issues.

Interesting seems like a pretty economical way to set it up. Thanks