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Old 26-11-2011, 22:37   #61
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Re: Alternator Regulators - Opinions ?

I had no idea AGMs could suck up the electrons that quickly. For a short term solution, I'm still tempted to go with the diode solution, but I'm concerned about your comments on burning out the alternator. I thought this statement in the engine technical manual might solve my worries:
Quote:
The IC regulator is of the temperature compensation type and, therefore, regulated voltage varies with temperature.
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Old 26-11-2011, 22:50   #62
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Re: Alternator Regulators - Opinions ?

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Originally Posted by cwyckham View Post
I had no idea AGMs could suck up the electrons that quickly. For a short term solution, I'm still tempted to go with the diode solution, but I'm concerned about your comments on burning out the alternator. I thought this statement in the engine technical manual might solve my worries:
Yep, and you're proposing to defeat that feature by adding diodes!
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Old 27-11-2011, 02:27   #63
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Re: Alternator Regulators - Opinions ?

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Yep, and you're proposing to defeat that feature by adding diodes!
??
I don't understand. The diodes are there to add about 0.6V to the output. If the alternator starts to overheat, the regulator will still successfully reduce the voltage being put out and therefore the current being applied. If the temperature continues to rise, it will cut back further. Isn't it just a closed feedback loop?

Perhaps if it isn't a feedback loop, but rather a look-up table, then the alternator would run at 0.6V higher than it otherwise would, but it sure seems easier to run it as a feedback loop. I guess I was assuming that was how it worked. Can you educate me on the inner workings of a temperature compensated internal regulator?
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Old 27-11-2011, 06:01   #64
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Re: Alternator Regulators - Opinions ?

The problem isn't increased voltage, per se. Rather, it's increased amperage output (and heat generation).

At higher voltages, the batteries will accept more amperage.

I don't know how your "temperature-compensated regulator" works, either; maybe someone on this board does...specifically.

But with higher voltage you're going to have higher amperage, and generate more heat. Point is, those alternators were designed for automotive applications, where they only put out a lot of amps for a very short time. They weren't designed to be run for hours at high output.

You might get away with it for awhile, but IMHO with those AGMs you'd be much better off doing it right, i.e., beefing up your alternator and adding a smart external regulator.

Bill
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Old 28-11-2011, 18:07   #65
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Re: Alternator Regulators - Opinions ?

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Originally Posted by cwyckham View Post
??
I don't understand. The diodes are there to add about 0.6V to the output. If the alternator starts to overheat, the regulator will still successfully reduce the voltage being put out and therefore the current being applied. If the temperature continues to rise, it will cut back further. Isn't it just a closed feedback loop?
I agree with your expectation that your regulator's temperature compensating behaviour should not be affected by insertion of the diode as you describe. I would expect it to compensate to the same degree whether the diode is present or not.

The bigger picture painted by the very experienced Bill Trayfors when pointing out that typical auto alternators are not designed to put out large currents for hours on end, is the real worry.

Like you, I'm also stressing my 80A automotive alternator a bit and I do expect it to fail due to that (I have a spare, and eventually will look to get a large-frame alternator).

In the mean time, I'm not out on a cruise so it's convenient to experiment - I'm rolling the dice and will see for how long the current one can take the heat.
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Old 28-11-2011, 21:55   #66
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Re: Alternator Regulators - Opinions ?

I think that I am now sold on the idea of beefing up the alternator, at least in the long run. I'm a bit cash poor right now, so it's tempting to try a temporary fix with the diodes and try to see if I can get away with it for a year. However, I'd rather not end up in a pickle in the middle of my one long trip of the year...

Food for thought, anyways. Thank you for all your help.
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Old 29-11-2011, 03:13   #67
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Quote:
Originally Posted by Marqus

I agree with your expectation that your regulator's temperature compensating behaviour should not be affected by insertion of the diode as you describe. I would expect it to compensate to the same degree whether the diode is present or not.

The bigger picture painted by the very experienced Bill Trayfors when pointing out that typical auto alternators are not designed to put out large currents for hours on end, is the real
Yes that's correct , but that has nothing to do with external regulators.

With modern regulators all internal regulators are smart. What you may get with external regulators is more set points and a facility to easily change them. Also you may get battery sending and battery temp sending.


