Charging voltage

[Moody Blue]

Have a 92 Mariner 40HP 4cyl ELPTO. The volt meter (dash) shows over 16V when running above 3000RPM. Drops to within "normal" range below 3000RPM. Can this damage the battery ? I have not checked actual readings with DVM yet. Ran the boat all summer with no ill effect (I think).

 

[Laddies]

Re: Charging voltage

That engine don't have a voltage reg. Ck. voltage at the battery with a test meter, it's probibly alright but a bad connection at the battery or a battery thats going bad can cause high voltage readings also

 

[jlinder]

Re: Charging voltage

i agree that you need to check the voltage at the battery with a voltmeter. In addition measure the voltage at the output of the alternator.<br /><br />Here is a longshot - I have a 3 wire alternator. The 3rd wire is sense voltage to control the alternator. Acording to ARCO who made my replacement alternator, the sense voltage comes via the ignition switch, and over time resistance creeps in and the sense voltage is falsely low. <br /><br />The alternator then compensates and raises its output voltage. ARCO tells you to disconnect the original sense wire and jumper the alternator output to the sense teminal. <br /><br />Just a thought.

 

[Moody Blue]

Re: Charging voltage

Thanks for the feedback. You are correct, this motor does not have a regulator. What safeguards are there to prevent overcharging or overvoltage. Does this motor have a separate alternator or does it somehow use the flywheel/ignition system to generate the voltage ? Interesting comment about the sense wire - makes good sense. Will have to wait a few more months before looking into this any further. The boat is in storage under 12" of snow and the lake has 20" of ice on it. Can't wait till ice out !!

 

[Paul Moir]

Re: Charging voltage

There's a stator up underneath the flywheel that has an electric current induced into it by permanent magnets attached to the flywheel. There is no alternator like you would find on a car. The stator also supplies power to the ignition system via a separate & independant set of coils.<br /><br />With no regulator, there's no protect for overcharging or overvoltage. The battery is used for voltage regulation. If you were to detach the battery from the running outboard the voltage would spike to the point where the rectifier on the outboard would begin to conduct both ways. When that happens, it quickly burns out.<br /><br />The only protection you have from overcharging is that the system is relitively weak. I'm not sure what the maximum current output is for your outboard, but it's likely not more than 10 amps. A large, non-maintanance free battery that you can add water to as it's lost by overcharging is your best bet.

 

[Moody Blue]

Re: Charging voltage

Very informative. Didn't realize you can't disconnect the battery from a running outboard. I learn something new here everytime. What a wealth of knowledge here on this forum. Thanks again.

 

[Boatist]

Re: Charging voltage

If your voltage is 16 volts that is too high. With no regulator about all you can do is to increase the load on the battery. Try turning on your running lights or your bildge blower. If it is still 16 volts then make sure you check your water levels in the battery often.

 

[Moody Blue]

Re: Charging voltage

How is the charging voltage and water level related ?

 

[ziemann]

Re: Charging voltage

If the voltage is too high, it over charges the battery creating heat thus boiling off water....<br /><br />In this scenario, you just need to check that much more often...

 

[Moody Blue]

Re: Charging voltage

I see. Something I have not made a habit of until now. Will at it to my periodic check list. Thanks.

 

[imstillatwork]

Re: Charging voltage

My evinrude 70 (1981) will run with the battery disconnected. (no seperate alternator)<br /><br />whats really neat is my 1970 Yamaha CS3 (bike)<br /><br />It's starter is also the generator. give it juice and it startes the bike, after its running, it charges the battery, runs lights, etc.. never seen a nything like that before.

 

[Boatist]

Re: Charging voltage

Imstillatwork<br />It may run without the battery if you have some load but it will soon blow all your output diodes in your rectifer and will no longer charge at all. Most alternators this will happen even if someone turns battery switch thru the off postion with the motor running. If you have run with out the battery and it still works you are very lucky. Most will blow in a second or two.

 

[18rabbit]

Re: Charging voltage

Originally posted by Boatist:<br /> ... Most will blow in a second or two.

Make that a millisecond or two.