Bad ground?

R

rythmstrat

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The water pump for our pressurized water on the boat has been sounding differently for about two months. It's performed as normal, but had a louder, 'pushing harder' noise that was new. I had hoped to limp thru to the end of our boating season, which we have done, and was resigned to replacing it in the spring with a new one, figuring it was of unknown age

However, the last two weekends a new thing has happened...whenever the water is turned on, and the pump starts, the radio, (which is near the pump), cuts out briefly (a second or two), then recovers. It's on a seperate breaker than the water pump. I'm puzzled why this would happen? Someone today suggested it sounds like a bad ground connection somewhere?? Does this sound likely? And if so, how would I troubleshoot this?
 
are the gnds common ?? checking the connections and wiring is a start.
 
Check the ground and power wire on the pump and the radio. The motor on the freshwater pump could be throwing out spikes and might be near it's end of life. I would try for the heck of it running the radio off a stand alone battery and see if the problem stays. If it stays I think the freshwater pump's motor is arching if the problem goes away then you might have corrosion in the wiring. If they are both fed off of the same battery it's also possible the battery could have a bad connection or has seen better days.
Sometimes freshwater pumps sound like they are under a heavier load or noisy it can be clogged filters at the pump, this depends on the pump. Clogged filters can make the pump draw higher than normal current which would or could lead to damaging the power splices feeding the pump. It's a long shot but worth investigating.
Bill
 
Run a wire from the negative side of the battery to the pump. Disconnect the old ground and wire nut to the new wire. Run things as normal and see if anything changes. Could be a bad ground or the pump could be going bad, or you're getting low voltage to the pump. Gotta start somewhere.

Billy K.
 
Thanks guys, good suggestions. I will try running some new wires from the batteries next weekend, to both the radio and pump and see if I can seperately recreate/isolate the problem, and report back.
 
Are the pump and radio on the same battery but different circuit? Like in house battery...not engine battery.

Bad ground on engine battery won't crank starter so it's not a ground issue if pump and radio are on engine battery.
 
I'll almost bet the problem is in the common ground "bus bar". If the ground lead from the pump and the radio terminate at the same screw on the ground bus, a simple loose/corroded screw could cause the symptom described (been there done that). The positive leads may be on separate breakers, but the ground leads nearly always go to a common point. If ONLY the radio is affected, and ONLY by the pump, I'd suspect the ground bus, usually located close to the breaker panel.
 
Heh! I was thinking Ground BUSS, too, but I couldn't think of it...getting Old Timers...
 
I am thinking bad or weak battery.
I had a issue like that where when I keyed my VHF radio my FM radio would cut out.
I thought it was a feature until I realized the lights also went dim.
Changed battery and they all worked fine!
 
First thing will be to check the voltage using a meter at the house battery terminal and see what happens when the pump starts, see how much it drops. How old is the house battery (bank). What else is running on that battery. Fridge?

Check the negative bus, probably near the helm or DC breaker panel. This is where all your black negative DC wires are likely to be connected to the main negative wire coming from the battery,
 
quote:
Originally posted by PascalG

First thing will be to check the voltage using a meter at the house battery terminal and see what happens when the pump starts, see how much it drops. How old is the house battery (bank). What else is running on that battery. Fridge?

Check the negative bus, probably near the helm or DC breaker panel. This is where all your black negative DC wires are likely to be connected to the main negative wire coming from the battery,

Click to expand...


Hmm. I will check voltage drop when pump comes on. Yes, radio and pump are connected to the house batteries, and it does include the fridge.
I have a pair of 12v batteries for my house, the batteries are known to be good, new at the start of this year. In addition, I've checked their voltages mid-season, and load tested them.... all fine.
I did have a poor ground connection at one of the house pairs, because of a lousy installation on my part. That's been corrected for some time, and yes, they start the motors fine.

But, the other thing I did not mention (thinking it unrelated) was that I have experienced my GPS quitting inexplicably from time to time. As a few have suggested, I think it's my ground bus...it's located at the helm. And it's probably me creating the problem because of banging on the top of the dash, trying to stop my tachs from acting erratically.!! I bet I've loosened connection at the negative bus.
 
"banging on the top of the dash, trying to stop my tachs from acting erratically"

aka: "The Faria Slap" ( used to be, may still be, Common w/ Faria gauges... )
 
quote:
Originally posted by Radioactive

"banging on the top of the dash, trying to stop my tachs from acting erratically"

aka: "The Faria Slap" ( used to be, may still be, Common w/ Faria gauges... )
Click to expand...


============================================

apology for tiny thread hijack, but couldn't resist.

so it's not just me.......

I flick the glass of my Faria pyrometer with a finger flick.

And the one that doesn't require the flick has a bad seal getting moisture in it.

The clock is a POS too.

RWS
 
The ground connection TO the buss from the Batt also has to be good as well as all grounds to the buss
 
That's the stock answer (bad ground) to every electrical problem given by people not familiar with electricity.

Remember, current flows in both the positive and the negative (ground) portion of a circuit and a fault in either will cause problems. The positive portion usually has a lot more potential points of failure. Fuses, switches, etc.

It's simple enough to measure voltage in circuits if you know how. It's also simple to substitute temprary conductors to determine a fault.

Assuming anything can easily send you in the wrong direction when troubleshooting.
 
All of the above are good however a clogging filter will also cause extra load on the pump and all the symptoms you describe. check that first since it is the simplest to find and fix.
 
To answer the original question BAD GROUND? I say "it might be a bad ground".
Ron you are absolutely correct it could be either side of the DC circuit. I also suggested that the RO check his freshwater pump filters (attached on my FW pump). This could lead to excessive current draw and the pump sounding strange.
I'll just say this checking your house batteries at mid-season means -0-. Well it means they were good when you last checked them. A battery bank can get weak or problematic in as little as a day. I have seen bad batteries right out of the box, it's rare but it can happen.
Checking voltage drops or differentials when troubleshooting a particular DC powered device should be done by on/ off testing at the source (in this case the house battery bank) as well as at the end of the line at the device. If there is substantial voltage drop work your way back to the source or start at the source your choice.
When I have had DC problems with my boat I always tried a quick temporary 12VDC power source at the device eliminating the boats wiring. If the device performed properly I already had cut out the connectors so I started there and worked my way back to the battery bank. I'm fortunate in that I can dial in 2 different house banks to virtually eliminate the source or battery. Not everyone has that luxury. I do know that freshwater pumps will tolerate a voltage drop where a VHF radio will not especially on 25 watt transmit.
I live by the 3% voltage drop rule for all my boat's DC components. Many boats use the 3% for sensitive active electronics and 10% drop for pumps, blowers and similar devices.
I can't tolerate a 10% loss of my available power to heating the wires feeding the devices, it's a waste.
Bill
 
Again...thanks to all for their suggestions/tips. (and keep them coming, if so inclined!)

Returning to the boat tomorrow for the first time since my orig post...
I will check to see if there's any blockage or debris at the pump first, there are no inline filters anywhere. This is all water out of my water tank, manually added by me. There should be no debris to speak of, but you never know... It IS the easiest thing to check.

I mention the mid-season state of the batteries, as the condition existed then as well, so it's unlikely the batteries or connections there, are the culprit. I WILL isolate the radio using a direct feed from a new 12v source, to see if condition persists. This will be a helpful clue, I believe.

The push is on for me...we have now had snow at the marina, apparently, so the winterizing process begins in earnest!...I will have less time to diagnose this than I would have liked. We haul on Tuesday, so we'll see what I can get into over the next two days, and will report what, if anything I can find.
 
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