Eliminating the 1-2-Both-Off Battery Switch

[Q Xopa]

Originally Posted by 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.

Ok fine not disputing what you said, but the thread title is a question your reply didnt answer

[Q Xopa]

Originally Posted by john61ct

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.

Yes couldnt agree more.

Reserve banks not working when asked to.

System design is one thing but the operator is mostly weak link. Not understanding the system so not operating it correctly or not maintaining it properly.

Liferafts not serviced, Lithium booster pack wont work a damn if left rundown and not maintained. Is that a system design or equipment defficiency?

[john61ct]

Originally Posted by 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

bit extreme


> House loads must never compromise the ability to start the engine, and therefore must be isolated from the starter battery.

No one with a clue is suggesting this switch type be used for that purpose.

I agree that the B option is rarely useful, but 1-2-off switches can ve very valuable.

It is just a tool. Whether it it used wisely or not is the question, and it's a design issue.

Powerboats and airplanes of course have entirely different requirements from a cruising sailboat.

[pcmm]

Originally Posted by john61ct

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.

I'd be interested in learning of these other designs. (not meant as sarcasim,
really interested in other ideas) As far as I've seen the single paralleling switch IS the modern way to go when designing a system that has robustness, ability to isolate and both disable and parallel in mind

[john61ct]

Originally Posted by Q Xopa

Is that a system design or equipment defficiency?

Neither. And over-engineering to make a system "foolproof" is fine for charter fleets or the like, but I'm not paying to try to get there.

Of course a 12B switch should not be used to direct charging current, that much is clear. Don't need to be a fool to be forgetful.

[tdgaffney]

On my Olson 40 Mustang Sally I completely replaced the 36 year old electrical power system including six new identical 96ah batteries, one for starting and five for the house. I purchased the "Blue Sea ON-OFF battery switch with Automatic Charging Relay" package (PN 7650). When one side is being charged (e.g. Start Battery) the ACR automatically charges the off-side battery (e.g. House Battery bank).

Blue Sea Diagram
Blue Sea Pn 7650 Diagram - Cruisers & Sailing Photo Gallery

The text associated with the Blue Sea diagram states Engine Off - No charge present, which is true. Naturally, when the Engine is On it means charging to the start battery is present. The ACR will then cross-charge the house side if it needs it. Not discussed is that this works in reverse as well. For example, when your shore power battery charger feeds the House side, the ACR will cross-charge the Start side if it needs it.

I also have simple ON-OFF switches at each house battery bank, the three batteries to port and two to stbd. (Start is also to stbd but is not switched, except with the PN 7650 as discussed above.) And I have an emergency battery cable available to link the Start battery to the two stbd House batteries. Ya never know.

Mustang Sally Diagram
Sally Overall Schematic - Cruisers & Sailing Photo Gallery

Check out Blue Sea's part number 7650 and associated FAQs.
https://www.bluesea.com/products/765...Kit_-_120A/FAQ

[Panope]

Originally Posted by pcmm

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!

Thanks pcmm, I was not aware of that interesting product. It does indeed provide the fuction that I stated (able to energize house loads while keeping the engine de-energized) (something that a 1B2OFF switch cannot do).

However, it does not have the ability to isolate a malfuctioned battery from the system (something that a 1B2OFF switch can do).

As far as I am aware, only the "3 on/off switch" arrangement can do it all.

Steve

[smac999]

Originally Posted by john61ct

Powerboats and airplanes of course have entirely different requirements from a cruising sailboat.

most sail boats and power boats do the exact same thing around here. go for 2-7 days at anchor and come back to the dock to plug in. same power systems. same electrical systems. same demands. only difference is more alt power from a power boat.

[smac999]

Originally Posted by Panope

As far as I am aware, only the "3 on/off switch" arrangement can do it all.

Steve

dual 1,2,b switches are still the best. one to feed house, one to feed engine. each fed from both batteries.
either load can be taken from either battery, or paralleled if needed.

[Uncle Bob]

Originally Posted by smac999

dual 1,2,b switches are still the best. one to feed house, one to feed engine. each fed from both batteries.
either load can be taken from either battery, or paralleled if needed.

And really simple and obvious.

[Singularity]

Originally Posted by smac999

dual 1,2,b switches are still the best. one to feed house, one to feed engine. each fed from both batteries.
either load can be taken from either battery, or paralleled if needed.

Why do you say that the 1,2,b system is superior to the ~1 switch alternative described by MaineSail, Calder, used by many, and otherwise spelled out in post #41?

Are you saying that the alternative system (with aux/start battery on an echo charger) is more likely to result in a can't start situation? More likely to result in a can't use the lights/radio/keep the cold food situation? That most significant "real-world" failures occur in WWIII conditions such that you really need the WWII 1,2,b switch and wiring already in place to save the day?

[smac999]

Originally Posted by Singularity

Why do you say that the 1,2,b system is superior to the ~1 switch alternative described by MaineSail, Calder, used by many, and otherwise spelled out in post #41?

they are suggesting a 3 switch setup. this is a 2 switch that does everything the 3 does, but less switch and easier to use if labeled correctly

I would rather do this. allows full isolation of either battery (if one is bad, run both swtiches off the good one), allows the starter to be off while the house is on. allows paralleling.


emg = emergency use

acr or echo charger. doesn't matter. alt not shown. would be run to house bank. no chargers shown.

[Q Xopa]

Originally Posted by john61ct

Neither. And over-engineering to make a system "foolproof" is fine for charter fleets or the like, but I'm not paying to try to get there.

Of course a 12B switch should not be used to direct charging current, that much is clear. Don't need to be a fool to be forgetful.

Ok so we agree.

Yes also agree that anyone and everyone does snd will make mistakes. The best we csn hope for is to minimise mistakes.

As for trying to make a system 'idiot proof'. There's always a better idiot.

[john61ct]

I agree there is no "one true way", room left for other owner choices, but

Originally Posted by smac999

I would rather do this.

is more precise than

Originally Posted by smac999

dual 1,2,b switches are still the best.

In your setup, what is the scenario where the B is genuinely helpful?

What protection is there from running both banks down in the event B is switched accidentally or forgotten about?

[captainwd40]

A lot of good information contained in the numerous replies.

Just wanted to chime in on the "why would you change out the battery 1-2-Both switch. I used to have to change out this switch on my old boat every 3-4 years due to it wearing out after a lot of use and its location. Disconnecting and reconnecting the wires is a real pain on a single switch and rewiring as stated in the diagram with 2 vs 1 makes it a lot easier with less wires on each switch and you only will typically replace the one switch that appears to wear our routinely. The other ….. reserve switch usually lasts a lot longer requiring less maintenance.

My 2 cents for what it is worth...…...