Charging problem - Cummins Diamond 450

scbob

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Yet another opportunity .......
The starting batteries seem to charge fine, but not the house, from the engine. They charge fine from generator and shore power.
There's a "little red box" in the circuit that I believe splits the charge between start and house batteries.
A friend is looking after the boat for me and sent me the following info:
He temporarily wired an ammeter into the circuits and got the following info:

The alternator was charging 14 amps to starter battery and 0 to 1 amp to the house bank, at idle I believe.
Starting battery showed 12.9 volts; house showed 12.6 volts.

It seems to me that this "little red box" is something that prioritizes charge to start batteries, up to a voltage, then switches charge to the house. There's no apparent way to adjust this unit, that we can see.
There's also a Xantex Freedom 20 100 amp inverter/charger; but I believe this is not part of this alternator charging issue.
Does this make sense to anyone please ?
Do I just need to replace the unit or what please ?
Once again, thanks in advance
Bob
 
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WoundUpMarine

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It sounds like the little red box is an auto charging relay(ACR), and that it isn't closing to let the house battery charge. Any way you can get a few pictures from your friend so we can see what all the components really are?
 

scbob

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Thanks Wound up.
Well he just had knee surgery and is not really up to crawling around engine right now.
I live 6 hours away, and no plans to go in short term.....
I've done some reading up in meantime, and maybe this is one of those diode systems, judging by the heat sink fins on the "little red box".
 

Diesel Jerry

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Thanks Wound up.
Well he just had knee surgery and is not really up to crawling around engine right now.
I live 6 hours away, and no plans to go in short term.....
I've done some reading up in meantime, and maybe this is one of those diode systems, judging by the heat sink fins on the "little red box".
It sounds more like an isolator to me rather than an ACR. Normally an ACR is installed between batteries so to speak. An Isolator is usually wired off of the alternator.
 

djmarchand

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The voltages are low, well duhh!. A fixed output alternator which is probably what you have (one without an external regulator) should put out about 13.5 volts at the alternator terminals. Measure the voltage at that point. Then the diode isolator if that is what it is, will have a voltage drop of about 0.5 volt, so the output (the battery sides) should be at about 13.0. But one output is significantly lower.

After checking the alternator output voltage I would bypass the "red box" and see what happens. Both battery side voltages should jump to the same level. Let the engine run for a while, several hours if you can and see where it stabilizes. If they all stabilize at 13.5 or so the replace the red box, preferably with a combiner (see yandina.com) or an ACR such as Blue Seas.

David
 

Diesel Jerry

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The voltages are low, well duhh!. A fixed output alternator which is probably what you have (one without an external regulator) should put out about 13.5 volts at the alternator terminals. Measure the voltage at that point. Then the diode isolator if that is what it is, will have a voltage drop of about 0.5 volt, so the output (the battery sides) should be at about 13.0. But one output is significantly lower.

After checking the alternator output voltage I would bypass the "red box" and see what happens. Both battery side voltages should jump to the same level. Let the engine run for a while, several hours if you can and see where it stabilizes. If they all stabilize at 13.5 or so the replace the red box, preferably with a combiner (see yandina.com) or an ACR such as Blue Seas.

David
Yup....do that. 100% agree.
 

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That little 'red box' sounds like an Isolator, as Jerry said. NOT a fan of the traditional diode isolators. Aside from inducing a huge voltage drop (usually around 1V) which is what you'd see on the stud coming off the isolator, only causes bigger issues further down the line as the voltage drops as it passes through other terminals, cables, etc. HIGHLY recommend going with a combiner AKA charging relay (see Blue Sea's ACR), which essentially will allow the engine bank to reach a stable voltage, usually 13.7VDC before combining the charge from the alternator to both the engine AND house banks, with a FRACTION of the voltage drop. Talking less than a tenth of a volt.. That said, there are companies that make FET isolators which have the same low low voltage drop, and are easier to swap in some cases from a traditional isolator. Victron makes their ArgoFET isolator, you just have to select one that makes the output of the alternator (can't see you having an alternator putting out more than 200A, I think the OEM alternator was rated at 105A, but that's something Jerry would know better.) I would confirm which alternator you have. Here's a link to that Victron FET isolator page
Argo FET Battery Isolators - Victron Energy

