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Old 25-09-2012, 10:38   #1
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Hitachi 55 amp alternator

My system is basic- 55 amp alternator/internal regulator charging 2 100 ahr AGM batteries (no separate starting battery). When cruising I let both batteries discharge to the 50%-70% level before charging. When new I would see 50 amps and 14.6 volts when charging began and naturally the amperage would taper off as the batteries charge. The Lifeline battery manual says full charge is when the current drops to 0.5 amps per battery.

Now the alternator is 10 years old and the batteries are new (same type). The voltage at start-of-charge is 13.8V to 14.1V and the current is rarely above 35 amps. I carefully checked all my wiring for voltage drops and found no problems- the output voltage measured at the alternator seems to be low. The Hitachi manual says the regulator is set at 14.4 +- 0.3 volts so it is still close to being within spec. Lifeline says the absorption voltage should be 14.65V so obviously we are charging much slowing than we could be.

I am not looking to upgrade as the original system reasonably met my needs. I would like to restore my system with minimum $. Here are some options: (1) Replace regulator/brushes, (2) Replace alternator, (3) Convert alternator to external regulation (and find an inexpensive adjustable regulator), (4) Live with it as it is.

A new 55 amp alternator is $170, Balmer regulators are more than that. But if I get a new alternator the output voltage might only be 14.4V and there is no adjustment.

Anyone have any suggestions?
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Old 25-09-2012, 11:25   #2
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Re: Hitachi 55 amp alternator

So where does the voltage sense wire from the alternator connect to the system. After 10 years, there is probably some corrosion on the connections and terminals which could effect the voltage both at the sense connection and on the high amp wiring.

Also, what was the SOC of the batteries. Alternator output is based on SOC of the batteries. If the batteries were mostly charged then I would expect about 35 amps out of the alternator. The Amp output of the alternator is not constant and is reduced as SOC and internal battery resistance rises. The alternator will only put out what the batteries and system will accept.

In the 80's and 90's, the thought was to install a 100 amp or larger alternator. Mainly to reduce engine run times while charging at anchor. Now a days with solar and wind being the primary means of charging, I really don't see why people are still spending big money on high output alternators.

Really its a bit outdated to put a 100-200 amp alternator on a boat when at anchor the power is coming from solar and wind (or a honda generator). I find that when I motor its for hours at a time, so the 55 amp hatachi works very well without excess side loading on the water pump bearings or larger belts.
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Old 25-09-2012, 11:53   #3
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Re: Hitachi 55 amp alternator

I have owned 5-6 boats over the years with that Hitachi alternator on GM and JH Yanmars. I don't think I ever saw 50 amps from them. Typically 20-30 amps with 50% SOC batteries, quickly dropping to 10-15 and then just a few amps at the end. So I am not sure that you can get back to where you were.

Might I suggest at the very least adding a Group 24 starting battery and isolating it through a 1,2,all switch. That way you will be able to save your starting battery for starting.

The next step would be to replace the Hitachi with a Balmar, Hehr, Hamilton Ferris, etc and a three step alternator. But that is at least $600 worth. So if you don't need it why bother.

David
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Old 25-09-2012, 12:13   #4
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Re: Hitachi 55 amp alternator

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Originally Posted by sailorchic34 View Post
.....

In the 80's and 90's, the thought was to install a 100 amp or larger alternator. Mainly to reduce engine run times while charging at anchor. Now a days with solar and wind being the primary means of charging, I really don't see why people are still spending big money on high output alternators.

Really its a bit outdated to put a 100-200 amp alternator on a boat when at anchor the power is coming from solar and wind (or a honda generator). I find that when I motor its for hours at a time, so the 55 amp hatachi works very well without excess side loading on the water pump bearings or larger belts.
Sorry, but I've got to disagree with this. In fact, the opposite is true, i.e., there's more need now for big alternators than ever before.

The evidence is mounting: as cruisers/boaters put more and more electrical stuff aboard, and their electrical budget grows accordingly, and as they often opt for AGM batteries, there's mounting evidence that the benefits to be had from these expensive batteries can only be realized if the onboard charging system is up to the job.

An AGM battery, like the Lifeline 4-D, can easily take 1.3 times its CA rating in charging current when it's 50% discharged. If it's further discharged, it can take as much as 5X its CA rating, i.e., a deeply discharged 200AH AGM battery can accept as much as 1,000 amps in the beginning. And, there's evidence that this is good for the battery, i.e., better than slowly charging it.

