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Old 24-06-2018, 10:00   #31
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Re: Two house battery banks - necessary?

If you need a larger House bank, replace everything at once, should comprise identical units including mfg date.

Or wait to do a banks redesign / consolidation when it needs replacing.
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Old 24-06-2018, 10:00   #32
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Re: Two house battery banks - necessary?

There is no harm putting multiple disparate charge sources outputting to the same bank concurrently, amps will be additive, regulation works out overall.

As long as each source is not in itself harmful, the combination won't be.
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Old 24-06-2018, 10:42   #33
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Re: Two house battery banks - necessary?

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Originally Posted by john61ct View Post
If you need a larger House bank, replace everything at once, should comprise identical units including mfg date.

Or wait to do a banks redesign / consolidation when it needs replacing.
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Originally Posted by john61ct View Post
There is no harm putting multiple disparate charge sources outputting to the same bank concurrently, amps will be additive, regulation works out overall.

As long as each source is not in itself harmful, the combination won't be.
I replaced all my batteries with brand new about 6 weeks ago. Only one 3-day passage since then, otherwise plugged into shore power. So this would probably be a good time to make any changes.

The only issue I need to think through is what is the easiest/most efficient way of paralleling the eng start batt into the house bank. Right now the eng start is wired to a separate On-Off switch, and has its own alt charging through the starter circuit. So if I parallel it to the house bank using battery cables I lose the ability to isolate the eng start batt. Perhaps the easiest way might be to run a single pos cable from one of the house batts to the eng batt with another On-Off switch interrupting the cable run. That way I could turn the switch on & off for distribution purposes, but the two alts would charge in the same fashion. Although isolating the eng batt by turning the switch to Off during alt charging might help the alts out a bit.

Either that or request a PAID consult with good ol' Maine Sail! (You know what they say about boatowners with a lil' bit of knowledge . . . ).
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Old 24-06-2018, 11:03   #34
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Re: Two house battery banks - necessary?

If you measure 14.4V at the batteries that is pretty dam good with an internal regulator. If it is lower I would consider to rebuild the house alternator for external regulation. Then I would look closely if it is not possible to run a positive cable from the standard alternator to your house bank. It might not be that difficult. Just make sure that the negative cable also have the correct dimension. I do not really fancy alternators that take advantage of the starter cabling. many times not up to the job.

The high voltage is not a problem if you motor as we normally do. But at rare occasions it can be a little bilt longer. I did one crossing in the Med. that included 50 hours of motoring with ambient temp. around 35 C.
Engine was running for 50 hours. I was happy that the regulator went in float!
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Old 24-06-2018, 13:01   #35
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Re: Two house battery banks - necessary?

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If you measure 14.4V at the batteries that is pretty dam good with an internal regulator. If it is lower I would consider to rebuild the house alternator for external regulation. Then I would look closely if it is not possible to run a positive cable from the standard alternator to your house bank. It might not be that difficult. Just make sure that the negative cable also have the correct dimension. I do not really fancy alternators that take advantage of the starter cabling. many times not up to the job.

The high voltage is not a problem if you motor as we normally do. But at rare occasions it can be a little bilt longer. I did one crossing in the Med. that included 50 hours of motoring with ambient temp. around 35 C.
Engine was running for 50 hours. I was happy that the regulator went in float!
OK, I think I'm understanding the attraction of external regulation a bit better. So you're saying that, even if my alts are not producing 14.4v (at the batts) but more like ~14v, there's a possibility of damage from overcharging from long engine runs, even at 14v and esp. in hot weather. So really, the problem with internal regulation is typically both undercharging when the batts. are down, and (potential) overcharging when they're full. Yes?

As for the wiring run, my house alt has its charging wire run through the house batt switch and not directly to the batts. Must be a good reason for this but I don't know what it is. Maybe because my batts don't live in the eng compartment and it's probably another 6'-8' from the eng to where they do live (aft cabin). I wonder if I could simply re-route the eng alt charging wire that goes to the starter and instead have it routed to the eng batt switch? Much shorter run, and fewer changes to my existing set-up. The add'l on-off switch I'm contemplating could then be turned off for perhaps more efficient alt charging, and on for distribution from all 3 8D's.
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Old 24-06-2018, 13:50   #36
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Re: Two house battery banks - necessary?

