Alternator check?

FlyWright · Sep 3, 2014

A 7 year old pair of GCs as the house bank might be approaching the end of their life expectancy. If your batteries are weak, they won't be able to accept the charge available. It's the acceptance rate of the batteries that will determine the current flow. If the batteries are sulfated, they will suffer a reduced acceptance rate.

Have you noticed reduced battery capacity during extended periods on the hook? Do you have a SOC meter?

Larry M · Sep 3, 2014

Brooksie · Sep 3, 2014

BobH said:
Take it to an alternator shop, not AutoZone or O'Reilleys. Most alternator shops will test it for free.

Saves a lot of time and frustration.

Bob

That's what I am going to do.

Brooksie · Sep 3, 2014

FlyWright said:
A 7 year old pair of GCs as the house bank might be approaching the end of their life expectancy. If your batteries are weak, they won't be able to accept the charge available. It's the acceptance rate of the batteries that will determine the current flow. If the batteries are sulfated, they will suffer a reduced acceptance rate.

Have you noticed reduced battery capacity during extended periods on the hook? Do you have a SOC meter?

I did a load test on the batteries first and they were good. That's when I decided to "load test" the alternator. My reasoning: each load I turn on, pumps lights reefer causes a rise in the output of the alternator, so why not turn on the 150A load tester and see if the meter will go up to the 90A set point I put on the regulator.No, no SOC meter, never saw the need. How would one help in this situation?

FlyWright · Sep 3, 2014

Brooksie said:
No, no SOC meter, never saw the need. How would one help in this situation?

It would give you a good picture of the health of your house bank. Not a perfect picture, but a good one.

FF · Sep 4, 2014

One hassle to remember when having the shop bench test an alt is the unit will be cold.

Many light duty auto style will loose 25% to 50% of their charge ability when Hot

bayview · Sep 4, 2014

I think we have a winner now that we know the batteries may be getting long in the tooth.

Brooksie · Sep 4, 2014

bayview said:
I think we have a winner now that we know the batteries may be getting long in the tooth.

Could very well be, I plan to replace them this winter anyway. I may just continue on and finish the season out b/4 doing anything.

Brooksie · Sep 4, 2014

Reporting back...
I did take my alternator to a shop to have it checked and no it was not putting out full amperage nor even the 90A that I had set on my regulator. It was. however, putting out correct voltage.

And yes, my method of putting the battery load tester on it was correct, it should act just like any other load you switch on and cause the ammeter to jump up just like a pump or light does.

By the way, I bought it from Alterstart in TX in 2007 for $100 and it has worked well for all these years.

I'll report again on the shop's findings.

Forkliftt · Sep 5, 2014

That's good info about how you used the load tester for added draw.

1983 Present 42 Sundeck
Twin Lehman 135's

Brooksie · Sep 12, 2014

Brooksie said:
Reporting back...
I did take my alternator to a shop to have it checked and no it was not putting out full amperage nor even the 90A that I had set on my regulator. It was. however, putting out correct voltage.

And yes, my method of putting the battery load tester on it was correct, it should act just like any other load you switch on and cause the ammeter to jump up just like a pump or light does.

By the way, I bought it from Alterstart in TX in 2007 for $100 and it has worked well for all these years.

I'll report again on the shop's findings.

Shop said "some bad diodes"

Alternator check?

FlyWright

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Larry M

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Brooksie

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Brooksie

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FlyWright

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FF

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bayview

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Brooksie

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Brooksie

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Forkliftt

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Brooksie

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