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Old 09-04-2016, 09:00   #1
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Alternator Direct To House Bank

Planning on using a Yandina voltage controlled relay to connect the starter & house batteries when the alternator is charging. That's the easy part.

Since most charging work will be for the house bank, the recommendations to connect the alternator direct to the house bank makes sense. The Yandina relay connects the starter bank so that both banks are charged when the engine is running.

The house bank is 200ah and may be expanded to 300ah. That is a lot of power
at the alternator output bolt just waiting for a wrench to accidentally touch it.

A fuse or switched breaker could destroy the alternator if forgotten in OFF or on a power surge. An overly high amp rating could defeat the purpose of having it.

Do people disconnect their alternator to house bank connection when working on the engine?

Does anyone use a diode based combiner as an alternator protecting connection on the alternator side of a breaker, so that house current can be blocked from the engine, but alternator current can always find a path to a battery?
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Old 09-04-2016, 09:14   #2
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Re: alternator direct to house bank

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Originally Posted by dave777 View Post

<SNIP>
A fuse or switched breaker could destroy the alternator if forgotten in OFF or on a power surge. An overly high amp rating could defeat the purpose of having it.

Do people disconnect their alternator to house bank connection when working on the engine?om the engine, but alternator current can always find a path to a battery?

<SNIP>
Don't bother with the diode.

Use a switch, you already should have a fuse at the battery on the AO from the alternator. Leave the switch ON all the time, unless you're working on the alternator. I bought a switch years ago, never installed it, just remove the fuse when I work on the alternator.

KISS,
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Old 09-04-2016, 09:19   #3
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Re: alternator direct to house bank

A fuse right at the battery connection really is the right safety solution. Yes, you run the risk of a fuse blowing while charging and ruining your alternator rectifier. But the risk there vs. the risk of fire, electrocution, etc. is relatively small, so general recommendation is to use a fuse.

There are blown fuse monitors that could open the field connection when a fuse blows. I've never seen one fitted in this application, and I suspect they might not be fast enough to save the alternator, but if I was really concerned would investigate.

I have used a diode separator for years, but they are inefficient. You absolutely must have a battery voltage sensing wire for the regulator, the diodes will eat 0.5 to 0.8V. That also means they will get quite warm, so a good heatsink is required. Have you considered a MOSFET isolator? A lot of the advantages of the diode isolator, without most of the voltage drop.

And yes, wrenches and screwdrivers can be a problem, if your terminals aren't well insulated on both ends then probably a good idea to open the fuse when working near the connections [EDIT] or install a switch as Stu says, that's how we have things wired[/EDIT]
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Old 09-04-2016, 10:12   #4
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Re: alternator direct to house bank

I have a Zap Stop diode installed on my alternator to protect the alternator if the load is suddenly removed (such as a blown fuse). These are not the same thing as a diode charge splitter. I think you can just use the right spec diode but here's a Balmar product:

https://www.emarineinc.com/Balmar-TS...ector-Zap-Stop
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Old 09-04-2016, 12:31   #5
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Re: alternator direct to house bank

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Originally Posted by dave777 View Post
...
A fuse or switched breaker could destroy the alternator if forgotten in OFF or on a power surge. An overly high amp rating could defeat the purpose of having it.

...
It of course wont actually "destroy" the alternator, just blow some diodes. Not a difficult repair to do, or just carry a spare bridge rectifier.

Anyway, in my configuration, alternator output is routed directly to the house bank, but there is a nice big fuse and a disconnect switch in the engine room. Disconnect switch to off and both banks (house and start) are disconnected from alternator/engine.

Heavy duty relay controlled by smart regulator (Next Step) is used to parallel house/start automatically.

Works great, have never needed that spare bridge rectifier I carry around.
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Old 09-04-2016, 13:02   #6
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Re: alternator direct to house bank

Here is a basic diagram.
You can route the alt. output to House SWX if you prefer your House Bat. to get priority charge. You would have to change the VSR sense to other bat. also

https://www.dropbox.com/s/l7fuzp9c45...ching.pdf?dl=0
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Old 09-04-2016, 13:41   #7
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Re: alternator direct to house bank

Yandina 600Amp VCR/ACR- Impressive !!
Is it available in Canada/ US ?
Catalog Frame
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Old 09-04-2016, 15:31   #8
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Re: alternator direct to house bank

I disconnect everything when I work, both positive and negative.

