Charging voltage

Kevin W

Petty Officer 1st Class
Joined
Apr 18, 2006
Messages
256
Re: Charging voltage

the charging system is an unregulated system.
so with that said...it depends.
if you are at idle it will be most likely around 12.5 -13, @ 2-3K it will be roughly 14-16 depending on load on the system.
it also depends on the starting battery.
voltage regulation is done with the size of the battery.
if its a automotive, low CCA or cheap marine battery it will overcharge at higher RPM's around 17+V

There are voltage regulators that can be installed but they are not real cheap.

if my memory serves me correctly your charging will produce 6A so if you have much load on there the voltage will not rise alot.
 

R.Johnson

Rear Admiral
Joined
Sep 24, 2003
Messages
4,446
Re: Charging voltage

You won't have to worry about over charging with that 6 amp system, there is no need for a voltage regulator.
 

Cricket Too

Lieutenant Commander
Joined
May 14, 2003
Messages
1,732
Re: Charging voltage

I take it that holds true for a 1976 Johnson 115? I thought I had a charging problem last year, when I had charging voltages close to 18V at higher RPM. It drove me nuts for 2 or 3 weeks, I finally put an OMC regulator in it from an early 80's V4, keeps the voltage at about 14.5V at WOT.

So your saying that even at 17 or 18V, a 6amp charging system won't hurt anything? Man wish I knew that last year. Good to know.
 

R.Johnson

Rear Admiral
Joined
Sep 24, 2003
Messages
4,446
Re: Charging voltage

I'm trying to think what was causing that high voltage on the 115.Was the battery sound, with all solid connections?
 

Kevin W

Petty Officer 1st Class
Joined
Apr 18, 2006
Messages
256
Re: Charging voltage

For the most part 17-18 V will not damage most things.
Some fishfinders will shut down.
The batteries do not like that high of voltage though.
I would keep an eye on the water level in the battery.

There are many reasons to use a larger non-automotive high quality battery.
It can handle the abuse of a non regulated outboard much better and it will last ALOT longer.
 

60hpomc

Cadet
Joined
Apr 23, 2007
Messages
25
Re: Charging voltage

Ok I'm only getting 12.34 @ idle is that a problem or do I need to check it at WOT?
Thanks guys
Chris
 

Cricket Too

Lieutenant Commander
Joined
May 14, 2003
Messages
1,732
Re: Charging voltage

Chris, sorry I didn't mean to jump on your thread man, just figured I'd offer some insight into how I solved it on my engine.

12.34V sounds OK to me at idle, I would check it at a higher RPM. What I did was clamp my meter onto the battery posts and checked it at higher RPM in fast idle, highest I went was to about 3K and it was in the low 17V range. It's not the best idea to rev your engine in neutral above 2500 too much, so I took it out with a friend, got up to about 4500, and checked at the battery with a meter, and was getting just about 18V. I'd give that a shot.

I was, and am, running a decent marine deep cycle on that engine, but I heard that the old unregulated charging systems don't work well with modern batteries, as they aren't made as well as they used to be when those systems were made.

My electronics were shutting down, depth finder and VHF. At WOT they would only stay on for about 2 minutes, at lower RPM like trolling they would stay on. Figured they didn't like the 18V, once I saw that voltage.

I put a external regulator on from an early 80's V4, just put it in series at the terminal strip where the rectifier attaches. I was lucky, a fellow Iboats member was nice enough to send me one he had laying around for no charge. Not sure what they cost, but maybe you can find an old one that somebody's not using. It solved my problem as soon as I attached it, charges at about 12.5 at idle and 14.5 at WOT.
 

mikemartyo

Seaman Apprentice
Joined
Sep 14, 2004
Messages
37
Re: Charging voltage

I have a similar question. I have a 77 85 hp. at idle in the driveway the voltage off the stator shows 18-19 volts, the red and yellow wire off of the rectifier shows at 14 volts, but i am not getting this voltage down to the battery.

where does the wire go? i am looking on the wiring diagram, it looks clear, but i am not getting charging of the battery.

any suggestions? i do not see a reason why if i am getting power out of the rectifier, i would not get power to the battery..
when i check the battery - it reads about 12.3 v and the rectifier - read from the terminal block positions 7 & 8 gives me 14v.
Mike
 

Cricket Too

Lieutenant Commander
Joined
May 14, 2003
Messages
1,732
Re: Charging voltage

Mikemartyo....If you are getting 12.3V at your battery at idle then that's fine. Your not going to get the same voltage that you see at the rectifier all the way at the battery, your going to get a voltage drop over the wire and the resistance of the battery, unregulated charging systems use the battery as a regulator, at least they were designed that way.

If you continue to measure your voltage at the battery at higher RPM's you will see it go up.
 

mikemartyo

Seaman Apprentice
Joined
Sep 14, 2004
Messages
37
Re: Charging voltage

i hope so, i had just had the battery on a charger. it doesnt seem to be charging the battery when it runs, i replaced the stator last year and everything worked fine, but at the end of the year, it wasnt charging.
now it doesnt seem to be charging. . .

if i am getting that voltage off of the rectifier at idle, do you think there are any other problems that i am missing? Mike
 

Cricket Too

Lieutenant Commander
Joined
May 14, 2003
Messages
1,732
Re: Charging voltage

mikemartyo.....your best bet would be to start your own post for this problem.

If you read the above posts or the ones in the other thread you wrote into, you can see that 12.3 is about all your gonna get at idle, also that your charging system charges at a relatively low amperage, so you can't expect all that much in the way of charging.
 

mikemartyo

Seaman Apprentice
Joined
Sep 14, 2004
Messages
37
Re: Charging voltage

I think my problem went away - it must have been a loose connection or something, now it seems to be charging. I like cheap repairs.
Thanks for your help.
Mike
 
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