Also, as you mentioned, you're only getting 12.9 at the starting bank, and usually that alternator would be putting out close to 14VDC, so checking the output AT the alternator would tell a better story, as it's possible that red box is a more sophisticated relay that is waiting to see 13.7VDC at the engine bank before combining and charging both banks. Have him crank the engine up from idle to at least 1800RPM or your 'cruise' RPM to see the true output of the amperage and voltage of the alternator. Also, in these cooler temps, it should actually charge closer to the rated RPM if it's a stock unit as most alternators once they heat up, put out considerably less current than as advertised.

One other important note; you mentioned you had that Freedom Inverter charger; some of those units were installed with a Link display/controller, and there was a Link 1000-R or Link 2000-R which actually included an alternator regulator. It was rare, and usually paired with a higher output alternator on sailboats/trawlers or any other single engine boat where a HOA required regulation. If that's what you have, that's something you need at least need to consider, although with the symptoms don't exactly point to a regulator issue, more of a charger distribution issue. Here's a link to that manual, you should be able to see on the Link if it's an R model or not. Worth at least checking out. Good luck!
http://www.xantrex.com/documents/Discontinued-Products/Link200R-445-0197-98-01_Rev-1(vendor).pdf
 

scbob

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Great info thanks.
Last night my buddy told me there was 14 volts or so from the alternator.
A new Victron Argo 100 or 200 is really quite cheap - for once its not the typical $1,000 to fix something. LOL
I need to get to the boat and do these tests as you suggest, and get the problem fixed.
Thanks again,
Bob
 

Pequod

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Also consider where the sensing wire of the alternator is. It should be on the battery side of the charge divider to overcome the voltage drop from the diodes.
 

djmarchand

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Also consider where the sensing wire of the alternator is. It should be on the battery side of the charge divider to overcome the voltage drop from the diodes.
Good point. Not all alternators have external voltage sensing terminals. But if yours does then hooking it to the battery side, preferably the house battery side, will let the alternator put out a high enough voltage to compensate for the isolator's voltage drop. This way the house battery will get the full capability of the alternator output.

David
 

captjohn

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I have the Argo FET Battery Isolators that Warf Rat mentioned. I have twin engines and a generator, with 4 batteries (two starting batteries, one house battery and one starting battery for the generator). I installed two isolators, one per engine, AND I moved my alternator sense lines from the alternator stud, to the input stud on the isolators, to compensate for any voltage drop between the alternator and the isolator. It's been probably 5 years now, and I couldn't be any happier with the setup. Everything is completely isolated, the voltage drop is insignificant, and no moving parts to worry about. I highly recommend this kind of setup. I wouldn't install anything else!!!
 

captjohn

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Good point. Not all alternators have external voltage sensing terminals. But if yours does then hooking it to the battery side, preferably the house battery side, will let the alternator put out a high enough voltage to compensate for the isolator's voltage drop. This way the house battery will get the full capability of the alternator output.

David
I'm not a fan of hooking the output line up directly to the battery in this application. If you develop high resistance in the wire between the battery and the isolator output the alternator will increase the voltage, which flows to both batteries. This could cause the second battery to boil off water, to the point where it could fail. Potentially leaving you with two dead batteries, rather than one. Just my two cents.
 

scbob

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Original poster here. Got a pic of the offending "little red box".
Turns out its black. Does anybody recognize what type of "isolater" this is please ?

IMG_2339.JPG
 

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A very basic diode style isolator, maybe a Guest, but a single input (alternator) with a dual bank output (engine bank and house bank). There should be a sticker on it that shows the model or at least the amperage rating. That definitely should be removed and replaced with a FET style isolator, would be the easiest solution to eliminate the charging headaches. Also, could you confirm the size wire connected to those terminals? Tough to tell from the pic.
 

scbob

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Thanks for ID.
The alternator is probably 100 amps, as you suggest. I don't know wire gauge but would imagine it's correct spec as Provincial a reputation for doing it right.
I'll order the Victron Argo FET.
Thanks for all the help.
Bob
 
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