Electrical problem in OMC 5.8

[jmarine225]

And the hits keep on coming. I have a 93 Four Winns Vista 245 and have a two battery system in it with new batteries this season. I leave my boat on battery 1 every weekend, come back and its down to like 7 volts or something. I'll switch to all batteries, start the boat up and let it charge. The battery will go up to around 12 volts but dies very quickly when the boat is not running and I'm using the stereo. Also when the boat is running on the Volt gauge its reading somewhere around 10-11. Does anyone know if this is a problem with the battery possibly or is my alternator dying or any other suggestion. One key note, our marina DOES NOT have shore power to charge the batteries.

 

[Bondo]

Re: Electrical problem in OMC 5.8

Also when the boat is running on the Volt gauge its reading somewhere around 10-11.

Ayuh,... That should be 13.5/ 14....Sounds like the Alternator....

 

[Don S]

Re: Electrical problem in OMC 5.8

Also when the boat is running on the Volt gauge its reading somewhere around 10-11

Either your alternator is not charging or you have some wiring problems in your system.
You should be seeing 14 to 14.5 volts when the engine is running around 1500 rpm. 10 to 11 indicates a dead battery and nothing is happening.
As Bubba mentioned, have the batteries load tested first. A shorted battery can cause the same thing.

 

[jmarine225]

Re: Electrical problem in OMC 5.8

thanks for your help with this matter. So I can kill two birds with one stone after following the advice, I tried locating in the tech info and manuals which alternator I may need for my engine with no results. I have a 1993 Ford Cobra 5.8L 351 with 260 HP. Is there anywhere I can find the alternator info or do I have to pull it off and try to find a number? Also they system is definitely charging the battery but not to much because it doesn't last too long after being charged so I figured my alternator is weak.

 

[bruceb58]

Re: Electrical problem in OMC 5.8

Also they system is definitely charging the battery but not to much because it doesn't last too long after being charged so I figured my alternator is weak.

How did you make this determination? Did you use a hand held multimeter and check the voltage while running?

 

[jmarine225]

Re: Electrical problem in OMC 5.8

on the electrical panel inside the cabin there is a battery tester. I put the switch on battery and hit the tester and it gives me the voltage. After letting the boat run for a bit I can get it up to about 12. I shut the boat off and it doesn't last too long with my stereo on....maybe 15 minutes then I'll check the battery tester again and it will be down to about 6-7 volts.

 

[proxyx]

Re: Electrical problem in OMC 5.8

To protect battery (you say the're new) charge them properly with a charger. Don S is right, anything less then 14V (14.5 is normal) with engine running at 1500 (this is the point regulator kicks in) means alternator not charging, just pretending. 12V from alternator will NEVER charge the battery. Have it rebuilt. If this is max you're getting then your meter shows your battery voltage with alternator contributing ZERO. Slipping v-belt can cause this as well, check it. 7 Volts is way too low for a battery to survive, suggests oxidized terminals/bad connection on battery/alternator too.
Btw. loud stereo can kill your battery really fast... careful.

 

[bruceb58]

Re: Electrical problem in OMC 5.8

on the electrical panel inside the cabin there is a battery tester. I put the switch on battery and hit the tester and it gives me the voltage. After letting the boat run for a bit I can get it up to about 12. I shut the boat off and it doesn't last too long with my stereo on....maybe 15 minutes then I'll check the battery tester again and it will be down to about 6-7 volts.

It is very possible you have two problems...battery and alternator...but you have to check the voltage while the engine is running to determine if the alternator is charging.

 

[jmarine225]

Re: Electrical problem in OMC 5.8

Well you made a good point here. I would start the boat up and let it idle, which it idles under 1000 rpm. So I guess you're saying then the battery will not be charged by the alternator at an idle. I'll drive the boat for a few minutes, maybe 15 or so before I hit the cove and shut it down. When I get the rpms up though the gauge does go up and the battery does charge but it will not hold the charge for long when I shut the boat down and turn the stereo on. The stereo is a 25W x 4 with no special amps or anything but it seems the CD player kills the battery. Any idea how long it should take to charge the battery up to 12 volts and how long it should last?

 

[rbh]

Re: Electrical problem in OMC 5.8

just a couple of thoughts
first thing which has been mentioned, charge your batteries good. It takes more than half a hour running your motor above idle to charge your batteries.
make sure all connections (wires and posts) are "clean and tight", you will not get a very good charge if they are not.
when you run you boat, run it with the battery switch in the dual battery position
make sure the charge rate is above 13.5vdc, but not over the 14.5 vdc+/-.
dont leave the battery switch on unless you are using the boat, if you billage pump has a float switch, hard wire it to the battery, as that is the only thing that should work when your not around (hope you dont have lots of leaks, or it rains alot)
my take on it
rob

 

[jmarine225]

Re: Electrical problem in OMC 5.8

I've been leaving my battery on battery 1 when I leave the boat for approximately 1 week. I guess I could turn it off though since my bilge pumps are wired to the battery, just thought it was safer to do it that way. Another added possibility I don't know much of---while running the boat on two occasions I asked someone to switch the battery to battery 1 to charge it and the turned it to off, shutting down the engine. What does this do? Also a half hour above idle to charge the battery? I never run it that long. I leave the slip, head to the cove and party on.

