Marine Batteries - Danger or Electrocution?

[Iliade]

As an (almost) aside, UK third rail electrification is at 750V DC. That will not just kill, but it will render the body down to something resembling charcoal.

With damp salty hands I have found 24v to be unpleasant - I dare you to stick a 9v PP3 across your tongue...

I wouldn't worry about being hurt by the 12/24v boat though. Having said that, if inversion is expected it could cause expensive damage to the electrics, so I would waterproof the system as far as I could, including painting plastic dip over the terminals and encasing the motor in a waterproof compartment (cooling might then be a bigger issue though.)

 

[srah1953]

Excuse my ignorance, but what's a waterproof battery? In a picture the only obvious difference is the connectors are shaped differently

 

[vyv_cox]

I recall in a physics lesson at school that the master arranged two copper plates on a bench with a lead to each supplying DC. He then got a volunteer to place the palm of a hand on each plate whilst calling to a another pupil to slowly increase the voltage. The subject called a halt to it at about 50 volts. Would never be allowed nowadays.

When I worked in labs we were allowed to build rigs containing electrical wiring but not mains AC electricity nor DC voltages higher than 50 volts. At these points electricians had to be called in.

 

[lw395]

When I worked in labs we were allowed to build rigs containing electrical wiring but not mains AC electricity nor DC voltages higher than 50 volts. At these points electricians had to be called in.

I once worked in a lab where I was allowed to build things running hundreds of amps and sometimes over 1,000V.
But I wasn't allowed to put a mains plug on the kettle.

 

[andsarkit]

I have only once had a shock from a 12v battery but that was when fixing the engine in the bilges of a dhow in Abu Dhabi in 45deg heat and 100% humidity and dripping in sweat. If you use a gel battery with a fuse the biggest danger is dropping the battery on your foot.

 

[danielefua]

I have only once had a shock from a 12v battery but that was when fixing the engine in the bilges of a dhow in Abu Dhabi in 45deg heat and 100% humidity and dripping in sweat. If you use a gel battery with a fuse the biggest danger is dropping the battery on your foot.

This is quite interesting and I wish it could make someone think over his "firm NO".
Vain wish...

Daniel

 

[JumbleDuck]

I have chosen to go with the Rhino Cobold 18 lbs Trolling Motor and the Yuasa 12V AGM 22AH Waterproof Battery.

You need a bigger battery. Rhino don't quote current draw for the Cobold, but their other motors running at similar thrust consume 25-30A. The 22Ah battery will only last about 15 minutes before it's flat.

It all depends on what power setting is needed. My crew sometimes buzzes around in a dinghy with trolling motor and a 36Ah Yuasa gives over an hour of fun at reasonable speeds.

With damp salty hands I have found 24v to be unpleasant - I dare you to stick a 9v PP3 across your tongue...

As a child I once put a 22.5v flash battery across my tongue. Once.

I once worked in a lab where I was allowed to build things running hundreds of amps and sometimes over 1,000V.
But I wasn't allowed to put a mains plug on the kettle.

Same here. The lab two doors down from mine had an old AC/DC mains radio with live chassis and no casing. The departmental safety officer dropped in for an inspection, saw it and without saying a word took a pair of wire cutters from his pocket, clipped the plug off and went away with his. Had he returned the following day he would have found the radio back in use, with the stripped ends of the mains cable inserted directly into the live and neutral of the 13A socket ...

 

[AntarcticPilot]

When I worked in labs we were allowed to build rigs containing electrical wiring but not mains AC electricity nor DC voltages higher than 50 volts. At these points electricians had to be called in.

When I was a lad, at the age of about 18 (post A-level), I built a simple linear motor. The plans in Eric Laithwaite's book were simple and straightforward, but required the provision of a three-phase supply, with the suggestion that a complicated system of inductors and capacitors could produce that from a single-phase domestic supply. Eager to see the thing work after spending days cutting mild steel strips to make the stator, we found out that the school had a three-phase supply, so I just wired it in to the main distribution panel of the school! It worked, shooting small bits of aluminium around at quite high velocity. But I don't think I'd get away with doing that these days.

