Battery drain, short or hot ground?

[jsakat1]

electrical question....

I am not the most inclined mechanically so I ask this question.

I have a 130 Yamaha on my 170; so far the experience is fun. I carry two batteries, 1 dual purpose and and starting. I feel that with the stuff I have the batterys drain fast. When the engine is off and the anchor lights, nav lights, GPS, Fish finder, bilge pump and radio are on, the readings on the digital gauges and the Fish finder tell me the battery is running at around 12 V. When the engine is on and we are in motion they charge up to about 14.4 to 14.7 volts. I checked the batterys today while the boat is on the trailer and they were at 12.45.  The motor is great starts right up; however, sometimes when Im out and its time to start it takes a while to start, like there is not enough juice for the starter to pick up.  I shut everything off and then try and it starts up.

Now could this be a battery problem or a starter problem or no problem; I don't know. Could I have an open circuit or a short or nothing? How do I find out. I checked for continuity and my switch panel fuses had power when they turned on and the battery was on and when they were off and the battery selector was off they had no power. I put the multimeter on the fuses on the panel, on the 20 DC position and they read 4.3 one read 4.19. I don't think I did this right. The one that read 4.19 (anchor lights) had a loose connection and some green corrosion so I clipped it off and put an new end to it.

Hope someone can give me some feedback. The fuses are 15 amp ATOs. How do I test with the multimeter for a short or open circuit or a hot ground? any tutorials around? I'm not sure if I am fussing over nothing but I feel I might have something. Looking forward to your suggestions. Am I worrying about nothing here?

[slvrlng]

Well, I know less about elec than you do but you could go to www.fluke.com and look at one of their manuals on line or even ask them a question. To me it sounds like a ground thats going bad. Does the hard to start happen after you have sat for a while or if you shut it down and try to crank immediately? If one wire was corroded I would bet there are more.

[GoneFission]

Sounds like a loose or corroded connection on the battery leads.  Check where the cables enter the terminals - should not be loose or have corrosion there.  Also, clean the terminals and the battery connections with a wire brush or some sandpaper until they are nice a shiny.  Tighten everything down well to ensure a solid connection.  

Also check the connection on the starter motor and solenoid (under the motor hood - follow the battery cable to the connections).  Sometimes these connections can corrode as well.  Make sure everything is clean and tight.  If you find a place where the cable is loose or corroded where it goes in the terminal, you will need to get a new terminal installed.  

Hope this helps - good luck and see ya on the water!

[MichaelO]

when Im out and its time to start it takes a while to start, like there is not enough juice for the starter to pick up.  I shut everything off and then try and it starts up.
[snip]

Would you please elaborate?  When you say it takes a while to start, do you mean it won't crank, cranks slowly, or cranks fine but, doesn't start easily?

Good advice so far.  Don't clean terminals so much that you clean the tin right off.  The copper beneath will corrode faster, and any scratches from cleaning will geometrically increase the rate of corrosion.  Use the mildest abrasive that you can, like a little brass brush, or the finest scotchbrite you can find.  Not sandpaper, and never steel wool.  Think clean and polish, not scratch and scrape.  Use dielectric grease on the terminals when you replace them to discourage further corrosion (cheaper at the auto parts store than at the chandlery).

If you have your meter along when the issue occurs, measure the voltage _at_the_starter_while_cranking_.

Here are some facts:
The starter's torque increases with voltage.
The battery's voltage decreases with load (current, amps).
Each corroded wire and terminal causes a voltage drop proportional to the load.

Some potential causes of your issue:
1. A corroded wire or junction is causing a voltage drop.  The voltage drop increases with increased load.  As for your load, probably an amp each for the bow and stern light, two to five amps for the bilge pump (depending on the size), maybe one to two for the gps, and 1/3 to one and a half for the fishfinder: probably about 6 amps total.  This shouldn't affect your starting on a good battery unless you have some problem connections or undersized wiring.