 

[jmarine225]

Re: Electrical problem in OMC 5.8

I don't shift at 1000 rpm. I said under 1000. My engine says idle rpm is 800 so it's somewhere in that range if not lower. Sorry I wasn't so specific on that but I thought that was irrelevant to the problem I'm having with the electrical system.

 

[rbh]

Re: Electrical problem in OMC 5.8

a battery has only so much power in it, so if your going to party hardy and dont want to worry about power usage, let some one else provide the tunes for a while. Other wise you will have to set yourself up with a charge routine.
45 min music/half hour charging +-
you will figure it out eventually
and if you dont have big (group 27) batteries you might want to look into one
rob

 

[bruceb58]

Re: Electrical problem in OMC 5.8

Another added possibility I don't know much of---while running the boat on two occasions I asked someone to switch the battery to battery 1 to charge it and the turned it to off, shutting down the engine. What does this do?

Well, that incident could have fried your alternator right there if it wasn't already.

Do this...beg borrow or steal a handheld meter. put the rpm at 2000 rpm and measure the voltage and report back.

Also, an alternator is going to put out around 60 amps maximum. Your battery is probably a 70 Amp Hour battery give or take. Assuming the the charge tapers from 60A down to 0 when fully charged, it would take over 2 1/2 hours if running at cruise RPM to charge one of your batteries.

If you are running off of your batteries a lot and not running the engine enough to fully charge the batteries, you need to have a battery charger on it when not in use. A battery that is stored in a non charged condition is going to fail...FAST.

If your battery that is being discharged is a deep discharge battery. Do not run it down below 12.0V. This is the half discharge point of a battery. If the battery you are using is a standard start battery, you don't want to be using it at all for any significant loads when the boat is not running.

You need to get something that allows both batteries to charge even though the switch selects one battery or the other. Do some research on ACRs. You really need to install one. I like this one:

http://bluesea.com/category/2/productline/overview/387

 

[jmarine225]

Re: Electrical problem in OMC 5.8

My mistake on this. I have a selector switch where I could use/charge one or both batteries. As far as the using the meter to test it, what do I place the meter on to test the voltage since I have a meter? The no shore power I believe is killing me here since I don't drive the boat too much but on a weekend we'll sit on it for about 5-6 hours at a time. The batteries are Everstart Marine batteries from Walmart. I don't run the boat near 2-2 1/2 hours at any time. My 2 battery is good though. I'll pull the first also and put it on a charger.

 

[bruceb58]

Re: Electrical problem in OMC 5.8

Put the meter across the posts of the battery that is selected by your switch.

 

[jmarine225]

Re: Electrical problem in OMC 5.8

Ok. How do I test the alternator?

 

[bruceb58]

Re: Electrical problem in OMC 5.8

This IS how you are testing the alternator!!!!!!!!!

Measure the voltage with the engine running at 2000RPM and let us know what you have. 13.5V to 14V means you alternator is working!!!!

 

[proxyx]

Re: Electrical problem in OMC 5.8

...
Also, an alternator is going to put out around 60 amps maximum. Your battery is probably a 70 Amp Hour battery give or take. Assuming the the charge tapers from 60A down to 0 when fully charged, it would take over 2 1/2 hours if running at cruise RPM to charge one of your batteries.
...

That's the simple fact.

If you have a selector set on 2 batt. then the effect of your 20 min. trip is close to zero. Basically you're running all the time on the batteries and not recharging them at all. The fact they recover to 12V is normal but they are drained anyway. Charge them fully. For short trips only you need to do it regularly to maintain them correctly (same with the car).
How to measure? Your Volt gauge should jump to 14V when over 1500rpm. This is what it's for. If not alternator/belt/contacts need checking.

 

[jmarine225]

Re: Electrical problem in OMC 5.8

Thanks for clarifying that. When I run the engine the voltage gauge definitely goes up on the dashboard. I have a battery tester on my electrical panel also and that goes up over 12volts with the engine running. I'll have to run it hard this weekend and see what the voltage gauge on the dash gets up to. The batteries definitely charge but don't hold the charge long so I'm not sure if the battery is shot or it's not receiving an adequate charge. I'll report back after I charge the battery up and run the boat.