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Go Back   SailNet Community > On Board > Gear & Maintenance
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  #1  
Old 01-24-2009
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Question New electrical setup

I was looking for some opinions on my setup. I have a 2007 Hunter 36. Original setp was a house bank with 360 amps (2 batteries) and a engine start battery (90 amps I think). After a nite at anchor I always found myself running the engine half the day to recharge before our next day at anchor. So I decided to increase the house bank size since a bigger alternator was not possible due to the engine box size. So I left the boat at my local repair shop for the winter to do the upgrade. I wanted to double the house size, and upgrade the shore power to DC charger, currently a 20 amp charger.
Here's what they did: they installed two more batteries so now I have 720 amps. They separated the banks with a selector switch so that only one bank is in service at a time. They rewired the alternator so it only charges the engine start bank. To charge the house bank I have to be plugged into shore power and can ony charge one bank at a time with the original 20 amp charger. They were concerned with the amp pull with the bigger bank and damage to the alternator trying to charge that big bank?
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Old 01-24-2009
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I dont know where to start!
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Old 01-24-2009
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Wrong, Wrong, Wrong. If the 'local repair shop' did indeed leave you without a way to reacharge your house bank away from shore power....then they should never ever get another job from you again.

What you did right:
1. Increased the size of your house bank to meet your needs.
2. Felt something was amiss with the 'repair' and came to Sailnet to confirm.

What you (they) did wrong:
1. Leave you without a way to charge your house bank.
2. Didn't fully understand the problem (as you describe, charging takes longer than you'd like/prefer, etc)

It is fully acceptable to create 2 separate house banks, plus a third 'bank' for the starting battery.

That said, the most commonly recommended setup is one large house bank, plus the starting battery. These banks are completely isolated from each other. Normally, the alternator output is directed to the house bank, with a paralleling relay or echocharger rigged in to charge the start battery.

I completely disagree that a larger alternator cannot be swapped in as a direct replacement for the OEM unit. With a 720AH bank and lead acid batteries, you can put in 25% of total AH capacity, or in this case 180 amp alternator. But, you wont be able to drive that big of a load with the auxillary in your Hunter....I'm guessing 100 amp alternator max.

Now, let's get realistic...I'm not sure if you're willing to spend the $$$ to reverse the work that's already been done. You should, but I've always like to spend other people's money :-).

At a minimum, you should have the output of the alternator moved back to the house bank.

You should consider combining the (2) 360 AH banks together, but this is not 100% necessary and since all 4 batts were not replaced as as set...

Add a paralleling relay or echo charge from the house to the start bank.

If you want to break the bank....replace all 4 house batteries with AGM type batts, these will suck up all the current your alternator can thow at them. This will ultimately solve your initial problem of 'it takes too long to charge'

Replace the OEM with a drop in replacement P-type (externally regulated) alternator up-rated to 100 or so amps.

Can anyone tell I haven't had my coffee yet....I am a little wordy in the AM.

JS
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Old 01-24-2009
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I would kindly ask for my money back and ask how this "helped"....they should have least suggested a charger adequate to charge the whole bank...

Buy DOn Casey's book, a couple of reputable solar panels, a good MMPT controller and perhaps you can undo what they have done...you may want to add this yard to the list of less than great "help"

It should be fairly easy to add a HO alternator in the present enclosure, may have to add a bracket or pulley, but should be do-able...a smart regulator is easy...

all the best
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Old 01-24-2009
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I forgot to say I am also installing a wind gen that will be hooked to the house bank, so that will be one way to recharge away from the dock.
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Old 01-24-2009
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What a mess! This is all wrong.
Exactly what size and type batteries do you have? I am not aware of any battery size that provides 180ah's at the standard 20 hour rate.
Do you only do (or plan) weekend cruising?
I am skeptical about not being able to fit a decent alternator within your box. The Balmar small case alternators are designed to replace standard alternators. Have you actually checked the dimensions vs. what you have now? I believe you have a saildrive...perhaps a call to Balmar to see what they say about a replacement that will fit would be in order.
http://www.balmar.net/PDF/Alternator...naldrawing.pdf

If all you do is charge batteries all week long and then go out for weekends, you essentially have 360amp hrs. to work with before you NEED to recharge...if your electrical uses are typical, this should be plenty for a couple of days before heading back to the dock. If you do MORE than weekending...you will now need to run your engine twice as long as you used to to charge back up.
If you DO go for longer trips your present setup will be completely unsuitable and you need a way to get more juice in your batteries while away from the dock. One way is a 100amp range alternator...the other way is a larger charger (75amp) driven by a Honda2000 portable generator or equivilent.
Your boatyard was right to split your bank to protect your small alternator but I would get rid of that split if you CAN get a more powerful alternator.
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Old 01-24-2009
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Sorry to rain on the parade of upgrade paths, but from your original post it appears that the presenting problem was too long to recharge the 360AH house battery bank (2 batteries).

