ghost in the machine ?

[ab59]

Well --#$!@#$%#$&^%$$^%@# after all the progress I made I have run up against another electrical problem being the Alternator I guess. I now have the engine running. Before starting it today I checked the battery and it was 12.1 volts , a little low I know but I had been cranking on the engine for a while when finishing up on carburetor work. . When I start the engine it falls to 11.73 volts while running ! This is the second Alternator I have put on this engine and I thought I had it tested at the rebuilders shop when I bought it because it was a used alternator but extremely clean and looked new. Wiring of the Alternator . I am unclear as to how this is supposed to be hooked up now because I have found two different wiring diagrams for the same alternator . Now I am wondering if I hooked it up wrong and burned up the new ( to me ) alternator ! It is surely not putting out any juice . If it was putting out current then I should have seen a higher reading at the battery when running , Right ?
Can one fix his own alternator ?
After testing the alt. I changed the position of the purple and the red wires as to test again but got no difference . Don't know if I screwed up something else doing that.

 

[ab59]

oops forgot to say that the tester is alright I guess I used it on the v setting and it measured out the battery fine. Don't know if you meant to test the meter across the terminals on the same setting that it was on when i did the previous test .I left the battery hooked up overnight , key off , and the battery had about 12.50 volts or about the same as yesterday .

 

[alldodge]

My guess is the ALT isn't getting powered. The red wire should have 12V all the time with key on or off. The purple wire gets 12V once the key is turned on

 

[ab59]

Output key on, note difference



exciter circuit , no reading at key off---reading is at key on
For whatever reason this last picture was moved to the top of the column and reads 10.39
will continue in next post.

 

[ab59]

Sensing wire key on ,no current key off.




I am referencing the tests through a link you provided in another post for my information but I just can't seem to grasp exactly what this means . Does this mean that the voltage regulator is bad ?

 

[alldodge]

Your readings is showing the battery may have a dead cell because its real low. The orange wire goes directly to the starter post thru a 90 amp fuse, so what you see on the orange you should see the same directly on the battery post. If bat post and orange are different then there is an open circuit or corrosion

Your excite lead (purple) is working correctly, only issue is voltage is to low (battery)

The since lead should be the same as the Orange wire and battery because it comes off the 50 amp breaker, The 50 amp breaker comes off the starter post and may or may not go thru the 90 amp fuse

 

[alldodge]

I have been over looking something, this is an OMC right?

 

[ab59]

yup , I have a 1988 Starcraft with OMC 5.7 and Cobra sterndrive. I know that my wires do not really match the book colors and that is how I may have got the wires on there backwards at first . Still not absolutely sure about wire position so I just figured that the pinkish wire with the white stripe must be the red wire that the book refers to and goes to the sensor tap and that the blue wire goes to the exciter tap. Like i said , I'm still not positive that i have them hooked up right even now.

 

[ab59]

I better charge my battery before any more testing . I cranked on it a lot yesterday and the day before and did not fully charge it back up. I know that he battery is in good shape , just a little run down.

 

[alldodge]

The OMC uses a splice connection where the red/purple and the purple come together before the ALT. They should still stay separated, but they all come together in one location. Have a look at it and try to determine that there is no issue with one wire connecting to the other

 

[ab59]

OK , I already unwrapped the loom and have exposed the splice , everything look alright at a glance but I will give it a good once over. I broke down and took the alternator down to the rebuild shop and the guy said that it is definitely not putting out current . He also pointed out that several of the housing screws were loose as if some one had already been inside it. I don't know who did or if they even did but the rebuilder is going to tear it down and let me know how much to fix it. I have a feeling that it's going to be more than I can buy a new one for but we will see.
At least I know it's not putting out juice . This is the second alternator I've had on this thing and I hope it's just coincidence that neither one worked and not something in the wiring that is killing them.

 

[ab59]

Just heard from the rebuilder and he says that the regulator and the rectifier are shot . Just the regulator would cost 79+ never mind the rectifier that he said would be at least that much plus his labor so looks like the days of having an alternator fixed are long gone. He said he could order one for at 179..00 plus shipping and taxes but I see many for sale on ebay for 100 or less , some more some less and they include shipping so guess that's the way I'll go.
I hope to get the new one wired up right the first time this time around. So much conflicting information and my wires not being the color the book is makes it a little more difficult to get right .

 

[alldodge]

bummer, but did sound like your last one had some quality control issues

 

[poconojoe]

I don't mean to insult your intelligence but you are using a marine alternator correct?
Also, may I suggest a battery switch? This way all power is disconnected when not using the boat. If you keep the boat in a slip, make sure the bilge pump is connected directly to the battery and properly fused of course.

 

[ab59]

Alldodge-- I found a brand new 63 amp 3 wire Marine alternator on ebay for 55.95 free shipping !The one I'm replacing was a 51 amp. Don't think I could have repaired it for that even if I bought the parts myself and put them in.
yo, poconojoe---yep , both of my last two alternators were motorola marine alternators. I am considering a battery switch but I have decided that unless I go ahead and put in a second battery ( and I probably will ) as a dedicated starting battery I will do without the switch as I have found and fixed my key off drain problem. I vaguely remember how to set up a two battery charging setup but I'm sure there is plenty of info here in the forums to walk me through a two battery system with an isolator.

 

[alldodge]

You should be good without change

If you want to install another bat I would suggest a ACR over an isolator

 

[ab59]

I know I might not understand what it is but I have to ask what an ACR is ?

 

[alldodge]

Its an automatic charge relay
https://www.bluesea.com/products/7610/SI-ACR_Automatic_Charging_Relay_-_12_24V_DC_120A

 

[ab59]

thanks. a little pricey for me at this point but maybe in the future. would be nice to have onboard though.

 

[poconojoe]

You can set up two batteries with a battery selector switch and add the ACR later. For now you will have to manually select which battery to use/charge with the selector switch. The ACR will automatically charge either battery that needs it with no input from you.