Eliminating the 1-2-Both-Off Battery Switch

[Panope]

Originally Posted by CptCrunchie

I can do that. One main battery switch to the house bank. Then one 200A continuous solenoid bridged between the start and house banks, connected to (engaged by) the engine ignition switch. You start the engine, everything charges. You shut the engine down, only your house is being used. There is nothing you need to switch over.

CC, I believe that your proposal would leave engine connected to battery negative through the instrument panel. I suppose one could re-wire the panel to isolate the "ignition" switch (don't forget to add a second solenoid to break the engine's main negative) in order achieve the "ease of use" that you proposed.
However, I was much more concerned with keeping the "instalation" of the system easy and inexpensive.

Steve

[Stu Jackson]

Originally Posted by Panope

Stu,

Please describe an easier/cheaper 12 volt system (than my 3 switch set-up, above) that will allow the engine to be completely disconnected from the batteries while the house load is energized.

Steve

Steve,


The answer is blowing in the...oops, the answer is in the links. 1-2-B or three switches.


Just. Like. Yours.


Excellent job.



What's not to like?





PS - Taken out of context this reply and its quote may be misleading. Steve's comment was from one of my earlier posts about trying to avoid reinventing the wheel.

[Panope]

Cheers,

Steve

[hellosailor]

IIRC there were a couple of recalls and safety warnings about 20 years ago. A generally respected Cole Hersee and another brand, both 1-B-2 switches (NOT 1-2-B) with make-before-break connections. And one lot of them were overheating, melting the plastic, with the contacts not properly making contact so the make-before-break function was lost and alternators were also going out.

That's an intrinsic problem with the 1-B-2 rotary switches. Yes, they allow battery switching on the go. And if you get one with dual contacts, you can also route an alternator's voltage sense lead to two battery banks.

But as those oddball folks at Beneteau have been criticized for SO many years...having simple on/off switches and relying on the owner/operator to throw the one they need, certainly can work. Costs less, has fewer invisible failure modes.

You say tomato, I say tomatoe. Really, does it make a difference?

[john61ct]

Blue Sea, properly rated

[Q Xopa]

Originally Posted by john61ct

Blue Sea, properly rated

Bluesea make both
on/off and
1 2 B types.
Which ones are you suggesting?

[john61ct]

Whatever suits your design goals.

Just saying they are a robust, quality product, unlikely to fail if properly sized, m-Series vs e-series vs HD

IMO such components are best for bank master and load direction, not so much for switching charge sources. But if needed, the AFD feature is well worth checking out, implementation needs RTFM with good attention to detail, pro's get it wrong.

Dual Circuit Plus DPST is interesting.

[roger_l]

If you're trying to eliminate the problem of accidentally having the wrong battery selected and getting drained by the house load then Marinco does a switch that is fairly foolproof. It goes off -> 1 -> 1 & 2 (separate) -> 1 + 2 (parallel). On my boat, I had 1 as the house load and 2 for engine. Unless you switch to parallel because one or the other is dead, then they are always separate. Charging is handled by a VSR.

Pro Installer 400A EZ-Mount Dual Bank Control Battery Switch - MC10 | Marinco

[MVDarlin]

I've never trusted the 1, 2, both, off battety switch. When I am at a remote location at anchor I use a seoarate "off" switch located on the. Start battery to be sure will not drain overnight. This has served me well for 15 years..

[TrentePieds]

Whyever would you not trust that a 1-2-B-OFF is truly off when that position is selected? Have you ever taken one apart to see how it is physically constructed and just how it operates?

There is ZERO chance that the switch can make of its own accord. It takes a fair bit of torque to move it from position to position. So much, in fact, that it cannot be done by an accidental impact.

TrentePieds

[pcmm]

Originally Posted by Panope

Stu,

Please describe an easier/cheaper 12 volt system (than my 3 switch set-up, above) that will allow the engine to be completely disconnected from the batteries while the house load is energized.

Steve

Panope ( great anchor videos by the way!) This is the switch you are looking for to simplify the whole setup

https://www.defender.com/product.jsp...060&id=2541071

pos 1 is just the house bank, leaving the engine de-energized.
pos 2 is both house and engine energized
pos 3 is parallel between banks

neat and simple, but this switch is harder to find! should be standard now!

[dreuge]

There is a BIG issue with the current design. The starter should not be live all the time that the house bank is in use. It should only have power at times when you need the engine. It is a safety issue.

I have a set up that is a slight modification to that originally suggested in Maine Sail posting. It is a battery switch set up which includes a dedicated ON/OFF switch for a starting battery but also retains a flexibility of a 1/BOTH/2/OFF switch to use the house bank for start redundancy.

See my post: S/V Johanna Rose: BatteryWork

The on/off is for the starter and the 1/2/b/off allows for using any bank, seperately or combined, for any purpose. The later is mounted in the engine compartment away from "helpful" hands whereas the on/off is accessible near the companionway.

It is also not smart to have an isolated "reserve". You are better off using dedicated house and a dedicated start. Batteries degrade for many reasons, and using it lets you know if a problem is arising. Actually the starter consumes very little total charge (100A * 5s = 0.14 A*hr) which takes even a small alternator little to replace. I know of two cases where people use the reserve concept, and in both cases, their reserve battery failed to start the engine.

[john61ct]

Originally Posted by pcmm

Panope ( great anchor videos by the way!) This is the switch you are looking for
..

this switch is harder to find! should be standard now!

Marinco is fine, but not as well engineered nor robust as Blue Sea. Same parent co.

And whether it is "more simple" or not depends on the overall system design.

Which issues are comprehensively outlined in the threads cited above.

Finally, many excellent schemes do not require that design switch at all, calling it "standard" is now pretty outdated.

But it's fine, as long as it fits into a well thought out overall system design.

[john61ct]

Originally Posted by dreuge

I know of two cases where people use the reserve concept, and in both cases, their reserve battery failed to start the engine.

IMO that's an implementation failure not design.

The Reserve can be the default for cranking purposes.

Or at least regularly used for that purpose as a test.

And more stringent tests regularly run.

The key element is, the Reserve is not used except after House has failed, and then only for Essential loads.

It is not there to take over just because House is empty in normal use, other steps are needed to prevent that.

Finally, a lithium jumpstarter powerpack is well maintained as a backup redundancy, belt & suspenders.

[parkstone bay]

When I am Dictator of the World, I will condemn the guy who invented the "1-2-Both-Off" rotary switch to whole life imprisonment in the deepest salt mines, and longer if at all possible! If - and I stress "IF" - users could be trusted to view their battery voltages and amps, and altered their switch settings accordingly, that'd be fine. But humans are just that: human, and therefore fallible. Everyone agrees that on all boats, but power boats even more so, it is important that the starter battery is always charged, and (by definition) is charged preferentially to the house batteries. House loads must never compromise the ability to start the engine, and therefore must be isolated from the starter battery. The only practical, non-human intervention way on a single engine/single alternator layout of which I'm aware is by using either a voltage-sensitive relay or split-charge diode (or something whizzy and electronic that does the same thing), so that the starter battery gets charged first. On a twin engine set-up, and I believe that this system is used on multi-engine aircraft, is to have, say, the starboard engine charging the starter battery bank only, and the port charging the house bank, only. You always start the starboard engine first, then the port. (If you are really concerned about needing additional power to start in a really dire case - add a separate switched link to the the house bank, (which is, of course, normally, not used)).