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Closet Powerboater
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Discussion Starter · #1 ·
On my new nauticat I have a fairly standard battery setup (house and starting), but the charging options are complex. Specifically I have a main engine with alternator, and a diesel generator with it's own alternator. The generator supplies 110V power, which in turn supplies a Xantrex battery charger wired to both banks.

Currently my battery switch is 1-2-both with a second switch to bring the genset into play. I'd like to start over with the battery switches and make good use of what I have.

If I ignore the genset, what I would do is wire the main engine alternator directly to the house bank and use a blue seas battery combiner to have it charge the starting battery.

The genset powers a Xantrex charger, which is a "smart-ish charger" and charges both banks, but I'm left wondering where to wire the genset's alternator to? It seems like whichever battery I wire it to will confuse the battery charger. For example if I wire it to the starting battery, the starting battery will show 14.5volts and the charger will always think it's charged.

Suggestions?

MedSailor
 

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Closet Powerboater
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3,925 Posts
Discussion Starter · #3 ·
Does the genset have its own starter battery? If so, wire the genset's alternator to the genset's starter battery.
It shares the starting battery with the boat's main engine. Even if it did have it's own starting battery, it would still be confusing the smart charger I would think... I want the smart charger to have a chance to do it's magic of float charging etc.

MedSailor
 

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Closet Powerboater
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Discussion Starter · #6 ·
OK, more seriously, why not add a battery for the genset? Then you have nice, redundant power systems.
I might just do that. Redundancy is my friend... :)

I'm still stuck on the general problem of wanting the smart battery charger to be able to charge the batteries from time to time but it seems like any battery I put the generator's alternator on is always going to see the 14.5V and won't get any benefit from the smart charger.

Another related question is, would there be any benefit to putting both alternators on the house bank? If they're both on at the same time would there be additive effects from them?

MedSailor
 

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Asleep at the wheel
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It's been a while since I've done any work along these lines, but what about putting diodes in line with the chargers/alternators? The diode would keep the current from finding its way out of one charger and into an alternator, for example.
 

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Closet Powerboater
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Discussion Starter · #9 ·
It's been a while since I've done any work along these lines, but what about putting diodes in line with the chargers/alternators? The diode would keep the current from finding its way out of one charger and into an alternator, for example.
I hadn't even thought about that...

I was more worried about the alternator immediately bringing the electrolyte up to 14.5V and tricking the "smart" charger into thinking all is well and going into standby mode.

MedSailor
 

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A separate start/charge on the gen is probably #1 but a simple off switch on the gen's alt might solve the dilemma and still be available when all else is kaputing.
 

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Closet Powerboater
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Discussion Starter · #11 ·
A separate start/charge on the gen is probably #1 but a simple off switch on the gen's alt might solve the dilemma and still be available when all else is kaputing.
I was thinking of that, but if your alternator doesn't have an outlet for it's output doesn't it fry it's diodes?

MedSailor
 

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I was thinking of that, but if your alternator doesn't have an outlet for it's output doesn't it fry it's diodes?

MedSailor
Only if you remove the load suddenly while it's running. Disconnecting it entirely is almost exactly the same as a fully charged battery from the alternator's perspective.
 

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Main engine alt should charge both and be sized to do so. Depends on your batt type, but systems can be set up to do so automatically. Not convinced the genset alt needs to charge anything, unless it had its own start batt. It could do the shared start, but suspect it's too small for the house and you would be running your 110v chargers anyway.

The main thing you need is an A/B switch that allows you to start the main off the house, if the start gives up the ghost.
 

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Closet Powerboater
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Discussion Starter · #15 ·
I agree the genset alternator is not only not necessary but seems to be getting in the way. If I could just switch it off then it could be kept in reserve and only used if a charger crapped out.

I think i like this....

So can someone just run the hot wire from the alternator to an on off switch?

Medsailor
 

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The genset alternator will not get in the way. Wire its output to the start battery. The start battery, if dedicated, will be almost fully charged all the time anyway. It's no different than a boat with solar or wind gen as additional charge sources.

Diodes will limit output voltage and are not needed in any case.
 

