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Safety questions regarding small water pump/battery system

gramineus

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Sep 19, 2021
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Hello,

I'm a beginner, and I'm looking for help to determine if I'm creating a fire hazard or if I'm going to overload any of the components. I'm trying to run a small pump to create a water feature for wild birds/other critters to bathe in and drink from. There is a timer, so that the pump will run off the battery from dawn to dusk, but if the battery power is too low to operate the pump for part of the day, or even for multiple days, that's not a concern because there will still be pools of standing water for the birds.

The pump is a 12-18V DC submersible pump (17W/~1.2A @ 12V), with a JVR 12V DC timer and a 12V 18Ah SLA battery. The battery will be charged by a 100W solar panel and a Renogy Wanderer 10A 12/24V controller.

I placed a circuit breaker on each wire between the solar panel and the charge controller, mostly to have a way to disconnect the panel if needed. My first questions are about fuses; is it necessary to place fuses between the battery and the charge controller? From reviews of the charge controller, it sounds like there are already fuses inside the controller. If I do need to buy fuses, would I need a fuse for each battery cable? Is it also necessary to place a fuse between the charge controller and the timer, or between the charge controller and the pump?

Another question I have relates to the two 6 AWG stranded copper battery cables that do not fit in the receptacles on the charge controller. Is it safe to trim off enough of the strands so that the cables can fit into the receptacles? It looks like the 6 AWG cable would have to be trimmed down to about 10 AWG. Or can I splice a section of smaller gauge wire to them with wire nuts and connect the smaller wire to the charge controller?

Thanks so much for any advice you may have about potential safety issues or other problems I may have overlooked.
 
My first questions are about fuses; is it necessary to place fuses between the battery and the charge controller? From reviews of the charge controller, it sounds like there are already fuses inside the controller.
Yes. There should be a fuse close to the battery. If there is a short the battery will dump all the power it can into the wire and that is a fire hazard.
If I do need to buy fuses, would I need a fuse for each battery cable?
No. A fuse on one side will suffice. It would work on either, but traditionally it is always put on the positive side.

Is it also necessary to place a fuse between the charge controller and the timer, or between the charge controller and the pump?
I am having a hard time picturing your wiring. Could you provide a diagram?
 
Another question I have relates to the two 6 AWG stranded copper battery cables that do not fit in the receptacles on the charge controller. Is it safe to trim off enough of the strands so that the cables can fit into the receptacles? It looks like the 6 AWG cable would have to be trimmed down to about 10 AWG. Or can I splice a section of smaller gauge wire to them with wire nuts and connect the smaller wire to the charge controller?
6AWG seems pretty big for what you are describing. Please include the wires sizes in the diagram.
 
Thank you, here is a diagram of the wiring. Someone who had purchased the same timer posted a video of his setup and I basically copied what he'd done.
The battery has nut and bolt tabs and I wasn't sure what cable to buy. Could have made a mistake there. It is very thick cable and has 6AWG printed on it.
 

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Thank you, here is a diagram of the wiring. Someone who had purchased the same timer posted a video of his setup and I basically copied what he'd done.
The battery has nut and bolt tabs and I wasn't sure what cable to buy. Could have made a mistake there. It is very thick cable and has 6AWG printed on it.
Got it. You are using the load output of the charge controller. I have never used this so I forget it even exists.


Yes. The 6AWG is *way* oversized for the need. The most it will ever see is ~8.3A from the solar charge. 14AWG could handle that.

1632082652284.png

You could cut some strands from the 6AWG to make it fit, but I would just go get some 14AWG.
Fuse 2 in the diagram may not be needed if the Charge Controller has current protection on the output that is lower than what the timer can handle.
 
Thanks FilterGuy, I appreciate you taking the time to help. I'll definitely include those fuses.
 
Hook the motor straight to the solar panel. Run a buck converter on it to slow it down and adjust the speed.

I use these on alot of projects. For your application it is a perfect match.
Solar to buck converter to pump.
You won't need the battery, or the controller.


Order more than one
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