High voltage issue causing alarms and equipment malfuncions

[subcrx]

I have a 87 Bayliner with and OMC 5.7 and Merc outdrive conversion. I'm sure this has been asked before but I can't find a threat similar enough to my problem.. The problem happens when running on 1 battery but more when I switch the perko to ALL. With the engine running and switch on battery 1 the voltage is about 14.7 and rises on higher RPM. At that voltage everything works except my AC inverter with will not function and throws an overvoltage fault. The only way I can use the inverter is with the engine off and battery on 1. If I switch to ALL with the engine running the voltage jumps well over 16 and my GPS throws a High Voltage alarm and shuts itself off and so does my VHF radio. Is there something I need to install to keep the voltage under control?

 

[subcrx]

Charging issue. Causing equipment failure.

I have a 87 Bayliner with and OMC 5.7 and Merc outdrive conversion. I'm sure this has been asked before but I can't find a threat similar enough to my problem.. The problem happens when running on 1 battery but more when I switch the perko to ALL. With the engine running and switch on battery 1 the voltage is about 14.7 and rises on higher RPM. At that voltage everything works except my AC inverter with will not function and throws an overvoltage fault. The only way I can use the inverter is with the engine off and battery on 1. If I switch to ALL with the engine running the voltage jumps well over 16 and my GPS throws a High Voltage alarm and shuts itself off and so does my VHF radio. Is there something I need to install to keep the voltage under control?

 

[gm280]

Before throwing parts at this problem, I would start at the battery(s) and clean every terminal including grounds to bright shiny metal. And follow on with every type connection both boat and engine. So many times corrosion is the problem. Especially when it once all worked good and just started doing this. And merely looking at the terminals isn't the way to go. Corrosion gets between terminal contacts and while they look great, the problem lies out of sight. If that doesn't fix your problem, you can always get a regulator for the electronic equipment to keep the voltage from going too high. However, that is not how I would solve this issue. There is a problem and a band-aid isn't the way to fix it. JMHO

 

[subcrx]

It actually has had high voltage for quite a long time. Recently I have been upgrading all my electronics and using the boat more often. All connections are good. The alternator is original and looks very old. But that's a thought.

 

[kenny nunez]

How old is the #2 battery? Will the engine turn over as fast on #2 as #1?

 

[subcrx]

Both batteries are about a year old, bought them at the same time.

 

[kenny nunez]

Does each battery spin the engine about the same? I have had “new” batteries that were the problem. Have you ever tried adding a separate ground wire from the engine block to the instrument panel as a ground for the electronics?
A weak ground will always cause a voltage spike. Is the negative side of the batteries each have a separate lead going to the engine block? They should.

 

[Lou C]

Also:
i learned this from ARCO marine when buying a new alternator...some OMCs have high resistance in the wiring for the alt sense circuit. This leads to battery overcharging and short battery life. ARCO had nstructions in the box for the new alt that advised checking voltage at the batts not the dash gauge. I checked and had 15.5 V at the batts. I then re wired it the way they advised and that dropped it to 14.2v. What I had to do was disconnect the S wire at the alt and tape it up, then make up a jumper from the alt B+ terminal and the S terminal. That cured the over charging issue. Also had a low voltage to the ignition system and dash gauges, this I fixed by running a supplemental power lead from the battery switch common terminal to the positive terminal on the fuse box. This solved the low voltage to the ignition system and gauges. In fact what led me to start checking was when I found I had 15.5v at the batts yet I saw barely 13v at the dash gauge. Thought it was just old gauges old wiring but put a digital meter in the voltmeter terminals and it was dead on accurate. I had batt volts at the pos terminal on the fuse box but it dropped to 11v as soon as I turned on the ignition. I tried running a supplementary ground first, that did not change any thing; so tried this on the positive side and it worked. Wired in an 8 gauge wire from the batt switch common (fused) to the fuse box positive terminal. Now have normal batt charging voltage and normal gauge reading.

 

[Lou C]

Here are pix of my voltage readings before and after adding a supplemental feed to the fuse box....
top is after bottom is before....

 

[sam am I]

Sounds like you alt (load reg circuit) is toast. Test/replace it.........

 

[subcrx]

I ordered a new voltage regulator. Only 5 bucks. I'm going to try it out this weekend. Each battery is grounded separately to the engine block. However all my electronics at the helm go to one spot. I don't see an easy way around that.

 

[subcrx]

This turned out to be high resistance in the battery sense wire going from the alternator to the coil. I ran a new wire from the alternator to the perko main post now charging at 14.3 max.

 

[440roadrunner]

This is a common problem on old Mopars and on them is caused (partly) because the power/ IGN wire for the regulator is also the "sense" wire. Generally, VR's MUST see same potential at the case as battery NEG and MUST see no voltage drop from the battery--through the harness path--to the VR whatever is used as "sensing."

One way to check this is to "rig" whatever you need for an extension wire--need not be larger than 18--to reach from battery to your meter at the VR. With the key "in run" and engine stopped, check between battery + and the sensing lead or the IGN/ power lead at the VR if that is what they use. ANY measured drop read there will ADD to the VR setpoint. So if the VR is correct at nominal 14, a 1/2V drop measured there will bring charging V up to 14.5

Also check the ground. Run engine if possible at low/ medium cruise RPM and measure from battery NEG to VR case/ ground point. Again you should read very little, the lower the better, and zero is perfect

Sources of drop are "anywhere in the harness" connectors and terminals, or the ign sw and switch connector.

A dodgy (sulfated etc) battery can also cause this issue.