1-2-Both-Off question

[geem]

I think the issue is more about speed. It's unlikely that it will happen BUT if it does one can almost guarantee that it will happen when it is most inconvenient and when the engine is needed NOW i.e. the becalmed boat and a large ship on a collision course in an area where it can't really manoeuvre. ( Think Brambles turn in the Solent!) - Flick a switch and you can start the engine in seconds. If you have to head below, grab a spanner, get access to the battery box, remove a lead and then move to the other bank and then head back to the cockpit and you could be 5 minutes.

I can see that scenario. Aren't those 1 2, both switches wonderful

 

[jac]

I can see that scenario. Aren't those 1 2, both switches wonderful

No they are the work of the devil!!!!

Isolators and dedicated batteries /circuits for me with a separate switch to be used to start the engine from the domestic bank in an emergency!

 

[Daydream believer]

I found Bradwell enough of a challenge with an engine with a particularly difficult wind. Not one of my favourite places.

Bradwell marina is a great place. I always seem to end up going in & out at night after a trip from the continent. So I really should be able to get in & out without touching the bottom. I still often end up trying to get in too soon & having to wait half an hour whilst stuck in the mud in the channel waiting for the tide.
Plus of course it is only 4.4 miles from my house by road. So I can even do it by bicycle if I feel so inclined- Which is not very often , I admit.

 

[geem]

No they are the work of the devil!!!!

Isolators and dedicated batteries /circuits for me with a separate switch to be used to start the engine from the domestic bank in an emergency!

All those switches must get confusing

 

[riverliver]

For a 12Both switch owner this is a great thread thank you. Just one dumb question. I knew never to switch to off with the engine running but from this thread I'm ok to switch from 1 to 2 via both whilst the engine is running?

 

[geem]

For a 12Both switch owner this is a great thread thank you. Just one dumb question. I knew never to switch to off with the engine running but from this thread I'm ok to switch from 1 to 2 via both whilst the engine is running?

Yes

 

[Dellquay13]

For a 12Both switch owner this is a great thread thank you. Just one dumb question. I knew never to switch to off with the engine running but from this thread I'm ok to switch from 1 to 2 via both whilst the engine is running?

The contacts inside the switch are lengthened and overlapping to keep continuous contact with one battery or the other when switching between 1 and 2 via both, to protect your alternator

 

[WindyWindyWindy]

.

 

[Stemar]

On Jissel, my 12B switch was wired common to the engine, 1 to the engine battery and 2 to the domestic system, plus a cheap and cheerful headlamp relay fed from the lead between the charge warning light and the alternator. The domestic battery also had an isolator. This allowed me to use 1 for normal operation, 2 to start from the domestic battery and both to parallel both systems or, with the domestic isolator off, to run domestics, including nav lights and instruments from the engine battery in a dire emergency.

I can't use the same system now, as I have two engines, each with an alternator, but with one engine, the only thing I'd change would be to substitute a VSR for the headlamp relay, which I used because VSRs were expensive at the time and I was already spending far too much money installing a free VP2003 in the place of my dead MD1.

 

[Refueler]

The contacts inside the switch are lengthened and overlapping to keep continuous contact with one battery or the other when switching between 1 and 2 via both, to protect your alternator

Termed "Make before Break"....

 

[Refueler]

On Jissel, my 12B switch was wired common to the engine, 1 to the engine battery and 2 to the domestic system, plus a cheap and cheerful headlamp relay fed from the lead between the charge warning light and the alternator. The domestic battery also had an isolator. This allowed me to use 1 for normal operation, 2 to start from the domestic battery and both to parallel both systems or, with the domestic isolator off, to run domestics, including nav lights and instruments from the engine battery in a dire emergency.

I can't use the same system now, as I have two engines, each with an alternator, but with one engine, the only thing I'd change would be to substitute a VSR for the headlamp relay, which I used because VSRs were expensive at the time and I was already spending far too much money installing a free VP2003 in the place of my dead MD1.

I wired in a Headlamp relay - to stop my coolbox draining my batts down. When engine starts and alternator kicks in - the relay then allows power to the coolbox. Stop engine and relay disconnects power from the box.

I was fed up having to sort that box manually - and half the time forgetting to power it up ...

The same will be used when I replace it with the Vevor Fridge box later.