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Discussion Starter #1
I am rennovating the electrical system on a Midship 25 (later known as the Parker Dawson 26). The boat electrical system has a house bank of 2 100ah batteries and a starter battery , all three batteries are wet cells. The batteries are attached to a "1,2,both,off " switch. The previous owner had an AC extension cord arrangement, an auto battery charger attachable to a single battery at a time with alligator clips and a .9 amp solar cell wired directly to the house bank. The boat has an electric start sailmaster 9.9 connected directly to the starter battery.

My plan is to add a proper AC power arrangement, hardwire an AC charger for charging the batteries at the dock and hardwire the solar panel with a disconnect plug. I plan to use the solar panel to keep the batteries trickle charged when the boat is on the trailer or when shorepower is not available.

I have purchased a Flexcharge PV7D for the solar panel that is capable of charging 2 battery banks and I am researching AC battery chargers. I am also contemplating an ACR or battery isolator to allow the outboard to charge the house bank when the starter battery is fully charged.

I am now scratching my head about how all this will work together. I have several questions I would appreciate feedback on from the collective wisdom of this forum:

1. if I get a high end AC 3 phase charger that also conditions the batteries periodically, will an ACR or battery isolator interfere with its proper function?

2. Would it be a big improvement to get an AC charger that charges the three batteries individually vs. treating them as two banks? Will it work on all three batteries even if the two house batteries are wired together in parallel?

3. I am actually solving the same problem three ways with my approach. The ACR, Flexcharge unit and the AC battery charger are all three monitoring battery voltage and distributing power to batteries that need it and (in the case of the flexcharge and AC charger) following a charging profile that promotes battery health. Is there some economical way to solve this problem once and feed the three sources of power to that solution? Or is that a big boat only, expensive alternative.

I have gotten alot of value from this forum and I will appreciate any advice you can give me.
 

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I didn't read past the part in #2 in which you asked about charging individual batteries in a single bank separately. My suggestion before going further is that you may be lacking in some fundamental understanding of electrical systems. You cannot isolate batteries in the same bank.
 

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OK, so the answer to question 2 is no. I thought that might be the case, but I also thought that if the battery charger was connected directly to the terminals of all three batteries that the charger might sense the battery to which it was directly connected even though it was also connected to the other battery. I have read that when charging a two battery bank that one should connect the charger to the positive terminal of one battery and the negative terminal of the second battery. This implies that even though the batteries are not isolated, the charging system behaves differently depending on what batteries it is attached to.
 

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Salty
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I have read that when charging a two battery bank that one should connect the charger to the positive terminal of one battery and the negative terminal of the second battery. This implies that even though the batteries are not isolated, the charging system behaves differently depending on what batteries it is attached to.

The charging system looks at a battery bank as ONE large battery. It can not differentiate between individual batteries within the bank. That said, connecting the charger to both the house bank and starter battery will charge each entity as needed but not an individual battery within the house bank......or I could be completely out of my mind!
 

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Telstar 28
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Just curious, why did you go with a Flexcharge PV7D. It would make far more sense to go with a single bank charge controller and use an echo charger to deal with the starting bank.

An ACR won't interfere with a charger doing a battery conditioning cycle generally, since it is just a relay. An echo charger will.

Again, I wouldn't bother going to the expense of getting a two-bank charger, since it would make more sense to use an echo charger with a single bank charger.

IMHO, you're making the system overly complex, and spending more money than you have to. There is no need to treat the house bank as two separate batteries, and very little advantage in doing so.
 

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Try this book. The Marine Electrical and Electronics Bible (Hardcover)
by John C. Payne (Author) or many other 12 volt books
 

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Discussion Starter #7
Just curious, why did you go with a Flexcharge PV7D. It would make far more sense to go with a single bank charge controller and use an echo charger to deal with the starting bank.

Sailingdog, thanks for the feedback.

I thought the PV7D would help me provide a float voltage to both battery banks and keep my batteries healthy. I have read that an echo charger or ACR will not provide a float voltage to the second bank because the voltage on the first bank is too low to trigger the device. That is the same objective behind getting a two bank charger.

Will an echo charger permit both banks to be maintained in float mode?

IMHO, you're making the system overly complex, and spending more money than you have to. There is no need to treat the house bank as two separate batteries, and very little advantage in doing so.

Got it, thanks.
 

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Discussion Starter #8
Try this book. The Marine Electrical and Electronics Bible (Hardcover)
by John C. Payne (Author) or many other 12 volt books


Thanks for the tip, BadSanta.

So far I have read Calder's Boat Owners Mechanical and Electrical Guide and and Casey's Sailboat Electrics Simplified. The most often discussed scenario in these books is managing the output of the engine alternator. My Midship used to have an inboard westerbeake diesel with an alternator, but one of the previous owners removed it and replaced it with an outboard that is directly connected to the starting battery.

