Electrical Charging Problem
Printed From: CorrectCraftFan.com
Category: Repairs and Maintenance
Forum Name: Engine Repair
Forum Discription: Engine problems and solutions
URL: http://www.CorrectCraftFan.com/forum/forum_posts.asp?TID=1903
Printed Date: November-22-2024 at 8:16pm
Topic: Electrical Charging Problem
Posted By: AWhite70
Subject: Electrical Charging Problem
Date Posted: June-20-2005 at 2:34pm
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This weekend I ended up in the middle of a lake with a dead battery in my '79 SN. This has happened to me three times in the past three years and has finally annoyed me enough to do something about it. The problem is it's so intermittent.
I'll be driving the boat quite awhile and then I'll go to start it and it will barely turn over and not start, shortly after that it won't turn over at all. After charging the battery everything will be fine for the next 2-4 months and then the same thing happens. I've had the battery tested and it's good. The charging system must be working some of the time or I wouldn't be able to go 2-4 months between episodes. I'm thinking that either the alternator is charging intermittently or I've got a bad connection somewhere. All of the wiring in the boat is original and the alternator and starter are both old (I don't know how old) I'm going to start with replacing the battery cables since they're original and see where that gets me. Any other suggestions? Additionally for those of you with similar boats what does your Ampmeter (Amps not volts) read when you're underway? Mine typically reads just to the positive side of zero. |
Replies:
Posted By: David F
Date Posted: June-20-2005 at 6:16pm
| Positive side of zero is good...means alternator is putting out. After running the engine for awhile, the needle should get closer to zero as the battery is recharge and the alternator does not have to work so hard. As you turn on lights, fan and accessories, the needle should move furhter to the right as you require the alternator to work harder. With amp meters, you either know the alternator is working or not (not so with volt meters). |
Posted By: 79nautique
Date Posted: June-21-2005 at 6:43pm
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mine will start out at about 20 amps then go back to almost zero after a couple minutes. I was chasing a simular problem three years ago and never could track it down. Replaced the battery cables with marine grade cables, replace the voltage regulator, replaced the battery and even cleand all of the connection and replaced the ignition switch and still had the problem until I replaced the Alternator with an internal regulated model and engine wiring harness from skidim. What type of battery are you running, a deep cycle or one that has less than 650 CCA won't work very well on this year of nautique. A deep cycle takes to long to recover and cannot produce the CCA needed if on a low charge. The ford starters like a lot of current and if the Cold Cranking Amp rating of the battery is low then it has trouble cranking the starter especially when hot. ------------- http://www.correctcraftfan.com/diaries/details.asp?ID=756&sort=&pagenum=1&yrstart=1979&yrend=1979 - 79 nautique |
Posted By: AWhite70
Date Posted: June-21-2005 at 8:08pm
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I know my battery is a standard automotive grade. I believe it's 590 CCA.
I'd almost guess my alternator and starter are original. They look old enough to be. I've thought about switching to the 50A internally regulated unit but haven't done it yet. Now that I've got the new battery cables I'm gonna run the boat for awhile and check some voltages and see what I find out. |
Posted By: JEFF KOSTIS
Date Posted: June-23-2005 at 12:26am
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You might find the batt cables are not the problem. Charging the batt and everything is ok means the connections are probably ok. It sounds like a possible alternator problem. Sounds like you lost a few diodes in the alternator and its only doing a few amps, but a little less than whats required causing a slow drain. A voltmeter at the battery with everything on better read 13 volts or more. ------------- MUSTANG COUNTRY http://www.correctcraftfan.com/diaries/details.asp?ID=1074 - 1974 Mustang 17 http://www.correctcraftfan.com/diaries/details.asp?ID=1093 - 1976 Mustang 17 |
Posted By: AWhite70
Date Posted: June-24-2005 at 11:05am
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I ran my boat last night and did some more investigation of the charging system.