Note that for all intents and purposes you can forget the starting battery as consuming much recharging....it normally takes only a very few minutes.

I think that on a 36-footer, unless you have unusually heavy electrical demands, you could well have got by with the 360AH house bank, provided that you have adequate charging capability.

The upgrade path should probably have been:

1. install a smart, external regulator (like the Balmar MC-612); and
2. install a larger alternator, like 100A model.....same case size approx, so there'd be room to do that.

An alternator with an internal regulator is designed to recharge car batteries. It comes no where near delivering the amperage needed to recharge a depleted house bank efficiently. In other words, a smart external regulator is an indispensable must have.

While the regulator alone would greatly increase the average amperage going to your house batteries during a recharge even with the old alternator, you've gotta be careful not to overtax (overheat) the alternator. There are ways to do this with a smart regulator, including temperature sensing (for both alternator and batteries) and programming.

But, of course, it makes most sense to install a new higher-capacity alternator which is up to the charging task.

What to do now?

You've got additional battery capacity, but still haven't increased your ability to charge the batteries when away from the dock. IMHO, this is the crux of the problem, unless you plan on only recharging at dockside.

So....

First, wire all the house banks together. If they're physically separated, you can use a 1-2-Both-Off switch to do this, just run it in the "BOTH" position and be sure the wiring is of sufficient size (i.e., MUCH larger than you'd imagine).

Then, I'd replace the alternator with a 100A model AND install a smart regulator. Run the output of the alternator to the house bank. Do this even before adding the wind generator.

Then, install an EchoCharge device to keep the starting battery charged.

If you have a diesel boat, and you want to upgrade your battery charger (20A is too small IMHO), get an Iota 45 or 55A model with an IQ4 regulator. These are the best values on the market. Hook it up to your house bank, and toss the 20A charger.

If you feel unqualified or uncomfortable with any of the above, you might seek the services of a qualified ABYC certified marine electrician.

Under no circumstances go back to the local service you used....they clearly couldn't find their butts with both hands :-(

Sorry for your situation, but it's not catastrophic. You can recover nicely...it'll just cost a few bucks :-)

Bill
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Old 01-24-2009
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I think this is not entirely the shops fault. They did what you asked them to do! and then modified that a bit. You told them you could not add a bigger alternator so they dealt with the one you have.

Of course, a GOOD shop would have told you how to do it right, so they do have some fault too. But many shops take the attitude of 'the customer is always right'. They got tired of always fighting with the customer who would tell them how to do their job. The best outcomes are from an educated customer and knowledgable technicians. I think you both fell a little short here.

The very first chore should have been to deal with the lack of charging.

You can now add in the new charger and external regulator and fix the first problem.

Your biggest mistake was in not coming here FIRST!!!!!!!!

Oh well, no big deal, it's only money!

Keep the old alternator as a spare and note how it is installed. If your new alternator craps out, you have a spare to use. But the wiring will probalby be different with the external regulator on the new setup so you will need to be able to recreate the old wiring if you re-install the old alternator.

One other question...what is the condition of the old batteries? Were they cooked by a cheap shoreside charger? Your problem might have started with poor charging of the house bank while plugged into shorepower. You can ruin a good set of batteries PDQ. Take some specific gravity readings...with a good SG meter designed for batteries. You might have 2 bad batteries. You would end up with 4 bad batteries soon enough if the charger is the problem.
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Old 01-24-2009
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Actually it was the Boat Yard that tells me I can't install the bigger alternator. They also said without asking first we could not install the bigger ac-dc charger. My "old" battery bank is only two years old, never discharged below 12 volts. The original issue as many of you will relate with is going cruising with the wife and the associated amp-hours that go along with that!
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Old 01-24-2009
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Quote:
Originally Posted by brokesailor View Post
Actually it was the Boat Yard that tells me I can't install the bigger alternator. They also said without asking first we could not install the bigger ac-dc charger. ...
Wrong! And wrong!

I see you're located in Freddy-Patch, just a bit south of me. I do this for a living, and would be happy to spend some time on the phone with you discussing options....for anyone to do....for free.

PM me, or send me an email: bill at wdsg dot com

Bill
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