Upgrade water pump wiring?

haddy1 wrote:

If you want to argue about this issue, argue with Aquajet or Shurflo. I simply followed their installation instructions.

The title of this thread was "upgrade".
In most cases, an "upgrade" is NOT necessary.

Now, if there is a problem that needs to be fixed, that's an entirely different story.

When I replaced the garbage-grade OEM rocker switch that had fast-on terminals with a real switch, I could fill a pot full of water in fraction of the time and when the DW was using the shower the spigot in the kitchen sink actually worked.

Sam Spade wrote:

haddy1 wrote:
A 3 volt drop across the pump terminals is too much. The easiest fix is to install a 30 amp automotive type relay. I was able to reduce the voltage drop on my coach to around .5 volts using this remedy.

No it isn't. Not for the purpose which the pump is intended; that is , intermittant low volume use.

What exactly do you think you accomplished with your modification ??
Now you could probably use the pump to water the grass on your lot for a couple of hours at a time; so what ????

If you want to argue about this issue, argue with Aquajet or Shurflo. I simply followed their installation instructions.

haddy1 wrote:
A 3 volt drop across the pump terminals is too much. The easiest fix is to install a 30 amp automotive type relay. I was able to reduce the voltage drop on my coach to around .5 volts using this remedy.

No it isn't. Not for the purpose which the pump is intended; that is , intermittant low volume use.

What exactly do you think you accomplished with your modification ??
Now you could probably use the pump to water the grass on your lot for a couple of hours at a time; so what ????

GordonThree wrote:
Has anyone measured the voltage at their water pump while it's operating?

I'm seeing ~6 amp load and about 10 volts with the pump running wide open (multiple taps opened.)

Battery voltage is at 13.2, as provided by my temperature compensating charger (ambient = 80F)

A 3 volt drop seems high to me. Wiring to the pump is 14 gauge.

Thinking of putting in a dedicated 12 gauge run to the main fuse panel. No idea how many branches the wiring Elkhart put in has, or how many staples they put through it.

USCG / ABYC says max 10pct drop, but their charts show 14 gauge wiring is enough. Does RVIA have a similar standard. Do SAE standards apply, since an rv is considered automotive?

I can't say what the mfg says it should be but our pump pulls up to ten amps and ahs either ten gauge or eight gauge wiring.
Fourteen gauge sounds small, and certainly will be if you put in a higher output pump.
Check the manual, for the pump, and see what it recommends, for minimum wire size, and consider the length of run.
Not sure how they are wired. Ours has four different switches, to tun pump on but there is only one pressure switch and it is on the pump.
The power supply surely should be greater than 14 gauge.
The wire to our pump is either number 10gauge or 8gauge probably 10 gauge.

Updates are going to be slow coming, as the work week has begun again and earning money limits my play time in the trailer :)

My suspicious are the power lead to the pump is too long or rather, too small gauge for it's length. The circuit as best I can trace it powers every DC load in the front section of the trailer.

Over sink light
Over bed light
Nightstand light
TV Antenna / SensarPro
Basement light
COLP alarm
and finally the water pump

While these lights are all off during my testing, that's still a lot of branches / connections made to the line, meaning nuts sealed inside the walls. Every nut is a little voltage drop, and they add up.

A 3 volt drop across the pump terminals is too much. The easiest fix is to install a 30 amp automotive type relay. I was able to reduce the voltage drop on my coach to around .5 volts using this remedy.

On our unit the OEM pump wiring was quite long approx. 30' with ground. I installed a 30amp relay next to the pump in the pressure switch circuit. The control switch in the monitoring panel applies voltage to the relay coil which is grounded through the pressure switch. The pump motor power comes through the relay contacts directly from the fuse about 4'.

I also added a local switch to bypass the monitor panel switch to aid the winterization process.

For intermittent pumping it is fine. I speculate most RV pumps are similar.

If you can possibly manage, it would be instructive to measure the voltage drop in the power and ground lines to the pump. Simply hook the meter up between the battery positive terminal and the pump's positive, and then likewise for the negatives, both with the pump operating. It would be okay to use a wire to extend the voltmeter leads; the voltage drop in the sense wire will generally be utterly negligible for this sort of check as the current flowing through the voltmeter is on the order of microamps.

I haven't measured mine (nor have I had any reason to suspect I need to), but a 3V drop in the wiring to the pump is certainly neither normal nor acceptable.

On my RV, and maybe on yours, the wiring to the pump is rather extensive as the various switches to turn it on and off are all inline with its power lead. I happen to have two such switches, one by the outside shower and one on the inside, wired basically like a two-way switch for a hall light. I don't have a separate pump controller module with a relay as is sometimes done.