Voltage drop below 14

CAPTAINJEH

CAPTAINJEH

Member
Nov 1, 2007
117
Chain o lakes, IL / Lake MI / Lake Geneva, WI
Boat Info
1998 230 Bow Rider
Engines
7.4 mpi B1
if when running the engine at idle and I turn the blower on the voltage goes down from 14 to about ~13 or little less (if I remember correctly). I've had this boat for 5 years and still using the batteries that came with it so not sure how old they are, no date on them. Is that a sign they are at the end of their life or an alternator problem? i don't have a way to test alternator at the moment but wondering what you think? Oh and they are both starting batteries not dual purpose.
Thanks, Jason
 
Generally speaking, if you get 5 years out of a battery you're doing well. Cranking batteries are different than deep cycle batteries. Using a cranking battery to power the accessories on your boat will in fact decrease the life of the starting battery. I'd still want to test the batteries if they were mine but if for some reason i couldn't test them I'd be happy with my 5 years.

When replacing the batteries it might be beneficial to purchase a deep cycle battery and a cranking battery. Only use the cranking battery to start the motor and the deep cycle battery when the engine is off to run your accessories.
 
Thanks for the info. With my boat we only run the stereo at anchor a little bit and that's about it nothing else to run and use power so I never thought about a deep cycle. dual purpose had crossed my mind though. Is it true you shouldn't mix deep and starting and have the switch on both when running the motor?
 
I would follow 420's advice.
In addition, you could use a volt meter to verify the accuracy of your volt meter. Its probably not the issue though.

Also, are all other accessories off and switching the blower fan on immediately results in the voltage drop? Does increasing the RPMs bring the reading back up?
 
CAPTAINJEH said:
Thanks for the info. With my boat we only run the stereo at anchor a little bit and that's about it nothing else to run and use power so I never thought about a deep cycle. dual purpose had crossed my mind though. Is it true you shouldn't mix deep and starting and have the switch on both when running the motor?
Click to expand...

I have never read where you should not run the engine while the switch is in the both position if you have a mixed (deep cycle & cranking) set of batteries. If others chime in stating otherwise, we'll learn something. Let us know how your battery test goes and which batteries you decide to go with.

As a side note, I have read many times that you should never change position of the battery switch while the engine is running. Just an FYI.
 
At idle speed an alternator hardly has much output. Once it crosses the minimum RPM threshold it begins to produce current. So I am not surprised by what you are seeing. That said, having your batteries load tested would help. Does it behave the same when running in the 'both' position?

With the small load your boat has, sticking with good quality starting batteries is fine. If you plan to run in the 'both' position often, they should be the same size and vintage.
 
mwph said:
As a side note, I have read many times that you should never change position of the battery switch while the engine is running. Just an FYI.
Click to expand...

not sure that is correct....I think the caution is to never turn the switch to 'Off' while the engines are running....I believe it is OK to change the switch between the "1" "2" "Both" settings as wanted.....this assumes the switch makes the connection with the new setting before it breaks the connection with the previous setting....

I could be wrong....I am sure someone will correct me if so....

cliff
 
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Not sure where I heard the mixing battery thing is bad so it could be one of those old wives tail, can't say for sure. Same goes for changing the battery switch while running. Not sure how to find out the truth of those two things.

But anyway this whole thing came about because it never ever did that before at idle speed with the blower on. That's what leads me to believe something is not right anymore. I found Exide 1,000CCA starting batteries for $90 at Menards so I think I'll buy those since the current batteries are at least 5 years old and look even older than that and two different brands. I'll start fresh and let you know how it turns out.
 
Been watching this one, I have the same setup in my boat. Here is my input:

1. Changing the battery switch with the engine running is fine as long as you don't switch both batteries "Off". You can swtich between 1, 2 and Both without causing a problem. Switching to Off is the same as disconnecting the battery with the engine running, this can damage the alternator. Running with the battery switch on Both will charge both batteries, but the weaker one will bring the other one down- I usually keep on 1 or 2, not both.

