Eliminating the 1-2-Both-Off Battery Switch

[SVTatia]

Originally Posted by sveinung

Another problem with this setup is that you'll never know if your"reserve" has enough juice or able to deliver enough amps to crank your engine ...

I do have a Victron monitor and always keep an eye on the charge state of both banks. With the ACR I have not had a problem yet.

[rbk]

Originally Posted by sveinung

Another problem with this setup is that you'll never know if your"reserve" has enough juice or able to deliver enough amps to crank your engine .

I have two house batteries and an engine (and only engine) battery. A charge relay fills the engine battery first making sure that's always tolled up before it goes to the bank.
The shore power charger charge each battery individually.
The house batteries are deep cycle while the engine battery is high peak current.

This way I know I can always start even if I leave the light on. If the engine battery is dead but house is full I'm sure I can device a 1 ft jumper cable to get it going, not a scenario I need to optimize for.


This seems to be all in one solution, and it's prewired so you don't have make those hard to bend short cables yourself: https://www.amazon.com/BEP-Square-Ba.../dp/B0184S2S5Y

This is backwards. Should charge the house bank as the primary, starter as secondary for many reasons.

[Pizzazz]

The problem with multiple switches is that you are losing the make before break functionality which is key. If simplicity is what you are after then just wire starting to starter, house to everything else and alternator to starting and an ACR. You do not need the second switch unless working on the alternator and this is rare (as in you can just disconnect at the battery). But even then you will be better off with a 1-2 switch. Don’t mess it up.

[rbk]

Originally Posted by SVTatia

Long run. The batteries are very close to the switches and panel, but much farther from the starter/alternator.

How far and what output from your alt? If you don’t mind my asking? Also what is your main reason for eliminating the 3 way?

[SVTatia]

Originally Posted by rbk

How far and what output from your alt? If you don’t mind my asking? Also what is your main reason for eliminating the 3 way?

The switch is old and big. I am redoing the panel, and 3 switches will take less room than the one I have now. But this is not the only reason, as I explained above, I am using the 3-way now as an on-off since I only place it on #1 then on off.
The wire runs to the alternator/starter is about 10 feet one way, its a standard 50amp alternator for now. All the wires are in place and hooked up.

[Stu Jackson]

Originally Posted by Uncle Bob

Personally I can't see what you are trying to achieve, replacing one rotary switch that has the capability to connect one, both or the other batteries with two switches. I have to ask, why.

+1,000


Heck, if you really read Maine Sail's material, you should have learned about the proper use of a simple 1-2-B switch.


There is really no reason to reinvent the wheel.


Here's all of what he's written, and more. Keep the switch,m manage your stuff properly, or do a three switch arrangement all covered in these links:


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

[SVTatia]

Originally Posted by Pizzazz

The problem with multiple switches is that you are losing the make before break functionality which is key...

It is key because...? The alternator is directly wired to the house battery.
Remember, I will always turn one switch on when getting on the boat, no matter what I do which may or may not include starting the engine. This switch stays on until I leave the boat.

[Stu Jackson]

The make before break becomes an anachronism if you wire the AO to the house bank.

[SVTatia]

Originally Posted by Stu Jackson

+1,000


Heck, if you really read Maine Sail's material, you should have learned about the proper use of a simple 1-2-B switch....

Heck, I have Stu!
The switch needs to go for reasons already mentioned, and like I said, I will not replace it with another 1-2-both-off.
This is an excerpt from MS article:

"...Many have asked what my favorite switch configuration is, if I am not encumbered by a previous installation. When starting from scratch I generally prefer a switch system of three ON/OFF switches. In this situation the alternator and all other charge sources are wired to HOUSE bank and the START gets charged via an ACR or Echo type charger. The EMERGENCY SWITCH could also be used to charge both banks.

It provides:

*Full isolation (fully disconnected) of either bank if necessary
*START bank can be used for both HOUSE and START loads.
*HOUSE bank can be used for both HOUSE and START loads.
*EMERGENCY PARALLEL can be used for charging both banks.
*EMERGENCY PARALLEL can be used to parallel banks.
*STARTING isolation from house loads and electronics.
*HOUSE isolation from START voltage sags or transients..."

