Replacing 3 battery Isolation switches

[blmr04]

Hi
My Yacht, built in the early 70's has three battery isolation switches, marked engine, common and house. Can I easily replace these with one modern "1, 2, Both" switch?

Thanks in advance,
Blmr04

 

[CLB]

Hi
My Yacht, built in the early 70's has three battery isolation switches, marked engine, common and house. Can I easily replace these with one modern "1, 2, Both" switch?

Thanks in advance,
Blmr04

You could, but it wouldn't be the best way forward. 3 separate switches with a VSR would be a better option.

 

[jwfrary]

Commons probably a negative switch so no a 1 2 Both prob isn’t what you want.

You could consider

Add-A-Battery Kit - 120A - Blue Sea Systems

Allows you to keep the domestic and house separate, and has a automatic relay to provide the link for charging.

You’ll either need to combine the commons if they are neg with a buss bar or leave the isolator in place . Or if it’s actually an emergency link the. This kit will slide in with very effort little.

Trouble with a 1 2 both is it involves remembering to operate it to manage the charging as task that’s simply automated.

I think BEP do a similar kit.

 

[Stemar]

I can't see the problem with a 1-2-both switch, but it depends what you're trying to do. I have one, but all it does is decide which battery will start the engine. The common goes to the starter solenoid, 1 to the engine battery and 2 to the domestic circuits. Normal engine start is 1. If there's a problem, try 2, or parallel them on both, which also allows me to use the start battery for domestic circuits in an emergency (dangerous thing to do, but my nav lights and electronics are on the domestic circuit). The domestic battery still has its own isolator, and a relay connects 1 & 2 when the alternator's charging. It's a car headlamp relay, because VSRs were expensive when I did it, but I'd use a VSR if I were doing it again

 

[PaulRainbow]

Hi
My Yacht, built in the early 70's has three battery isolation switches, marked engine, common and house. Can I easily replace these with one modern "1, 2, Both" switch?

Thanks in advance,
Blmr04

Please don't it's a backward step. If the switches need replacing, fit new ones, if not, leave them alone.

If the "common" switch is switching the negative you could repurpose it as an emergency switch. Remove the negative cables and connect them all together on a terminal post, or a simple nut and bolt, suitable secured and insulated, then connect a cable from the load side of the domestic switch to one terminal of the "common" switch and another from the load terminal of the engine switch to the other terminal of the "common" switch. Finally, re-label the switch.

 

[PaulRainbow]

Commons probably a negative switch so no a 1 2 Both prob isn’t what you want.

You could consider

Add-A-Battery Kit - 120A - Blue Sea Systems

Allows you to keep the domestic and house separate, and has a automatic relay to provide the link for charging.

You’ll either need to combine the commons if they are neg with a buss bar or leave the isolator in place . Or if it’s actually an emergency link the. This kit will slide in with very effort little.

Trouble with a 1 2 both is it involves remembering to operate it to manage the charging as task that’s simply automated.

I think BEP do a similar kit.

I think these kits and in particular the on/off/combine switch isn't as good an option as having separate switches.

With separate switches, having the emergency combine switch connected to the load terminals of the engine and domestic isolators, you can isolate a faulty battery/bank and turn the emergency switch on, allowing everything to run from the good battery/bank.

With the BlueSea switch everything is paralleled, leaving a faulty battery in circuit.

 

[noelex]

If the "common" switch is switching the negative you could repurpose it as an emergency switch. Remove the negative cables and connect them all together on a terminal post, or a simple nut and bolt, suitable secured and insulated, then connect a cable from the load side of the domestic switch

Switching the negative supply can be very important for electrical systems on metal boats, and while it is not done frequently on boats constructed from non conductive materials, it still adds some safety and stray current protection. It is a requirement for some commercially classified vessels.

If wired originally this way, I would be very reluctant to change this set up. Dual pole battery switches (that switch both the positive and negative supply) are available and this reduces the number of battery switches required (if this is the aim).

 

[PaulRainbow]

Switching the negative supply can be very important for electrical systems on metal boats, and while it is not done frequently on boats constructed from non conductive materials, it still adds some safety and stray current protection. It is a requirement for some commercially classified vessels.

It's standard fit to many European production boats and has been for decades.

If wired originally this way, I would be very reluctant to change this set up. Dual pole battery switches (that switch both the positive and negative supply) are available and this reduces the number of battery switches required (if this is the aim).

Who'd have thought that dual pole switches are available, well i never.

 

[noelex]

Who'd have thought that dual pole switches are available, well i never.

Paul, you may be aware of this, but it does not mean that Blmr04 is.

My post was aimed to help Blmr04.

Dual pole battery switches could potentially reduce and simplify his battery selection switches although a wiring diagram would be needed to answer the question definitely.

 

[PaulRainbow]

Paul, you may be aware of this, but it does not mean that Blmr04 is.

My post was aimed to help Blmr04.

If you are addressing the OP, might it be better to quote him, rather than me ?

 

[dansaskip]

If you are looking to replace the switches it might be a good time to have a think about battery charging too - is your current system good ? or perhaps it would benefit from an upgrade at the same time? perhaps using a VCR as CLB suggests. Others have suggested looking at Blue Sea and BEP marine kit. I really wouldn't know which is better but I replaced my old switches and did charge splitter with a BEPmarine battery distribution & VCR cluster last year and its a vast improvement over the old setup.