2. Your starter solenoid is tired.  It needs max voltage to clap shut with enough force to make sufficient contact on corroded contacts to pass current to the starter.

3. Your ignition system is tired, or fed with a bad connection in the path, the starter spins the motor just fine but, the ignition needs max voltage to fire the plugs and you are getting an intermittant or weak spark while cranking, and when running, with the alternator boosting the voltage, it's fine.

4. You have corrosion between the starter case and engine case, resulting in a weak ground and slow cranking.

5. Your boat thinks going home is a terrible idea.  It wants you to stay to catch more fish and have more laughs with the other souls aboard.

How do I test with the multimeter for a short or open circuit or a hot ground?
[snip]

If you have a short, a fuse should blow.  With your meter set to "ohms," you will read a very low value, like 0.2 ohms on a digital meter, or the far end of the scale on analog.  Note, electronic loads can give a false reading, and high power draw items (e.g. starter, starter solenoid) will also read very low.

If you have an open circuit, nothing works on that circuit.  With the meter set to "volts" you will read zero, or something close to it.  You can use the ohms setting to find out which leg.  Connect your meter's black lead to the battery ground and test the ground leg (meter's red lead to ground at the load), you should see a short (see previous paragraph).  If that leg is fine, put the meter's red lead on battery plus and test the hot leg (meter's black lead to power point being tested) and again, a short indicates a good, and not open, connection.  (Electrically savvy readers will note it probably doesn't matter which color lead you use but, some meters are sensitive to a misstep).

If you have a hot ground, then likely you have an open ground, and are reading voltage through some electrical device (like a light bulb).  Disconnect the load, and check for voltage on the ground again.

And finally, a test light is a good tool in addition to the meter.  Often, a bad connection will pass the infinitesimal amount of current needed to indicate voltage on the meter, but, won't pass any significant current.

[RickK]

Where have you been MichaelO? Lurking for a long time :!:  :!:
We need expertise like yours around more often  

[slvrlng]

Now that is an answer! Hey michael if I drag my 19-6 up to my buddys house in Hartford you want to completely rewire it while I hang out with him? I think its only about a 14 hour drive!

[jsakat1]

Thanks for all your help....

Michael.... What I was trying to say was this. When I anchor and shut off the engine and I'm fishing. Sometimes, if I wait awhile and I try to turn on the motor. The starter doesn't latch on to the flywheel. I have digital gauges and I see the voltage drop to around 11 volts. I shut everything off, wait and then it turns off. Sometimes I take the cowling off and start it without the cowling and for some reason that always works. When I start the motor and move the batteries are supposed to charge. Like I said, I think they charge because the digital gauges show a reading of 13.8 to 14.7 volts.

Yesterday and today, I checked the connections and grounds; some of them on the switch panel were loose, one had a little green (I cut that one off and crimped a new connector on it) The others looked fine, a couple of them on the switch panel were a little loose and I fit them in more snuggly. Most of the connections have 16 or 18 gague wire for my lights and instruments have 16 or 18 wire, which should be fine. I also took off the wing nuts I had holding down the battery cables down because I read on easyacdc.com that they can contribute to draining battery and replaced them with locking nuts. The wires on the starter looked fine and tight.  

I'm going to replace the battery cables from the switch to the battery and put some di electric grease on the connections on the switch/fuse panel hopefully tomorrow. Saturday, I will look at the problem with more detail. Again thanks for your help.

[jsakat1]

Michael you wrote:

Would you please elaborate? When you say it takes a while to start, do you mean it won't crank, cranks slowly, or cranks fine but, doesn't start easily?

To me the starter seems to crank fine cause I can here it trying to latch on, it just doesn't catch the fleywheel. When it does that I see the voltage on the digital gauge sink down. When I put the boat at the ramp (batteries charged up before the trip), the motor usually starts right up. However after a while fishing or anchored with everything on I start it and it doesn't latch. I can hear it catching and moving.

