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intermittent tachometer and increasing charging voltage

PostPosted: Thu Sep 24, 2009 12:25 pm
by alison kim
I have a 100A Ample Power altenator and a Next Step (12P, SN 2001 on my boat and am experiencing problems with the unit(s). These units are both approximately 5-7 years old.

House and starting Batteries are Lifeline Grp 27, 12V AGM's ~ 5 - 7 years old

Problem sigantures:
After engine start, Tachometer works fine, regulator works fine . Initial Bulk charge voltage starts at ~ 14.5 V (indicated on DVM). Charge voltage notmally falls off to ~13.4 VDC after 2 Hrs or so..

Initial problem signature: Recently, after approximately one to one and a half hours of operation, tachometer drops out. Error indicator shows up on Next Step regulator. Battery charge voltage starts to creep up from ~13.5/13.7 VDC to 14.7 / 14.9 VDC. Unfortunately I was not able to capture the error codes on the fault indicator when the symptoms initially started to show. Tach display will return intermittently for varying periods of time, on occassions returning for good, at other times failing to return.

I have changed the tachometer out thinking it was a bad tach.

Most recent behavior (after changing Tachometer): I tightened the alternator belt tension slightly, and checked easily accessible wiring between the Tach, altenator and regulator for bad connections. None observed. Following engine start, tach works fine, charging voltage appear normal (starts at ~14.5 V and begins to drop slowly over approx 1-1.5 Hrs to 13.7-13.5 VDC. After approximately 1.5 Hrs of engine operation, Tachometer drops out, charge voltage starts to creep up from ~13.5/13.7 VDC to 14.7 / 14.9 VDC. The Next Step error indicator does not show any faults. Tachometer does not return. The fault signature appears to have changed

Got any suggestions?

Al Kim