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Old 12-03-2012, 13:24   #1
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Alternator / ACR Split / Split Diode Conundrum

Hi

I have nearly completed my wiring redesign, and install , but am having a mental block that maybe someone could help with?

My alternator B+ post is connected to the starter motor and then a heavy duty cable goes aft to an on off selector switch which is then attached to a 1,2both switch. This heavy cable worries me as it is not fused and the short link between the B+ and starter is surely a bad idea? (balmar 100 amp with balmar 612 smart regulator)

I would prefer to take the B+ cable back to a splitting diode that will split into 2 lines. 1 to house bank and 1 to starter battery. Then attach the starter to the start battery. Not the switch as it is now.

My mental block is that i have an ACR (blue sea 120amp SI),on a feed from the starter battery to a large bowthruster/windlass battery up front. Will the diode work with the acr? Will the starter battery tell the diode it is full and the diode stop supplying it before the acr has a chance to do its work to charge the bowthruster battery.?

Also if I do this will i effectivley done away with the selector 1,2 both switch ? And need to fit on off switches for each bank?

Any enlightenment will be greatly appreciated

Charlie
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Old 12-03-2012, 14:26   #2
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Re: Alternator / acr split / split diode conundrum

Charlie,

Your instincts are right!

Your boat is wired the way a lot of them are/used to be. It is not an optimum setup.

There is no fuse in that heavy cable going to the switch, because that is considered to be the 'starting circuit', and ABYC doesn't specify a fuse in this line. The alternator is just piggy-backing on the heavy cable.

Here's what you want to do:

1. Run a heavy cable from the alternator directly to the house bank. Size of cable depends on length of run, but AWG1 or 1/0 would likely be more than enough. Be sure to set up the battery sense wire to the MC612 directly from the batteries, not the alternator.

2. Put a 130A ANL fuse in this line, located near the house batteries.

3. Install a Xantrex EchoCharge between the house battery bank and the start battery. Very easy 3-wire install. This will automatically maintain your start battery. You do NOT want to put an isolator between these batteries, nor do you need a battery 'combiner'. The EchoCharge will do all that's needed.

4. Run a heavy cable -- same size as the alternator's positive cable -- from the alternator ground directly to the house battery bank negative or bus. This will ensure an excellent connection between the alternator and the house batteries, and will help to get full power back to the batteries.

5. I'd install another ANL fuse in the start circuit, even though it's not required under ABYC recommendations. It is a VERY good idea; I have one on my boat, and Nigel Calder says,'there's no good reason NOT to install one'.
Suggest a 250A ANL fuse, located close to the start battery.

6. Install a simple ON-OFF battery switch for the start battery (the Blue Sea Systems #6006 is perfect for this).

7. Some folks like to use that second (now vacant) position on the 1-2-Both-Off switch to install a jumper wire between the start battery and the house batteries, for emergency use.

Here's one way to wire things:

Bill
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Old 12-03-2012, 14:54   #3
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Re: Alternator / acr split / split diode conundrum

Actually, Bill forgot about the third battery in the bow. However his system has a the advantage that you are able to start the engine on the house bank if there is a problem with the starting battery. You also definitely want an on-off switch to the starting battery.

The diode splitter will work fine the way Charlie envisions it--it will have no problem activating the ACR and charging the bow battery. While the sensing wire for the Balmar regulator should go to the house bank, the charging voltage at the starting battery will be well over 13 volts after a few minutes.
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Old 12-03-2012, 15:54   #4
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Re: Alternator / acr split / split diode conundrum

Bill,

Since the 612 monitors amps in/out of the battery by the shunt in the ground cable shouldn't the ground wire from the alternator go to the shunt and not directly to the battery?

Skip
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Old 12-03-2012, 16:51   #5
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Re: Alternator / acr split / split diode conundrum

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Originally Posted by skipmac View Post
Bill,

Since the 612 monitors amps in/out of the battery by the shunt in the ground cable shouldn't the ground wire from the alternator go to the shunt and not directly to the battery?

Skip
Skip,

No, the 612 isn't a battery monitor. It's a smart regulator. All it needs to know is battery voltage and, if sensors are fitted, temperatures of the batteries and alternator.

