1-2-both switch! is it still required!

[seafox67]

I'm starting to think about upgrading my electrical system on a small boat.

I currently have 1 starter battery and 1 house battery
My power sources are 1. Shore power, 2. Solar power and 3. Alternator.

My shore power charger has 2 outputs (starter and house batteries).
My solar is a mppt that goes just to the house battery.

For my upgrade, I just want to use the starter battery for starting the engine only and my house battery only for boat electrics.
My plan is to use a victron dc-dc charger to charge the house battery from the starter battery (Giving me a charging source from the alternator to my house battery).

Can anyone think of a reason why I should still keep the 1-2-both switch? I can't think of anything but... i've been wrong the past! lol... and would hate to rip it all out and then discover I've messed up!


Cheers

 

[PaulRainbow]

A B2B is an expensive solution, a VSR would serve your needs.

If you fit a separate switch for the engine battery, one for the domestics and an emergency parallel switch (both), no need to keep the 1-2-B

 

[vyv_cox]

If you fit a separate switch for the engine battery, one for the domestics and an emergency parallel switch (both), no need to keep the 1-2-B

Is it justifiable to remove a serviceable 1-2-Both switch to replace with three new heavy duty switches that achieve exactly the same function?

 

[seafox67]

A B2B is an expensive solution, a VSR would serve your needs.

If you fit a separate switch for the engine battery, one for the domestics and an emergency parallel switch (both), no need to keep the 1-2-B

Thanks for your feedback Paul, Separate switches sounds like a good idea... Another reason for binning the 1-2-B is that it is very old! and worries me!

Yep, the B2B is an expensive solution. But I do like playing with the Victron app when I don't have the internet to entertain me! lol

 

[PaulRainbow]

Is it justifiable to remove a serviceable 1-2-Both switch to replace with three new heavy duty switches that achieve exactly the same function?

It is, because a 1-2-B does not perform the same function.

Using your 1-2-B switch, kindly explain how you have the engine connected to the engine battery, the domestic batteries connected to the domestic circuits, both systems independant and both on simultaneously ?

 

[Tranona]

Thanks for your feedback Paul, Separate switches sounds like a good idea... Another reason for binning the 1-2-B is that it is very old! and worries me!

Yep, the B2B is an expensive solution. But I do like playing with the Victron app when I don't have the internet to entertain me! lol

You do not gain anything by using a B2B except the ability to play with your phone - but Why? KISS

What Paul suggests is pretty much the standard layout for simple systems like yours and fitted to most new production boats with similar requirements.

 

[vyv_cox]

It is, because a 1-2-B does not perform the same function.

Using your 1-2-B switch, kindly explain how you have the engine connected to the engine battery, the domestic batteries connected to the domestic circuits, both systems independant and both on simultaneously ?

Well, I never do. The starter battery charge used to start the engine is replaced in a few minutes, so why does it need to be connected permanently?

I almost always start the engine on the domestic bank, which it achieves easily. My starter battery is a kind of emergency backup.

 

[seafox67]

You do not gain anything by using a B2B except the ability to play with your phone - but Why? KISS

What Paul suggests is pretty much the standard layout for simple systems like yours and fitted to most new production boats with similar requirements.

Reading up on the Victron Orion-tr smart, they say it will manage the charging of the house battery better... stop it from being over charged. Also, the app will give me an indication of any potential issues going on with the alternator

 

[Refueler]

My old boat has 1-B-2 off switch as used years ago ... and works fine .... I start engine on either battery - can then choose to charge which or both ... by simply turning one switch.
I have small solar panel with dual output controller- so it serves both batterys independently ... I have two 90 A/hr Lead acids.

My later boat just bought has split charge system ... somewhere is a VSR - but not found it yet - too many other things to sort first. But it has 2 single action switches - they remind me of the old single battery switches of before the 1-B-2 off switch !! They have the plastic T keys. Both are fitted at bottom of engine box front ... stbd one is domestic (single battery) .... port one is engine start battery (two batterys). Why two batterys for a 2GM23 ?? Not exactly the biggest engine to turn over !! My idea would have to have two batterys on domestic, especially that I have a fridge unit. That's three 90 A/hr in service + one spare 90 A/hr under the nav seat.
There is a solar panel fitted to deck in front of mast via a single output controller ..... somehow that charges all three ... something also to work out how !! Its an old controller - might be worth swapping for one of the new ones I have with display / USB's etc.

