intermittent tachometer and increasing charging voltage

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intermittent tachometer and increasing charging voltage

Postby alison kim on Thu Sep 24, 2009 12:25 pm

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
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Re: intermittent tachometer and increasing charging voltage

Postby Coulomb on Thu Sep 24, 2009 12:32 pm

What kind of batteries are you using?
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Re: intermittent tachometer and increasing charging voltage

Postby alison kim on Thu Sep 24, 2009 1:01 pm

Coulomb: refer to submittal of 09/24/2009
"Tachometer drop our and rising charge voltage"
Regarding your question about "What Kind of batteries are you using?"

Batteries are Group 27, 12VDC Lifeline AGM (Absorbed Glass mat)

Alison Kim,
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Re: intermittent tachometer and increasing charging voltage

Postby Coulomb on Thu Sep 24, 2009 2:23 pm

Here's what I think is happening - the batteries are so full that they can't accept even the current generated from residual magnetism in the alternator. The output current isn't high enough to drive the tach, but enough to overcharge the batteries.

For more info: http://www.amplepower.com/primer/tach/index.html It says, "One possible solution is to turn on some electrical loads, forcing the alternator to produce more output, and hence, more tachometer signal strength".
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Re: intermittent tachometer and increasing charging voltage

Postby alison kim on Mon Sep 28, 2009 4:44 pm

Columb,
My present charging systems consist of the following items going from the initial configuration (earliest => installation of the Ample power Altenator & Next Step 12P Regulator) to the last configuration chnage / modification

A) Installation (approximately 5 to 7 years ago) of the Ample power altenator & Next Step Regulator along with (5) Lifeline AGM's : 4- Group 27, 12 VDC for the house battery system and one Group-27 12 VDC for engine starting.
No Problems with Tach or Next Step regulator observed

B) Zantrex Link 1000 Controller fed by a Zantrex Freedom Model 20- Inverter / Charger that has been on the boat for approximately 2 1/2 years ( Dec 2007) . No problems observed with the Tach or the Next Step Regulator

C) Approximately 4-5 months ago, prior to installation of the Kyocera Solar panels and Blue Sky Controller (D below), I observed that the tach was dropping out infrequently. The tach would return to normal functionality quickly and I did not attempt to correlate any change in regulator output voltage at that time with the Tach drop out or the observation of any Next Step Error codes so I cannot comment on any Next Step Regulator misbehavior. When the symptoms first appeared, I dismissed the tach behavior as a "sticky / intermittent" Tach that needed changing.

D) 2 x 100 W Kyocera Solar Panels driving Blue Sky controller. The Blue Sky Controller feeds solar charging current to the (5) Lifeline Grp-27 batteries through the Zantrex Link 1000 controller. Just installed July 2009.

E)Tach drop out becomes more prolonged and I have observed error codes on the Next Step Reg after prolonged operation. Tach Drop out observed to be associated with rise in charging voltage.

I have observed that the Tach signal and a wire going over to the Next Step from the back of the Ample power altenator comes out of a plug from the back of the altenator. This plug (two wires) seems to be a little sloppy / loose. Could there be a problem with an intermittent connection at this altenator connector or the circuitry feeding the tach signal and the wire going over to the Next Step that might be susceptible to heating after the altenator has operated for a while?

I have thought about the batteries going bad as a possible cause, but I cannot identify any reason for the Tach signal to drop out when / if the regulator tries to bush current into the batteries as a result of a "full " battery. Am I not understanding something here, or is the Tach signal associated with some kind of control signal between the altenator and the regulator?

You suggested turning on some DC loads when I get a drop our. I have a DC refrigeration system that pulls approx 4 Amps (operating duty factor approx 30 % of the time) operating all of the time, and generally have a light (draws ~2 amps) on in my engine room when the engine is operating. When the Refrig and light are operating, the DC current load is approx 6 amps. when the light is operating by itself, the draw is about 2 amps SS. Do you I need to pull more load?
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Re: intermittent tachometer and increasing charging voltage

Postby Coulomb on Wed Sep 30, 2009 11:31 am

The Primer has been updated to cover the use of solar panels.

Re-read http://www.amplepower.com/primer/tach/index.html.
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