Water fountain pump

[ScottRanch]

I have a 100W panel connected to a deep cycle 12V battery, into a 20A charge controller. The pump says it's PMax 5W@12V. Will the panel be able to charge battery to keep the pump running 24x7 or will the battery go dead? I am new to solar energy. My first set up so I want to do it right. Thanks

[SunEagle]

Hello ScottRanch and welcome to Solar Panel Talk

That pump will use about 120 watt hours a day (5w x 24hr = 120wh). So you would need a 12v battery rated about 50Ah (120wh x 5 / 12v = 50Ah). If that 100watt panel has an Imp rating ~ 5 or more amps it should be able to recharge the battery but may have a problem if you do not get enough sunlight for a couple of days.

[ScottRanch]

The Imp is 5.62AH.The battery is a Duracell 12V deep cycle 105AH. My concern is if I am going to struggle with keeping the battery charged with the pump running 24x7. I think I can set the controller to 12hour and not 24. But I prefer to keep the pump running all the time to prevent stagnation of the water. I am using 14/2 wire between panel and controller and battery and controller.

[SunEagle]

Well that 105Ah battery is more than big enough to easily run the pump for 24 hours. But the problem is you will need about 10 amps of charging capability to keep that battery happy. Most FLA batteries require somewhere between 1/8 to 1/12 the Ah rating with 1/10 being the sweet spot. That would calculate out to 10.5amps which is more than a single 100 watt panel can output.

With only 5.62 amps you would be around 1/18 the Ah rating which is too slow. I would suggest getting a second 100 watt panel which that 20amp CC should be able to handle and now gets you more than 10.5 amps of charging capability.

As for the #14 wire. It may be too small to keep the voltage drop to less than 2%. The total distance could not exceed 3.7 feet. If the distance is about 10 feet you will need to go to a #10 AWG wire.

[ScottRanch]

So then is the battery TO big for this pump? I can't believe I need 2 100W panels for a little fountain pump. Maybe I should get a battery with lower AH? But I still need to keep it running 24x7

[Logan005]

I have a 100W panel connected to a deep cycle 12V battery, into a 20A charge controller. The pump says it's PMax 5W@12V. Will the panel be able to charge battery to keep the pump running 24x7 or will the battery go dead? I am new to solar energy. My first set up so I want to do it right. Thanks

I have done this as a personal knowledge experiment. great learning project. the problem is that little pump only uses a few dollars per year of grid energy, However a 110AH battery would have to be replaced every 5 years or so. about 100 dollars divided by 5 is 20 dollars per year. even if the pump cost 10 or 20 dollars of grid power per year to run, you would still be in the Neg. for any ROI
If grid power is avail, it does not make sense to use a battery.

[ScottRanch]

Thanks Logan005, I totally agree with that. Unfortunately, there is no power to where I have this water fountain. So unless I have a power cord running over the lawn, or trench for iit, this is my only solution. If I were to trench, I would have to go a long way to the nearest grid source. And it's not a straight shot.

[Logan005]

for something this small I would run 24 to 30 volts on 12 or 14 AWG wire in shallow trench, easy to do with Sod. use a 24 volt pump or a sealed step down converter for the optimal power of 12 to 14 volts, or for the water flow you desire. will cost much less than any solar battery system. and it's a neat low voltage project. totally safe and cheap, no unsightly panels or wires.

[ScottRanch]

SunEagle, what if I set the CC to be 12hr, not 24hr. will I be ok then with what I have?

[SunEagle]

SunEagle, what if I set the CC to be 12hr, not 24hr. will I be ok then with what I have?

If you are using the charge controller Load terminals to run that pump I believe you can set it for a time period.

Again you do not need 2 x 100 watt panels to run that pump but you need about 10 amps to charge that 105Ah battery. You could get away with a 50Ah battery and 1 x 100 watt panel as well as maybe being able to run the pump for more than 12 hours a day. If you do not get enough sun for 2 days you run the risk of dropping even that 50Ah battery to below 50% which will shorten its life. Otherwise you should be ok if you get a few hours of sunlight every day.

[Mike90250]

with solar, you often need much larger panels to recharge batteries because you only have a few solar hours to accomplish the recharge

[ScottRanch]

Mike90250, I am realizing that now about needing larger panels. Would hate to think I need more panels and a battery bank to just run a little water pump. Would look pretty ridiculous to have all that equipment for one little pump

[Mike90250]

My wife wanted the same thing, a little solar power fountain pump. I found one on fleabay for a couple bucks. When it arrived, it was in a box about the size of a pack of gum.
What a joke it was, we both got a laugh out of it, if you take a photo of something really small, zoom in on it, and scale it to fit a computer screen, it looks huge. It can move enough water to drown 3 ants (if you stun them first)
But for any garden effect, you will need a regular power cord to an outlet, or a very large solar setup.

[ScottRanch]

I charged my battery fully and hooked up my controller. less than 5 min later, the display on the Mohoo 20A controller doesn't show the "load" symbol any longer, like it wouldn't if it weren't plugged in. I ungplug everything and connect again and it shows up, but same thing. If I disconnect it all again and only connect the battery and pump, it runs fine. Now that I know it can't be because of a low battery, what could the issue be? Why would it just stop recognizing that the pump is connected after a few minutes? Is there a specific order I should be connecting that is causing this issue? Seems it's one thing after another with this set up. UGH

[Logan005]

in this order connect the battery to the CC, then the solar panel. then the load.

[SunEagle]

Are you connecting the pump to the battery or the CC "load terminals"? Some CC have to be programmed to run the "load".

[ScottRanch]

SunEagle , the CC has connection slots marked for panel, battery and load. Logan005, any thoughts as to why my load would just "disappear" from the screen as if it wasn't connected?

[Logan005]

If you are using the load terminals on the CC, It could be a street lamp CC that only turns the load on when the sun goes down. Your CC could have timers set. Or your battery is in a discharged state and your CC has disconnected the load terminals to protect your battery. Also keep in mind, these Cheap Chinese Controllers, may not handle much of a load, a few amps is ok, but CC will likely cut out if any more than that. I use a separate LVD with my setups.