12V Battery Fuse / Switch install.

SiteSurfer

SiteSurfer

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I'm contemplating fitting a VSR to my Prospect, currently as far as I can make out the 12V electrics are very 1970's and in need of a bit of a rethink.

The plan would be to fit a VSR across the 2 batteries (1 engine / 1 house) but keep the rotary 1/2/both switch - in my head that means that whatever setting the switch is on, when the engine is running it will charge 'something' rather than only the battery currently connected via the switch.

Then I think I'll need to put something at the +ve terminal on each battery prior to running to the switch in order to protect the upstream wiring/systems (such as a fuse) - is that appropriate?

I could in theory ditch the 1/2/both and fit 2 separate switches with a cross over on a key (for emergency starting) but that would involve a much much larger re-wire. I'm also (after last weekend) coming to the realisation that its a very real possibility that there is no fuse from the leisure battery to the 12v distribution panel - any recommendations on what to fit there?

I'm trying to avoid a complete rewire but stay comfortably on the safe side, it appears that 1970's electrics were a lot less protected than today. (Found some solid rusted through household cable on the bilge pump recently which had failed...)
 
There are a few threads on this very topic. The search facility on the forum is pretty poor, but Google should find them. One posting points to a post on http://www.cruisersforum.com/ about the use of VSR and 1-2-both switches that I took great interest in last winter when I rewired my 1980s boat. Following the logic of the Cruisersforum post I am not convinced there is a need for a VSR and have been running my boat on just a 1-2-Both switch this summer and have faster charging. If you are planning months at sea then you may have different ideas.
 
I also was following a thread with a wonderful diagram in that would be my go-to solution if I was to do a complete re-wire, at the moment though I'm trying to make what I have 'safer'. The VSR is possibly a red herring.

The boat is used for coastal weekend cruising with very occasional longer trips, just spent 10 days on board and had no issues with charging - save that I became increasingly familiar with the inside of the 12V distribution panel and associated birds nest!

I need to do more research on the correct way to use the 1/2/both switch I feel.

**Edit**
Found that link: http://forums.catalina.sailboatowners.com/showthread.php?t=137615

I suspect I was confusing the charging and use aspect of the switch, I had been setting it to both when the engine was running (to charge) and 2 when not - thinking that 1 was my engine start, didn't occur to me that both did the same job.
 
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SiteSurfer said:
I also was following a thread with a wonderful diagram in that would be my go-to solution if I was to do a complete re-wire, at the moment though I'm trying to make what I have 'safer'. The VSR is possibly a red herring.

The boat is used for coastal weekend cruising with very occasional longer trips, just spent 10 days on board and had no issues with charging - save that I became increasingly familiar with the inside of the 12V distribution panel and associated birds nest!

I need to do more research on the correct way to use the 1/2/both switch I feel.
Click to expand...

The use of a VSR with a 1, 2, both, off switch is a bit of a mish mash between the old manual system and a VSR controlled system

Ideally separate the domestic and engine wiring and use a VSR with separate isolators and an emergency cross over. Wire the crossover switch to parallel the circuits, rather than the batteries, so that a duff battery can remain isolated rather than being paralleled with the good one.

If you are going to retain the selector switch and use a VSR I suggest a bi-directional VSR, which will operate which ever battery is selected to be in service to charge the other


However there is nothing wrong with the 1, 2, both switch alone if you adopt a routine.

Select the battery designated as starter battery and start the engine.
Leave that battery connected until it has recharged as indicated by a volt meter and/or ammeter.
Then switch, via both, to the designated house battery.
Leave the house battery connected until you switch off or next want to start the engine.

If you want domestic power, without stating the engine, just select the house battery​


Someone will soon be along to rubbish the 1, 2, both switch!

Vyv cox , if he is around, will defend it


With a 1,2, selector switch fit fuses a close as possible to the switch in each circuit rated to protect the circuits connected.

Also mega fuses in each battery + connection capable of supplying the starter

Take care never to switch to off when the engine is running.

The skipper is the only one allowed to touch the battery selector switch.
 
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Thank you VicS, some great advice there. Particularly the routine bit - I have a 12V meter in the circuit and I should ideally check where its wired (hopefully to the common on the switch so that it shows the battery state that is connected).

Initially I need to establish fuses inline - that's first job, I think a couple of the Blue Sea 'direct to terminal' fuses for good measure. I would imagine that by doing this I should have each battery fused at source and then one fuse governing the 12v domestic/instrument circuit prior to a distribution panel (but after the 1/2/all switch). That covers each battery for starting AND domestic use.

**Edit**
Actually reading your post again, Its possibly easier to rewire the starter motor/alternator lead to the starter battery and VSR to the house battery, retain the 1/2 switch as a 'use' not 'charge' - that way i'm always charging both irrespective of the switch and can choose which one to use. Its a compromise until I get around to the full rewire.