[MichaelO]

RickK,

Thanks, that is very kind.  I haven't been lurking (much) but, I do pop in here and there for research.  I am very grateful for this forum, its members and supporters, as it has been an invaluable resource in getting my own Aquasport 170 into the water.

Lewis,

I'd love to rewire your boat.  But, unless you can convince me you are using it to save orphans or some such, it won't be free.  :)  Over the course of the next few months, as time allows, I will be rewiring my own boat, and will try to document it as it may be a benefit to some members.

Jsakat1,

You are correct, if you are seeing the battery voltage increase when the engine is running, the battery is charging.

I agree that 16 or 18 AWG is fine for switches and instruments (obviously, with very large boats and very long runs: excess of 25 feet, adjustments need to be made).  Watch out for courtesy and cabin lights circuits and especially daisy chained grounds: the current really adds up.  As an interesting aside, on mission critical industrial control systems, a double-ended ground is often employed.  The ground starts at the neutral point, is daisy chained through the various loads, and then returns back to the neutral point.  If any ground connection is broken (or inadvertently disconnected), it doesn't matter.  You would have to break two ground wires to lose ground.

I took a look at the easy acdc site you mentioned, concerning the wing nuts.  I believe the author's concern is connections which can easily become loosened.  This can happen due to the connections being bumped, stressed by motion, or shrunken by heat cycles or corrosion.  I recommend the use of stainless split ring lockwashers under the wing nuts.  In defense of the easy acdc author's approach, he/she has eliminated fiddling: if you make it difficult for a user to  tamper with a connection, you reduce the likelihood that it won't be put back right.  Loose connections at the battery are the worst.  Since the current is often very high, a loose connection will arc and microweld, causing the surface to crater, reducing the surface area of the connection, thereby increasing resistance and heat, as well as creating a ripe environment for corrosion.  The ONLY good electrical connection is a gas-tight joint.

Your starter problem sounds a lot like mine.  I went around and checked my connections, I greased the bendix, it was the same.  It seems worse when the engine is warm.  In my case, the issue is two-fold: first, the starter is a rebuild, and I don't care what anyone says, no rebuild will ever compare in quality to an original factory part, the second is the wire gauge.  My motor is wired with #6 AWG wire, and given the length and draw, it really should be #4.  So what is going on?  A few things are stacking up: the hot starter needs a bit more voltage to accelerate fast enough to drive the bendix, and the #6 wire causes a bit too much voltage drop (compounded by the age of the wire, it has some internal corrosion), and the rebuilt starter, with its wider tolerances, increases the need for maximum voltage.  I was able to verify this by attaching a long set of automotive jumper cables.

The fact that removing the motor cover always fixes your problem might be coincidence, but, it is possible that something about the motor cover is causing a connection to be stressed.  This one is a bit of a longshot but, I've seen battery terminals that had corrosion just inside the wire, and broken strands.  When the plastic battery box cover was applied, it bent the wire at the terminal, separating the broken strands, and increasing the resistance of the joint.

When you've got something that 'usually works, sort-of,' you are likely dealing with tolerance stack-up.  Here is a scenario:
-some terminal connection corrosion at the batt connections: 0.5 volt drop,
-3% voltage drop in the wire (which is what you get when you size by NMMA, ABYC, or USCG standards): 0.36 volt drop,
-wear at the starter solenoid contacts: 1 volt drop
-old or rebuilt starter wants 11 volts instead of, say, 10.5, for performance.

Add it up: batt (12.3 volts at partial charge) - 0.5 - 0.36 - 1 = 10.44 volts.  But!  Your old or rebuilt starter doesn't just need 10.5 anymore, it wants 11.  Now, I'm pulling numbers out of the air here to illustrate a point so, don't read too much into them.  I would hope that you take from this that often, if you'll forgive some cliches, there is no silver bullet, just too many pieces of straw on the camel's back.  Remove one straw to get things working; remove two or more to get them _dependable_.

Please continue to keep us in the loop as you resolve the issue.