Which Alternator for 2005 QSM11 670

[Jeremy Bendler]

I believe I have a bad alternator on my QSM11 670. I’m not at the boat right now. I’d like to order a new alternator but I’m not exactly sure what I need. Does anyone know off hand which alternator I need for a 2005 QSM11 670?

Dumb question but is this something that would be in stock at an auto parts store?

It’s going to be a few days before I can get to the boat so I’d love to show up with the part in hand.

Thanks, Jeremy

Topic

[Tom Mann]

Typo

“If the alternator doesn’t stop charging you’ll cook the battery” sorry for the additional post, I couldn’t edit my prior post.

[Tom Mann]

Battery voltage regulator

A voltage regulator sensor that’s built into the alternator is used to determine that the battery if fully charged. This allows the alternator rotor to spin without putting out any DC voltage so it doesn’t cook your battery. If the regulator does stop charging you’ll cook the batteries.

I was once offshore and my digital gauges were showing 14 volts then 15 volts on the port side. I shut down the engine, disconnected the alternator and stated my generator and used the battery charger to keep the batteries charged until I could find a new alternator.

[Tom Mann]

Battery load test

I would absolutely load test the batteries. You may have had a bad alternator, but you may also have one or both batteries that won’t hold a charge. If you don’t have a load tester, try to borrow one. If you always have your battery charger on while at dockside, then start the generator(also charger on) you’ll never know if your batteries will hold a charge. If you want to find out, fully charge your batteries, turn everything on 12vdc, (refrigerator, freezer, lights, etc, etc,) then try to start the engines without the emergency start switch (if you have one). Putting a full load on your batteries will tell you what condition your batteries are in. Also, the batteries should be checked every two months for water level (distilled only). In very hot weather, every month.

Tom

[Larry Backman]

Follow on question – how does an alternator sense battery charge?

The past 2 years I’ve been noticing my 8D battery pair needs about 1.5 gallons of distilled water every 2 months. This is after upgrading to a Reman QSM with a 130 amp alternator vs my old engines 80 amp alternator.

My alternator runs to a charging relay which delivers power to both batteries.

What regulates alternator output and how does it sense a full battery?

[Jeremy Bendler]

Tom Mann wrote:

I’m glad it worked out for you, how did you determine your alternator(s) were bad and it wasn’t the batteries? Did you load test the alternator and put a load test on the batteries? If you didn’t do a load test you could have been barking up the wrong tree.

Tom Mann

I’m not sure I followed the absolute best testing procedures but here is what I did:

With generator off, and shorepower off I tested the voltage at the alternators. I was showing 12.5 volts. With shorepower on and battery charger on I was showing 14 volts at the back of the alternator. With engines running and no generator or shorepower I was showing 12.5 volts at the alternators.

From this testing I concluded that 1. the alternators were sufficiently tied into the 12V system, and 2. the alternators were not generating voltage to charge the system with the main engines running. I replaced one alternator and ran through the three tests above again. The only change was voltage of 13.5 at the alternator with the engine running. I then replaced the second alternator and both are putting out 13.5-14 volts. Cummins gauges show 13.5 volts at the helm with the two mains running, no genny, no shorepower.

[Tom Mann]

Alternators for QSM11

I’m glad it worked out for you, how did you determine your alternator(s) were bad and it wasn’t the batteries? Did you load test the alternator and put a load test on the batteries? If you didn’t do a load test you could have been barking up the wrong tree.

Tom Mann

[Jeremy Bendler]

Thanks Guys! Turned out to be Delco 22SI 12V 160A. I replaced both alternators with Delco 22SI 12V 145A because that’s what I could find locally.

Install went well. Units cost me $133 each which I didn’t think was too bad. Cummins gauges at the helm show 13.5 v with both main engines running, no shore power and no generator.

Looks like that solved my issues.

Advance Auto didn’t take the old units for the core so I may look into having them rebuilt. I hate throwing stuff away.

[Tony Athens]

Although Tom’s answer could be right (that would be the typical default alternator–QSOL does not list it) but a couple of real good pics would pin it down.

Tony

[Tom Mann]

Alternator for QSM11

DELCO 22SI 130A 12V IREF
CUMMINS MARINE APPLICATIONS

[Jeremy Bendler]

It’s really cool that you took the time to check. Thanks Rob! I’ll check it out when I get to OCMD.

[Rob Schepis]

Serial number is not showing your alternator number which means it was supplied/installed afterwards – builder specific…. So you’ll need to see what you have on there now.

[Jeremy Bendler]

Thanks for the response. No pics. Not sure if stock but I believe it is. Serial number is 35104295. Diagnostic procedures: batteries are not being charged with engines running and generator off.

I’ll check the alternator Friday when I get to the boat. I’ll first check that I see battery voltage at the positive side of the alternator with all systems off. Then I’ll start the engine and see if the alternator puts out any additional energy.

if I could figure out the right part I’d like to take a replacement with me so I have it to make the swap.

Thanks again.

[Rob Schepis]

I guess you have no pictures of your alternator setup?
Are you sure it’s a stock setup? How about a serial number?
What symptoms are you seeing and what diagnostics did you do to determine it is the alternator?

[Author]

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