How to trace down this problem.

[LAC_STS]

I barely ever run at night but the two times recently I have run at night I have noticed this problem.

Everything I turn on electrically makes my V gauge go down noticeably. If I turn the NAV lights, and guauge lights on my V gauge goes from 14-15 to 12.

If I use my trim then it drops to probably 8. (Even with nothing electrical my trim always makes my V gauge drop. Usually its from 14-15 to 12 or so.)

But what I noticed the other night is that I have a brand new spot light, and with the spot light off if I plug it in the CD player/radio will cut off then turn back on and the NAV lights will flash.

It doesnt do this when I turn the spot light on, just when I plug it in.

I have two batts hooked up. One is new in march and is a regular wet battery and the other is new in August and is a yellow top Optima.

I tried switching between thenm and using the both setting and it wtill does the same thing.



What could do this and how do I chase it down?



Thanks

 

[Bifflefan]

Re: How to trace down this problem.

The alt or regulator may be at fault.
Also you may have some connection problems.
Id remove the alt and have it tested and also check all the connections every where for loose or corrosion or both.

 

[bruceb58]

Re: How to trace down this problem.

I can't explain what is happening when you plug in the spot light without it even being on but your voltage drop is caused by a resistive connection. At your starter, you typically have the cable coming from the battery and another smaller cable that feeds all your other electrical. I would start with that smaller cable and make sure the connector is clean and not corroded at the starter. May need to take it off and sand it down to bare metal.

Not likely your alternator.

 

[RickJ6956]

Re: How to trace down this problem.

A voltage drop of a volt or two is typical to read at the gauges when you turn on a blower, pump, or multiple lights.

The spotlight is another story, especially if it's off.

 

[bruceb58]

Re: How to trace down this problem.

A voltage drop of a volt or two is typical to read at the gauges when you turn on a blower, pump, or multiple lights.

I disagree. Should not be getting that kind of drop ever.

 

[LAC_STS]

Re: How to trace down this problem.

I didnt have much time yes but I went to the boat and looked at some stuff.

The connections on the starter and starter sol look good and clean.

The second battery I installed. When I bought the boat there was a spot and cables for the battery but no second battery. So the second battery has nothing but the main cables hooked to it.

BUT, the main (1st) battery has the main cables and then like 4 or 5 extra's on both the + and the -. I imagine its stuff the PO had hooked up. I know that some of the wiring has to be wrong because the CD player is hooked to the NAV lights switch.

So shouldnt there only be the main cables hooked up to the batt? Along with the bilge and float switch? Everything else should be wired to the panel with the breakers and switches?

If my wires on my starter and starter sol are good and clean where do I check next? I was thinking it was the alt at first. When I checked the V with it running at 1K RPM it is 15.5 V. I know the alt is old too. Just made sense to me that it doesnt handle the load well but I may be mistaken. Ill have to get it tested.

 

[bruceb58]

Re: How to trace down this problem.

Check the main engine harness connector although the fact that you get a voltage drop when you operate your trim means its probably just after the starter connection. Get a voltmeter and measure the voltage drop between the positive post of the battery and the positive bus at your fuse panel. Do the same between the battery post and the power to the trim. You need to isolate what section of the wiring is where the voltage drop is.

Like I said, its not your alternator.

 

[LAC_STS]

Re: How to trace down this problem.

Check the main engine harness connector although the fact that you get a voltage drop when you operate your trim means its probably just after the starter connection. Get a voltmeter and measure the voltage drop between the positive post of the battery and the positive bus at your fuse panel. Do the same between the battery post and the power to the trim. You need to isolate what section of the wiring is where the voltage drop is.

Like I said, its not your alternator.

K thanks Bruce! I will do that. hopefully tom or Monday when I can make it down there. then I will report back.


Thanks again

 

[RickJ6956]

Re: How to trace down this problem.

I disagree. Should not be getting that kind of drop ever.

It happened on all three of my previous boats and it happens when I run the fridge on DC in my present boat without the engines on.

Yesterday I walked around the marina and checked with 9 boat owners. With the engine(s) off and no electrical or electronics devices on, their gauges averaged about 13.5 volts. When the blower, pump, multiple lights or other high-draw devices were turned on the reading dropped to an average of 12.