With a modern temp protected alternator, you will not burn out any car alternator charging AGMs. These comments come from the past when no such protection was available and alternators working in a poorly ventilated engine room on a boat could suffer overheat. Much much less likely to happen now.

Dave
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Old 29-11-2011, 11:20   #68
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Re: Alternator Regulators - Opinions ?

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Originally Posted by FlyingCloud1937 View Post
Most house banks are going to be much larger then the start bank. So if you take a fully charged start bank, and a 1/2 discharged house bank. Next lets just say it take 6-8 hrs to completely charge the house bank. That's going to be at least 4 hrs of overcharge to the start bank.

Now how many hrs of over charge is going to accrue to the start bank over 30 days of cycling the house bank, how many hrs over 12 months is going to accrue?


Lloyd
Lloyd we were discussing an Echo Charger which limits the voltage to an AUX battery to 14.4V. In my experience the start battery rarely see's 14.4V unless the house bank is seeing some where around 14.7-14.8V.

So what is "over charge" of a start battery? I guess the millions and millions of car and truck batteries, with no temp compensation, and deadly high charging voltages should not be lasting us more than a few months based on the math above..?

If we take the suggestion that there is a potential for 4 hours of over charge, each event, at face value, when most boaters barely put 100 engine hours per year on what do we have? If we figured each event put 4 hours of over charge on that is still only 25 top up cycles or about 50 hours of charging at 14.4V+ per year.

My wife's Honda pilot has a standard thin plate starting battery. It lasted from 2003 until June of 2011. That is eight years and 141,000 miles. Due to having a toddler and a badly located dome light switch that battery was killed to flat dead over 12 times and once sat that way for four days before being noticed and charged. Every time the battery came back and worked again.

At an average speed of 30 MPH that mileage equates to about 4700 engine hours of use at these deadly voltages. Her alternator is regulated to 14.4V and seeing as the battery is usually fully charged it sees 14.4V almost continuously. I don't know too many boaters who ever put 4700 hours on an engine unless fishing commercially. These batteries are also never "maintained" like we do in boats. I never once checked it, never really cared, but I have checked the output voltage of the alt.

Honda also backs their car starting batteries with a 100 month warranty with the first 36 months being 100% free replacement. It then prorates. Even at 75 months they are paying for 30% of your new battery. That is over 6 years at 14.4V+ and the manufacturer is still willing to pay for 30% of a new battery regardless of engine hours..

Even if we figure an average driver does 15k per year at 30 MPH avergae speed Honda, Die Hard and others are covering batteries that will survive 14.4V+ charging for 1500 hours of engine run time with a 100% free replacement warranty. For the average boater, sailor especially, that is 15 years of engine run time at 14.4V. Something to think about...

Sears even puts a 4 year free replacement warranty on their DieHard Platinum battery. Many cars are regulated to 14.2V or greater these days. The battery in my car lasted 121,000 miles at 14.4+ volts....

The idea that an Echo Charger is going to kill a starting battery with a built in voltage limit of 14.4V, in short order, is just not a reasonable conclusion and not something I have ever experienced..

Food for thought...
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Old 21-01-2012, 13:27   #69
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Re: Alternator Regulators - Opinions ?

For info I bought the digital advance regualtor from Sterling Power Products and it has been a nightmare from start to finish - and the finish was scrapping it!

In my case I found it very difficult to get working and the so-called help comes direectly from Charles Sterling who will only give you the most terse one line comment. And don't whatever you do suggest his regulator is at fault or he gets really shirty!!!

I eventually took it to an electronics friend who was very amused as the poor design and pointed out that this type of unsealed circuit board has no place on a boat.

So there you are, its cheap, its nasty, and the support is useless.
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Old 21-01-2012, 14:36   #70
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Re: Alternator Regulators - Opinions ?

Concur with MaineSail's post on Echo Charger. Start batteries these days are designed for higher voltages. IMHO no ordinary pleasure boat needs a real "starting bank." They just need a single, decent sized quality starting battery that is normally used for nothing but starting the engine. Charge it with an Echo Charge or the cheap solution, which is a Trik-L-Start that maintains your starting battery at 0.2 volts below your house battery voltage.
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