RV 12v water pump noise and seperation

we Travel full time in an RV and since we’ve owned it whenever the water pumps run the lights flicker. This is because the pumps pulse in and off etc. I read somewhere to seperate the lights and water pumps. My pumps are directly next to my batteries so I could do this rather easily, however, I’d like some advise on how to sepeareate them. As it stands the water pumps and lights are already on a different fuse (inside a 12v fuse block).

so in my logical brain if it pulses inside the fuse block how does separating it stop the flickering. The pumps and lights always come back to the same origin?

perhaps I’m missing something.

I assumed I could install a power distribution block straight off the 24 to 12v converter and run the pumps from one pole here. But will this actually fix my issue?

dear @Ryang thanks for your post

if you do not mind me asking, could you share more information about 1) water pump model and 2) battery bank (voltage, Ah etc)

i cannot say for sure what it is right now; your description does sound like the pump is causing voltage droop, observed by lights dimming.

if the lights don’t take that much electricity, a simple 12VDC buck+boost regulator with a capacitor on the output might do the trick. eg https://www.pololu.com/product/2577 it takes in 3-30VDC and outputs regulated 12VDC. so your pump kicks on, battery droops by a volt or something, but the regulator doesn’t care and keeps output 12VDC to lights no flicker since it’s still within 3-30VDC. a theory.

i’m sure others on the forum will have better suggestions

maybe this one https://www.amazon.com/Victron-Energy-Orion-Tr-Isolated-Converter/dp/B01M0YCDJ8 victron dc dc converter isolated 24vdc to 12vdc 9A about 100W lights easy ~60usd install between battery and lights

High power car stereo will make the lights flicker also because of the way they pull power.
The fix is a capacitor as close to the amp as possible. You can use a capacitor the same way with your water pump.
This is a common MSD 8830 capacitor I use all the time when setting up a race car ignition. (they also pulse the power)
It will go in Parallel with the water pump feed. Use standard #10 ring terminals and connect it. Make sure you put the rubber cab it comes with back on so nothing can short across the terminals.

Led lights?

my lights do not flicker when the pump comes on (all LED's now)
but, if they are flickering, this indicates quite a voltage drop
my pump is ~7W, a small draw @12volt
you should check all your connections and monitor the voltage at various places to find the poor connection

The driver for LED lights is sometimes sensitive to voltage fluctuations that wouldn’t be an issue for old style incandescent bulbs. I have a LED drop light that turns off for two seconds whenever my air compressor starts. The wiring in most RVs is marginal at best and I’ll bet the DC “ground buss” is just a bunch of wires twisted together under a big wire nut. When a big load like the water pump kicks in in pulls the ground voltage up and that upsets the LED driver.

Ryang said:

I assumed I could install a power distribution block straight off the 24 to 12v converter and run the pumps from one pole here.

Click to expand...

I am wondering if the pump surge requirements exceed what the 24 to 12v converter can handle properly.
I would think isolating the pump on its own 24 to 12v converter would solve this if this is the underlying issue.

Another option would be to get a 24v pump on its own fused circuit directly from the batteries but that's probably more expensive.

MisterSandals said:

I am wondering if the pump surge requirements exceed what the 24 to 12v converter can handle properly.
I would think isolating the pump on its own 24 to 12v converter would solve this if this is the underlying issue.

Another option would be to get a 24v pump on its own fused circuit directly from the batteries but that's probably more expensive.

Click to expand...

x2

MisterSandals said:

I am wondering if the pump surge requirements exceed what the 24 to 12v converter can handle properly.
I would think isolating the pump on its own 24 to 12v converter would solve this if this is the underlying issue.

Another option would be to get a 24v pump on its own fused circuit directly from the batteries but that's probably more expensive.

Click to expand...

x3

didn’t have my coffee when reading originally

pump on a converter shared with lights sounds like dim town

MisterSandals said:

I am wondering if the pump surge requirements exceed what the 24 to 12v converter can handle properly.
I would think isolating the pump on its own 24 to 12v converter would solve this if this is the underlying issue.

Another option would be to get a 24v pump on its own fused circuit directly from the batteries but that's probably more expensive.

Click to expand...

Don’t believe this is it as it happened when I was running 12v batteries as well.

It only happens on the bigger main LED lights not the smaller ones (like reading lights).

Northernchateau said:

High power car stereo will make the lights flicker also because of the way they pull power.
The fix is a capacitor as close to the amp as possible. You can use a capacitor the same way with your water pump.
This is a common MSD 8830 capacitor I use all the time when setting up a race car ignition. (they also pulse the power)
It will go in Parallel with the water pump feed. Use standard #10 ring terminals and connect it. Make sure you put the rubber cab it comes with back on so nothing can short across the terminals.

https://www.summitracing.com/parts/msd-8830

Click to expand...

I like this idea the most. I’ll run a dedicated circuit and add in the capacitor.

I don't know the type of pump you have or the age, the newer pumps have pressure bypass systems built into them, they tend to cycle a lot less. Another thing to reduce cycling is an accumulator tank, readily available at RV places or if you have space you could use a home size one. When it's being used constantly the air cushion in the hot water tank reduces as well, I used to operate the TXV on the tank occasionally to drain out the excess water. Have an on demand now-don't go that route.....
The capacitor is a bandaid in my opinion, if you have a 24v system get a 24v pump

They are sureflo pumps. The pressure switch is always triggering but it’s by design, I just wanted to isolate it from the lights.