 

[Paulg25]

Having been an electronics/electrical/software engineer for over 40 years...

Cars have 12V batteries.
Caravans have 12V batteries.
Motorcycles have 12V batteries.
Some lawnmowers have 12V batteries.
Some childrens toys have 12V batteries.
Boats have 12V batteries.
Tractors have 12V batteries.
Halfords have shelves full of them!!
Lorries have 24V batteries.
My grand kids quads have 36V batteries.

The damned things are everywhere!

Where are all the dead people?

Where are all the warnings of electric shock stickers?

FFS get real everyone.

Rant over. ?

 

[anoccasionalyachtsman]

Having been an electronics/electrical/software engineer for over 40 years...

Cars have 12V batteries.
Caravans have 12V batteries.
Motorcycles have 12V batteries.
Some lawnmowers have 12V batteries.
Some childrens toys have 12V batteries.
Boats have 12V batteries.
Tractors have 12V batteries.
Halfords have shelves full of them!!
Lorries have 24V batteries.
My grand kids quads have 36V batteries.

The damned things are everywhere!

Where are all the dead people?

Where are all the warnings of electric shock stickers?

FFS get real everyone.

Rant over. ?

I think we're all perfectly clear that a 12v battery isn't likely to kill anyone.

What some of us were huffed up about was @Molteni's clear statement that dc won't kill. If he had the courage to admit that it was wrong the thread would be at least a page shorter.

 

[[163233]]

Excuse my ignorance, but what's a waterproof battery? In a picture the only obvious difference is the connectors are shaped differently

I guess that'd be sealed AGM or Gel and there are probably other types these days. The electrolyte is absorbed into glass mat or a gel rather than a liquid and the case is sealed so the gel cannot leak easily.

A better explanation here:-
5 Battery Types Explained - Sealed, AGM, Gel | BatteryStuff

 

[penberth3]

Having been an electronics/electrical/software engineer for over 40 years...

....Lorries have 24V batteries.....

Where are all the warnings of electric shock stickers?

FFS get real everyone.

Rant over. ?

If it helps to keep the thread going, Lorries use 2x12V in series, surely?

 

[JumbleDuck]

I think we're all perfectly clear that a 12v battery isn't likely to kill anyone.

You can get a really nasty shock from a 12V battery if you connect each terminal to a glass of brine and then put your hands in it. I believe it's because it encourage sodium ions to move around and that's how nerves work. It won;t kill you, but it feels horrible. Been there, done that. I suppose that putting hands on or very near the terminals of a 12V battery submerged in sea water may have the same effect.

 

[anoccasionalyachtsman]

You can get a really nasty shock from a 12V battery if you connect each terminal to a glass of brine and then put your hands in it. I believe it's because it encourage sodium ions to move around and that's how nerves work. It won;t kill you, but it feels horrible. Been there, done that. I suppose that putting hands on or very near the terminals of a 12V battery submerged in sea water may have the same effect.

According to a scary leaflet I have on the table here I'm not allowed within a few miles of anything magnetic or electrical as of tomorrow when they put a pacemaker in. Guess who bought a rather nice MiG welder last year?

I'll get the implant's tech specs tomorrow, and let y'all know whether its volts come out straight or bent.

 

[AntarcticPilot]

According to a scary leaflet I have on the table here I'm not allowed within a few miles of anything magnetic or electrical as of tomorrow when they put a pacemaker in. Guess who bought a rather nice MiG welder last year?

I'll get the implant's tech specs tomorrow, and let y'all know whether its volts come out straight or bent.

According to a scary leaflet I have on the table here I'm not allowed within a few miles of anything magnetic or electrical as of tomorrow when they put a pacemaker in. Guess who bought a rather nice MiG welder last year?