I've been doing some research with the Concorde Battery company on their Lifeline AGMs, in collaboration with a well-known expert in the field who will soon publish supporting data and is to be a speaker at IBEX and SSCA. Our research shows it is a very good idea to put the largest charging capability you can on your boat, especially if you use AGM house batteries, in order to cut charging costs dramatically and to extend the life of the batteries.

Yes, charging current cuts back as the battery's state-of-charge (SOC) increases. But, even if you provide the AGM battery with ALL THE CURRENT IT WILL TAKE, beginning at a 50% SOC, it will take 60-90 minutes before the charging rate reduces to that of lesser-capacity chargers (in the 10% to 50% of capacity range). During those minutes, the battery's SOC has increased dramatically, while with lesser capacity chargers it has changed little, and the batteries will need several hours more charging before they even reach a similar SOC.

AGMs need to be fully charged frequently. In reality, this rarely happens on a cruising boat unless long motoring spells are routine and/or they regularly tie up to a dock. It does happen to boats with large wind generators and/or solar charging capacity, and is greatly helped by having a large alternator.

Most small to mid-size cruising boats are limited in the alternator size they can easily upgrade to, usually in the 100-125A range. But that upgrade, plus a capable external smart regulator like the MC-612 or MC-614, is an excellent investment to keep those expensive AGMs in good condition.

Bill
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Old 25-09-2012, 16:13   #5
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Re: Hitachi 55 amp alternator

Well if you have a larger boat (perhaps a powerboat) with AGM's and lots O electrical loads, and not a lot of solar or wind generation, then yes a larger alternator makes sense. Though a power boat or a larger sailboat will have an auxilary generator too, most likely. So I still don't see the need for a high amp alternator on the main engine(s)

Me personally I would not use AGM's, A bit too spendy for this girls taste. I've seen a lot of owners put in agms with an older battery charger and fry the agms in a few months. Too high maintenance for me. That whole needs to be fully charged thingy with the AGM's is tough to do at anchor. To me the more forgiving and far less expensive wet cells works better.

I find that when I check for water levels in the typical wet cell, I get to check the electrical connections too. With AGM its out of sight out of mind.

I guess I should say for a 40 foot and smaller cruising sailboat, the $800 ish cost of the balmer alternator and controller could be better spent on three 130 watt panels and a charge controller.
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Old 25-09-2012, 19:50   #6
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Re: Hitachi 55 amp alternator

Thank you all that replied. These inputs are useful. To provide more information, most of my sailing is day-sailing and I have a 22W solar panel that seems to provide all the power I need if there is any sun at all. I get back to the mooring with batteries fully charged. The batteries lasted 8.5 years so I am happy with the life. The cost is a little high but there is no maintenance and they are safe in event of roll-over's, etc. (Small boat ocean sailors think about things like roll-overs!) AGM's work fine for starting the little motor so I don't need a third battery. This helps to keep the whole system simple.

I cruise several times each year and then they are actually discharged a significant amount. At these times the alternator must actually work hard and it seems to not be doing as well as it used to. David's comment said what I wanted to know. Another Hitachi might not do any better than the one I have. I think the only way to get higher voltage would be to have some sort of external regulator that could be accurately set. 14.4V just isn't enough (and 13.8V is even worse).

I've read about modifying this alternator for an external regulator but don't know of an inexpensive regulator. ??
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Old 25-09-2012, 20:14   #7
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I never thought I would be in opposition to anything Bill posts, but in this case I concur with all that Sailorchic34 has said.

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Old 25-09-2012, 20:24   #8
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Re: Hitachi 55 amp alternator

Theres a bunch of Good alternators out there! GM made some 100 amp that are internaly regulated, they were used on 3500 diesel pickups, ambulances, tow trucks ect ! they can be made to work well with almost any battery set up wet or any other type! your local auto electrical shop can set it up for ya !! Much cheaper then anything from a marine company ! Ive used them for yrs and never had a problem one with them! and ya can get them fixed almost anywhere !
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Old 25-09-2012, 21:09   #9
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Re: Hitachi 55 amp alternator

The alternator has probably been overheated many times over the last 10 years and thus has lost a lot of its generating capacity. In fact much of the cutting back that you used to see was probably because the alternator was running hot. Get an IR thermometer and check the temp. of the alternator as it is running. It should not get above 190 - 195 F. Hot rated high capacity alternators can run hotter but you would have to check the individual specs.
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Old 25-09-2012, 21:56   #10
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Re: Hitachi 55 amp alternator

One other note. Hitachi alternators are in many cars too and its pretty easy to find a Hatachi alternator on ebay with fan for $95 ish.

