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Water Pump Wiring

HARG Hunter

Thirsty for Off-Grid Knowledge
Joined
Jul 10, 2020
Messages
210
Location
Iola, Wisconsin
I am designing my water system, and just want to figure out the best option for wiring the water pump.

Looking at hooking a tankless water heater and 12v water pump up to feed the cabin with water from a rain collection barrel.

What is the best way to hook up the water pump?
It is a 12v DC pump.
I know Will is not a fan of hooking up the 12v DC to the charge controller directly.

So....Do I?:

A) Wire it directly to the batteries?
B) Have bus bars that come off of the batteries to connect the charge controller/inverter/12v pump together?
C) An option not above (Please describe)

Also - is there a wire preference for running the DC from the area to the pump?
Is running standard 12/14ga Romex OK?
More Info: Distance from the batteries/charge setup to the pump will be approx. 30 ft.

Thanks in advance for the help.
 
Is the pump float or pressure controlled? Does it have a run time limit or will it simply pump away until the trigger is satisfied?

What sort of battery are you talking about? You want some way to prevent the pump from over-discharging the battery. With a lithium battery the internal BMS will disconnect should the cells ever be discharged too low. With a lead acid battery you normally don't have this level of protection. If you have lead acid and the pump start up and run current is lower than the charge controllers' output load limit you could hook it directly to the load output terminals. If it's more you can use a slave relay on the load output to remove power from the pump on low battery voltage.

The gauge of wire will depend on the current the motor draws and the acceptable voltage drop. Voltage drop will make the pump run more slowly and if severe enough, not be able to start at all. Do you know the running amp rating of the motor?
 
Pump I'm looking at is the Camplux 12v Water System Pump.

Specifications
Model: JK-3206
Voltage : 12V
AMPS:6.0A max
DC Flow capacity : 1.6 GPM/6.0LPM
Water pressure: 65PSI
Item size: 7.4 x 3.9 inch
  • Self-priming allows it to be mounted above tank; able to run dry.
  • Built-in 65 PSI pressure switch, it automatically turns on and off as you turn your tap or nozzle on and off.Adjustable CUT-OFF Pressure : default 65 PSI, MAX 80 PSI. It doesn't mean 6.0L/min jet at 65 PSI
  • 1.6 gallons per minute (6.0 liters per minute). 1/2" male hose thread.
I hope this helps answer your questions.

My battery bank is made of SLA's.
 
FYI, Most pumped water systems have an accumulator, so the pump doesn't come on every time you crack a faucet. It pumps water into a pressurized container holding a few gallons, then the container supplies water under pressure until nearly empty and the pressure drops enough for the pump to come on and refill the accumulator again.
 
OK, you definitely want low voltage cut off so you don't nuke the batteries if something goes wrong with the pump control and it stays on. If your charge controller can handle 20A on it's load output terminals that should be OK to run the motor. You can then use the SCC's low voltage setting to remove power from the pump if the batteries are low. If you want to isolate the motor from the SCC you can use a relay connected to the load output terminals, and in turn switch the pump through that. The relay will always draw power when the SCC says the voltage is OK, maybe 3 watts. You could also use an external low voltage cut off device, plenty available on ebay etc, and not have the SCC involved in it at all.

10 AWG over 30' should be OK IMO. Voltage during pump start up should go down to around 10.9V, assuming the motor peaks at 18A, and that should be fine. Listen to what other people say about this, I'm only making educated guesses as to how much current your pump will draw at start up. You could even contact Camplux and ask them what they have found the start current to be, and then we can use that to see if you can use lighter wire.

handy voltage drop calculator
 
All of my components are finally arriving.
I am indeed hooking up an accumulator so the load on the pump and batteries is eased a little bit.

Going to wire it directly to the batteries and install a switch on the positive line near the pump so I can turn it off when we're not there to prevent an unnecessary draw from the batteries.
 
Providing an update.
The pump has worked great.
I did wire it directly to the batteries, and installed a switch, so when we are not running the water, we turn the switch off.

The accumulator I got is pretty much useless.
I got one that was recommended as a match with this pump, but it's tiny and the pump pretty much runs every time we open the faucet.

2 questions...

#1 - Anyone have recommendations on a decent accumulator/pressure tank?
We don't run this often, mostly for washing dishes, but eventually we'll be putting in a shower, so I think a decent sized tank would be good.

#2 - Anyone have methods you've used to reduce the noise on the vibration the pump makes when it's running?
I have it attached to the wall right now, but there must be a way to mount it to reduce the noise.
 
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I am designing my water system, and just want to figure out the best option for wiring the water pump.

Looking at hooking a tankless water heater and 12v water pump up to feed the cabin with water from a rain collection barrel.

What is the best way to hook up the water pump?
It is a 12v DC pump.
I know Will is not a fan of hooking up the 12v DC to the charge controller directly.

So....Do I?:

A) Wire it directly to the batteries?
B) Have bus bars that come off of the batteries to connect the charge controller/inverter/12v pump together?
C) An option not above (Please describe)

Also - is there a wire preference for running the DC from the area to the pump?
Is running standard 12/14ga Romex OK?
More Info: Distance from the batteries/charge setup to the pump will be approx. 30 ft.

