Josh,
I’ll head out there this weekend (weather permitting), change the belt
(it’s been a while) and do some tests.
Since you have a 37+ too, how do you get back there to test the
alternator terminals? I’m considering adding an access port in my head so I can
get to the port side of the engine.
All the best,
Edd
Edd M. Schillay
Starship Enterprise
C&C 37+ | Sail No: NCC-1701-B
City Island, NY
Starship Enterprise's Captain's Log
On Jul 31, 2014, at 2:58 PM, Josh Muckley <[email protected]> wrote:
> Edd,
>
> Do you have an internal or external voltage regulator (charge controller).
> Regardless the alternator is probably putting out the amount of voltage
> required by the regulator. Often times the voltage being supplied by the
> alternator is different than that being sensed by the regulator. Recently
> one of the listers had his sensing line corroded to the point of falling off.
> In this case regulator sensed too low of a battery voltage and drove the
> corresponding alternator output up...to ~33v! Likewise if high resistance on
> the output cabling or voltage being dropped across a battery isolator diode
> is causing the regulator to think there is more voltage being sent to the
> batteries than there actually is then the regulator would drive alternator
> oupltput down. The voltage drop across an isolation diode is about 0.7v and
> the normal full charge voltage for a standard wet lead acid battery is 14.4v.
> So 13.7v is easily explained. If the contacts or cabling are getting old
> and corroded then the remaining 0.5v drop to 13.2v is explained. The cabling
> included the ground connections made by mounting the alternator to the engine
> and the bonding/ground cable feom the engine to the batteries.
>
> Check and compare the voltage at the alternator output terminals, the battery
> terminals, and the sensing terminals.
>
> Yes a loose belt can cause low output but you would probably hear it. Once
> it stops slipping the output returns to normal.
>
> Good luck,
>
> Josh Muckley
> S/V Sea Hawk
> 1989 C&C 37+
> Solomons ,MD
>
> On Jul 31, 2014 2:13 PM, "Edd Schillay via CnC-List" <[email protected]>
> wrote:
> Listers,
>
> Lately, when the engine running, I’m seeing the voltage reach 13.2 tops
> when it used to be much higher (13.7 to 14.0).
>
> Is this an alternator issue or is it the belt tightness? Any
> suggestions would be much appreciated.
>
>
> All the best,
>
> Edd
>
>
> Edd M. Schillay
> Starship Enterprise
> C&C 37+ | Sail No: NCC-1701-B
> City Island, NY
> Starship Enterprise's Captain's Log
>
>
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