going through rectifiers

[prestonv]

i was haveing tach problems on my 82 140 johnrude. i replaced the rectifier following the thread by joe reeves. i have started haveing problems again and have used my boat maybe 15-20 hours since i put it on. i tested the rectifier again and it shows it being bad. it has to be hot and when it is acting up and i get the bad readings it is hot to the touch. if i pour cool water over the rectifier the tach will read for a short bit and then go back out.. i really dont care about the tach. i can do with out it but it is the chraging system i am worried about. have you guys ever heard of this problem? is something else causeing it? dont be afraid to give diag steps.. i work on cars and understand wiring and electircal but im stumped on this one.. thanks for any advice
preston

 

[R.Johnson]

Re: going through rectifiers

Are all connections' tight? Wing nuts' on the battery maybe?

 

[TerryMSU]

Re: going through rectifiers

If it is hot, you are drawing to much current for the rectifiers. Are these the originals (or OEM replacements)? If so, you have a problem on the load side. If not, get some higher current rated parts or the OEM parts. It also occurs to me that the battery may be bad. That would cause the rectifier diodes to draw to much current and run hot.

TerryMSU

 

[prestonv]

Re: going through rectifiers

i went through all my connections and cleaned them about the same time i reploaced the rectifier.

terry
i got the part from a local marina so i assume it is an equvilant if not factory replacement.. thats just an assumption though. how could i check the draw on the system? i would not think i have much draw because oif the fact that i only have a gps a fish finder and vhf radio and running light5s on the boat. but i could try testing that. is there a way to ask for a heavier duty rectifier. if im not mistakeing my charging system is only a 9amp system anyways.

 

[jonesg]

Re: going through rectifiers

You can get your battery load tested free at autozone, if its marginal it will do the same as on a car "you need a new battery AND alternator".

Because the battery was worn out and took the alternator with it.
The rectifiers are usually inside alternators.

 

[HighTrim]

Re: going through rectifiers

As RJohnson asked, you are not hand tightening wing nuts are you?

 

[TerryMSU]

Re: going through rectifiers

Try running the boat with all the extra stuff off. Typically, you would run all accesories off a separate battery (for example a trolling motor battery.) The separate battery would get charged off a plug-in battery charger. All that extra current must be drawn through the diode. If the thermal problem goes away, you have found the issue. If so, you may or may not have damaged the rectifier.

Typically, the charger in a car has a LOT of current capacity, the charger in a boat is much less powerful. It is really only capable of recovering from an occasional motor start.

High Trim and Rjohnson... are you thinking that he is running the alternator with no load for a short period of time. (This is what is called "Load Dump".) Wouldn't that result in a hard (permanent) failure of the rectifiers. Cooling them off would not likely fix that problem.

TerryMSU

 

[karlow1]

Re: going through rectifiers

Be careful or you might end up on fire!
That is what happened to the previous Tracker/70Hp Johson.
Make sure the batteries are charged prior to going out. A long run with bad or dead batteries might overheat the rectifier.
Check to be sure the battery will charge up to a voltage above 12.5VDC (typically 14.5). If it is not above 12.5 after charging it might have a bad cell.
If you have operated the engine with a bad, or no connection to the battery at any time, for just a moment, the you blew it again Also be carfull to avoid overcharging the batteries as well. The battery should not exceed 16Vdc, or you will boil it.
On my boat it was burnt when I got, I repaired it. It was overchagring that battery. I hooked it to the trolling, and starting battery. It would still get them above 16Vdc. I added a RV type duel battery addapter (diode pack).
That fixed it, but I'm not sure why the charging system was powerfull.

Good luck

 

[jonesg]

Re: going through rectifiers

"It would still get them above 16Vdc. I added a RV type duel battery addapter (diode pack).
That fixed it, but I'm not sure why the charging system was powerfull. "

could it be due to a blown regulator.?