With the engine off the battery voltage was 13.4 volts. I was surprised to see it that high but I'm guessing it's because it had been on the charger for 2 days. With the engine on and warmed up the battery voltage and the voltage at the alternator output read 13.75. Even with the engine rev'd up to 2500 or so. Sounds to me like the alternator is shot, looks like I'll be ordering a 50A alternator and new harness from SkiDIM today. What do you guys think. Since my boat doesn't have any accessories the current draw on the battery should be pretty low. I'm guessing that's why I was able to go a couple months between battery chargings. |
Posted By: 79nautique
Date Posted: June-24-2005 at 11:12am
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The voltage reading looks normal to me 13.5 volts is pretty much normal if it was down around 12.5-13.0 volts then I would be worried. have you tried changing the votage regultor? Also have you hooked a test light in series with the negitive cable to check if there is a battery drain? ------------- http://www.correctcraftfan.com/diaries/details.asp?ID=756&sort=&pagenum=1&yrstart=1979&yrend=1979 - 79 nautique |
Posted By: JEFF KOSTIS
Date Posted: June-25-2005 at 12:58am
79 nautique is right on. 13.75 v is certainly fine. Try turning on the blower and lights and measure the voltage at the battery with the engine on. If you measured it at the alternator stud, you may find it alot different at the battery. You could have the ammeter shunt opening up or a connection problem. With your accessories on, the voltage may be as high as 15 v at the alternator stud and 13.8 at the batt. The batt voltage is whats important. The voltage difference between the two are a direct result of voltage drop in the wire and usually is tolerated due to the "sense" or "field" line that makes the alternator put out more. Thats why its never a good thing to hook the "field" wire to the alternator stud directly.  ------------- MUSTANG COUNTRY http://www.correctcraftfan.com/diaries/details.asp?ID=1074 - 1974 Mustang 17 http://www.correctcraftfan.com/diaries/details.asp?ID=1093 - 1976 Mustang 17 |
Posted By: billgatesceo
Date Posted: June-25-2005 at 2:01am
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How is your starter? When I first got mine, I could charge the battery all night...go to try to start it up for the first time, and it would usually start. If I tried it again, it would get harder and harder to start. It ended up being a bad starter and it was dragging the battery way down trying to start.
Also, I would check the belt to make sure it is tight. You should not be able to turn the pulley by hand easily (this was another of my problems). |
Posted By: Guests
Date Posted: June-25-2005 at 3:10pm
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I would also work on replacing that amp meter with a voltmeter... It makes no sense to send the entire charging current from the alternator up to the dashboard, thru the meter, then back to the battery. It's an electical problem waiting to happen, and as others have stated, the amp meter is impossible to read while underway since the scale of the meter is so inaccurate right near "zero".
Take the wire that runs to the amp meter and cut out the excess by running the charging wire straight to the battery. A voltmeter will fit in the same hole. Tom |
Posted By: Jim_In_Houston
Date Posted: June-25-2005 at 5:07pm
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Interesting. Anyone else agree with Tom? Why did the factory use ammeters in the first place? ------------- Happy owner of a '66 and a '68 Mustang |
Posted By: JEFF KOSTIS
Date Posted: June-26-2005 at 1:42am
The ammeter serves several purposes. In the best case possible, a voltmeter and ammeter combined are really whats needed. The thing nice about an ammeter is you can instantly see the output (current) of your alternator by draining the battery a bit and then starting the engine. It also tells you the status of the current flow. A (+) reading indicates the alternator is charging the battery. A (-) reading indicates the alternator is not keeping up and current is comming from the battery, and will eventually go dead. A zero indication tells you that the battery is fully charged. A voltmeter is good because you could have a bad diode on the alternator and not charge the battery up to 13.5 volts, it may be only 12.8 volts. Voltmeters are only accurate if the are wired direct to the battery with their own +/- line to eliminate voltage drop readings as several boats have. You may read 12v on the gauge, but actual battery voltage may be 13.8v. The main reasons why voltmeters are used today is the fact that the alternators are bigger, which means huge wires going up to the dash and back. Its cheaper for boat manufactures to install a voltmeter instead. Hope this helps!!  ------------- MUSTANG COUNTRY http://www.correctcraftfan.com/diaries/details.asp?ID=1074 - 1974 Mustang 17 http://www.correctcraftfan.com/diaries/details.asp?ID=1093 - 1976 Mustang 17 |
Posted By: David F
Date Posted: June-27-2005 at 2:27pm
| Jeff is right on (IMHO). Simplified: Ammeters tell you the real time status of the charging system. Voltmeters tell you the status of the battery. With a voltmeter, you can have a charging problem and not know about the problem until the battery discharges enough to cause starting problems. |