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saillessinseattle 10-07-2013 10:55 AM

battery twist switch accident
 
This weekend we were motoring entering a marina in a narrow dragged channel when all instruments went dark. The entire panel was dark in fact. It took us 5 tense min of circling around to figure out a guest had knocked the house battery switch to the off position.

Problem averted, but now I am thinking, what would have happened if they had knocked the engine battery cutoff switch instead? Why are these things not out of the way, short runs for thick wires?

Alex W 10-07-2013 11:50 AM

Re: battery twist switch accident
 
On a diesel engine (and probably the A4 too) nothing will happen if you disconnect power while the engine is running. The battery is only used at startup to turn over the engine.

The switch needs to be close to the batteries to be practical. You could make a cover for it though. I haven't tried, but I'd guess that a double gang outdoor outlet cover might fit over most battery switches.

TQA 10-07-2013 12:54 PM

Re: battery twist switch accident
 
Quote:

Originally Posted by Alex W (Post 1100315)
On a diesel engine (and probably the A4 too) nothing will happen if you disconnect power while the engine is running. The battery is only used at startup to turn over the engine.

Err not the case on quite a lot of modern diesel units which have a solenoid operated cut off device. Lose the power to that and it shuts down.

svHyLyte 10-07-2013 01:00 PM

Re: battery twist switch accident
 
I cannot imagine how switches could be positioned where someone could accidentally trip them. IF so, however, they should be under covers.

BubbleheadMd 10-07-2013 02:24 PM

Re: battery twist switch accident
 
Quote:

Originally Posted by Alex W (Post 1100315)
On a diesel engine (and probably the A4 too) nothing will happen if you disconnect power while the engine is running. The battery is only used at startup to turn over the engine.

The switch needs to be close to the batteries to be practical. You could make a cover for it though. I haven't tried, but I'd guess that a double gang outdoor outlet cover might fit over most battery switches.

Incorrect.

Unless the battery switch has an AFD (Alternator Field Disconnect), you can smoke the alternator if you switch it to "OFF" while the engine (diesel or gasoline) is running.

In fact, if you look at many of these older "1/2/BOTH/OFF" switches, they often say right on them, not to do this. See this photo:
PERKO Battery Switches at West Marine

Newer ones have the AFD, and you can do whatever you like. Note in the WM ad, you can choose with or without the AFD function.

hellosailor 10-07-2013 03:25 PM

Re: battery twist switch accident
 
It is common enough to bump a "throw" switch and trip it. That's why you can find SPST switches with safety covers on them. In the surplus stores, aviation suppliers, and even the auto parts stores for a boggling ten bucks a piece.

But accidentally TWISTING a switch? What is that, a two year old exploring the universe? No one accidentally grabs a switch and twists it.

svinshallah 10-07-2013 03:30 PM

Re: battery twist switch accident
 
You don't have to be a two-year-old. My battery switches were located conveniently to the nav station so that when you walked past you could rub against them. If you hit them wrong, they would turn off. After the first time I did it, fortunately not when the motor was running, I put a cover on them.

hellosailor 10-07-2013 03:34 PM

Re: battery twist switch accident
 
I've never seen a rotary battery switch that could be moved by just rubbing against it. The ones I've met all have to be gripped and twisted. No doubt someone could be thrown against the cover and still knock out the power as they tore it all off.<G>

Maine Sail 10-08-2013 10:28 AM

Re: battery twist switch accident
 
Quote:

Originally Posted by Alex W (Post 1100315)
On a diesel engine (and probably the A4 too) nothing will happen if you disconnect power while the engine is running. The battery is only used at startup to turn over the engine.

The batteries also serve as the load source for the alternator. If you open the circuit while the alternator is running, most boats are wired through the battery switch for the alt circuit, you stand a very good chance of blowing some or all of the alternator diodes and destroying the alternator.

Battery switches should not be flipped off when an engine is running unless you've direct wired the alternator to the house battery bank so it always sees a "load"...

The OP ideally needs to cover the switches or physically move them to a safer location.

macwester26 10-08-2013 02:07 PM

Re: battery twist switch accident
 
Quote:

Originally Posted by TQA (Post 1100365)
Err not the case on quite a lot of modern diesel units which have a solenoid operated cut off device. Lose the power to that and it shuts down.

Just found that out myself so have done away the the solenoid and gone back to the pull cable type . I was thinking if I had a solenoid fault and yes I have been told it could happen There would be no way of starting the engine again..


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