Do I find one better than other ..... no. Do I prefer one over other ? Not really ..... but I suppose because of all the many years of using the 1-B-2-Off ... it suits me ...

My question to OP is this ..... if you only have simple use - like my older 25ftr ... and it works as is - why the need to change ?

I would think about using the money to reduce the power demand on the domestic battery - changing cabin lights / nav lamps / etc. to LED .... gain extra time on the batterys ... thats been my path ... the difference is significant.

 

[PaulRainbow]

Well, I never do. The starter battery charge used to start the engine is replaced in a few minutes, so why does it need to be connected permanently?

I almost always start the engine on the domestic bank, which it achieves easily. My starter battery is a kind of emergency backup.

That's because you have adopted, as is your right, a different procedure to most.

The 1-2-B switch cannot perform the same functions as 3 separate switches.

 

[Refueler]

Well, I never do. The starter battery charge used to start the engine is replaced in a few minutes, so why does it need to be connected permanently?

I almost always start the engine on the domestic bank, which it achieves easily. My starter battery is a kind of emergency backup.

I put it down to being used to a way of doing things .. it appears I have two boats - one with one system - other with other system ... I will probably come to appreciate the later system - but so far I am not impressed.
I have left my 1-B-2-off switch on by mistake before ... but soon got into habit of checking before closing up.

Already I have left the later two switch system on more times in one month than total of my older in years !!

 

[seafox67]

My question to OP is this ..... if you only have simple use - like my older 25ftr ... and it works as is - why the need to change ?

Yep... already gone down led route etc... I can just about get away with the one lead acid battery (I don't want to go down the lithium route). The idea I had about getting the Victron Dc to dc charger was the hope that it would get the best performance out of the house battery. The 1-2-B switch is as old as the boat and I can't see a reason to have it now. My starter battery is designed for starting, more grunt and less amps which has never failed me yet. If it did, I have some jump leads! I'm thinking with using the dc to dc charger, I can get away with Paul's suggestion of using isolation switches.

 

[VicS]

Yep... already gone down led route etc... I can just about get away with the one lead acid battery (I don't want to go down the lithium route). The idea I had about getting the Victron Dc to dc charger was the hope that it would get the best performance out of the house battery. The 1-2-B switch is as old as the boat and I can't see a reason to have it now. My starter battery is designed for starting, more grunt and less amps which has never failed me yet. If it did, I have some jump leads! I'm thinking with using the dc to dc charger, I can get away with Paul's suggestion of using isolation switches.

A neat solution is to use one of the BEP switch clusters consisting of two isolation switches, an emergency paralleling switch and a VSR

Two versions to choose from but if you opt for one of these ask here again for instructions on reconfiguring it so that the emergency paralleling switch parallels the loads not the batteries.

 

[Tranona]

Reading up on the Victron Orion-tr smart, they say it will manage the charging of the house battery better... stop it from being over charged. Also, the app will give me an indication of any potential issues going on with the alternator

Why do you think that might happen at all with such a simple system? I first installed a BEP switch cluster in the mid 1990s on a simple boat like yours appears to be - one small start battery, one house battery and a Yanmar 1GM (no solar in those days). No problems over the next 20 odd years. Same system on a bigger Bavaria 37 and now on a Golden Hind 31. The only negative is that the emergency switch parallels the 2 banks rather than just switching the house to the start circuit, but as I have never needed it probably irrelevant.

If you keep the 2 banks separate and match your house bank capacity to your usage pattern plus keeping the house bank fully charged when you are not using the boat (with solar or shorepower) you don't need any of that fancy stuff.

As an aside, but related, consider using an AGM for the house bank as not only do they have higher acceptance rates but low self discharge. Typically 30% more expensive than leisure batteries, but easily 50% longer life. The photo shows my latest setup with 2*95Ah stop start automotive AGMs chosen partly because I had them in my last boat but mainly because they fit the space being lower than most. The start is an Odyssey AGM, very expensive but the only type which fits the space. If I had more space it would be a simple diesel car battery around 60Ah. Engine is a Beta 30 with a 75A alternator. No solar as I have shorepower. BM1 battery monitor more than adequate to keep an eye on charge rates and SOC. The photo of the batteries was taken before the wiring was completed, just enough connected to run the new engine.

