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Old 06-06-2013, 08:20 PM   #1
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Replacing the Alternator

Before I started our trip to Alaska this spring, I replaced the original 83 amp alternator on a Perkins 6.354 with a Balmar 100 amp with a separate charge controller. The first alternator "ate itself" and is back at Balmar being "evaluated". The second one works as planned. In the course of replacing it, I also replaced an old West Marine ACR with a Blue Sea ACR. During the installation, both the instructions and local marine installer recommended connecting the charge controller sense wire to the house bank, since that was the bank with the most charge demands. I did that and things worked fine until about day 3 in our trip, when the charge voltage jumped up to 15.9 volts on initial startup and the ACR refused to combine the house and start banks (It won't work above 15.6 volts.) I shut things down and did a quick inspection and fired things up and everything worked correctly. The same thing happened two days later. At that point, I decided the problem was the sensing wire looking at the voltage on the house bank and the charge controller wanting to throw everything at the house bank even though the ACR had not combined the house and start banks. The voltage escalated up to 15.9 volts because no matter what the controller did, it didn't see a change on the house bank voltage as the ACR hadn't switched yet. I moved the sense wire over to start bank and everything has worked as you would expect for the last 18 days. The only thing I have noticed on a couple of occasions in this configuration is the alternator won't initially output anything until there is a sufficient voltage drop on start battery to trigger charging. This generally occurs after running for a long period bringing all battery banks up to 100% and then shutting down for fueling and then starting back up.

Hope someone can use this experience.
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Old 06-07-2013, 12:33 AM   #2
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Sounds like a voltage regulation problem rather than a combiner problem.

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Old 06-07-2013, 06:01 AM   #3
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Perhaps the next combiner should come from the RV store , $17.00 and the solenoid doesn't give a damn about voltages , it simply works.
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Old 06-07-2013, 11:03 AM   #4
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Your BlueSeas ACR must be different than mine (ACR-SI) Mine has no sense wire and combines when either bank charges. Works great and seems to do exactly what I tried to remember to do with the 1,2,both switch. I like it and no problems.
It does have another wire, which when connected to the starter, seperates the banks while you are starting. Which I didn't use.
I don't know which mod# you have but why would it need a sense wire? It is already connected to each bank.
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Old 06-07-2013, 01:10 PM   #5
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The sense wire is on the voltage regulator and is the basic means the voltage regulator uses to determine the charge state of the batteries and the amount of current to throw at them. If your alternator has an internal regulator, it is always sensing the start battery bank for charging. I think what I saw was a consequence of using an external regulator where I could pick the source for voltage sensing and the one I picked confused things.
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Old 06-07-2013, 01:18 PM   #6
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Quote:
Originally Posted by tpbrady View Post
The sense wire is on the voltage regulator and is the basic means the voltage regulator uses to determine the charge state of the batteries and the amount of current to throw at them. If your alternator has an internal regulator, it is always sensing the start battery bank for charging. I think what I saw was a consequence of using an external regulator where I could pick the source for voltage sensing and the one I picked confused things.
Sorry, I thought you meant your ACR had a sense wire and couldn't understand why. I should read more carefully...
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