Thanks in advance for the help.

Tankless water heater - gas or electric?
A tank-type electric water heater, running off the inverter and enabled when batteries are fully charged, would PV power otherwise not captured.
This can also be DC, but you need an element with DC thermostat built in.

Can you have a gravity-fed tank at some elevation above the cabin? If no hill, then maybe a barrel up a tree (on a hunting stand).

DC motors tend to be forgiving of low voltage, just run slower.
12/2 + ground romex has 3 wires. If you use 12/3 + ground, that has 4 wires so you could use two wires for positive, two for negative, cutting IR drop in half.
Romex not so sunlight or water resistant, but UF is good for that.

You could wire pump to batteries through a relay, and have the load port of the charge controller supply power to the relay coil through pressure or float switch. I suppose you'll have float switch in collection barrel and pressure switch on output. And a switch you can turn off so it doesn't run the entire time you're away if something springs a leak.

My first water line from a spring I used 3/8" clear tubing. Critters chewed many holes through it. Black NSF tubing the next time. Drip irrigation tubing is readily available but not approved for drinking water, must have the wrong chemicals in it.
 
RV pumps are noisy, although some are quieter than others.
2 things that can help.
First have the hoses that attach to the pump be flexible hoses (like what is under the sink on your regular house). That helps reduce vibrations.
Second put the pump on some rubber mounts to reduce the vibrations going into the wall. Also you could make a small box to absorb the sounds too.
 
FYI, Most pumped water systems have an accumulator, so the pump doesn't come on every time you crack a faucet. It pumps water into a pressurized container holding a few gallons, then the container supplies water under pressure until nearly empty and the pressure drops enough for the pump to come on and refill the accumulator again.
Never would have occurred to me. Thanks for the FYI there. So it is basically like a water boiler only its purpose is to supply the pressure. Man you can learn so much on this forum.
 
Tankless water heater - gas or electric?
A tank-type electric water heater, running off the inverter and enabled when batteries are fully charged, would PV power otherwise not captured.
This can also be DC, but you need an element with DC thermostat built in.

Can you have a gravity-fed tank at some elevation above the cabin? If no hill, then maybe a barrel up a tree (on a hunting stand).

DC motors tend to be forgiving of low voltage, just run slower.
12/2 + ground romex has 3 wires. If you use 12/3 + ground, that has 4 wires so you could use two wires for positive, two for negative, cutting IR drop in half.
Romex not so sunlight or water resistant, but UF is good for that.

You could wire pump to batteries through a relay, and have the load port of the charge controller supply power to the relay coil through pressure or float switch. I suppose you'll have float switch in collection barrel and pressure switch on output. And a switch you can turn off so it doesn't run the entire time you're away if something springs a leak.

My first water line from a spring I used 3/8" clear tubing. Critters chewed many holes through it. Black NSF tubing the next time. Drip irrigation tubing is readily available but not approved for drinking water, must have the wrong chemicals in it.
It is a propane heater, running off of a small 20lb tank. The only electricity needed is for the starter, which runs off of 2 D batteries. We've had this running for a few months now. Very happy with it. We usually have hot water to the sink within 5 seconds of running the water. It's a Camplux Model. This was a great purchase!
Camplux Tankless Water Heater

The pump itself works great also, I ended up using 12/2 to make the run. I know it's not optimal, but I will eventually replace it with stranded.

The collection barrel (250 gallon IBC Tote) feeds the pump through gravity alone through a heavy duty garden hose. The pump creates the water flow. It's only about a 10 foot run between the tote and the pump.

Like you mentioned, I installed a regular "light" switch between the pump and the batteries.
When we leave the cabin after the weekend, we turn off the switch and empty the water lines.

So far so good. My main 2 problems are the noise the pump makes when it turns on and the need for a bigger accumulation tank. I think I'm going to get some thick foam and put it between the pump and the wall it's mounted to.

I think I'm going to buy this accumulator tank to help reduce the frequency that the pump needs to run especially when you just need little bursts of water from the faucet:
5 Gal. Accumulator Tank
 
RV pumps are noisy, although some are quieter than others.
2 things that can help.
First have the hoses that attach to the pump be flexible hoses (like what is under the sink on your regular house). That helps reduce vibrations.
Second put the pump on some rubber mounts to reduce the vibrations going into the wall. Also you could make a small box to absorb the sounds too.
I did use flexible, but I now see some clear plastic hoses that are supposed to help reduce vibration. Seems like some of the vibration is also from the hoses touching the wall. I like your box idea, or even a "stand" that I mount it to so it's not on the wall. I think the floor would absorb a lot of the vibration and reduce noise. It is located in the bathroom, which will be closed up soon.

Maybe putting pipe insulation foam over the hoses would help too.
When I'm done it'll probably look ugly, but in the end if it gives us the luxury of running water without the noise, it'll be a victory!
 
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