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Problem constructing a solar powered waterfall, please help? Answered

Hello, I have constructed a waterfall in my garden. It consists of a small dc pump which consumes 0.35a at 12v and a bigger pump which consumes 0.87a at 12v and a 5050smd led strip encased in a tube to make it waterproof, which consumes 3.7a at 12v totally 4.9a at 12v. I have a solar panel with 12v 30w and a solar charge controller with 12v 6 a capacity and a sla battery 2v 7ah capacity. I calculated a runtime of 1.4 hours when all three devices are connected together. But they last for only 30 seconds and then the charge controlled shuts them down with low battery indicator. I don't know what went wrong, can someone please help?



Best Answer 5 years ago

Whatever ah's a battery is rated for, you would only want to use 40 to 50% of it. Cycling a battery lower than that may damage it. With that being said, now you would only be looking at best 3.5 ah to work with in your battery. If your drawing 5 amps to run all your pumps and power strip, then you wouldn't get your expected output of 1.4 hrs. Don't use your charge controller because you may pull more juice from your battery?

Your battery may not be fully charged or not actually able to produce what it claims.

I purchased the charge controller because on a sunny day I pulled out the panel in the sun connected the multimeter to it and although it is a 12v 20w panel, the multimeter reading was 27v. I thought if I connect the battery straight to it for charging, the battery will not survive. Do you suggest I use the panel straight to the battery? Will it be safe without the charge controller?

Thanks for the help.

probably not safe for long periods as 27v is alot for a 12v battery but I do it with my rechargeable 6 volt battery. I've read all the stuff online about what's safe and what's not but I like to try things out for myself. So far my 21v panel is charging my 6v battery just fine and probably because the current isn't all that much.400 amps has a lot to do with it as well. your charge controller may be a player in this problem but to be sure you need to just know the! full battery capacity and if it's actually charging that high. I've had similar issues with a different battery bank I have and best I can figure is everything I've learned online is some fact and some theory. Batteries are not created equal! Also remember that deep cycle batteries are not designed to give off huge amounts of current quickly. Rather they will give off smaller levels of current over a longer period of time and this may be key here since you seem to be maxing out the batteries output. I'd consider adding a few more like batteries to the system and see how that works out for you. Also, adding a load to the solar panels such as a battery, actually lowers the output a little so you may not be pumping 27v into the 12v battery. Sorry for all my speculation here but I'm just suggesting some potential contributors to your issue. I'm not an expert just a solar panel hobbiest who knows some about batteries as well.

Thank you both for all the help, I removed one pump and connected that with another small solar panel I had lying around. I also replaced the LED strip with a lesser powered LED strip. I also found the best spot for the panel to grab all the sun. Now it works perfectly as I wanted it to. Next I am going to fix a remote controller to switch the lights and pump on and off from a distance.
Thanks a lot guys for all the help.
This is how it looks.

Measure the volts ON the battery when it's charging. I suspect it still be ok.

Did you actually measure current ?
Is the battery new and charged ?

I'd've used a much bigger battery, because you will be discharging the one you have to flat every time, and that isn't good for the battery at all, even if it is a deep cycle one.

I have a clamp meter but for ac only so I could not measure the actual current. But I am going by the values mentioned in the device documents. The battery is new. I would have got a bigger battery, but didn't realise that the led strip would consume so much power. Was just expecting it to take very little power. Now I think I will try using only the two pumps and see how long it will last. Or as a last resort I will get another low power led strip. Anyway this one is so so bright that it illuminates my house from the waterfall.

Might be a good idea to throttle back those leds. That's a lot of light you're describing!!