Topic: Bad Voltage Regulator - What's the Potential Damage
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Forum: ContinuousWave: Small Boat Electrical
Topic: Bad Voltage Regulator - What's the Potential Damage |
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| Name | Post |
| newt |
posted 07-28-2005 07:02 AM ET (US)
Either I have a bad battery or the voltage regulator on my 1990 Johnson 150 is on the way out. Last time out in the boat my voltage guage would hit the peg at 16 volts when the engine was wound up over 3500 rpms. Several trips prior to that everything was normal, but one trip back in June I had some funny voltage reading also. So, in if I do in fact have a bad voltage regulator, what is the potential damage to the engine and electronics if I go ahead and use the boat this weekend? |
| Chuck Tribolet |
posted 07-28-2005 09:21 AM ET (US)
Or you have a bad gauge, though it's not likely because reading high is not a usual failure mode for that type of guage. It's probably not a bad battery. Batteries fail with low You could fry everything (though I suspect you would have All of this assumes that engine HAS a regulator. Some don't,
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| jimh |
posted 07-28-2005 09:40 AM ET (US)
Continued operation of your boat with the engine charging circuit forcing the battery voltage to 16-volts will likely cause: --reduced battery life from overcharging --damage to electrical devices designed for 12-volt nominal operation, including your marine electronics, pumps, and lighting devices Some modern electronic devices will shut themselves off if the voltage to which they are connected is too high. I replaced the regulator on my 1992 OMC V6 after it began to put out more than 14-volts intermittently. I believe the regulator on your engine is similar to the one used on mine. Mine was an integrated assembly which included some circuitry related to the engine tachometer and alarm/shut-down circuits. The OEM replacement was about $230. The regulator is mounted into the engine block water jacket to receive cooling. It is a bit of a chore to replace it as there are some other components which are mounted above it that have to be removed, too. The regulator assembly is a sealed unit and there are no serviceable parts inside. You have to replace the whole unit. I would retain the old one as an emergency spare, since the engine will still run with it in use. |
| Buckda |
posted 07-28-2005 10:08 AM ET (US)
Wouldn't your fuses on your electronics protect them in this case? I just replaced my voltage regulator on my 1986 Merc 150 and had the same bad (high) readings within a couple of weeks when running over 3,000 RPM. The electronics are behind two protective measures: the first is the power distribution panel/circuit breaker that is supposed to "throw" at 15 AMPS, and the second is that my electronics (GPS, VHF) are protected by the appropriate in-line fuse. Right now, I think I'm just working my batteries really hard, until I figure out just what is going on (or perhaps not going on) with the regulator. |
| phatwhaler |
posted 07-28-2005 10:25 AM ET (US)
If you are looking for an alternate source of supply for an OMC regulator look here. You might have to call Rapair and ask them who distributes their products in your area. My Merc has two regulators that are listed at $150 bucks a piece. I ended get them both for $156.00. phatwhaler out. |
| newt |
posted 07-28-2005 12:45 PM ET (US)
Thanks for the advice. I mentioned that I may have a bad battery for two reasons. First, while surfing thru Google results for "Johnson Voltage Regulator" I came across several posts on other forums where the authors indicated that a sulphated battery or bad battery connections could cause high system voltages. Second, the high voltage readings are not consistent from outing to outing and since I alternate batteries each time out, it is possible that I only have high readings with one of the two batteries. I will probably take a chance and run the boat this weekend and hopefully rule out a battery problem, then order a new regulator. |
| frostbite |
posted 07-28-2005 01:12 PM ET (US)
Leave your electronics off when you run your next voltage check, just to be cautious. Fuses protect from high current, not high voltage. |
| jimh |
posted 07-28-2005 01:19 PM ET (US)
Fuses protect against OVER-CURRENT, not against OVER-VOLTAGE. If a device acts as a resistive load, increase in voltage will cause a proportionate increase in current. Unfortunately, in most cases the fusing of a branch circuit in a boat will not be done with a fuse whose over-current rating is sensitive enough to react to a small increase in current. Fuses usually only blow quickly if the fault current is two or three times their rating. A new, strong battery will tend to hold down its terminal voltage and act as a regulator when a charging current source tries to drap the battery to higher voltages. This is the basis of operation of many small outboard motor's that have unregulated battery charging output. |
| Jerry Townsend |
posted 07-28-2005 04:29 PM ET (US)
Newt - With your charging system performing differently with each battery - your regulator and meter are probably OK and the problem is probably with a battery. Clean the contacts to that battery, check those cables and your problems may just go bye-bye. If not, you are probably looking at a new battery. Another indication of a battery problem is the high voltage - because a battery is a pretty good self regulator. ---- Jerry/Idaho |
| LHG |
posted 07-28-2005 05:52 PM ET (US)
I had the same problem a few years ago. Chances are you are going to have to replace both the battery and regulator. I had to. |
| JOHN W MAYO |
posted 07-30-2005 12:26 PM ET (US)
Buckda, The fuse protects mainly against high [current] that is in excess of the rating of the fuse; unless the voltage was very extreme I do not think they would protect the system. |
| Liteamorn |
posted 07-30-2005 05:16 PM ET (US)
Most quality electronics have a window that will read your voltage (my old Lowrance fish finder and now my Garmin gps does just that). Double check your voltage that way. The volt meter on my Montauk is almost always pinned but my electroncs read the correct 14.7. Ed |
| Freeport Alan |
posted 07-31-2005 12:42 PM ET (US)
My 1994 40 Merc 4 cylinder doesnt have a voltage regulator, came from the factory this way as did all Merc 4 cylinder 40's & 50's over the decades. You need the proper marine deep cycle battery & not a bad idea to keep the running lights on often while running { this keeps the voltage down a bit } . Also keep an eye on the water level in the battery. Granted I only have a 12 V port for my handheld & spot & running lights & horn but have had no issues from this condition Year & 1/2 60 + hours I've owned & run the boat. |
| newt |
posted 07-31-2005 06:28 PM ET (US)
Here is the latest. I started the day on battery #2. The in-dash voltage guage was pegged at 16 volts, while the fishfinder indicated 13.7 volts. I switched to battery #1 which apparently was not fully charged and the in-dash guage started at 14 volts and slowly climbed until it was pegged. The fishfinder started at 12.4 volts and evened out at 13.6. At home in the driveway with the key on and motor off, the in-dash guage read 14 volts, and the fishfinder indicated 12.5 volts. Switching batteries gave the same readings. I think I can rule out a bad battery, and I am starting to suspect the in-dash voltage guage. Is it possible to have battery voltage of 14 volts? When I get a chance, I will check battery voltage with my multimeter. |
| Chuck Tribolet |
posted 07-31-2005 11:49 PM ET (US)
Newt: I agree that it is smelling like the guage. I'd check it with at least two multimeters. Borrow a couple from your buds and neighbors.
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| kaige |
posted 10-25-2009 01:09 PM ET (US)
A battery under ideal conditions will only give you 2.2 volts per cell thus giveing you 13.2 volts and the normal is about 12.6 volts |
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