Electrical Gremlins "pumps"

[msmith4050]

Help, I need some suggestions from those of you much wiser than I when it comes to AC/DC. heres a quick overview.

SV Dream Weaver, current location Bequa Grenadines. 47 Vagabond departed Boston Nov. 2010.

prior to departure
1. Replaced both orginal bilge pumps and added high water alarms.
2. added AC. Replaced cold plate circulating pump with a higher capacity to accomade AC needs.

current status
1,The new bilge pump has failed/ replaced currently working.
2. the circulating pump has failed twice/currenly running on the orginal awaiting replacement.
3. the orginal fule transfer pump failed on route/replaced/new replacement just failed.

There is some justifaction related to the circulating pumps location being above sea level. But no good reason for a brand new bilge pump and fuel transfer pump to fail.

All seem to be overheated and locked up in some capcity.

Help?? Am i just paying my dues to the gods of Karma? or does the number of failures indicate some other potential problem. Electrical Spike?

have:shore power, generator,high output alternator, solar, wind.

Any suggestions or advise would be greatly appreciated.please remember im a sailor w a good tool kit,not an electrical engineer.
Thank You,
Cap "frustrated" Mac

[sailingdog]

Have you checked the wiring to the pumps for resistance? Is the wiring oversized a bit or undersized? Is it corroded? Have you checked the voltage at the pumps?

Motors burn out pretty readily if they're supplied low voltage. If your wiring is undersized, corroded or both, then you're likely losing too much voltage and the pump motors are dying early because of it.

Also, some pumps are just lousy designs. For instance, Mermaid A/C units often come with a raw water circulation pump made by Teel. This is a crappy pump and undersized for its intended purpose in most cases. Upgrading to a higher capacity, more expensive, March-series pump often reduces maintenance and problems with the A/C system.

[msmith4050]

Thanks for the good advice. Do i just use my tester to determine voltage at the pump? How do I test for resitance? My Trace invertor seems to indicate good voltage, so perhaps it is in the wire. How do I determne proper Gauge. i know its based on draw and length of run. fortunatley, i found a local used electric pump, for the transfer and have a new March pump clearing customs today. By the way, I have some very odd stray current. Could that effect things at all?

Thanks again

Captain Mac

[captflood]

check for voltage drop or spike, correctly wired, choked piping , try fitting anti-surge, fuses straining boxes to keep pipes clear. Go Safe

[LakeSuperiorGeezer]

Originally Posted by msmith4050

1. The new bilge pump has failed/ replaced currently working.
2. The circulating pump has failed twice/currently running on the original awaiting replacement.
3. The original fuel transfer pump failed on route/replaced/new replacement just failed.

All seem to be overheated and locked up in some capacity.
Cap "frustrated" Mac

These symptoms are hard for me to figure out since the old items work, which indicates the wiring is OK, but all of these failing together really seems peculiar which makes me think wiring, like maybe a ground return wire that services all these items. Take the “burned out” bilge pumps and put them in a pan of water, hook to a battery and see if they work to find out if it is the pump or the wiring. Do not confuse positive and negative, as the pumps will probably run backwards if reversed. Are both bilge pumps on the same fuse? Should be separate fuses for redundancy for better reliability. Your problems would be a good argument for the installation of a large manual bilge pump as failure of electrical bilge pump at sea could perhaps sink the boat if there is power failure (dead battery) or wiring issues. Also make sure the float switches for turning on the new bilge pumps are operating properly. Voltage spikes should not affect pumps unless there are electronics in them that sense the presence of water and turn the pumps on. The engine starter can cause electrical spikes (burns out sensitive electronic devices) but you will only see that with an oscilloscope. New fuel pumps are usually very reliable even if they have electronics in them as there are ways to protect against spikes, and a fuel pump is going to be operating while the starter is cranking the engine. Well, maybe not a fuel transfer pump, but an electric pump supplying the engine will be and same design for any fuel pump I would think. By the way, what is a fuel transfer pump for on your boat? I thought usually you would select a tank and draw from that, but that there would not really be a need to balance the boat with respect to fuel weight. It’s not an airplane. Check the voltage operaton range on the various pumps, then put a voltmeter on them where they are wired up to the boat and see if the voltage range drops below their rating. No not let any positive connectors or even wiring contact bilge water as battery driven electrical currents can eat metal parts very quickly

[sailingdog]

Check the wires at the pump for voltage. A common problem is that people use either non-marine wiring or don't use adhesive--lined heat shrink terminals for connections in the bilge and the wiring corrodes, causing high resistance and a large voltage drop.

Originally Posted by msmith4050

Thanks for the good advice. Do i just use my tester to determine voltage at the pump? How do I test for resitance? My Trace invertor seems to indicate good voltage, so perhaps it is in the wire. How do I determne proper Gauge. i know its based on draw and length of run. fortunatley, i found a local used electric pump, for the transfer and have a new March pump clearing customs today. By the way, I have some very odd stray current. Could that effect things at all?

Thanks again

Captain Mac

[GaryHLucas]

I have a little trouble in believing that low voltage is causing motor failures on what sound like centrifugal pumps. DC motors are used in industry to get speed control, by lowering the voltage. I've run large DC 12 volt motors on 1 volt for hours on end without failures over many years. Centrifugal pumps obey a squares law with regard to load. Slow the pump down by reducing voltage by half and the load on the pump drops to 1/4. So the motor will be under less load not more. I regularly operate pumps up to 75 hp with Variable Frequency Drives and you can see by the power meter how the load on the motor drops off.

On bilge pumps I would be suspicious of pumping things like strands of fiber from towels or clothes, and strands of human hair. These can get through the finest strainers and wind around the impeller shaft and that would overload the pump.

A DC ammeter would show you directly how much load is on the pump. Unlike AC motors where amps bear little relation to actual load, DC amps relate directly to motor torque. Most VOM meters have a 10 amp scale nowadays. You have to hook the meter in series with the motor. Measure the amps on the new pump and check it occasionally to see if it is changing. Note that if your batteries are low and the pump is running slower the amps will be lower too.

Hope this helps,

Gary H. Lucas

[LakeSuperiorGeezer]

Originally Posted by GaryHLucas

...On bilge pumps I would be suspicious of pumping things like strands of fiber from towels or clothes, and strands of human hair. These can get through the finest strainers and wind around the impeller shaft and that would overload the pump.

A DC ammeter would show you directly how much load is on the pump. Unlike AC motors where amps bear little relation to actual load, DC amps relate directly to motor torque. Most VOM meters have a 10 amp scale nowadays. You have to hook the meter in series with the motor. Measure the amps on the new pump and check it occasionally to see if it is changing. Note that if your batteries are low and the pump is running slower the amps will be lower too.

Hope this helps,

Gary H. Lucas

You make good points Gary. Take a look at the impellers and screens in the strum box for the bilge pumps. There is still the issue of fuel transfer pump and AC plate pump failures. Need to remove pumps and test I think. We need more information from the boat owner. Also as was mentioned, good electrical connections suitable for boating are needed: Marine Wiring and Connectors and click on Marine Electrical Supply