electrical 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=4848
Printed Date: November-27-2024 at 1:34pm
Topic: electrical problem
Posted By: jimbo
Subject: electrical problem
Date Posted: September-24-2006 at 7:18pm
Was having problems with the boat starting. Put the battery on the charger, cleaned the terminals and applied di-electric grease.
Boat started fine but noticed the volt meter on the dash was reading around 11 V. Turned off the blower; went up to 12 V. Turned on blower, blidge and lights, went down to 10 V.
Started thinking it was the alternator so I disconnected the negative clamp from the battery. Engine didn't slow or die but volts went up to 14. So the alternator is good, right?
Voltage meter isn't working either so I couldn't check voltage at the alternator.
Any ideas what to check next? Wire grounding out somewhere? Bad battery? It's only a year old I think. Maybe I'll put the battery back on the charger tonight and check it again tomorrow.
Just confused because volts went up after discontecting the battery.
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Replies:
Posted By: eric lavine
Date Posted: September-24-2006 at 7:46pm
hey jimbo, this may or may not be true, i was taught years ago to never pull a cable while engine is running to check the altenator because it full fields the altenator, true or not i dont know, maybe we will get some feedback on this one, but sometimes you need a fully charged battery to excite the altenator i ran into this last week on a car. the volt meter read 11 volts with the bad battery and i thought because of the voltage the altenator was bad. so i knew the battery was bad anyways and installed a new one, fired up the car and still had 11 volts. sat for a bout 20 seconds and revved the engine and guess what... the volt meter shot up to 13.5..... go from there Eric
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"the things you own will start to own you"
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Posted By: JEFF KOSTIS
Date Posted: September-24-2006 at 9:15pm
Eric, good question on the full field thing. I am not sure, as without any battery, you will get some real dirty DC to everything since a battery acts as a large capacitor. Will it affect and confuse the field to go to full output??? Good question!!
Jimbo, I would suggest a good digital voltmeter and do some checks first.
Jeff...
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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
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Posted By: jimbo
Date Posted: September-24-2006 at 9:47pm
Yeah, I've heard someting along those lines about disconnecting the battery. I wouldn't do it on my truck because I'd be scared it would fry the computer but I figured it would be ok on the boat.
I'm going to charge the battery overnight and pick up a new meter tomorrow' unless I can figure out what's wrong with the meter.
Anyway, I should see:
--13.5 V coming of the alternator
--13.5 V at the battery
--13.5 V at the solenoid
right?
What else should I check?
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Posted By: JEFF KOSTIS
Date Posted: September-24-2006 at 10:12pm
Jimbo, I agree about the computer!!!
You will find the voltage a bit higher at the alternator stud than at the battery in most cases. Best bet is to turn on everything and see what the battery voltage is, and does with all on, then off. If it maintains and doesnt drop too bad, youre ok there. Check the dash meter for accuracy as well, as maybe you might have dash feed issues.
Jeff...
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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
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Posted By: eric lavine
Date Posted: September-24-2006 at 10:19pm
a fully charged battery should read 12.69 volts, while engine running you should see 13.50volts thru out the system or more
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"the things you own will start to own you"
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Posted By: David F
Date Posted: September-25-2006 at 10:58am
I believe you risk blowing the diodes in the alternator if you disconnect it from the battery while the engine is running.
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Posted By: nuttyskier2002
Date Posted: September-28-2006 at 4:38am
Jimbo, I would take that battery to a place that sells them and have it load tested. Make sure it's completely charged first. If the battery tests good, I'd start looking at your alternator. Is all your wiring in good shape (mainly the heavy wire from the Alternator to the solenoid/battery)? Some auto parts stores have bench testers to check the condition on your alternator. But most of these don't put a load on it. Some have a diode checker instead. Just because the engine kept running with the battery disconnected doesn't prove that the alternator is good 100%. If you have blown diodes or burnt windings and the alternators output is diminished, removing the battery cable while the engine is running reduces the load on the alternator. So the voltage is going to go up. The alternator could be supplying just enough amperage to keep the engine running but not charge the battery.
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95 Malibu Echelon w/Mercruiser 350 Magnum Skier
Former boats:
88 Ski Centurion Tru Trac II
59 Chris Craft Capri (woody)
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Posted By: jimbo
Date Posted: October-04-2006 at 1:27am
I did a couple of quick voltage checks this evening. The battery read 12.6 volts. With the engine running it read 13.3 V and 13.1 v with the lights, blower and bildge on. The alternator read 14.9 v.
The dash gauge read 11 V and 10v with the accs on.
From this I conclude both the alternator and battery are in good shape and the problem must have been a poor conection. I'm going to clean the wiring harnesses, check the connections at the relay, starter, ect and run an extra ground from the battery to the dash as suggested in another post.
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Posted By: 79nautique
Date Posted: October-04-2006 at 10:42am
sounds like the right thing to do, If the extra/heavier ground doesn't help the gauge read correctly then you might need to get a new one. Did you check the leads at the back of the gauge to see what voltage was there? if you get a good reading on the multimeter at the gauge terminals then you might as well change the gauge because it's not a ground/wiring issue and it's old age on the gauge.
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http://www.correctcraftfan.com/diaries/details.asp?ID=756&sort=&pagenum=1&yrstart=1979&yrend=1979 - 79 nautique
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Posted By: jimbo
Date Posted: October-04-2006 at 8:28pm
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I tried to get the wiring harness apart but it wouldn't budge and I didn't want to force it and pull the wires loose. Can I use a couple sets of pliers and a friend to pull them apart? Am I being too gentle? Do they have shrink wrap on them or something?
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Posted By: 2fat2ski
Date Posted: October-09-2006 at 3:05pm
Rather than messing with the old wiring, I'd just run a new ground wire to the gauge. Use marine-grade wiring, "tinned" wire if you can. That way, you know the integrity of the wire is good. If you still get low readings, replace the gauge.
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Certified Correct Craft and PCM technician
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Posted By: JR_VIC
Date Posted: October-09-2006 at 7:38pm
I just experienced the same problem. I posted my fix in another post here at the bottom of the thread titled "Topic: are anybody’s gauges accurate?"
http://www.correctcraftfan.com/forum/forum_posts.asp?TID=4910&PN=1
Hope it helps...
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