Rare charging problem in Mercury 150 V6

[PRdiver]

I need help with a very rare charging problem. My engine is a 150 hp Mercury Black Max. Serial Number begins in 0C27xxxx. 40A Stator. I hope one of you can help me.
My boat is not charging if I measure the voltage at the batteries' terminals; around 12.4 VDC), but if I measure the voltage from the positive cable of the starting solenoid and the negative cable at lower end of the starter I have charging power. (13.x VDC). I really could not figure out because it is the same cable but at different ends.
I tested the regulator/rectifier already. From yellow to red, continuity in only one direction. Both yellow cable were tested. From red to ground no continuity in any direction. This should tell me that the regulator/rectified is good.
I need to say that in some occasions there was voltage above 13V at the battery. A friend of mine told me that he think the stator is bad, please confirm this.
When there is no charging, the engine does not work smooth.
Attached the schematic of my engine, if it can help ...
Please help me in this matter.
Thanks in advance
PRdiver

 

[j_martin]

Re: Rare charging problem in Mercury 150 V6

Try this. Disconnect and tape off the yellow wires from the rectifier. Does the engine now run well? If yes, replace the rectifier. If no, probably the stator is bad.

The bit about a large variance at either end of the two heavy battery cables is probably a matter of timing. One time it was working, another it wasn't. I'm assuming you don't have a large load on the battery in the boat.

All kinds of electrical ghosts manifest if the grounds are bad. First item in any of these projects is to closely examine and clean all the grounds. The rectifier mounting is one of them.

hope it helps
John

 

[sschefer]

Re: Rare charging problem in Mercury 150 V6

How old is your battery. If its a normal marine starting battery, then take it out an put it on a normal charger and see what it does then. Alternatively, take it to a decent battery shop (Interstate) and have it tested. If it's more than two years old, just replace it.

13-15v is normal at the engine, (13.3 would be perfect for a lead/acid battery). The battery should charge to 13v and then settle to 12.6v.

 

[Faztbullet]

Re: Rare charging problem in Mercury 150 V6

Are you sure you have a 40 amp system as the diagram you posted is for the 16 amp system. The engine came both ways in that year and the 40 amp system had a large water cooled rect/reg on the divider plate. If this is what you have you you cannot check it with a ohm meter but rather a ammeter and load tester if I remember correctly. The purple wire turns it on/off with the key like the old OMC 35 amp systems and has a seperate tach wire.

 

[achris]

Re: Rare charging problem in Mercury 150 V6

Do a voltage drop test...

With the engine running...

Put the black meter lead on the negative post of the battery (the actual post, not the terminal), then put the meter red lead on the engine ground. We are looking for SMALL voltages here, the smaller the better, zero is great. If it's not zero, put the red lead on the battery terminal. If it's still too high, then the battery terminal needs cleaning.

Now do the same for the positive lines. This time with the red meter lead on the battery positive POST...

See how you go with that....

Chris.........

 

[PRdiver]

Re: Rare charging problem in Mercury 150 V6

Are you sure you have a 40 amp system as the diagram you posted is for the 16 amp system. The engine came both ways in that year and the 40 amp system had a large water cooled rect/reg on the divider plate. If this is what you have you you cannot check it with a ohm meter but rather a ammeter and load tester if I remember correctly. The purple wire turns it on/off with the key like the old OMC 35 amp systems and has a seperate tach wire.

My engine has the big rect/reg on the divider plate. It is true, the drawing I posted has a different system. I used it because it says 40 amp at the top of the page. Sorry. Please let me know the test to perform.
Thanks once again.
PRdiver

 

[sschefer]

Re: Rare charging problem in Mercury 150 V6

The voltage you're reading at the Engine is correct.. No problem. The voltage you're reading at the battery is correct, again, No problem. The reason your battery voltage is lower is because you are reading voltage through the battery which is a regulator in itself.

This is also the same reason that we hook our volt gauges up at the engine if we want to see charging voltage and we hook a battery level gauge up to the battery if we want to see charge state.

You did not say what type of battery you have so I will assume that this is a lead/acid Marine starting battery and not a Marine deep cycle.

1. Make sure the battery cells are full by adding distilled water as necessary.
2. Place the battery on a good charger for 24 hours.
3. Remove the charger and immediately take a voltage reading. You should have 13.3-13.5 volts.
4. Let the battery sit for 12 hours and take a voltage reading. You should have 12.6 volts. If the battery is below 12.6 V replace the battery. If the battery is above 12.6 put a 12v light bulb on it for a load and test again. It should settle out. If not, replace the battery.

5. Let the battery sit for 24 more hours and take a voltage reading. You should still have 12.6 volts. If not, replace the battery.

