Is 16.5 -18 volts too much?

[TDmanager]

Hi, I have been lurking here in the forums for some time but this is my first post here. I have a 79 model 70 hp Evinrude 3 cylinder.

I purchased a new depthfinder and got it installed today. It has a readout for the voltage. Is shows 12.6 volts when the engine is not running. It reads 16.5-18 volts when going down the lake. Is that a problem?

For some time now my tach works sometimes and sometimes it doesn't. I have used the instructions I found here for testing the rectifier and it check out good. Does my engine also have a regulator that could be bad?

The engine runs great and has no problems. Should I be worried about the high reading on the voltage? Should I stop running the boat because of the high voltage readings?

Thanks in advance for your help!

 

[flargin]

Re: Is 16.5 -18 volts too much?

Yes, it is too high. there is likely a regulator bad. the motor can likely handle the extra voltage, and that is why it has never been a problem.

Electronics (like your new expensive depth finder, stereo, etc) have the biggest problem with them. I would get it checked/replaced to prevent damaging your new stuff.


Welcome to the forums... Great to have you aboard.

BTW, at that voltage you will likely start to evaporate the fluid in your battery, you should check them, add distilled water (or rain water) to re-fill. try not to use tap water.

 

[Joel K]

Re: Is 16.5 -18 volts too much?

I don't know your engine, but if your putting 18V into the battery it will be a problem. Your depthfinder won't take that for long either unless it has some built in shut down protection.
The tach could just be a loose connection.

 

[TDmanager]

Re: Is 16.5 -18 volts too much?

Will replacing the rectifier cure the problem or is there another part that I need to replace?

 

[Silvertip]

Re: Is 16.5 -18 volts too much?

There are two parts to the charging system 1) a rectifier and 2) the regulator. In some cases these are combined into a single unit. I suspect it is the regulator that is the issue.

 

[TDmanager]

Re: Is 16.5 -18 volts too much?

I looked at the parts breakdown that I found here on iboats and it did not show a regulator. Can anyone tell me if the 79 model 70hp Evinrude had a regulator? If not what else could the problem be?

I was out in it again today. The tach worked perfectly but the voltage was still at 17.1 volts when running half to full throttle. At idle it was about 12.9 volts. With the engine off it charging 12.6 volts.

Here is what I have checked:

• Rectifier - checks out good
• Battery - about six months old, has plenty of water - cleaned and tightened battery connections.
• Voltage reading - checked with Fluke multimeter for verification.

Could it be possibly normal for this old motor to put out 17 volts from the factory?

Any input is appreciated!

 

[flargin]

Re: Is 16.5 -18 volts too much?

possible it was exteral, but unlikely none, or it was designed for anything over 15v.

Most electronics have their own regulators in them. Regulators work by dissipating higher voltage for heat. The immediate heat will not cause a problem, until the heat cooks the chips. It is completely possible it is designed to handle even much higher voltages(+36v is possible on some regulators), but only the designer will know, they would not publish that data..

BTW, rectifiers are used to change alternating current (AC) into Direct Current (DC) Regulators, chop the top of the voltage off to limit out the output to a specific voltage.. If you wanted to know.

I would suggest calling a local shop and ask if they have a replacement/can order a replacement. if they say no, you may want to see if there was an external regulator for that era, which is possible. if they don't know, you can external on ebay/auto parts stores/ etc because they were used on cars.

 

[flargin]

Re: Is 16.5 -18 volts too much?

Also, as silvertip indicated, some are independent parts, and some are not. It is very possible you might just find the "rectifier" part #, and that would include the regulator.

 

[TDmanager]

Re: Is 16.5 -18 volts too much?

I'm not as concerned with the high voltage output hurting the depth finder as much as I am worried about damaging the stator, ignition electronics or some other electrical part$$$ on the engine. I would change the rectifier if I can find out for sure if it has a regulator built into it. I was hoping someone here would know. All the rectifier tests that I could find in the iBoat forums point to the rectifier being OK.

I was hoping that I could gather enough information here to avoid going to a dealer$$$

The help is greatly appreciated.

 

[flargin]

Re: Is 16.5 -18 volts too much?

may want to look at look here... sounds like it may have come with an external, but an internal regulator is possible...

A quick google search on External regulators found this site, with a bunch of external options, non-dealer... http://www.russellsnewoldparts.com/VOLTAGEREGULATORS.html

and a quick Iboats search found this page.... looks like rectifier only.

It looks like a combo unit is 18-5827

but I am not really an outboard guy. You may want to ask if these are the correct parts in the outboard forum... might have better luck... those guys know the actual units...

I would say you should do something, 17v really is a little high. You may be able to run fine with that, but I would be uncomfortable with it every time I went to high RPM.

I would venture to say there was an external Regulator, it died, someone pulled it to charge their batteries, and sold it to you

follow-up with what the guys in the outboard forum say, I would be interested to know.

 

[TDmanager]

Re: Is 16.5 -18 volts too much?

Thanks for your help. I appreciate it. I will ask about a regulator in the ourboard forums.