I think my charging system may be dead.....

[saltfisher]

Today i took my boat out and it was barely cranking over. Only used the battery 2 times. I called my dad and he gave me his battery he just got. I used it all day yesterday just for starting the engine, and running the livewells, and he said it was drained pretty good. I dont think my motor is charging my battery when im running. Is there a alternator on a motor? Its a 1988 150 black max. Not sure where to start with this. Is this a complicated system? or is it a one part replace to fix type thing?

Thanks

 

[hkeiner]

Re: I think my charging system may be dead.....

The problem could be with a variety of components in the charging system, but the most likely cause is a bad voltage regulator. These are easy to replace but relatively expensive. I would not suggest replacing them on a hunch (educated guess?). It would be better to first confirm that a voltage regulator is bad, by performing various troubleshooting tests, before replacing one unnecessarily. These tests, as described in your shop manual, require the use of various meters. If you don't have a shop manual or any of the required meters, then you will be pretty much guessing at the problem.

Others on this forum may have additional or better advice than this.

 

[Barnacle_Bill]

Re: I think my charging system may be dead.....

The simplest way to check to see if its charging is to check the voltage at the battery with the motor not running and then check it again with it running. If its working you will see an increase in voltage. You won't see much tho until the motor approaches about 2K RPM. If you have ever cause a spark like hooking up the battery cables backwards even for a second, your rectifier/regulator is toast.

 

[saltfisher]

Re: I think my charging system may be dead.....

At one point, yes i accidently put the terminals on backwards, then was wondering why the starter wasnt engaging. I figured terminals were switched. They were.... so i guess I fried the regulator?

 

[hkeiner]

Re: I think my charging system may be dead.....

I presumed that the system was not charging based upon the symptoms you described, but it is good to confirm this first using the voltmeter test method as wisely suggested by BHILE. Once it is confirmed that the charging system is not charging, you then need to figure out why. This is often caused by a failed voltage regulator, but not necessarily. The purpose of my earlier suggestion was to possibly save you the expense of replacing a voltage regulator(s) that is not really bad as they can be a bit pricey.

 

[saltfisher]

Re: I think my charging system may be dead.....

When you say the regulator is quite expensive, about how much are we talkin? under $200 or over $200?

I will try the battery test next time i go out, and make sure i have 2 starting batteries with me. I did hook up the terminals backwards at one point, but dont think it was charging before i did this. So if i test, and the battery is not being charged, it could still be anything in the charging system?

 

[hkeiner]

Re: I think my charging system may be dead.....

You can check the Marine Store on this web site for some pricing information and/or check the web. There are several brands of voltage regulators available and many retail sources. The Mercury OEM regulators are the most expensive. Sierra and CDI/Rapair brand regulators are a lot cheaper and have good reputations as far as I know. I installed two new CDI/Repair regulators on my motor last fall and they still work fine so far. They were just under $100 each as I recall.

I suggest first bench testing the regulators for failure. They are the probable culprits. However, if they pass the various bench tests (as described in the shop manual for your motor), then you can think about other tests of the charging system.

 

[JMRuth72]

Re: I think my charging system may be dead.....

A very good place to start is to check the battery voltage as described above motor off then motor on. If there is no change see if you can test the input voltage and output voltage at the regulator with the motor running. I am not sure what it is supposed to be. If there is a good voltage in, but not out then your regulator is bad. The way I was taught to trouble shoot electricity is to start roughly in the middle of a circuit. If you are getting what you are supposed to be getting move towards the load (the battery in this case), if you are not then you move towards the source (the generator in this case). Always working near the middle of the known points.

Example:

Components in order from generator to battery.

1.) Generator (Source)
2.) Voltage Rectifier (converts A/C voltage from generator to D/C Voltage.)
3.) Voltage Regulator (takes variable D/C Voltage and stabilizes it at about 14.4 VDC.)
4.) Battery (Load)

This is assuming that the Rectifier and Regulator are 2 assemblies They are regularly one assembly, but it demonstrates below what I meant by working at roughly the middle. If you know that a particular part is a high failure item that is a good place to start and work from there. To start testing you would check the components in roughly the following order.

1.) Regulator voltage in/voltage out (D/C in and D/C out).
no voltage in = move to Rectifier
good voltage in/no voltage out = replace regulator
good voltage in/good voltage out = check connections between regulator and battery.

2.) Rectifier voltage in/voltage out (A/C in and D/C out).
no voltage in = move to Generator
good voltage in/no voltage out = replace rectifier
good voltage in/good voltage out = check connections between rectifier and regulator.

Continue using above technique until you find the source of the problem keeping in mind that it can actually be wiring. It doesn't always have to be a part.

Note about using a multimeter, if you have your multimeter set wrong you may replace a part that didn't need it. Keep in mind that some multimeters only use symbols to label ie a wavy line for A/C, straight for D/C and Omega for ohms. Finally probably the two most important things are safety related. Never use the ohmmeter function with a circuit under power, it can not only fry your meter but with sufficent voltage hurt or kill you and NEVER put your fingers on the metal part of the probe.

As thoroughly as possible you also want to visually inspect all wiring for signs of chafing/shorting or any other defect. Troubleshooting electricity is not hard, but it can be very tedious especially on a airplane. Compared to that small boats are easy. Take care, be careful and hope you find the problem.

Good Luck.

 

[Barnacle_Bill]

Re: I think my charging system may be dead.....

There is a possibility you don't have a regulator. Just a rectifier. Go to Mercurypartsexpress.com and plug in your serial no. You can then look at exploded views of your motor and see what you have. In any case I can assure you hooking the battery up backwards has fried the diodes in your rectifier.