So far I have a basic understanding about each of the parts of the electrical system but I am struggling with how they all fit together in a practical arrangement. My objective is a charging arrangement that I can set and forget for a month or more if I need to. The previous owner had the boat fill up with water at the dock and on the trailer several times because the charge on the bilge pump battery (currently the starter battery) was not managed properly in spite of the availability of shore power and a solar panel.
 

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Discussion Starter #9
Just curious, why did you go with a Flexcharge PV7D. It would make far more sense to go with a single bank charge controller and use an echo charger to deal with the starting bank.

An ACR won't interfere with a charger doing a battery conditioning cycle generally, since it is just a relay. An echo charger will.

Again, I wouldn't bother going to the expense of getting a two-bank charger, since it would make more sense to use an echo charger with a single bank charger.

IMHO, you're making the system overly complex, and spending more money than you have to. There is no need to treat the house bank as two separate batteries, and very little advantage in doing so.
Sailingdog, thanks for the feedback.

I thought the PV7D would help me provide a float voltage to both battery banks and keep my batteries healthy. I have read that an echo charger or ACR will not provide a float voltage to the second bank because the voltage on the first bank is too low to trigger the device. That is the same objective behind getting a two bank charger.

Will an echo charger permit both banks to be maintained in float mode?
 

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SD knows what he is talking about. The answer is yes, an echo charger will do what you want. Keep doing your homework and sometimes you will find that you spent some money that could have been better spent, just ask me:D
 

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Discussion Starter #11
SD knows what he is talking about. The answer is yes, an echo charger will do what you want. Keep doing your homework and sometimes you will find that you spent some money that could have been better spent, just ask me:D
Fortunately I have not bought the AC charger yet, so I am only out the $80 I spent on the Flexcharge unit. I am glad I sought the advice of this forum before getting any deeper into this project.

Right now my outboard is connected to the starter battery. I am assuming that if I go with the echo charger arrangement that I should connect the outboard to the house bank and let the echo charger handle this arrangement to. Or maybe this is too complicated an approach to handle the occasional 6 or 8 amp output of the outboard generator.
 

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Yep, I got alot of spare parts. It took awhile and some classes and alot of reading till I figured it out. I wonder how large your out board alternator is and if it is large enough.
 

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Discussion Starter #13
Yep, I got alot of spare parts. It took awhile and some classes and alot of reading till I figured it out. I wonder how large your out board alternator is and if it is large enough.
The motor is a 1983 OMC sailmaster for which I have no documentation. I am searching ebay to find an owners manual, service manaual and parts manual for that year -- so far without success.

The browsing I have done on the web tells me that the electric start 9.9's have a generator that puts out around 6 amps. Whatever it is, I have what I have. I wish I could go back to an inboard but the shaft and strut have been removed and the opening in the hull is glassed over. All I have left is a cockpit hatch and engine mounts.
 

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Connected to shore you will be fine. At anchor you will have a problem. You are forced to live with it. Remember if you cant make more electric you will have to reduce your use. As you go along try to convert lights to LED and refrigeration may be out. If you have a large enough battery bank you may be OK for several days till you return to dock charge. You dont want to run your outboard for 24 hours just to keep the drinks cold. Best of luck
 

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Hinterhoeller HR28
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On our boat (which used to be equipped with an OMC 15), we went to one bank, period. The 9.9 can be pull started if the battery or starter fails for some reason. No need for an exotic setup with a start battery. Our deep cycle group 31 is plenty. The 9.9's amp draw (under 20 amps cranking) does not require a start-only battery. A deep cycle is fine.

Also, the 9.9 makes, at best, 5 amps (wide open), and just isn't going to recharge from any serious amount of house draw, period. It's basically set up to replenish what was used during cranking. Ours used to actually have a net LOSS if below full throttle with a bilge blower running.

While the solar unit (I would make sure it has a charge controller to keep from boiling the battery dry) will help while on the hook, to make up for anything much beyond an fm stereo, you will want to use a shore charger or other means. If you will spend time at the dock, and decent Guest or similar Marine, 3-stage charger will be fine. We used to use a 10-amp model (Guest 2610, I believe), and it was adequate, unless refrigeration was running while we were using all the cabin lights, etc.

Ditch the automobile-type charger. They are famous for leaking AC to the 12v side, and ours corroded the outboard LU so badly that I thought it was going to start leaking lube. Seriously.

We adding proper shore power, and refurbishing the 12v side of the wiring, we have since gone to a 20 amp charger (10 plus 10, tied together on our one battery), and just cannot overwhelm it in normal use at the dock.

We cruise a lot, and we tie to the dock a lot. Only time we have any concerns is on the hook. An LED anchor light helps a lot.

