Battery not charging

[ricardo100]

Hi, newby from New Zealand. I have a 1988 Mariner 150 with this problem. At 1500 rpm the Alternator is putting out 30v per yellow wire, the rectifier was putting out 6.5v on one terminal and 1.5v on the other. Thought I'd found the problem so I tried a new rectifier but it reads exactly the same. Any ideas? Cheers. Rich.

 

[Faztbullet]

Re: Battery not charging

Does it have the seperate regulator on top of block? If so disconnect it and re-test. I would re-test the stator as the volt readings per leg is not correct for what you output is.
Not Charging the Battery
1. With all wires connected and the engine running at approximately 1500 RPM, check the DVA voltage from each yellow wire to engine ground. The two readings have to be within 2 volts of each other (i.e. if one is reading 20 volts, the other has to read between 18 and 22 volts). If the readings are not equal, go to step 3. If they are equal, go to step 2.
2. Check the DVA voltage from the yellow wires to the red wire going to the solenoid. The two readings must be within 2 volts of each other. If the readings are unequal, replace the rectifier. If they are equal on this step and step 1, the rectifier and battery charging portion of the stator are OK.
3. If the readings are unequal, mark across the connection(wire) between the stator and rectifier stud on the low side. Turn the engine off and swap the stator leads. Crank the engine up and retest. The component that has the marking with the low reading is bad.

 

[j_martin]

Re: Battery not charging

That's way more complicated than it needs to be.

1. Disconnect the yellow wires. Between them should be less than 1 ohm resistance, but not 0. Between either one and ground there should be an open circuit, ie no response on the highest setting of your ohmmeter.

If still in doubt. hook an ordinary light bulb across the yellow leads, and measure the voltage when the engine is running. It should be about 15V per 1000 rpm engine speed. (12 or so at idle, 30 at 2000, etc.)

The rectifier can be tested with an ordinary ohmmeter. Look in the FAQ section of this board for instructions.

The magnets are important, but the engine wouldn't run and would likely sound like a thrashing machine when cranking if they were bad.

Theory wise, it's an ungrounded coil feeding a full wave bridge rectifier.
hope it helps
John

 

[ricardo100]

Re: Battery not charging

Thanks for the info. Testing the Rectifier seems tricky, I get very different reading from those suggested, but since I have fitted a new one and it is still not charging, it's reasonably safe to assume it's not that unless Ive been unlucky enough to fit a dud. Unlikely as the figures coming out of the new rectifier while running were the same as the old one.
Some more info...

- This outboard does have the second 2 wire regulator on top of the block, and another sealed, bigger black box beside it.

- When I tested the stator, I disconnected the two yellow wires from the rectifier and go the same reading from both at approx 30v ac

I still don't think it's the rectifier, but just to answer these ...

Instruction- "With all wires connected and the engine running at approximately 1500 RPM, check the DVA voltage from each yellow wire to engine ground. The two readings have to be within 2 volts of each other (i.e. if one is reading 20 volts, the other has to read between 18 and 22 volts)"

Result.... approx 6 volts from the rear rectifier post, 1.5 from the front post.


Instruction- "Turn the engine off and swap the stator leads. Crank the engine up and retest. The component that has the marking with the low reading is bad"

Result.... Same reading from both posts as before, with yellow wires swapped.

I will do some testing with the top Regulator disconnected and see what I get.
Many thanks.
Rich.

 

[j_martin]

Re: Battery not charging

Your rectifier is bad. Maybe the new rectifier is bad.

BTW, if the output (red wire) is not connected to the battery, a new Mercury rectifier will be functionally equivalent to a penny in a heartbeat. They're junk. If you use a 200V bridge rectifier instead, you won't hurt it.

What matters on the diode test is that you get a reading going one way, and not the other through each diode. There should always be a voltage drop, therefore a resistance reading. What the "resistance" will be depends on the meter as it's not actually a resistor, but a non linear junction you're measuring.

Voltage on the open circuit stator is meaningless unless either it is loaded (a lamp) or you have measured the resistance between them and found it to be fairly low. (1 ohm or less)

 

[CharlieB]

Re: Battery not charging

Load testing, DVA test, are critical to soling stator questions. A broken, yet abutted wire in a coil will still generate open circuit voltage, and can fool one into believing the stator is good, yet fail once any load is applied.

The light bulb test a an easy load test, visually apparent, if the stator fails you will not light up at all.

 

[ricardo100]

Re: Battery not charging

Thanks for your input guys. I took the boat in to the local marine shop in the end and they replaced both the rectifier on the side and the top. Charging well now.
I still have an alarm problem though, even after they said they had tested all the alarm systems. Beeps intermittently only after about 15 mins of running, then becomes a continuous beep beep beep after about 20mins. Then will still beep continuously when the key is turned whether the engine is running or not.
Top oil tank is completely full and I have tried another top oil tank cap/sensor but still the same result. Plenty of oil getting to the engine also. Does anyone know if these motors have a water pressure sensor? Any other thoughts?
Many thanks. Rich.

 

[chatay]

Re: Battery not charging

i have a 1989 40 hp mariner magnum outboard. my battery is not being charged by my motor. can someone tell me what to check and how to check it? please explain it in simple terms as i am not an outboard mechanic. and cant afford to bring it to one to find the problem. thanks

 

[CharlieB]

Re: Battery not charging

chatay, this is considered an 'old thread' AND it is also frowned upon to piggy-back your problem on someone else's thread.

Simply start a new thread, list your motor model and serial, give an explanation of your problem and what you have already done or tried to fix it, we will then respond with our best advise on how to solve you problem in the most cost effective manner.

Together, we should have your motor working fine again quickly.

CharlieB

 

[ricardo100]

Re: Battery not charging

Hi Chatay. Find your Voltage regulator/rectifier on the right side of the engine, it's diamond shaped with red and yellow wires, replace it. Look for another regulator on top of the engine looking the same, if you find one there, replace it too. It's going to be one or both of these. I dicked around for ages testing everything and wasting time. Test results were varied and inconsistent. Gave up and took it to my local marine shop who just replaced these and sent me a huge bill. My parts had to come from Aus so were pricy. Expect to pay about $400 to $500 for parts alone. Not sure if this will effect anything else electrical, but if you don’t want to part with that sort of loot, buy a spare battery for $200 and just keep it on board, don't run electrical equipment and just swap it over when the first one gets low from engine starting duties. Rich.

 

[aussieflash]

Re: Battery not charging

Even better, just buy a new boat with a motor that works......great advice Ricardo.
Considering he just told us he cant afford too much.Just because you couldnt take direction doesnt mean Chatay cant.
After all this is a repair forum....We all know where the mechanic is.

 

[ricardo100]

Re: Battery not charging

Aussie flash, your clearly not flash as your name suggests, just a Muppet. There is no way around this problem without spending money. Maybe you can pull expensive marine parts out of your butt for free but I can't, and I don't think Chatay could either. I gave Chatay the cheapest option with the back-up battery. These parts give up with age, not just use so cheap second hand parts are no good either. Interestingly I didn't see any advice from you Aussie Muppet, just a sarcastic tone meant to make yourself feel like someone big in your tiny world of self importance. Jealousy is a very ugly emotion.