DC Tools underwater?

[Celestialsailor]

Again...I think we were talking about salt water here...Big difference...BIG DIFFERENCE. Salt water conducts electricity. You are essentially short circuiting the battery.

[Lancerbye]

So does normal tap water that has not been distilled which is why everthing has to be, and can be sealed. Salt water is just more conductive. If you can tape the housing connection point of the battery should be ok. If I needed that arrangement I would be confident in sealing my pricy Milwalkee to the point that it would return from the job unharmed. Having said that, I think it would be easier to seal a cheap type that uses the built in batterries.

[Strygaldwir]

Isn't there some principle about electricity following the path of least resistances? So the question would be is there less resistance in the saltwater than the metal connection? This is particularly an issue in low voltage systems, not much force to push electrons across the higher resistance of the ionic solution (salt water). Pretty easy to check, just put a small electric d.c. motor in a bucket of salt water. Probably work for a while i'd bet. Now what happens to the motor after you remove it is another question! I'd flush it with copious amounts of fresh water, then apply liberal amounts of WD40 (Water dispersant?). When my dinghy motor spent a few hours in the drink, this approach worked, engine seems fine 3 years later.

If the battery is sealed, it should work just fine, I'd think. Once again I don't think the concern is shorting across the terminals, too low a voltage, too far apart. If the cells are open, definitely not going to work very long. But, we are talking about sealed electric drill batteries.

I think I'll have to try this!

[bill good]

It brings up whether air tools might not have some application here?

Regards Bill Goodward

[Robertcateran]

I have seen a video of someone spraying their drill with copious quantities of some water dispersing oil and then using the drill underwater in marine conditions.

[GordMay]

Originally Posted by bill good

It brings up whether air tools might not have some application here?
Regards Bill Goodward

Professional underwater power tools are usually Hydraulic (water powered about 5 - 16 gpm @ 1000 - 3000 psi).

[Ram]

WHos gonna carry air or Hydraulic on a cruising yacht?

[witzgall]

Doesn't conduct?

Originally Posted by Celestialsailor

Again...I think we were talking about salt water here...Big difference...BIG DIFFERENCE. Salt water conducts electricity. You are essentially short circuiting the battery.

[cal40john]

I've read stories of people calling for help after their boat was half submerged, IIRC at least one of the stories said the batteries lasted 20 minutes. If we take sea water as 5 S/m (S= 1/ohms), battery posts approx. 0.3 meters apart. ohms= 0.2 ohm meters / .3 meters = 0.6 ohms.
12 volts/ 0.6 ohms is drawing 20 amps out of your battery, or completely discharging a 100 amphr battery in 5 hours. Since this isn't at the standard 20 hour discharge rate, it would actually be less time. Also since there are bound to be several other paths conducting at this point reduce the time even more. Depending on how your batteries are grouped together, such that posts are much closer together, you would discharge even quicker. But this points out that in some (many?) cases submerging your batteries does not necessarily mean instant and complete loss of power.

Water conductivity - Lenntech

John

[Strygaldwir]

I would think the issue is flushing out of the electrolytic solution in a lead/acid batter would be the issue. If the battery is sealed, discharge across sea water is certainly going to be an issue.

I was thinking this was a portable hand tool with one of those removable batteries. There, the batteries are sealed and contamination is less an issue.

Isn't resistance going to increase as the sum of the Square or some such?

[Celestialsailor]

Electrical conductivity - Wikipedia, the free encyclopedia
Electrical Conductivity; Liquids

The following links show conductivity of electricity in distilled water and salt water. It states clearly that distilled water does not conduct while fresh water does slightly and salt water does readily.

[witzgall]

I have yet to see a distilled water lake. Fresh water, coming from the tap or in lake Erie, has minirals in it, and the water conducts. How else would Mel Gibson have gained that ability to hear woman's thoughts?

Chris

Originally Posted by Celestialsailor

Electrical conductivity - Wikipedia, the free encyclopedia
Electrical Conductivity; Liquids

The following links show conductivity of electricity in distilled water and salt water. It states clearly that distilled water does not conduct while fresh water does slightly and salt water does readily.

[bg9208]

Originally Posted by Celestialsailor

I can't see how any electrical tool could be used in salt water. Whether A.C. or D.C., salt water contucts electricity. It would short out the tool.

Well, that's what I thought but many years ago, working on my boat at it's mooring in Langstone harbour using a little Honda generator with an old but good Wolf angle grinder plugged in, I dropped it over the side with the power on button locked down. The generator fuse didn't blow so I hauled it up, using rubber gloves after about a minute, still running , dried out the cord the just carried on as normal. Still works after 30 years!
I dont pretend to understand why, I'm only and Aeronautical (Now Aerospace) Engineer.
Incidentally, I did meet a guy and saw his dinghy powered by a starter motor clipped to a car battery.