However, if there is a battery monitor and a shunt, yes, it would make sense to connect the alternator ground wire to the load side of the shunt.

Thanks,

Bill
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Old 12-03-2012, 16:56   #6
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Re: Alternator / acr split / split diode conundrum

Charlie,

Don is right...I completely missed the batteries up front for the thruster/windlass. Sorry, I was running to an appointment when I posted that.

Yes, in this case, an ACR makes sense because it has a relatively large amp capacity, whereas an additional EchoCharge or DuoCharge in the thruster/windlass circuit have a max. current of 15A and 30A, respectively. Conceivably, you could be in a situation with a low or bad battery up front and you'd want a large amp capacity option to run the windlass or thruster.

And, you DON'T need a 'diode splitter'. Among other ills, these devices have a voltage drop which is particularly not helpful in this circuit. The ACR (just a smart relay, really) will do the trick just fine.

So....EchoCharge for maintaining the start battery (more than enough) and an ACR for maintaining the thruster/windlass battery. No 'diode splitter' needed!

Thanks, Don, for catching this.

Bill
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Old 12-03-2012, 17:32   #7
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Hi

Thanks guys for your input.

I agree about the alternator connection to house bank and fuses. Buuut... If i put an echo charge between the house and start battery, bearing in mind that the bowthruster/windlass battery is "linked" to the start battery via an ACR, i womder if the echo charge would be able to supply enough to the start/ bowthruster and windlass battery. Could i put another ACR between the house and start to go along with the one betwen start and windlass? Is daisy chaining ACR's acceptable?

Just to be clear starting from aft going forward I have a large house bank which will have alternator connected to it, then a small start battery which will have the starter motor attached to it, than a cable with an ACR going forward to a large battery for windlass/ bowthruster.


Cheers

Charlie.
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Old 12-03-2012, 19:34   #8
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Re: Alternator / acr split / split diode conundrum

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Originally Posted by btrayfors View Post
Skip,

No, the 612 isn't a battery monitor. It's a smart regulator. All it needs to know is battery voltage and, if sensors are fitted, temperatures of the batteries and alternator.

However, if there is a battery monitor and a shunt, yes, it would make sense to connect the alternator ground wire to the load side of the shunt.

Thanks,

Bill
Oh, Duh. I was getting the Victron 602 monitor confused with the Balmar 612 regulator. I mean it's only one number difference. Have to make allowances for old guys.
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Old 12-03-2012, 20:03   #9
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Re: Alternator / acr split / split diode conundrum

Quote:
Originally Posted by Sulaire View Post
Hi

Thanks guys for your input.

I agree about the alternator connection to house bank and fuses. Buuut... If i put an echo charge between the house and start battery, bearing in mind that the bowthruster/windlass battery is "linked" to the start battery via an ACR, i womder if the echo charge would be able to supply enough to the start/ bowthruster and windlass battery. Could i put another ACR between the house and start to go along with the one betwen start and windlass? Is daisy chaining ACR's acceptable?

Just to be clear starting from aft going forward I have a large house bank which will have alternator connected to it, then a small start battery which will have the starter motor attached to it, than a cable with an ACR going forward to a large battery for windlass/ bowthruster.


Cheers

Charlie.
Charlie,

The assumption I made is that you will only be using the thruster and/or windlass while the engine is running and that these devices will be powered from the house batteries (which, in turn, will be under charge via the 110A Balmar alternator).

However, if you intend to use the start battery to provide charging current to the bow thruster/windlass battery then, yes, a second ACR would likely be the way to go.

It would be good to sit down with a pencil and paper...and a beer...and make some calculations and go thru some scenarios to be sure how best to set this up.

In my case, I have a windlass battery bank (2 T-105s under the V-Berth) which was sized to be able to operate without any charging current, since I sometimes like to sail to anchor, and off anchor without using the engine at all.

Charging for these batteries is via a dedicated 55A Iota battery charger, powered from one of three sources: shorepower, onboard generator, or inverter. But, I have enough battery power to drop and recover the anchor 5-7 times without any battery charging.

Bill
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