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Old 07-23-2011, 12:56 PM   #1
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alternator problem?

Hi everybody,

yesterday i was cruising at 2100 rpm and suddenly my RPM and amp meter went down like ... it was not charging or really charge at minimum. After 5 minutes it return at normal.

I check* the belt tension... it was ok, check all connections on the alternator....ok

what could be the problem? any suggestion.
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Old 07-23-2011, 10:26 PM   #2
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RE: alternator problem?

Quote:
septembre wrote:
yesterday i was cruising at 2100 rpm and suddenly my RPM and amp meter went down like ... it was not charging or really charge at minimum. After 5 minutes it return at normal.

I check* the belt tension... it was ok, check all connections on the alternator....ok

what could be the problem? any suggestion.
Assume your engine rpm's did not go down?* If not, then you've already done the easy stuff:* It's almost always either belt slippage or electrical connections.* But it might be electrical connections away from the alternator.* Check all your grounds, especially those connected to your engine.

Good Luck.
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Old 07-24-2011, 04:29 AM   #3
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RE: alternator problem?

Depending on the batt bank size , and the brain in the V reg , this is not unusual.

When at the V reg,a need for zero charge is felt , no charge is given, so Zero amps.

Turn on something , fan , bilge pump , and the alt output should go up.

A really $mart V reg will understand the fully charged state and switch to a lower voltage to save batt water.
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Old 07-25-2011, 02:39 AM   #4
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RE: alternator problem?

Hi everyone, THought i would add my thoughts on this thread as just recently i diagnosed the same problem on my boat.

Basically my house bank would not charge while underway. The start bank was fine. Both alternators are new, putting out required voltage etc. The checks i did were:

Measure alterator voltage with motor running and got 14.2 volts or so. THen measure voltage at house battery terminals. Got 12.9 volts after having just been on charger via shore power. Batteries are good as new.

what was happening was the alternator output was not reaching house bank...

Reason: CHecked all the ground terminals and the main terminal from engine to house bank was completely loose and coming out of the terminal lug.

All i did was for now,*postition the ground wire*back into the lug as*hard as i could and taped it up tight. Checked voltage with engine running at house battery and it is all perfect with same voltage as alternator. So problem solved.

I then went and checked all grounding terminals and found some other suspect ones.

Hope this works for you.

*

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Old 07-25-2011, 06:09 PM   #5
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RE: alternator problem?

i think some alternators also are tied in with the tachometer and transmit the rpm to the instrument gauges.
so if his rpm went to zero, it could mean there is something wrong, the alternator is not spinning or if it spinning there must be some internal problem with the unit.
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Old 07-26-2011, 03:48 PM   #6
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alternator problem?

my tachometer is connect to the alternator and when this thing happened it went to 2200 rpm to 500 rpm on the tachometer.

and , i forget , the alternator was turning normally.


-- Edited by septembre on Tuesday 26th of July 2011 03:49:34 PM
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Old 08-11-2011, 02:02 PM   #7
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RE: alternator problem?

UPDATE,

there was a bad connector attach to the alternator.

this connector was close to the voltage regulator and with the motor vibration...was touching the casing of the regulator.

I changed :wire and connector.... everything is working fine now.

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Old 08-11-2011, 02:43 PM   #8
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RE: alternator problem?

Awesome. Glad it was easy.

I always have said that a good visual inspection on a routine basis solves many problems.
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