2. In a boat your size and the small electric needs you have, there is no reason to have a special house battery - if you start running things past the stereo you might consider a different setup. I have two marine starting batteries that I alternate between each time I use the boat. When putting the boat away I just swtich to the other battery so next time out I am ready to go.

3. As far as the voltage meter dropping when you run the blower, I see that as somewhat normal. Mine drops slightly when I turn on the blower, especially at idle.

4. I think you have two things going on here: 1. Your at idle and the blower is a pretty big electric draw. 2. You probably have one maybe two week batteries, so a larger portion of the alternator output is going to charge the batteries, so when you put an electric load on (turning on the blower) you see a larger than normal drop in the voltage output.

5. The alternator is going to put out a little less at idle versus higher rpm. But it should be putting out between 13.5 - 14.5 volts. Put a volt meter on the alternator to verify the voltage.

6. Put a volt meter on the batteries with the engine off and after they have sat overnight - Generally speaking (battery charts vary some) a fully charged 12v battery should ready 12.6v or more, a discharged battery is going to be around 11.70v and a severely discharged battery < 11.5v. The true test is to take it somewhere and have them test it, but honestly on a 5yr old battery by the time you do that, just buy a new one, it's served it's time. FYI, 5yrs is about what I got out of mine (Interstate Group 24 625CCA)
 
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Another possible issue/possible cause is dirty/loose connections or corrosion that has wicked it's way up inside the sheathing.

The battery switching thing while the engine is running... There's some truth to both sides of the story. Whether you can switch between 1-2-Both, or not, depends on the type of switch. It needs to be a "make-before-break" type switch. In other words, as you turn the switch, the electrical connection to the next selection is made before the previous selection is broken. Some switches are NOT made this way - I believe most are nowadays, but am not sure on that. The "standard issue" switch from Sea Ray is this way, though. If you're not sure, copy down the model number of the switch and check it out with the manufacturer (Guest, Perko, etc).
 
Agree with Dennis it's easy to check if your switch is a no break or not with engine off & battery switch on 1,2 or both have someone hold your horn switch down while you slowly change to the next on position if the horn stops blowing while changing positions it's not a make before break switch. If not certain contact manufacturer to verify. A Sea Ray dealer showed me that trick on an older Bayliner that the owner killed an alternator changing positions while running.

I'm going on 6 years with Interstate wet cell batteries 1 starting 1 deep cycle just load tested them there like brand new check those connections.

My boat will fluctuate from 12.8 to 14.4 depending on what comes on or off like the fridge while running at no wake speed.
 
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Bob & Sue said:
to check if your switch is a no break or not with engine off & battery switch on 1,2 or both have someone hold your horn switch down
Click to expand...

Now, why didn't I ever think of that! Good idea!
 
CAPTAINJEH said:
if when running the engine at idle and I turn the blower on the voltage goes down from 14 to about ~13 or little less (if I remember correctly). I've had this boat for 5 years and still using the batteries that came with it so not sure how old they are, no date on them. Is that a sign they are at the end of their life or an alternator problem? i don't have a way to test alternator at the moment but wondering what you think? Oh and they are both starting batteries not dual purpose.
Thanks, Jason
Click to expand...
Is this a digital or analog gauge that you are reading this drop on? If so, get a digital volt meter for testing and start at the back of the gauge and move up stream to the battery if there is indeed a 1+ volt drop at the helm. You may find the issue is possible the blower itself, or a corroded helm supply B+ or B-.
 
New batteries went in last night and the voltage drop when blower is turned on is hardly anything. Looks like the old batteries were at the end of their life. Thanks for all the help. Launch is tomorrow so let the fun begin!!!!
Jason
 
You'll be chasing the answer to your questions all season long and never really be comfortable with any answers, no matter what you do/test, because you're dealing with old batteries. 5++ years on them? First thing I'd do is replace them. Diagnosing alternator and charging issues is a pain when the real problem is the batteries themselves. Every time that voltmeter swings you'll be left with a question. My .02
 
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