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ContinuousWave: Small Boat Electrical
Chronic Dead Battery On 60-HP Outboard
|Author||Topic: Chronic Dead Battery On 60-HP Outboard|
posted 09-16-2007 11:42 AM ET (US)
Hello everyone. I have been surfing this site for a year now. I am new to boating . I have a 1985 15-foot center console with a 1985 60-HP Evinrude, bought new in Florida by a cousin used about dozen times. My brother went down and brought it up north and used it with his kids. According to him it has always had a battery problem: battery goes dead trying to start. The boat had every type of electrical lights, gauges radio, fishfinder. He just slowly cut one piece at a time; his way of fixing problem. So as it sits the only remaining active electrical is the key switch and choke.
I bought a battery August 20, used the boat during that week. used the boat about eight times, now the battery is dead. I would like to get boat back to original. Can I buy a wiring harness and start from the beginning? Why is my battery dead?
posted 09-16-2007 12:07 PM ET (US)
A battery stores electrical charge and when this charge is used up the battery must be recharged. The usual arrangement in a boat is to have the motor provide charging current to the battery. From your narrative it sounds as if the motor is not providing charging current to the battery, or if it is providing charging current it is not providing sufficient charging current to maintain and restore the charge.
Do you have an accurate electrical voltmeter that can measure DC voltage in the range of 0 to 16 volts with a resolution of 0.1-volts?
posted 09-16-2007 01:27 PM ET (US)
Jim, have a snap-on multi meter, not sure if it will work on this motor,
posted 09-16-2007 09:50 PM ET (US)
Dan--Check the charging system on your motor as follows;
Measure the battery terminal voltage with the motor shut off. It should be around 12.6 volts, depending on the state of charge of the battery. If the battery voltage is below 12.2-volts it is badly discharged. Obtain an AC-powered battery charger, and recharge the battery until it is back to full charge. For information on how to deduce the state of charge from the terminal voltage of a battery see my article in the REFERENCE section,
Start the motor and operate it at a fast idle speed of 1,500-RPM.
Measure the battery terminal voltage. If it is 14.2-volts or slightly higher then you can assume your outboard motor is supplying charging current to the battery.
The next step is to determine how much charging current. Many older outboard motors have very modest charging current output, often less than 10-amperes at peak and tapering to even less at lower engine speeds. Check the owner's manual for your motor to discover the specified charging current output. On some OMC motors there was a standard low-current charging circuit and an optional high-current charger available.
It is not unusual that the charging circuit of an outboard motor has failed, but the motor runs perfectly well. The charging circuit is often completely separate from other electrical circuits in the motor, and it can fail or malfunction without affecting the operation of the motor.
posted 09-16-2007 09:51 PM ET (US)
Report the results of your tests, and I can offer some advice on what to do next.
posted 09-19-2007 12:03 PM ET (US)
Battery was at 12.93 Starting the boat and running
at about 1500 rpms it read 13.30
posted 09-19-2007 04:58 PM ET (US)
What was the battery terminal voltage when the motor was not running and when you were not cranking?
posted 09-20-2007 07:34 AM ET (US)
before starting boat battery was at 12.93
running at 1500rpms it read 13.30
posted 09-21-2007 02:20 PM ET (US)
Well I spent time cleaning the connections from the battery to the starter made sure everything was tight it started right up. Took boat out this morning and all was fine.
posted 09-23-2007 02:31 PM ET (US)
The observation that the terminal voltage of the battery rose when the motor was running as compared to when the motor was not running is a positive indication that the motor is delivering some charging current to the battery. However, the voltage rise was quite modest, and we can infer that the amount of charging current was similarly modest.
The only way (that I know) to determine the precise amount of charging current being delivered is to insert a current measuring device in the circuit. This can be hard to do because during starting there is very high current flow, and a regular ammeter would not be suitable for the job.
At this point I would guess your motor charging circuit is operating, but it may not be providing as much charging current as your operating style demands in order to reliably recharge the battery from just running the motor. You may need to supplement the battery charging with a shore-power AC-operated battery charger.
posted 09-25-2007 11:29 PM ET (US)
One final thought. The charging circuit can run your battery down when the engine is not running if your regulator is bad. Not real common, but they have been known to do this. Get a cheap-o digital multimeter, or anything with a current scale (amps). With everything disconnected, connect it between a battery terminal and corresponding battery lead. See if you are still drawing current. If so, try disconnecting the regulator and see if the draw goes away. I have had this problem on cars that I have owned in the past too.
posted 09-26-2007 10:52 PM ET (US)
If all else fails, install a battery shut off switch. It is a good idea even if you find and fix the root cause of the problem.
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