Current 12v setup:
One grp 31 deep cycle flooded battery
One 20a (10/10) 3-stage charger charger
6 amps from Nissan 9.8 OB when running 3/4 throttle.
No solar, no wind charging
No 1-2-both-off switch; just a cheap on-off batt sw.

Current 110v setup:
One 30a shore inlet
One twin 30a main breaker, feeding:
One 10a breaker for charger, and
One 20a breaker for outlets.

No refrigeration: Built-in icebox, and Coleman peltier-effect cooler, that can run on either 12v (or 110v with the adapter). Very electrically inefficient, BTW -- 4a of 12v all the time. But we usually run it on shore power, where it uses 0.4a of 120v.

Has worked great for 3 seasons now.
 

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Discussion Starter #16
Thanks for sharing your configuration, pvan1. My two bank set up goes back to the time when the boat had an inboard engine. I agree that it is probably no longer necessary, but I will probably keep it as it is.

Your observation about the automotive charger probably explains the severe corrosion present on my 9.9

A few questions:

1. Do you have any problems running 20 amps of chargers on a 10 amp breaker? I plan to have a similar 30 amp ac configuration to yours and I was thinking about breaking it out into 2 15 amp breakers, one for charger and one for outlets. I have been assuming that this will limit my charger to 10 or at most 15 amps.

2. What LED anchor light did you use? Currently my boat does not have an achorlight - just a kerosene lantern hoisted on a halyard.

3. Did you install an separate AC panel for your shore power or use a breaker box?

Thanks.
 

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ABYC states that you cannot use alligator clips on the charger connection. The springs die, then the connector drop into the wet bilge areas. Boom.

If you have a propane stove onboard, you are going to want an ignition protected marine charger. Propane gas is heavier than air and drops into the bilge spaces where your charger is most likely located. Boom.

ABYC also requires a breaker on the incoming shorepower AC within 10' of the deck connector. You need a double breaker, 1 on the hot, 1 on the neutral with a polarity warning system,

so that if the shorepower connector on the dock is electrically reversed the power is physicaly shut off by the breaker. All AC outlets should be GFCI outlets as you are dealing with water everywhere. Look at and print off this diagram to get an idea of what is required. The boat attached to the diagram is a 22' Tanzer so it'll fit your boat without problem.
 

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Hinterhoeller HR28
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1. The 20a charger puts out 20a at 12vdc. That translates into only 2a (plus losses) on the 120v side (ohm's law). Figure the 12v amps are roughly 10x the 120v amps. So no, the 10a breaker does not ever trip. I could have used a 5a breaker, but the 10 was on the shelf.

Since the single group-31 battery is about 130 amp-hours (we try not to drain it below 70%), a full recharge is done at the dock in under 6 hours. The original setup from the factory used a small group-24 battery, which wasn't adequate for two-week cruising, especially if you throw in some night sailing. You don't want to drain the battery all the way down, or it really shortens its life.

2. The anchor light is an old Forespar unit, but I replaced the festoon bulb with an aftermarket LED array when it burned out. Pops right in -- direct replacement lamp. Sea-Dog makes some economical LED units as well. Kerosene would work OK, and accidentally leaving it on during the day wouldn't run down the battery.

3. The AC breaker panel is a cheapie, maybe Ancor brand, that has provision for 4 "world" breakers (the standard marine units). The inlet must feed a double breaker (like a 220 breaker in a house), that trips both wires, to meet ABYC standards, because there is always the possibility that you plug into a reversed outlet at someone's dock. So when it's tripped off, the AC is definitely off, regardless of bad shore wiring. That leaves exactly room for the 2 other breakers, which are fed from the Black leg of the double. The panel is installed in a bulkhead, and the back is covered (per ABYC standards) to keep everything neat and safe.

While on that topic, the shore inlet is a standard Marinco 30a twist-lock, wired to the panel with 10 awg Ancor marine-grade wire (yes, you need 10 awg or bigger to safely accommodate 30 amps). Do not run residential wiring anywhere on the boat. You must use marine-grade, stranded wire, preferably fully-tinned, with proper marine-grade terminations on the ends.

Long story short, by running only one battery, the maintenance is a lot cheaper and easier. If I already had a 2-battery switch, I would probably still just run one battery bank -- either two batteries, with the switch set to "both", or one large battery. Amp-hours for the buck, one big battery is much more economical.

BUT, If it was an inboard, then I would want a "start" battery that could not be run down by the cabin lights and accessories. In that case, I would either run a switch, or an isolator, to allow parallel charging from the OB.
 

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Hinterhoeller HR28
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What happens if a boat doesn't meet ABYC standards, anything ?
Lack of reliability, less safety, lower resale value, and increased incurance premiums.
 
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