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I think the house bank is the critical issue here. One should be able to use an A/B switch to start the main off the house bank, if charging the starter was a temporary problem. The genset alt is unlikely to have the output of the main alt, so if I lost the house charger, I would probably just run the main. However, no harm done running the genset alt to the house.

One just needs a system that allows for them all to be on at once, which could be the case. For me, I do not want to have to play the rubix cube of switches each time I turn some thing on, especially if making a mistake was going to fry something, so it would all have to be auto.
 

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I might just do that. Redundancy is my friend... :)

I'm still stuck on the general problem of wanting the smart battery charger to be able to charge the batteries from time to time but it seems like any battery I put the generator's alternator on is always going to see the 14.5V and won't get any benefit from the smart charger.
We need to stop being paranoid with all the myths and lore that surround charging & "confusion" of charge sources...

Generally all charge sources go to the house bank. All sources are voltage regulated and thus if one charge source can maintain 14.5V then you simply don't need the others. There is no "confusion" as I have seen it referred to in the past, there is only voltage superiority. If one charge source has the slightly higher regulation point the others will simply drop off the system. If they were needed the high volt source will not be able to maintain the voltage and it and the others will simply kick back on when the voltage decays. All this happens in fractions of a second and is seamless...

If a battery immediately comes up to 14.5V it is either:

A) Sulfated and dead

B) Not as deeply discharged as you thought.

Contrary to popular myth and misconception charge sources don't simply "put out 14.5V" onto the system bus. They supply a constant current which gradually RAISES the voltage over a period of time to the absorption voltage level. If the batteries immediately come up to limiting voltage, see above A or B....


Another related question is, would there be any benefit to putting both alternators on the house bank? If they're both on at the same time would there be additive effects from them?

MedSailor
Yes the benefit would be additive, in bulk charging, which is where you want it to be additive. Once into absorption the alternator with the lowest voltage would simply drop out of the charge loop and the other alternator would continue to charge. If that alt could not maintain voltage the other alt would simply cut back in until one source could maintain it.


For a boat with a gen set there are 80 ways from Sunday to wire it. I never complain about keeping or adding a genset battery. You don't need anything more than a group 24, 27 or 31 deep cycle. Feed its alt directly to that battery. Use a cross connect switch so the rest of the boat could be fed from this bank, in an emergency, or the main engine could be started from it..

I would use a Blue Sea ML ACR for this, the one with the yellow manual override switch and remote control switch.

Feed all other charge sources, including the shore charger, directly to the house bank bus and allow another ACR or an Echo Charger to feed the main engine start battery.

In any system with multiple banks we want to design for:

Redundancy -
Each bank on-board should be able to serve all purposes if the need should arise

Isolation - Each bank on-board should be capable of 100% isolation in the event of a failure.

For general running leave the genset ML-ACR to OFF. If you need the extra boost from that alt into the rest of the system, on top of the engine and charger, then simply activate the ML-ACR... Otherwise the genset alt will always keep its own battery charged.

You can also use a single bank for "starting" both the main engine and the genset but for the added weight of a dedicated genset battery it is often well worth it......
 

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I might just do that. Redundancy is my friend... :)

I'm still stuck on the general problem of wanting the smart battery charger to be able to charge the batteries from time to time but it seems like any battery I put the generator's alternator on is always going to see the 14.5V and won't get any benefit from the smart charger.

I was more worried about the alternator immediately bringing the electrolyte up to 14.5V and tricking the "smart" charger into thinking all is well and going into standby mode.


We need to stop being paranoid with all the myths and lore that surround charging & "confusion" of charge sources...

Generally all charge sources go to the house bank. All sources are voltage regulated and thus if one charge source can maintain 14.5V then you clearly don't need the others. There is no "confusion" as I have seen it referred to in the past there is only voltage superiority. If one charge source has the slightly higher regulation point the others will simply drop off the system. If they were needed the high volt source will not be able to maintain it and the others will simply kick back on..

If a battery immediately comes up to 14.5V it is either:

A) Sulfated

B) Not as deeply discharged as you thought.


Another related question is, would there be any benefit to putting both alternators on the house bank? If they're both on at the same time would there be additive effects from them?

