Changing the battery

Is it safe to take out and old battery from a car and touch the
contacts? If you touch them both at once will you get hurt. How does
that all work?

Also my dad had a battery that was leaking and a lot of the metal
inside is corroded. What is a good substance to remove this stuff?

) writes:
> Is it safe to take out and old battery from a car and touch the
> contacts? If you touch them both at once will you get hurt. How does
> that all work?

Yes, 12 volts is not enough pressure to pass a charge through your body.
It just a bit more than your transitor radio batter at 9 volts.

>
> Also my dad had a battery that was leaking and a lot of the metal
> inside is corroded. What is a good substance to remove this stuff?

battery acid? bakling soda.
rust? elbow grease or abrasive (sandpaper ro wire brush) on an electric
drill.

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"William R. Watt" > wrote in message
...
>
> ) writes:
> > Is it safe to take out and old battery from a car and touch the
> > contacts? If you touch them both at once will you get hurt. How does
> > that all work?
>
> Yes, 12 volts is not enough pressure to pass a charge through your body.
> It just a bit more than your transitor radio batter at 9 volts.
>

It is a common misconception that you cannot get shocked from a car
battery. Voltage does not kill people, current does. And not a lot of
it. Here's a URL for this:

http://hypertextbook.com/facts/2000/JackHsu.shtml

Clean dry skin does have enough resistance to prevent a 12 volt battery from
killing you. And oil soaked fingers are a plus as oil is an insulator.

But if the battery is wet and the water is not pure, such as rain water, all
bets are off. I would not want to have both hands wet with rusty water and
place both hands on the + and - terminals of a car battery.

Even more importantly though is that car batteries can generate tremendous
currents if they are shorted. If you for example drop a wrench across a
set of car battery terminals on a charged battery you can easily weld the
wrench
across the terminals, and in a minute or so as the battery drains through
the
wrench you can generate enough heat for the battery to explode. And it
might explode faster than that. If your hand is in the vicinity you will
not
be happy with the result.

> >
> > Also my dad had a battery that was leaking and a lot of the metal
> > inside is corroded. What is a good substance to remove this stuff?
>
> battery acid? bakling soda.
> rust? elbow grease or abrasive (sandpaper ro wire brush) on an electric
> drill.
>

The best way to handle this is to lightly mist the metal area that is
corroded
with water until it is throughly wet down, then dust dry baking soda on all
exposed and wet metal and let it sit until all reaction has stopped. Then
flush with copious amounts of water from the garden hose. Then use a
wire brush on a drill and brush all rust away that you can, flush with more
water until it is clean.

Then you have a choice. The traditional way is to let it sit until bone dry
then
use Naval Jelly on it, which will dissolve the rust (hopefully) down to bare
metal, then wash that off and dry it with something like a heat gun, then
prime it immediately and paint it. If you don't get all the Naval Jelly off
(which is not easy) it will ruin the paint and the rust will come back.

The newer way is as soon as you get all the loose rust off, use more water
and a detergent (like Tide, or some such) to completely degrease it, then
more water to completely get that off, then saturate it with a product like
Exit Rust or FE-123 or Rust Doctor, then paint that.

Ted

--
Remove *flaps* to reply
"Ted Mittelstaedt" > wrote in message
...
>
> "William R. Watt" > wrote in message
> ...
> >
> > ) writes:
> > > Is it safe to take out and old battery from a car and touch the
> > > contacts? If you touch them both at once will you get hurt. How does
> > > that all work?
> >
> > Yes, 12 volts is not enough pressure to pass a charge through your body.
> > It just a bit more than your transitor radio batter at 9 volts.
> >
>
> It is a common misconception that you cannot get shocked from a car
> battery. Voltage does not kill people, current does. And not a lot of
> it. Here's a URL for this:
>
> http://hypertextbook.com/facts/2000/JackHsu.shtml
>
> Clean dry skin does have enough resistance to prevent a 12 volt battery from
> killing you. And oil soaked fingers are a plus as oil is an insulator.
>
> But if the battery is wet and the water is not pure, such as rain water, all

your saying that if the water is not distilled water i.e. is rain water I can
get shocked or maybe killed by a 12 volt lead acid battery?
How, please explain?