I do not see any problem if you disconnect the negative as then the engine will not start and so the alternator will not get damaged. Unless you have separate starter and alt negative wires. Is this common?

We have a relay (plain vanilla 50A Bosch unit) here too and it kicks in as soon as the alt kicks in. As starter bat and house bat negatives are joint, you can place the positive on either bank but should the relay go, your engine battery will not get charged. And so we have our positive charge done onto the engine bat and the relay feed the 'excess' to the house bat, only when the alt is up and charging.

Many ways to skin a cat I guess.

b.
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Old 09-04-2016, 16:09   #9
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Re: alternator direct to house bank

I have 2 A/B battery switchs to isolate the 4 pairs of 6 volt house batteries.

I turn them both to Off and the alternator wire is dead.

The start battery and thruster batteries both have On/Off switchs.
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Old 10-04-2016, 08:30   #10
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Re: alternator direct to house bank

We rewired our eng alternator to feed our combined house bank (3 sets of Trogen T105s). We also connect our windgen (via a controller) and our solar(via its controller) to the combined house bank. And then we use a Duo-Charge to connect the house bank to the isolated start battery. The house bank recharges as needed, and as soon as the starter battery has a lower voltage than the house, current flows to the starter battery to keep it fully charged. The very small alternator on our genset also is wired only to the start battery. Made the changes about 5 years ago, and has worked flawlessly since.
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Old 10-04-2016, 09:07   #11
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Re: alternator direct to house bank

I have this type of hookup (11 years on current boat, plus prior boat) and have had no problems.

I use an Echo-Charger, connected to the house bank, to pick up the start batteries.

In addition to battery fuses and convenience disconnects located at the house bank (primarily for maintenance), I have a circuit breaker disconnect on the alternator output. I only rarely use it, but the convenience and safety are worth the slight additional cost.

My alternator is 110 A, serving a 460 AH house bank, plus start batteries for the main engine and the generator.
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Old 10-04-2016, 14:53   #12
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Re: alternator direct to house bank

With an ACR (VSR) connected between start and house bank it is best to wire alternator output to the larger of the banks - typically the house bank. If the alt output is wired to the start battery it can lead to chattering. The ACR closes and opens as voltage on the start battery increases and then drops when the ACR is closed sending current to a house bank that is low.
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Old 10-04-2016, 19:05   #13
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Re: alternator direct to house bank

fuse at 150% Of alt rating. this is standard practice for charge circuits. it should never blow. alt wire should be able to handle 150% of current anyways since it's rated for drop not for current.


cover wire / bolt with cover at alt.
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Old 11-04-2016, 18:56   #14
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Re: alternator direct to house bank

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Originally Posted by Dsanduril View Post
A fuse right at the battery connection really is the right safety solution. Yes, you run the risk of a fuse blowing while charging and ruining your alternator rectifier. But the risk there vs. the risk of fire, electrocution, etc. is relatively small, so general recommendation is to use a fuse.
What size fuse/breaker would you use on a 60A alternator Yanmar 3YM30 engine? Also thinking of upsizing to a 100A alternator.

Don't know if alternators put out surges of current in some conditions, which could complicate things.

I'm thinking that I'd put in a switched breaker so it would serve to dual purpose of depowering the line to the alternator when working on the engine.
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Old 11-04-2016, 19:01   #15
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Re: alternator direct to house bank

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Originally Posted by redsky49 View Post
I have this type of hookup (11 years on current boat, plus prior boat) and have had no problems.

I use an Echo-Charger, connected to the house bank, to pick up the start batteries.

In addition to battery fuses and convenience disconnects located at the house bank (primarily for maintenance), I have a circuit breaker disconnect on the alternator output. I only rarely use it, but the convenience and safety are worth the slight additional cost.

My alternator is 110 A, serving a 460 AH house bank, plus start batteries for the main engine and the generator.
Nothing like a picture.

Wouldn't anticipate using it much either, but after thinking about the huge house bank always live to the alternator I started thinking about Murphy.

OK, it's on the todo list this season.
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