High Voltage

[Bill3434]

I have a 1977, 70hp Johnson motor up until my last outing all my accessories and voltage meter indicated 14.7 max. My last outing I was getting close to 17 volts. I'm thinking its the rectifier but I can't find what the reading should be on a DVM. I'm only getting readings in one direction though.

 

[Fed]

Re: High Voltage

Sounds pretty normal for an unregulated power supply on a fully charged battery, make sure your battery connections are solid and that your battery meets the minimum motor specs.

 

[RandyJ]

Re: High Voltage

Readings in only one direction? Yup, that sounds like what a rectifier does.... converts alternating current into DC which is only one direction flow of electrons.

 

[boobie]

Re: High Voltage

Have your battery load tested to make sure it's okay and then check your battery connections on both the battery and the mtr for being clean and tight.

 

[Bill3434]

Re: High Voltage

Don't know what happened to the reply. My battery is fairly new, all the terminals have been cleaned due to problems earlier in the season. Just never seen my voltage go so high. Wondering if it could be the rectifier going bad. I wouldn't think I would get a high voltage reading from corroded connections.

 

[RandyJ]

Re: High Voltage

not trying to be a smarty pants here but possibly bad meter?

 

[Bill3434]

Re: High Voltage

I thought of that but the voltage on the fishfinder and gps read the same. It reads properly when the engine isn't running just like it always as. The rectifier does look like the one that came on the motor. The rubber seal is cracked but doesn't appear to be dry rotted if that makes any sense.

 

[RandyJ]

Re: High Voltage

oh well, if you're really concerned then spend a few bucks and replace the rectifier. I have no idea if it limits the voltage but I do know that it does limit one side of the sine wave so that you only get dc from an ac current. BTW, my old cuddy cabin with the AQ125a volvo i/o will kick well over 14 volts until the battery reaches full charge. I've been out in the boat and got concerned about overcharging only to be relieved a few minutes later when it was back down between 12-13 volts. If I recall correctly 13.8 volts is normal for a healthy 12 volt battery sitting on a shelf.

 

[Bill3434]

Re: High Voltage

That's what I was planning on doing. Just didn't want to waste money on something I didn't need. You are right about the voltage for a healthy battery. Didn't want to blow battery either had enough problems this summer with other electrical problems, spent more time on the lake turning wrenches then fishing. Made it last weekend with using them, now that the algea bloom is going away I might get some serious fishing in.

 

[LongLine]

Re: High Voltage

Don't just check the terminal corrosion - also check the wire connection to the terminal.

Tom B.
(LongLine)

 

[RandyJ]

Re: High Voltage

Just for the sake of satisfying yourself... have you checked the voltage with an analog meter? I do know that DVM's will pick up stray voltages and odd readings on some circuits.

 

[Fed]

Re: High Voltage

BRP website says your motor has no voltage regulator on it, 17V is exactly what you should expect across a fully charged battery.

 

[Bill3434]

Re: High Voltage

BRP website says your motor has no voltage regulator on it, 17V is exactly what you should expect across a fully charged battery.

Thanks for the info. I had just not seen it read that high before. I guess cleaning all the terminals and connections dealing with other issues I had made a difference.

 

[Bill3434]

Re: High Voltage

Just for the sake of satisfying yourself... have you checked the voltage with an analog meter? I do know that DVM's will pick up stray voltages and odd readings on some circuits.

Didn't think of that but from the feedback I'm getting from others 17V is in the norm. But I will take your advice later tonight and pull the analog meter out to see what is says on the rectifier. Then next trip on the lake I see taking some meters out with me.

 

[guy74]

Re: High Voltage

17 volts is nothing unusual for an unregulated system when the motor is tunring high rpms. I see 17+ on long wide open runs with my 60hp. I was concerned about it 5 years ago when I put a volt-meter in my boat, but the high readings are normal with those motors.

 

[Bill3434]

Re: High Voltage

17 volts is nothing unusual for an unregulated system when the motor is tunring high rpms. I see 17+ on long wide open runs with my 60hp. I was concerned about it 5 years ago when I put a volt-meter in my boat, but the high readings are normal with those motors.

Thanks for the info, I guess that means the battery can handle it. Now that adds to another problem to solve on my winter project list, was looking at some compact led light to put on the boat but they are voltage sensitive.

 

[Bill3434]

Re: High Voltage

Hope someone is still monitoring this thread. I took my boat out this afternoon I didn't have my volt meter with me since I was doing trailer work. I left my engine running while working on the trailer (just over an hour boat in the water) I noticed while recoverying the boat that my volt meter was showing 18v. I took the volt meter out and tested it at home it was reading properly. Now I got more questions.

1. Is this excess voltage going to damage my battery?
2. Is this voltage a warning about something going to fail; like the stator or rectifier?
3. Could I take a automotive voltage regulator to control my voltage?

Thanks in advance to those that know more than me.

 

[Bill3434]

Re: High Voltage

One more note; my battery with no load reads 12.96. The battery is a Duralast Marine Battery(1000 amp) and was purchaced Memorial Day 11.

 

[guy74]

Re: High Voltage

1. The excess voltage doesn't seem to hurt the battery in my boat, the one in it now is 4 years old and still working fine.

2. The high voltage is just because there is nothing drawing on the system, and the surface charge builds up, like I said before, the system is "unregulated", and they all build high voltage like that.

3. An automotive regulator will not help on this system, but you can use a voltage regulator like motorcycles use, the kind that direct excess voltage to ground. It is only a 6 amp system so not hard to find a regulator that can handle that, just need to locate it where it can air cool.

I hope this helps.

 

[Bill3434]

Re: High Voltage

1. The excess voltage doesn't seem to hurt the battery in my boat, the one in it now is 4 years old and still working fine.

2. The high voltage is just because there is nothing drawing on the system, and the surface charge builds up, like I said before, the system is "unregulated", and they all build high voltage like that.

3. An automotive regulator will not help on this system, but you can use a voltage regulator like motorcycles use, the kind that direct excess voltage to ground. It is only a 6 amp system so not hard to find a regulator that can handle that, just need to locate it where it can air cool.

I hope this helps.

Thanks. It helps some what, It's just got me concerned since I never saw these readings until I cleaned all my terminals dealing with a starting issue. And I've never heard of 17-18v going into a 12-13v system being good. Then again if I were an expert in this I wouldn't be asking questions, thanks again.