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Low voltage

adam_g

adam_g

Contributing Member
1995 Sea Ray 7.4 L Bravo 1
I changed out my dual batteries this year only because the other batteries were 5 years old.
When I start the boat I notice that I only have about 10 V wihile idling and pulling away from the dock.
Once I get the RPMs up over about 1500 the voltage jumps to 14V and it does not go back down, even at idle. I have checked the dash voltmeter with an accurate voltmeter - checks OK. I am beginning to suspect a faulty voltage regulator or maybe a bad diode in the alternator. Does anyone have any ideas?
 
What is the voltage reading after you shut down for awhile and then start and let it idle, still 10V?
Bert
 
adam_g said:
1995 Sea Ray 7.4 L Bravo 1
I changed out my dual batteries this year only because the other batteries were 5 years old.
When I start the boat I notice that I only have about 10 V wihile idling and pulling away from the dock.
Once I get the RPMs up over about 1500 the voltage jumps to 14V and it does not go back down, even at idle. I have checked the dash voltmeter with an accurate voltmeter - checks OK. I am beginning to suspect a faulty voltage regulator or maybe a bad diode in the alternator. Does anyone have any ideas?
Click to expand...

Ayuh,... Sounds pretty Normal to me....
 
guyjg said:
Take it to an alternator shop and get it refurbished.
Click to expand...

Might it be prudent to determine if the alternator is the source of the problem if indeed there is a problem?
Why not replace the entire electrical system just to make sure?
How about covering all of the bases with an entire new engine?
A new boat would surely resolve the issue.

I am not of the Obama school of throwing money at problems I don't understand in the hopes that they will go away......especially when it is my money.
 
Might it be prudent to determine if the alternator is the source of the problem if indeed there is a problem?
Click to expand...
I understood that the 10 volt issue just occurred. If the alternator tests ok at the repair shop you are only out your time and a small test fee or maybe nothing but your labor. If it was mine I would have the bearings relubed while there if it has never been done since it is a 95 model. Refurbish means to repair/service as needed. Most people do nothing to their alternator until it smokes or quits charging. It is a serviceable part; wear parts are bearings and brushes.


You came to this site with an issue percieved by you to be a problem and three members responded with good advice. You are welcome Mr. SA.
 
It is not uncommon for a altenator to do this, Not normal but not uncommon.

The exictation curciut needs a certian voltage and rpms to do it job.

Check the terminal at the altenator make sure it is clean and tight both + and -.

Mine did it and last year after 25 years my alt died while on the water...Also having dual bateries can create some voltage issues.......Mine was running two for many years......so many contributing factors it is hard to point to one.

corroded connections, high resistance due to this, wires getting old, loose alt belt, worn alt belt,

as you said just keep an eye on it but be prepared for a failure.

Also whe starting a engine it is best to run it at at least 1500 - 2000 rpms for the first 30 seconds or so........
 
guyjg said:
I understood that the 10 volt issue just occurred. If the alternator tests ok at the repair shop you are only out your time and a small test fee or maybe nothing but your labor. If it was mine I would have the bearings relubed while there if it has never been done since it is a 95 model. Refurbish means to repair/service as needed. Most people do nothing to their alternator until it smokes or quits charging. It is a serviceable part; wear parts are bearings and brushes.


You came to this site with an issue percieved by you to be a problem and three members responded with good advice. You are welcome Mr. SA.
Click to expand...

Maybe two members responded with good advice.
I read "refurbish alternator" not "test alternator"
refurbish [riːˈfɜːbɪʃ] vb (tr) to make neat, clean, or complete, as by renovating, re-equipping, or restoring refurbishing , refurbishment n
I don't see test



Also the Delco alternator bearings that I have seen have been sealed.
 
You asked us for ideas and I provided one assuming you had limited knowledge. It was a simple one that would have a professional test and refurbish it for you and give you peace of mind on the water for a nominal fee. Yet you respond w/a negative attitude when asking for ideas. There are a few among us that would tear you a new one if you commented that way to them...I am more forgiving to those w/their head up their derriere. Keep your money and good luck w/the alternator.
 
guyjg said:
You asked us for ideas and I provided one assuming you had limited knowledge. It was a simple one that would have a professional test and refurbish it for you and give you peace of mind on the water for a nominal fee. Yet you respond w/a negative attitude when asking for ideas. There are a few among us that would tear you a new one if you commented that way to them...I am more forgiving to those w/their head up their derriere. Keep your money and good luck w/the alternator.
Click to expand...

Ayuh,... Agreed,.... Unnecessary attitude,... Good luck in the future...
 
guyjg said:
You asked us for ideas and I provided one assuming you had limited knowledge. It was a simple one that would have a professional test and refurbish it for you and give you peace of mind on the water for a nominal fee. Yet you respond w/a negative attitude when asking for ideas. There are a few among us that would tear you a new one if you commented that way to them...I am more forgiving to those w/their head up their derriere. Keep your money and good luck w/the alternator.
Click to expand...


I am one of them.


You will not always get the opinion you want to hear.
 
well, I will give you my opinion...with your boat... This is common for a lot of delco alternators. It has to do with the voltage regulator. Sometimes the revs need to come up before the voltage regulator will cut your alternator in and start charging. I have seen, and tested , many delco alternators that need to be revved past 1200 RPM before that alternator gets energized. As for your attitude..... I have used this forum several times in the past and these guys are great. They have helped me through some frustrating problems and they are a great wealth of knowledge..... TRY paying a little RESPECT to the people that you ASK for help!!! If you cant do that, then don't ask. good luck with your boat and safe boating

Glenn
 
This is not an issue at all, when you start the boat, the voltage regulator maintains it at 10V but as soon as you give it some rpm, the charging circuit provides way more voltage and the regulator then maintains it at 14V to charge the batteries. This 14V is then kept constant by the regulator to charge the battery. I don’t think you’d be happy if the voltage fluctuates with your RPM, which will be a problem then.
 
Hey guys, I think he has a single wire alternator vs. a three wire setup. I think you guys are right about the 1200-1500 rpms for it to excite with the 1 wire. I have the three wire and have heard good and bad about it. What's your verdict for the three wire setup? Does it not help when trolling or say using alot of electronics at low rpms? Pros and Cons? Thanks, Tom
 
1973 Browning Marine said:
Hey guys, I think he has a single wire alternator vs. a three wire setup. I think you guys are right about the 1200-1500 rpms for it to excite with the 1 wire. I have the three wire and have heard good and bad about it. What's your verdict for the three wire setup? Does it not help when trolling or say using alot of electronics at low rpms? Pros and Cons? Thanks, Tom
Click to expand...

Ayuh,.... It don't Matter, once it begins to charge,.... it Charges....
 
This thread is from September 2012..... I'm sure hoping that the OP has resolved the problem by now. :D

But on topic..... I too would suspect a Delco 10si single wire alternator (self exciting), in which the kicking up the RPM in order to excite the unit is very normal.
Once excited, these remain excited until shut down again.


.
 
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