I'll get the implant's tech specs tomorrow, and let y'all know whether its volts come out straight or bent.

I wouldn't get too concerned. My wife has a pacemaker, and works with high voltages at high frequencies and substantial current densities. When she got the pacemaker, a technician from the hospital came to check it out, and said it was safe for her to be near the generators and other equipment. He checked electric and magnetic field densities. Of course, the voltages concerned are such that contact with them certainly wouldn't be conducive to long life, though it might save on cremation costs.

 

[JumbleDuck]

According to a scary leaflet I have on the table here I'm not allowed within a few miles of anything magnetic or electrical as of tomorrow when they put a pacemaker in. Guess who bought a rather nice MiG welder last year?

I wouldn't get too concerned. My wife has a pacemaker, and works with high voltages at high frequencies and substantial current densities. When she got the pacemaker, a technician from the hospital came to check it out, and said it was safe for her to be near the generators and other equipment. He checked electric and magnetic field densities.

I used to work in a magnet lab, with a mixture of superconducting, water-cooled resistive and hybrid (water cooled core in a superconducting outer) research magnets. About the time I left a new hybrid was installed which could get up to 60T+ (iirc) and there was a "No pacemakers beyond here" line round it, much of which was painted in the car park outside.

 

[AntarcticPilot]

I used to work in a magnet lab, with a mixture of superconducting, water-cooled resistive and hybrid (water cooled core in a superconducting outer) research magnets. About the time I left a new hybrid was installed which could get up to 60T+ (iirc) and there was a "No pacemakers beyond here" line round it, much of which was painted in the car park outside.

Well, the advantage is that my wife usually gets through airport security before me!

 

[lw395]

Having been an electronics/electrical/software engineer for over 40 years...

Cars have 12V batteries.
Caravans have 12V batteries.
Motorcycles have 12V batteries.
Some lawnmowers have 12V batteries.
Some childrens toys have 12V batteries.
Boats have 12V batteries.
Tractors have 12V batteries.
Halfords have shelves full of them!!
Lorries have 24V batteries.
My grand kids quads have 36V batteries.

The damned things are everywhere!

Where are all the dead people?

Where are all the warnings of electric shock stickers?

FFS get real everyone.

Rant over. ?

I think there is a difference between 'electrocution' and the possibility of electric shock-assisted drowning.
The thing about this phenomenon is that most deaths were thought to be simple drownings.
Quite a lot of people do manage to drown.
It's a very bold statement to categorically say someone won't kill themselves by any particular means, however bizarre.
There are a lot of people in the world, sometimes it looks like a fair fraction are looking for novel ways out.
Reminds me of:
Andy Riley The Book Of Bunny Suicides

The OP is more likey to be dragged under after getting tangled in the wiring with a sinking battery or something.

 

[lw395]

I used to work in a magnet lab, with a mixture of superconducting, water-cooled resistive and hybrid (water cooled core in a superconducting outer) research magnets. About the time I left a new hybrid was installed which could get up to 60T+ (iirc) and there was a "No pacemakers beyond here" line round it, much of which was painted in the car park outside.

One job I had, I did some work with OldSkool radars.
I didn't see anyone's pacemaker explode.
But one of the guys took photos as we took one to bits, using his phone.
It took a big screwdriver to lever his shiny new iphone off the magnetron, luckily it was so new they replaced it without asking awkward questions!

 

[anoccasionalyachtsman]

I think there is a difference between 'electrocution' and the possibility of electric shock-assisted drowning.
The thing about this phenomenon is that most deaths were thought to be simple drownings.
Quite a lot of people do manage to drown.
It's a very bold statement to categorically say someone won't kill themselves by any particular means, however bizarre.
There are a lot of people in the world, sometimes it looks like a fair fraction are looking for novel ways out.
Reminds me of:
Andy Riley The Book Of Bunny Suicides

The OP is more likey to be dragged under after getting tangled in the wiring with a sinking battery or something.

And that reminds me of