Voltage Gauge and alarm intermittent

[homer12]

Have a 330 Excalibur in a 2004 SV211. Im randomly getting dips in the voltage gauge and low volt warning on the dash. I dont think there is any problems witb batteries (2) or voltage at all. It seems like a sensor, gauge or wiring issue. Any suggestion on where to start troubleshooting?

[bturner]

I'll take a shot at this since no one is chiming in. Let's start here....

Why don't you suspect the batteries?
Unless you've load tested the batteries, this is where you always start. It's amazing how many times people will state that it's not the batteries then the post ends with the problem being fixed.... by replacing the batteries. If you're going to do troubleshooting on your own always start with eliminating stupid whenever possible then moving on to the more challenging areas. Assuming a 2 or 3 year old battery is good, is well, you get the picture.

Battery cables
Probably the first place even before pulling the batteries I would be going after would be the cables. Your boat is nearly 20 years old and operates in a wet environment with months of storage. This is the perfect environment for corrasion and along with the wear/tear of connecting/disconnecting the cables at least twice a year, is a great formula for a possible voltage drop. time to closely examine the cables, not just at the battery but at the engine. REALLY look them over closely. If they're remotely damaged, don't connect well, the wiring is loose going into the connector or there is any swelling or corrosion going up into the cable, replace them. I've had friends tell me they checked their wiring only to go over to help and find garbage cables.

Grounding
This is actually part of the above but I thought I'd mention it again. Cable condition is very important but between the hot and ground, my experience has been that grounding is the most important in a boat. This is because unlike a car the ground is completely dependent on the cables. The boat is made of plastic so there is no metal to carry and form a ground other than the wiring. Bad or marginal cables/wiring, bad ground and all kinds of problems.

Battery switch
If I had a dollar (amount adjusted for inflation) for every bad battery switch I've had to replace, I could probably buy a beer (again adjusted for inflation and trying to be realistic here as I don't do this professionally). They go bad quite a bit and the ones I've seen go bad do so in 2 ways. The first would be, they basically blow apart internally. You pull the switch off the mounting to check the cables and they quite literally fall apart in your hands. These are the easy ones.

The others are the burnt posts which you can't see but sometimes you can diagnose then by wiggling the switch which triggers the issue you're having. Switches go bad all the time and on a 20 year old boat this would be high on my list of areas to check.

Key switch
I don't know your boat so I don't know if you have a key or not. If you do this is another area like the battery switch that goes bad. Look for issues when wiggling the switch or the wires connected to the switch.

Nut and boat
So again this kind of is part of the above (see a pattern here?) but the last place I go only because it's no fun. If the easy stuff isn't getting you to where you need to be then a can of electrical contact cleaner and some dielectric grease are next. At this point you're going to start at one end of the boat (I personally like starting at the engine) and you're going to examine, clean and tighten every connection from one end to the other. How deep I go with this depends on the issue I'm troubleshooting. In your case I would focus on the larger cables/connectors. I'd do the batteries first, then the engine, then move under the dash to the terminal blocks.

Wild card
One place I probably should have started is at the condition of the boat wiring. I'm not talking about all of the above but the actual design or implementation of the wiring. A lot can happen over 20 years with boat wiring and this includes owners and stereo shops doing some god awful installations. As I buy used and flip boats from time to time I've seen some real gem installations. These types of questions come to mind....

• Do you have any DIY installations in the boat, like a "custom" stereo installation or (lord help me) a fish finder?
• When looking at your wiring, can you see anything that is not marine rated or residential type materials like wiring nuts being use?
• Do you have an "tape balls" that someone has created to make connections?

Any of these types of items should be red flags and possible areas that could very well effect your issue. Even if they are not a direct problem now, now would be the time to fix any garbage installation issues.

Well that should get you started and is what I would do and in the order I would do it. But then again, this is just how I would approach this and who knows, I could be completely wrong.

[homer12]

Great set of info BTURNER and thank you!
The reason I haven't assumed it was cables and bad power connections I guess is the voltage would dance up and down - i.e. gauge would go to 9.5V to 13.8V or so. I assumed if the cabling or connections were causing problems it would stay in one place. However, electricity is funny and I could see your point here. I'll start with the big cables and power and go from there. thanks!

[homer12]

Quick update here.
1. I've pulled the battery switch selector out, pulled all wires off and cleaned and tightened back up. Looks good.
2. I cleaned the engine ground with electra clean.
3. I replaced terminal wire ends on the battery that didn't have them changed within the last couple of years by me.
4. Lastly, I changed the alternator. I upgraded to the 100A Alt kit. The kit came with a new red (positive) cable which I replaced and a new black ground cable which I didn't replace because it was too short.

The boat is now still doing the same thing, only voltage isn't going as low. It's bouncing from normal down to about 12.4 to 11.5, to 11 V mostly. Sometimes it will stay close to 14V where is should be. So, I've ordered a new black ground from the alternator to engine block and will see if that will make it better.

Any other thoughts? The battery cables in this boat don't look original. I've had the boat for 8 years and haven't changed them but they look like someone has since 2004.