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OK, I think I'm understanding the attraction of external regulation a bit better. So you're saying that, even if my alts are not producing 14.4v (at the batts) but more like ~14v, there's a possibility of damage from overcharging from long engine runs, even at 14v and esp. in hot weather. So really, the problem with internal regulation is typically both undercharging when the batts. are down, and (potential) overcharging when they're full. Yes?



As for the wiring run, my house alt has its charging wire run through the house batt switch and not directly to the batts. Must be a good reason for this but I don't know what it is. Maybe because my batts don't live in the eng compartment and it's probably another 6'-8' from the eng to where they do live (aft cabin). I wonder if I could simply re-route the eng alt charging wire that goes to the starter and instead have it routed to the eng batt switch? Much shorter run, and fewer changes to my existing set-up. The add'l on-off switch I'm contemplating could then be turned off for perhaps more efficient alt charging, and on for distribution from all 3 8D's.

14V at the batteries is low but not unusual for internal regulators. The result is under charging. 14V can be a little bit high for float.

If your cables from the main switch to the batteries are able to handle the charge from both alternators, I would connect the eng. alternator to the same switch. (paralleling the alternators to the house bank)

Iím assuming your house main switch is close to the engine room?

Personally I would not like to have a switch on the alternator cables. If it is only an on/off switch you could move the cables to the battery side of the switch. Switches in the wrong position could damage your alternator. Switches is also another voltage drop that will reduce charge.

Your engine battery can be charged with a Balmar Duo charger,
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Old 24-06-2018, 14:05   #37
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Re: Two house battery banks - necessary?

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14V at the batteries is low but not unusual for internal regulators. The result is under charging. 14V can be a little bit high for float.

If your cables from the main switch to the batteries are able to handle the charge from both alternators, I would connect the eng. alternator to the same switch. (paralleling the alternators to the house bank)

I’m assuming your house main switch is close to the engine room?

Personally I would not like to have a switch on the alternator cables. If it is only an on/off switch you could move the cables to the battery side of the switch. Switches in the wrong position could damage your alternator. Switches is also another voltage drop that will reduce charge.

Your engine battery can be charged with a Balmar Duo charger,
Yes, all 3 switches (house, eng, gen) are close to the engine compartment. I'm aware of never turning the switch off when the alt is running, but haven't confirmed which side of the switch the charging wire is on.

If the Balmar Duo is a charging relay commonly used to charge eng start batts, the problem is I already have a VSR BEP relay (same thing?) that charges the gen batt off the eng batt. The purpose of that was to keep the gen batt topped up after long spells of not running the gen. Not sure it's advisable to relay off a relay(?)

I hear ya about voltage drop going to the switches, but wouldn't it be worse going another 6-8' directly to the batts? Alt charging wires are typically what, 10 or 8 gauge perhaps?
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Old 24-06-2018, 15:21   #38
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Re: Two house battery banks - necessary?

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Originally Posted by Exile View Post
I replaced all my batteries with brand new about 6 weeks ago. Only one 3-day passage since then, otherwise plugged into shore power. So this would probably be a good time to make any changes.

The only issue I need to think through is what is the easiest/most efficient way of paralleling the eng start batt into the house bank. Right now the eng start is wired to a separate On-Off switch, and has its own alt charging through the starter circuit. So if I parallel it to the house bank using battery cables I lose the ability to isolate the eng start batt. Perhaps the easiest way might be to run a single pos cable from one of the house batts to the eng batt with another On-Off switch interrupting the cable run. That way I could turn the switch on & off for distribution purposes, but the two alts would charge in the same fashion. Although isolating the eng batt by turning the switch to Off during alt charging might help the alts out a bit.

Either that or request a PAID consult with good ol' Maine Sail! (You know what they say about boatowners with a lil' bit of knowledge . . . ).

He's already written this up for you!


I saved his diagrams, here, and some of my own, from my own Electrical Systems 101 topic, often quoted here:


OEM 1-2-B Switch Wiring History Alternator/Batteries & "The Basic" 1-2-B Switch BEST Wiring Diagrams

Basic Battery Wiring Diagrams This is a very good basic primer for boat system wiring: Basic Battery Wiring Diagrams

This is another very good basic primer for boat system wiring: The 1-2-B Switch by Maine Sail (brings together a lot of what this subject is all about)
http://forums.catalina.sailboatowner...d.php?t=137615

This is a newer primer for boat system wiring design with a thorough digram: Building a Good Foundation (October 2016)
http://forums.sailboatowners.com/ind.../#post-1332240

The Short Version of the 1-2-B Switch Stuff: Electrical Systems 101 This is a link to the Electrical Systems 101 Topic, reply #2

What are ACRs, Combiners & Echo Chargers? (by Maine Sail) [scroll to the top]
http://forums.catalina.sailboatowner...d.php?p=742417 and Battery isolator / voltage regulator / batteries
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Old 24-06-2018, 16:08   #39
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Re: Two house battery banks - necessary?

