alternator either charging too much, or not enough

[kopy kat]

1999 mercruiser 5.7 EFI--battery meter on console shows 12 volts on start up & warm up phase-but goes to 14 + volts upon increasing RPMs over 1200-and stays there all day (until engine shut down-and restarting = 12 volts again). The battery is fairly new, and fully charged with an automatic deep cycle charger before leaving home-fluid level checked ok--if left at low RPM too long, i.e. trolling speed, battery meter drops below 12 volts. Any ideas would be appreciated--thanks, Larry

 

[imported_Curmudgeon]

Re: alternator either charging too much, or not enough

Might be a precurser to an alternator problem, but if it ain't broke (yet), don't fix it (yet).<br /><br />Rev it up over 1200 and go about yur business!

 

[Don S]

Re: alternator either charging too much, or not enough

That is absolutly normal on how an alternator will act.<br />At the lower rpm, there is just not enough electrical (amperage) output to keep the battery charged, the higher rpms do work.<br />Might get your battery load tested, it may not be holding up as well as it used to.

 

[waterone1@aol.com]

Re: alternator either charging too much, or not enough

That sounds normal to me. please keep in mind that 12 volts is actualy low for a modern boat battery. We usually see 13.5 volts as normal for a battery with the engine running/charging. As a side note, if your volt meter is at the ignition switch, it is normal to see lower voltages if several accessories are running.

 

[kopy kat]

Re: alternator either charging too much, or not enough

thanks for the responses----will running the system at 14+ volts (on the console meter) for extended time overcharge the battery?

 

[Haut Medoc]

Re: alternator either charging too much, or not enough

No.

 

[mkast]

Re: alternator either charging too much, or not enough

The volt meter on your boat is more than likely not reading correct voltage. Get a digital mulitimeter, measure the voltage, at the battery before starting. Measire the battery voltage during warmup. Measure battery voltage over 1500-1800 RPM. Normal engine running voltage is 13.5 to 14.5 volts.

 

[f_inscreenname]

Re: alternator either charging too much, or not enough

Originally posted by mkast:<br /> The volt meter on your boat is more than likely not reading correct voltage. Get a digital mulitimeter, measure the voltage, at the battery before starting. Measire the battery voltage during warmup. Measure battery voltage over 1500-1800 RPM. Normal engine running voltage is 13.5 to 14.5 volts.

If his Volt meter as it is now is not reading correctly then he "has a problem". According to the gage it is right where it should be. <br /> If you are over charging the battery's it will show. If the battery's are fine (not bulging, hot or leaking) then trust what your gage is telling you, everything is fine.