Phew! Are all boats of this era similar?
 
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SiteSurfer said:
The boat is used for coastal weekend cruising with very occasional longer trips, just spent 10 days on board and had no issues with charging - save that I became increasingly familiar with the inside of the 12V distribution panel and associated birds nest!

I need to do more research on the correct way to use the 1/2/both switch I feel.

**Edit**
Found that link: http://forums.catalina.sailboatowners.com/showthread.php?t=137615
Click to expand...
They are fun those birds nests!
I went along the lines of a big battery (230AH) as my main battery this starts the engine and runs the small amount of power that I need, and a backup (85AH) that is in reserve. I start on 1 switch to both and when the engine goes off switch back to 1. From time to time I start on 2 and run on 2. When getting on-board I check their voltage and do so daily when away from the mooring.
 
Camelia said:
I went along the lines of a big battery (230AH) as my main battery this starts the engine and runs the small amount of power that I need, and a backup (85AH) that is in reserve. I start on 1 switch to both and when the engine goes off switch back to 1. From time to time I start on 2 and run on 2. When getting on-board I check their voltage and do so daily when away from the mooring.
Click to expand...

That's an awful lot battery capacity to start a small yacht engine and provide a "small amount of power"

No technical reason why not I guess but smaller batteries would be less weight, lighter/ easier to handle when necessary and a whole lot lighter on the wallet when they need replacing
 
SiteSurfer said:
Its possibly easier to rewire the starter motor/alternator lead to the starter battery and VSR to the house battery, retain the 1/2 switch as a 'use' not 'charge' - that way i'm always charging both irrespective of the switch and can choose which one to use.
Click to expand...

If I've understood you right, you will then only be choosing which battery to use for the services, not the engine. Is that something you'd regularly want to make different choices for? Why?

Pete
 
Hi Pete.

Re-reading my drivel I have to agree that I'm a moron. I was planning on using one battery for the engine and one for the house, but wiring directly to the starter motor would mean only using one for the starting ever.
I'll go with VicS solution for now and wire a bi-directional VCS - when and only when I have sorted out the more important issues like the fuses..
 
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SiteSurfer said:
Re-reading my drivel I have to agree that I'm a moron. I was planning on using one battery for the engine and one for the house, but wiring directly to the starter motor would mean only using one for the starting ever.
Click to expand...

Sure and what's wrong with that? One battery for the engine, one for the services. Put a VSR between them and then both will charge when the engine is running. Job done.

If you want the option of starting the engine off the service bank (should never be needed now that the services can't accidentally run down the starter, but shit happens) then you can either add a paralleling switch, use a VSR with a manual activation button either built in or remote, or simply tuck a single jump lead away in a locker.

Pete
 
SiteSurfer said:
Essentially the switch would then do pretty much nothing except turn off the house battery - so would be a reasonable time to simply replace it with a couple of heavy duty toggles.
Click to expand...

Got it :encouragement:

A simple on/off isolator for each battery.

I have this switch: http://www.barden-ukshop.com/blue-sea-5510-dual-circuit-battery-switch-e-series-2982-p.asp which is electrically two separate isolators, but in the same housing so that turning the handle switches them both on. I turn it on when I arrive at the boat, turn it off when I leave. They also make a similar version which includes the emergency link facility - I didn't need that because my VSR includes a manual activation button that serves the same purpose.

That's very neat, but it's fair to say that three separate switches (engine battery isolator, service battery isolator, emergency link switch) gives you more flexibility. I could have done with that when I got a short in the starter motor and had to kill the power. The combined switch meant I lost lighting, GPS, depth sounder, etc until I opened the battery box and disconnected the engine supply cable, then I could turn the switch back on to regain the service supply without energising the faulty starter motor. So if I was starting again I'd seriously consider separate engine and service switches. Note, incidentally, that the classic 1-2-both arrangement would have suffered exactly the same problem.

Pete
 
Len Ingalls said:
I have had that Dropbox complaint before. Sometimes it works.
Click to expand...

It works if you post the right link :)

There's a few details in that diagram that could be debated either way, but one that seems definitely odd to me is wiring the windlass before the service battery isolator. That means that the foredeck buttons are always live, even when the boat's unattended and closed up, as is a potent source of energy (read, fire risk) snaking through the interior. Against that, I can't see a single advantage for it. Explain?

Pete
 
pvb said:
Ah, now I see it. Your diagram is based on one I posted here. Like prv, I disapprove of by-passing the isolator switch for the windlass feed.
Click to expand...

Hi pvb could you point to me to the original thread /drawing

Michael
 
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