Shurflo pump circuit...dedicated?

[jftompkins]

From the Shurflo manual: “ The pump works best on an individual filtered circuit.” So my situation (2017 23FB which we luv it)... Believe that the bathroom LEDs are also on the same 12 V 15 amp DC circuit ...near the pump switch. There are times on battery power (maybe low) that when the pump runs - the lights flicker - back to the word “filtered”....?. Being a PD pump imagine that the current draw is kind of noisy.... affecting the LED voltage...? So since the manual suggests putting the pump on a individual 15 amp circuit.... I am guessing this gives me the best chance if LED’s not being affected during pump operation. The pump underneath the wardrobe is close to the panel... but was wondering if anyone had split the pump off of another individual circuit (have a spare) and where that split might be? to rewire ??

[TG Twinkie]

Sounds like voltage drop issues. Caused by too small of wire feeding all the devices on the pump circuit. LED's are sensitive to voltage drops. So are incandecent bulbs but their reaction time is slower do to the filament having to heat up and cool.
There isn't a constant load by the pump since it is a diaphragm type. The pump is pushing on the diaphram, then backing of for the next stroke. Kind of like the old oil cans where you pushed on the bottom to deflect the metal thus pushing the oil out the spout.

[cwf]

LED's are actually 'dimmed' by a process called 'pulse width modulation'.. PWM for short.

The power is 'pulsed' rapidly enough to keep the LEDs from getting to full brightness.

When you have a device which draws power in 'pulses', such as your pump, it will cause voltage 'drops' like pulses.. but the duration is longer, so your eyes can sense the pulsing. The PWM pulses near 60cycles, like the AC power we have in the US, so the eye/brain cannot sense the change.

Our 1999 Excella once had similar problem, it was a weak battery (One of the 2 onboard), some grounding issues and loose (not properly torqued) connectors.

From the 'factory', the wiring was connected with 'crimp' connectors. These loosened over time. Removed, cut to fresh copper and properly re-crimping helped a lot. The pump even ran better (faster)!

Those are symptoms / causes which can occur at any time with mechanical thingy's. Often with new things, like Airstreams, too.

So.. check battery connections.. at battery, converter, fuse panel (ensure fuse is properly snug), at the 'pump' switch and any connectors in the pump power circuit.

Just kidding.. it is actually Mister Mxyzptlk causing the issues... https://en.wikipedia.org/wiki/Mister_Mxyzptlk

[jftompkins]

Thanks...agree “too small of wire”....with other devices along with PD pump power draw being “noisy” ;.so am thinking how to find wire to split and put pump on separate circuit. The pump is right next to panel...so need to see if i can find where it is tied into other lighting?...back in the bathroom near pump switch? Or near pump? ....my next project. Getting way out there (or maybe stupid question)...capacitor in pump circuit?

[TG Twinkie]

You could disconnect the wire at the pump, cap it off.
Then run a new wire from the pump to an empty spot on the fuse panel.

[jftompkins]

Thanks - that helps confirm my thinking.... to keep it simple...which wire to cap to keep the pump switch in the bathroom in play... can check with a meter. I am guessing the switch is wired on the ground side of the pump....maybe?

[cwf]

Originally Posted by jftompkins

Thanks - that helps confirm my thinking.... to keep it simple...which wire to cap to keep the pump switch in the bathroom in play... can check with a meter. I am guessing the switch is wired on the ground side of the pump....maybe?

No... the switch should always carry the power (+ side in this case).. mostly because that is the fused side.. and a ground between the load and ground would not be controlled.