LAC-STS seems to have an issue, though, because his post indicates that his engine is running when the drop happens. If my engines are running the volts meter never drops.

 

[LAC_STS]

Re: How to trace down this problem.

Confused. so what do you mean rick? Yea it does happen with engines running.

I thought, although could be wrong that the alt would keep putting out more power to keep up with everything. Thats why I was referring to the alt.

But Im gonna check what bruce said when I make it to the boat and report back.

 

[windsors03cobra]

Re: How to trace down this problem.

I would say the way most boats are wired that volt gauge is more of indicator of "helm voltage" rather than "battery voltage" and thats ok but it sounds like you may have some connection problems with the wire that feeds your helm or maybe it is a bit undersized and you are really stressing it out.

Likely a big wire runs from your battery and feeds your IGN SW, trim controls, blower, bilge pump, lighting and other accessories up there and your voltage gauges reads that voltage and not the batteries. When you turn that blower on it is a major draw and over that long run of wire between your battery and helm there is some voltage drop, that is likely what you are seeing.
And of course as stuff ages and resistance builds up things get worse and sometimes do weird things like what you are experiencing.
The alternator keeps up fine (it always starts and does not run out of battery power after hours of running right ?) likely your voltage @ the battery is probably mid 13's

 

[LAC_STS]

Re: How to trace down this problem.

The alternator keeps up fine (it always starts and does not run out of battery power after hours of running right ?) likely your voltage @ the battery is probably mid 13's

I have only been out at night twice since I got this boat. Just about a 2 hours run and yes the engine never dies and it will start if turned off.

 

[bruceb58]

Re: How to trace down this problem.

Yesterday I walked around the marina and checked with 9 boat owners. With the engine(s) off and no electrical or electronics devices on, their gauges averaged about 13.5 volts. When the blower, pump, multiple lights or other high-draw devices were turned on the reading dropped to an average of 12.

Since a fully charged battery measures 12.6V and no more than that, something is very wrong with your numbers.

Never trust a dash mounted gauge. Use a multimeter and measure the voltage.

 

[LAC_STS]

Re: How to trace down this problem.

Ok so I went to the boat today but it was raining off and on. I did take some measurements though. I let the engine fully warm up and then with engine running I took these measurements.


At the battery 14.95V
Alt. little wire 13.75
Alt. bigger orange wire 15.55
V gauge 14.1
Trim gauge 14.4
Hour gauge 14.5
BOTH hot wire on IGN key 13


I am not sure if someone before me rewired the gauges and breaker panel before but in both manuals I have looked at the diagrams and I have way more wires than it shows in the manuals. This is because ALL of the gauges are "chained" together. Like on the tach, instead of having one + and one - there are a couple + and a couple -. basically ALL of the - and + and gauge light wires are run from one gauge to another to another and so on.

I didn't measure the V at the trim when I push the trim button or the V at the trim switch but I will hopefully tom.

When you say to measure the positive bus at your fuse panel, what is this? I have a circuit breaker panel below my gauges with about 10 circuit breakers. I dont think I have a fuse panel. I do have 2 inline 50A fuses on top of the engine. I know one of them goes to the trim pump. The other goes into the harness I think.

So do these readings tell you guys anything? What else should I measure? Does me getting almost 2V less from batt to IGN key switch mean anything? What about almost 1V drop from batt to V gauge?


Thanks again

 

[bruceb58]

Re: How to trace down this problem.

At your fuse panel...or circuit breaker panel, there will be a large wire feeding it that basically comes back from your engine harness.

You need to measure the voltage at this point with no accessories on and with many accessories(lights etc on).

You should also make 2 other measurements but this will require a long wire with alligator clips at both ends. With all your accessories on at the dash, measure the voltage between the positive terminal of the battery and the positive fee at your fuse panel. The other measurement should be between the ground of the battery and the ground feed of the ground buss that is also next to your fuse panel. These two measurements(should be very low..0.5V max) are the voltage drops between the battery and the helm mounted fuse panel.

 

[bruceb58]

Re: How to trace down this problem.

Sent you a PM.