 

[PaulRainbow]

Yep... already gone down led route etc... I can just about get away with the one lead acid battery (I don't want to go down the lithium route). The idea I had about getting the Victron Dc to dc charger was the hope that it would get the best performance out of the house battery. The 1-2-B switch is as old as the boat and I can't see a reason to have it now. My starter battery is designed for starting, more grunt and less amps which has never failed me yet. If it did, I have some jump leads! I'm thinking with using the dc to dc charger, I can get away with Paul's suggestion of using isolation switches.

That's not a "get away with" solution, it's a better, more flexible solution, as fitted to the vast majority of modern boats.

 

[Stemar]

On Jissel, I had a 0-1-2-B switch. The starter was connected to the common terminal, starter battery to 1 and domestics to 2. I had a headlamp relay to connect 1 & 2 when the engine was running because VSRs were expensive when I did it and the budget was tight, but I'd use a VSR now. Domestics had a separate master switch controlling everything except the bilge pump, which had its own switch.

Normally, I'd turn to 1 to start and leave it there when on board. 2 allowed me to start from the domestic battery and both parallelled them.

On Jazzcat, with two engines, the starboard battery only starts the starboard engine, while the port bank also supplies domestics, though I have a switch that allows me to run domestics from starboard if necessary, and PR's three switch arrangement.

 

[PaulRainbow]

I put it down to being used to a way of doing things .. it appears I have two boats - one with one system - other with other system ... I will probably come to appreciate the later system - but so far I am not impressed.
I have left my 1-B-2-off switch on by mistake before ... but soon got into habit of checking before closing up.

Already I have left the later two switch system on more times in one month than total of my older in years !!

In the Olde days, when boats had one battery, fitting a second one, with a 1-2-B made sense. Today, it might still make sense on boats with simple systems and a pair of roughly matched batteries, but it makes little to no sense on cruising boats with more power requirements and bigger domestic banks.

If a boat has multiple batteries in the domestic bank you'd always have that bank selected, or it's pointless. So, you either start the engine on it's own battery, then switch over to the domestic bank, or start from the domestic bank, keeping the engine battery in reserve (think that' what Vyv does). Option 1 involves fiddling with switches, both options subject your delicate electronics to whatever power fluctuations the engine starting places on them. Two separate switches, with two totally separate systems, makes it all so simple. As simple as turning a light on/off. You cannot discharge all of the batteries, no matter what electronics you leave on, no matter how long you leave them for.

A 3rd, emergency parallel, switch allows various emergency situations that might arise. Arrive to find the engine battery won't start the engine, turn the EP switch on, start the engine, turn the EP switch off. Engine battery totally shot, turn the engine isolator off and the EP on, run the engine from the domestics, to get you home. Domestic battery failure, isolate the domestic bank, turn the EP on and the engine battery keeps the electrics alive (obviously keep an eye on the engine battery, or run the engine).

As for leaving both switches on.... no problem, they are separate systems. All of my boats have had the above systems and never a problem leaving a switch on. When i go away for a few days i never turn either switch off. Leave a 1-2-B on B and you have the potential to flatten all batteries and leave yourself with no way to start the engine, or call for help

 

[Refueler]

Paul - I'm not against newer systems ... as I pointed out - I now have boats with old and new setups ...

Of course if 'user' is not careful - problems arise ...

You admit yourself and was my point with OP's boat - simple setup works fine with either .... even that old 1-2-B ...

 

[Sandy]

I'd be interested to hear the sort of power needs boats have. I struggle to draw 10 amps with everything on and that is rare as the power consumption of most kit has been significantly reduced over the last 20 years.

 

[Refueler]

I'd be interested to hear the sort of power needs boats have. I struggle to draw 10 amps with everything on and that is rare as the power consumption of most kit has been significantly reduced over the last 20 years.

What I see often is that the modest requirements of a pocket cruiser are often overshadowed by advice to rip out and replace with systems more suited to higher demand applications.

Forgive me for being so - but that's my opinion.