Corrosion and Volt Drop issues.

This was the ground wire to the starboard alternator. The Alternator Does Not ground via the frame on this model as most marine alternators have an external ground. 
We had both our alternators overhauled by my friends at Johnson's Electric in Carrollton Georgia. We had used their services for many years and they are trusted and reliable. The Volvo Alternators did not have a problem but were 30 years old and I felt they needed a good look see at all there parts. They ran about 10 hours and the starboard engine showed low voltage on the gauge. I checked and the voltage was barely above 12.4 Volts

I wish my picture was better but the wire is green except where it overheated . All this was covered by the cap and insulation. Replacing the wire and connector fixed the problem and now the alternator charges fine. I wonder how many alternators are replaced because of problems in the circuit. 



This is a relay test for volt drop across the circuit. The starter relay is not clicking and there fore the starter doesn't work.

Good relay with bad circuit due to corrosion.  this section of the circuit going to relay is good. Look up stream for problem.

Using this tester is easy. The push button loads the circuit with a 100 ohm load


Understanding the circuit design allows you to quickly diagnose the problem.

Up on the dash at the switch now I find a circuit that is showing 13 Volts. When it should read near zero. The battery charger is on at this time. 



One terminal is corroded causing the volt drop and the starter not to operate. The terminal at the 9 O'Clock position is the culprit.




This is the terminal connection that has the offending connection. I by passed the connector and ran a new wire on this 30 year old boat. Because I knew how to test for volt drop I did not have to replace a bunch of good parts to fix the problem.
Here are some resources to help. https://autoteacher.net/Electronic_Q3HM.html  or you can google Volt Drop Test



Comments

  1. Jeff CurtisMarch 29, 2015 at 1:01 PM

    Volt drops, volt drops, volt drops... How many technicians yet need to learn this skill?

    ReplyDelete

Post a Comment

Popular posts from this blog

Cuban Landing @ The Dry Tortugas

Image
In the 1840s this pre-Civil War fort protected the Gulf of Mexico from foreign invasion. How is that working out for you? If we rely on the government for answers to our problems we get government answers. Pray for our families and neighbors. Care for one another, 1 John 3:23 is the one we have the most trouble with, the rest is religion. Semper Fi! Fort Jefferson, Dry Tortugas 70 miles West of Key West http://www.nps.gov/drto/index.htm Sailing Vessel Kanza  Two of my friends agreed to go for a sail with me to the Dry Tortugas in June of 2005. I had made six trips to the Keys (See  http://en.wikipedia.org/wiki/Conch_Republic  )  and the Dry Tortugas during the summers before with my sailing friend Dale Fasenmyer and one trip with my wife, Jean and sons. This year looked about the same weather wise. Yes, I know that is hurricane season, but we all were teachers and summer was our only time off work. Dale, Michael Smith, another teacher friend and I packed the Island Pac
Read more

2001 Mainship 30 Pilot, Steps to operate

Image
/ Steps to operate 2001 Mainship 30 1. Open seacock for the main engine and watch for water flow after starting. Pull the black ball to open the seacock on the strainer for mains. Shut down immediately if no water flows out telltale. 2. Open the main fuel valve on Port topside of the tank for main engine fuel flow to yellow switch valve, open black valve, and close the two primer valves to run main. Genset fuel cut is on the Starboard topside of tank with a separate filter system. Fuel system allows the operator to select the filter and prime without stopping if offshore 3. In-cabin, Remove steps, turn on bilge light and switch open valves for seacocks to feed seawater to Air Conditioner and Generator. Do not open "Flush Valves" to run AC or Genny.  Seacocks for AC and Genny are shown open. Close after use! Light switch on galley panel. 4. If the head is to be used open seacock for the head, Macerator seacock is closed! Breaker for electric head an
Read more

1968-1969

Image
Firebase near VCB 1969 Dewey Canyon, drawn by Silas Levi from a picture of  a Marine Firebase in North I Corp RVN Actual picture of Home is where you dig it. near VCB/LZ Stud 1969 1971 Sgt of the Guard Gitmo, Cuba   Boot Camp Parris Island January 1968      Standing on the passenger side of the bench seat in my mother's 54 Olds looking out the windows as she drove the dirt roads into town was cool to this kid. I would hold my hand out the window and pretend I was flying. There was one paved highway we eventually got to then she would say to me “Roll the window up son, I am gonna be doin 60 now we're on the highway!” There were no child seats and most disdained any restraint like seat belts. My 5 year old mind could not conceive the mileage, speed and distance back then. I could only watch as the telephone & power poles started to go by like fence posts as mom speed-ed up the powerful V8 car on the blacktop high way into the small town on the Western side
Read more