A GM alternator might be even cheaper still...

Plus I'm betting the engine in a dana 24 is at best a two cylinder, so 55 amps is a fair load already.
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Old 26-09-2012, 10:01   #11
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Re: Hitachi 55 amp alternator

If you can find where the internal voltage regulator senses its voltage and move it out to your batteries that will take care of almost any voltage drop in your wiring. You can also insert one or two diodes in this line to increase the charge voltage by I believe .7 V per diode. I set this up on a friend’s boat so he could fast charge. By putting a toggle switch across the diodes he could take them out of the circuit for when he was motoring for long periods of time. Just my two cents, Mike.
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Old 26-09-2012, 11:30   #12
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Re: Hitachi 55 amp alternator

I use similar alternators on my cat. I bought a spare from NAPA for less than $75. You should just replace your alternator and keep your old one as a spare. If that doesn't solve the problem then at least you know the alternator is good plus you have a spare.
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Old 26-09-2012, 11:48   #13
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Re: Hitachi 55 amp alternator

Personally I wouldnt change your system at all. It works good for you, is very reliable etc. a high amp alternator, or a regulator that pushes your alternator to the limit, comes with deficits like v belt wear, dust from the belt, shorter alternator life from heat, belt tension monitoring etc. You just need to figure out what needs fixed. Maybe you need an alternator rebuild, but I'm surprised you were seeing such high amps out of the Hitachi..... are you sure you are remembering right?
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Old 26-09-2012, 18:30   #14
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Re: Hitachi 55 amp alternator

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Originally Posted by EveningTide View Post

Now the alternator is 10 years old and the batteries are new (same type). The voltage at start-of-charge is 13.8V to 14.1V and the current is rarely above 35 amps. I carefully checked all my wiring for voltage drops and found no problems- the output voltage measured at the alternator seems to be low. The Hitachi manual says the regulator is set at 14.4 +- 0.3 volts so it is still close to being within spec. Lifeline says the absorption voltage should be 14.65V so obviously we are charging much slowing than we could be.
Batteries may be "new" and same type but that doesn't mean the design internally hasn't changed a bit. For your boat I think you may be overthinking this. Although a 10 year old alternator may need new brushes (not a hard thing to do) and I agree with sailorchic - high amp alternator on a small diesel is probably not worth it.

You load up everything more, engine, belts, pulleys and brackets.

Also as the batteries are "new" are they really getting down to a 50-75% SOC before you charge them?

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Originally Posted by Cheechako View Post
Personally I wouldnt change your system at all. It works good for you, is very reliable etc. a high amp alternator, or a regulator that pushes your alternator to the limit, comes with deficits like v belt wear, dust from the belt, shorter alternator life from heat, belt tension monitoring etc. You just need to figure out what needs fixed. Maybe you need an alternator rebuild, but I'm surprised you were seeing such high amps out of the Hitachi..... are you sure you are remembering right?
I have 3 AGMs and I don't even know what they charge at. I have a little red, yellow, green LED indicator. The batteries are 5 years old and it "seems" they don't get in the green for as long as they used to but I still have plenty of power for my needs.

If my electrical system were bigger and more complex I might worry more and design a better system.
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Old 27-09-2012, 14:04   #15
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Re: Hitachi 55 amp alternator

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... You can also insert one or two diodes in this line to increase the charge voltage by I believe .7 V per diode. I set this up on a friendís boat so he could fast charge. By putting a toggle switch across the diodes he could take them out of the circuit for when he was motoring for long periods of time. Just my two cents, Mike.
The toggle switch must be double through; one position in series with the diodes, the other across.
Position one (closed in series) the diodes provide about 0.6V drop (each), increasing alternator output.
Position two (closed in parallel, or across) the diodes are bypassed, providing normal "sense" voltage.
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