[rbk]

Originally Posted by SVTatia

The switch is old and big. I am redoing the panel, and 3 switches will take less room than the one I have now. But this is not the only reason, as I explained above, I am using the 3-way now as an on-off since I only place it on #1 then on off.
The wire runs to the alternator/starter is about 10 feet one way, its a standard 50amp alternator for now. All the wires are in place and hooked up.

With your 50 you could run 6awg @3% or if you’re planning on a 150 in the future you could go with 1awg @3% and will be easier to work with to the 2/0 you’ve planned. You could easily reduce that if you’re on a budget.

[Stu Jackson]

Originally Posted by SVTatia

Heck, I have Stu!
The switch needs to go for reasons already mentioned, and like I said, I will not replace it with another 1-2-both-off.>>>>>>>>>>>>>>>

OK, then you know that my links include that same article from MS thst you quoted.


Look, you know it is ONE of a few OPTIONS. As Rob & others have said, the three switch version is a complicated version of the 1-2-B and does offer advantages IF you are having electronics drop-outs. If not?


Your boat, your choice.


Since you have MS's wiring diagrams, not sure what you're asking, although your presentation is novel. Good luck.

[TrentePieds]

Quote: "Well, not quite. With this scheme, when getting on the boat turn the house switch on (SW1). When leaving the boat turn SW1 off. "

Restated: "... when getting on the boat turn the 1-2-both switch to "1" When leaving the boat turn the 1-2-both switch to off."


The 1-2-Both switch was developed PRECISELY to take care in the operationally simplest possible way of the problem you seem to think you have.

For the record: I use a 40 year old 1-2-both that I had to dismantle and clean when I bought the boat. I start off the house bank (the only bank) by using on even dates the "2". position and on odd dates off the "1" position so as to even out the use on the individual batts. The juice consumed to start my 20HP Beta is replaced by the standard 40A alternator in a matter of minutes regardless of which batt I take it from.

All the house draws are taken from one of the two batts in the same way: Odd dates: "1", even dates: "2". Assuming that your batts (and your engine) are sound, there will always be juice (in the other batt) to start the engine and make more juice even if the voltage in the "battery in use" goes low. If your power budget is sound, there will always be enuff juice to see you through the night.

Never, never use the "both" position. If you drain the "battery in use" in an attempt to start your engine you have a problem that has nothing whatsoever to do with your electrical system but requires rectification BEFORE you leave the dock!


TrentePieds

[guyrj33]

In general I agree with the first part of this statement.

Never, never use the "both" position. If you drain the "battery in use" in an attempt to start your engine you have a problem that has nothing whatsoever to do with your electrical system but requires rectification BEFORE you leave the dock!

I did have a situation where my batteries had aged and the start battery didn't have quite enough capacity to start the engine and the house bank was of a similar age and had been in use through the night and didn't have quite enough to start the engine. Both batteries could turn the engine over slowly. Combining the two banks did provide enough power to start the engine.
I did replace both banks later that week.

The second part of the statement confuses me, certification? really? we're sailors here, come hear to learn and therefore to be self reliant.

Has anybody here ever had their charging system certified? and by whom?

[NorthCoastJoe]

Single switches that will handle starter loads are big. To me it seems like you are just making more work for no gains. The 1,2 B switch is not that big if you compare it to 3 singles that can handle starter loads.

The "emergency battery" should be used as stated in earlier posts on a every other day or every other week use. Letting it sit makes no sense to me at all.

Seems to me that on a 33 foot boat a starting battery and a deep cycle (or 2 in parallel)should be all you need. Why get all complicated?

[rbk]

Originally Posted by guyrj33

The second part of the statement confuses me, certification? really? we're sailors here, come hear to learn and therefore to be self reliant.

Has anybody here ever had their charging system certified? and by whom?

Rectification not certification.