If you want to avoid all this, take it to a battery shop they can run a full set of tests in a matter of minutes. If your battery is more than two years old and they try to sell you a new one, buy it.

 

[PRdiver]

Re: Rare charging problem in Mercury 150 V6

The voltage you're reading at the Engine is correct.. No problem. The voltage you're reading at the battery is correct, again, No problem. The reason your battery voltage is lower is because you are reading voltage through the battery which is a regulator in itself.

This is also the same reason that we hook our volt gauges up at the engine if we want to see charging voltage and we hook a battery level gauge up to the battery if we want to see charge state.

You did not say what type of battery you have so I will assume that this is a lead/acid Marine starting battery and not a Marine deep cycle.

1. Make sure the battery cells are full by adding distilled water as necessary.
2. Place the battery on a good charger for 24 hours.
3. Remove the charger and immediately take a voltage reading. You should have 13.3-13.5 volts.
4. Let the battery sit for 12 hours and take a voltage reading. You should have 12.6 volts. If the battery is below 12.6 V replace the battery. If the battery is above 12.6 put a 12v light bulb on it for a load and test again. It should settle out. If not, replace the battery.

5. Let the battery sit for 24 more hours and take a voltage reading. You should still have 12.6 volts. If not, replace the battery.

If you want to avoid all this, take it to a battery shop they can run a full set of tests in a matter of minutes. If your battery is more than two years old and they try to sell you a new one, buy it.

Here is the information about my batteries. Battery 1, Autocraft Marine/RV Deep Cycle CA 625 CCA 500. Battery 2, Optima Blue Top Dual Purpose, the one that looks like a six pack of beer.
Thanks

 

[achris]

Re: Rare charging problem in Mercury 150 V6

If you have a different voltage between the battery lead at the engine and the engine ground to that of the voltage across the battery terminals, that only means one thing.... a voltage drop in the leads somewhere.... You need to find that. Forget about what type of batteries you have, find the fault.

Chris...........

 

[sschefer]

Re: Rare charging problem in Mercury 150 V6

Here is the information about my batteries. Battery 1, Autocraft Marine/RV Deep Cycle CA 625 CCA 500. Battery 2, Optima Blue Top Dual Purpose, the one that looks like a six pack of beer.
Thanks

If you don't have those two batteries isolated from one another you must do that. The Optima should be your starting battery since it has 800 CCA. The other battery should be charged with a separate charging system like an onboard charger. You could use it for your trolling motor but it's pretty small.

 

[Faztbullet]

Re: Rare charging problem in Mercury 150 V6

I would check and clean the cable connections at battery first as aChris suggested. The battery voltage from rectifier is low and my service notes says to only use a analog meter due to ignition system noise on digital meter.

1) Disconnect stator wiring at terminal block and test stator, yel to yel and each yel to ground. Yel to yel should read near infinity or 0 to .3 You should have no reading from yel to ground. Do not hold ends together with fingers as readings will be affected.
2) Measure voltage at solenoid and engine ground and note voltage.
3) Start engine and raise rpm to 1000 rpm's, voltage should rise and stablize @14.5 volts.
4) If voltage does not rise turn off engine and disconnect purple wire @ regulator. Turn key to On and measure voltage fom engine side of wiring, battery voltage should be present if not check wiring.
5) Connect meter to yellow stator wires at termnial at rear of engine,set meter to AC volts and start engine. If voltage is over 16 V regulator is defective.
6) If battery voltage is still low, hook meter to solenoid and ground and note voltage. Take battery load tester and drain battery for 20 seconds. Note battery voltage reading after load test,start engine and raise rpm to 1200. If battery voltage does not rise to 14.5 regulator is defective.
7) Regulator has a thermal overload internally and if insufficient water cooling from weak impeller or salt build up it will trip and not charge. Also if engine has had a impeller failure (overheat) it can damage regulator internally and may not show up till months later.

 

[achris]

Re: Rare charging problem in Mercury 150 V6

My boat is not charging if I measure the voltage at the batteries' terminals; around 12.4 VDC), but if I measure the voltage from the positive cable of the starting solenoid and the negative cable at lower end of the starter I have charging power. (13.x VDC). I really could not figure out because it is the same cable but at different ends.

Charging voltage looks ok to me, Could be a bit higher, but that may be because of the other fault down the line.... Regulator getting the wrong reference voltage.... Don't have a circuit of the regulator so I can't be sure how it's set up..

If your measuring at the battery posts, then take the terminals off and clean the battery terminals. If you're measuring at the ends of the cables, you have a bad cable end crimp/solder joint. Repair same.

Chris.......