MedSailor
Yes the benefit would be additive, in bulk charging, which is where you want it to be additive. Once into absorption the alternator with the lowest voltage would simply drop out of the charge loop and the other alternator would continue to charge. If that alt could not maintain voltage the other alt would simply cut back in until one source could maintain it.


For a boat with a gen set there are 80 ways from Sunday to wire it. I never complain about keeping or adding a genset battery. You don't need anything more than a group 24, 27 or 31 deep cycle. Feed its alt directly to that battery. Use a cross connect switch so the rest of the boat could be fed from this bank in an emergency or the main engine could be started from it..

I would use a Blue Sea ML ACR for this, the one with the yellow manual override switch and remote control switch.

Feed all other charge sources, including the shore charger, directly to the house bank bus and allow another ACR or an Echo Charger to feed the main engine start battery.

In any system with multiple banks we want

Redundancy -
Each bank on-board should be able to serve all purposes if the need should arise

Isolation - Each bank on-board should be able to be 100% isolated in the event of a failure.

For general running leave the genset ML-ACR to OFF. If you need the extra boost from that alt into the rest of the system, on top of the engine and charger then simply activate the ML-ACR... Otherwise the genset alt will always keep its own battery charged.

You can also use a single bank for "starting" both the main engine and the genset but for the added weight of a dedicated genset battery it is usually well worth it......
 

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I might just do that. Redundancy is my friend... :)

I'm still stuck on the general problem of wanting the smart battery charger to be able to charge the batteries from time to time but it seems like any battery I put the generator's alternator on is always going to see the 14.5V and won't get any benefit from the smart charger.

I was more worried about the alternator immediately bringing the electrolyte up to 14.5V and tricking the "smart" charger into thinking all is well and going into standby mode.


We need to stop being paranoid with all the myths and lore that surround charging & "confusion" of charge sources...

Generally all charge sources go to the house bank. All sources are voltage regulated and thus if one charge source can maintain 14.5V then you clearly don't need the others. There is no "confusion" as I have seen it referred to in the past there is only voltage superiority. If one charge source has the slightly higher regulation point the others will simply drop off the system. If they were needed the high volt source will not be able to maintain it and the others will simply kick back on..

If a battery immediately comes up to 14.5V it is either:

A) Sulfated

B) Not as deeply discharged as you thought.


Another related question is, would there be any benefit to putting both alternators on the house bank? If they're both on at the same time would there be additive effects from them?

MedSailor
Yes the benefit would be additive, in bulk charging, which is where you want it to be additive. Once into absorption the alternator with the lowest voltage would simply drop out of the charge loop and the other alternator would continue to charge. If that alt could not maintain voltage the other alt would simply cut back in until one source could maintain it.

Even if it did have it's own starting battery, it would still be confusing the smart charger I would think... I want the smart charger to have a chance to do it's magic of float charging etc.
If you are cruising, and your charger has gone to float, off the genset, you are simply wasting fuel and lightly loading the genset..... If anything you want extended absorption charging after multiple cycles of partial state of charge to help shed some sulfation.

Float is really for dock side use, solar or a loooooooong motor run but you would need an external regulator to accomplish this.

For a boat with a genset there are 80 ways from Sunday to wire it. I never complain about keeping or adding a genset battery. You don't need anything more than a group 24, 27 or 31 deep cycle. Feed its alt directly to that battery. Use a cross connect switch so the rest of the boat could be fed from this bank in an emergency or the main engine could be started from it..

I would use a Blue Sea ML ACR for this, the one with the yellow manual override switch and remote control switch.

Feed all other charge sources, including the shore charger, directly to the house bank bus and allow another ACR or an Echo Charger to feed the main engine start battery.

In any system with multiple banks we want

Redundancy -
Each bank on-board should be able to serve all purposes if the need should arise

Isolation - Each bank on-board should be able to be 100% isolated in the event of a failure.

For general running leave the genset ML-ACR to OFF. If you need the extra boost from that alt into the rest of the system, on top of the engine and charger then simply activate the ML-ACR... Otherwise the genset alt will always keep its own battery charged.

You can also use a single bank for starting both the main engine and the genset but for the added weight of a dedicated genset battery, on a Nauticat, it is probably worth it......

The ultra simple system would be two banks...
 
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