Quote:
Originally Posted by Stu Jackson View Post
He's already written this up for you!


I saved his diagrams, here, and some of my own, from my own Electrical Systems 101 topic, often quoted here:


OEM 1-2-B Switch Wiring History Alternator/Batteries & "The Basic" 1-2-B Switch BEST Wiring Diagrams

Basic Battery Wiring Diagrams This is a very good basic primer for boat system wiring: Basic Battery Wiring Diagrams

This is another very good basic primer for boat system wiring: The 1-2-B Switch by Maine Sail (brings together a lot of what this subject is all about)
http://forums.catalina.sailboatowner...d.php?t=137615

This is a newer primer for boat system wiring design with a thorough digram: Building a Good Foundation (October 2016)
http://forums.sailboatowners.com/ind.../#post-1332240

The Short Version of the 1-2-B Switch Stuff: Electrical Systems 101 This is a link to the Electrical Systems 101 Topic, reply #2

What are ACRs, Combiners & Echo Chargers? (by Maine Sail) [scroll to the top]
http://forums.catalina.sailboatowner...d.php?p=742417 and Battery isolator / voltage regulator / batteries
Ha! Yes, time to do some more homework, I agree. I've read much of this but many of my questions it seems are rather unique to my system. But it can't hurt to get a refresher! Thanks Stu.
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Old 24-06-2018, 23:21   #40
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Re: Two house battery banks - necessary?

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Yes, all 3 switches (house, eng, gen) are close to the engine compartment. I'm aware of never turning the switch off when the alt is running, but haven't confirmed which side of the switch the charging wire is on.

If the Balmar Duo is a charging relay commonly used to charge eng start batts, the problem is I already have a VSR BEP relay (same thing?) that charges the gen batt off the eng batt. The purpose of that was to keep the gen batt topped up after long spells of not running the gen. Not sure it's advisable to relay off a relay(?)

I hear ya about voltage drop going to the switches, but wouldn't it be worse going another 6-8' directly to the batts? Alt charging wires are typically what, 10 or 8 gauge perhaps?


Hi,

As you already have a VSR you are good, just make sure that both alternators charges the house battery.
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Old 14-08-2018, 02:47   #41
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Re: Two house battery banks - necessary?

Batteries , depending on type and how they are used , have a 3 to 5 year life span , so 960 amp hrs seems waste of money , I would reduce the amp hours by half and spend more on a Solar Power system
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Old 14-08-2018, 07:22   #42
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Re: Two house battery banks - necessary?

Why just because **you** think that's a big bank?

Why assume funds are limited?

Some use appliances that require large banks.

As long as DoD is getting down to 50% at least occasionally, then your bank isn't too big.

And no problem long as you have energy inputs to get ir back to 100% Full a few times per week.

Cost and weight can be downsides, but that depends on the context.
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Old 14-08-2018, 13:43   #43
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Re: Two house battery banks - necessary?

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Why just because **you** think that's a big bank?

Why assume funds are limited?

Some use appliances that require large banks.

As long as DoD is getting down to 50% at least occasionally, then your bank isn't too big.

And no problem long as you have energy inputs to get ir back to 100% Full a few times per week.

Cost and weight can be downsides, but that depends on the context.

+1 Absolutely correct. A pair of group 31s is plenty for some boats. 5kwhr might be about right for others. Then, there are us odd fellows using EP that go as high as 30 kwhrs and use the bank for EP and also house loads. Its not one size fits all, at all.


My first boat electrical system was a bunch of wire and a car starter battery from the junkyard. Of course there were no laptops or cell phones then.
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Old 15-08-2018, 04:39   #44
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Re: Two house battery banks - necessary?

Ive recently upgraded my bank(s).

I have one 675Ah bank and one 225Ah. Mostly I combine them giving me 900Ah. If offshore or somewhere remote I seperate them for redundancy.

I rarely see the voltage first thing in the morning below 12.6v when combined (or not). On a cruising boat rarely is a battery bank to big, Ive never complained about to much water or to much electricity, neither has my partner. More batteries is also more redundacy. I see alot of value in a large simply set up FLA bank x 2.
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