> bets are off. I would not want to have both hands wet with rusty water and
> place both hands on the + and - terminals of a car battery.
>
> Even more importantly though is that car batteries can generate tremendous
> currents if they are shorted. If you for example drop a wrench across a
> set of car battery terminals on a charged battery you can easily weld the
> wrench
> across the terminals, and in a minute or so as the battery drains through
> the
> wrench you can generate enough heat for the battery to explode. And it
> might explode faster than that. If your hand is in the vicinity you will
> not
> be happy with the result.
>
> > >
> > > Also my dad had a battery that was leaking and a lot of the metal
> > > inside is corroded. What is a good substance to remove this stuff?
> >
> > battery acid? bakling soda.
> > rust? elbow grease or abrasive (sandpaper ro wire brush) on an electric
> > drill.
> >
>
> The best way to handle this is to lightly mist the metal area that is
> corroded
> with water until it is throughly wet down, then dust dry baking soda on all
> exposed and wet metal and let it sit until all reaction has stopped. Then
> flush with copious amounts of water from the garden hose. Then use a
> wire brush on a drill and brush all rust away that you can, flush with more
> water until it is clean.
>
> Then you have a choice. The traditional way is to let it sit until bone dry
> then
> use Naval Jelly on it, which will dissolve the rust (hopefully) down to bare
> metal, then wash that off and dry it with something like a heat gun, then
> prime it immediately and paint it. If you don't get all the Naval Jelly off
> (which is not easy) it will ruin the paint and the rust will come back.
>
> The newer way is as soon as you get all the loose rust off, use more water
> and a detergent (like Tide, or some such) to completely degrease it, then
> more water to completely get that off, then saturate it with a product like
> Exit Rust or FE-123 or Rust Doctor, then paint that.
>
> Ted
>
>

wrote:

> Is it safe to take out and old battery from a car and
> touch the contacts?

Contrary to what action movies indicate, it's not possible to hurt a
person by hooking his nipples to a car battery with jumper cables. Any
injury is the result of the cable clamps, not the measily 12 volts of
the battery. Just don't short the battery's two terminals together,
such as with a wrench.

> Also my dad had a battery that was leaking and a lot of the metal
> inside is corroded. What is a good substance to remove this stuff?

Water, baking soda and plenty of scrubbing. Rinse, lather, repeat.

Yes, people are dying left and right from this in Ted's neighborhood.

Ted Mittelstaedt wrote:
>
>
> It is a common misconception that you cannot get shocked from a car
> battery. Voltage does not kill people, current does. And not a lot of
> it. Here's a URL for this:
>
> http://hypertextbook.com/facts/2000/JackHsu.shtml
>
> Clean dry skin does have enough resistance to prevent a 12 volt battery from
> killing you. And oil soaked fingers are a plus as oil is an insulator.
>

> Ted
>
>
But more specifically it is Ohm's law that determines the current. As
Ted says, the resistance is what determines the current. But also, with
Ohm's law, the voltage must be high enough so that the ratio of voltage
to resistance supplies sufficient current. Regardless of how wet the
surroundings, it is very hard to get enough current through the body
with 12 volts. One would almost have to implant electrodes into the
proper part of the body. The current must flow around the region of the
heart. Current just from one finger to another won't do it. Since
frame of car is not generally grounded, it doesn't matter if you are
standing in water or not.

Backbone wrote:

>your saying that if the water is not distilled water i.e. is rain
water >I can
>get shocked or maybe killed by a 12 volt lead acid battery?
>How, please explain?

It only takes a few microamps of current flowing through your chest
cavity to alter (or stop) your heartbeat. The reason you can easily get
shocked by your house outlets (110 or 220V) is that this is enough
voltage to easily overcome the resistance of your skin, which is a poor
conductor.

12 volts from a car battery cant *normally* overcome skin resistance. If
your hands are wet with conductive water (salty water, sweat, battery
acid residue + water, etc.) then its REMOTELY possible for you to get a
noticeable shock, especially if it doesn't have to go far through your
body- like one finger to another finger. Its harder still for 12V to
push current through your whole body from one arm to the other.

The odds of you getting killed from a 12V battery are REALLY slim- you'd
almost have to work at getting one hand on each battery post and making
really, really firm contact with your hands soaked in sal****er for it
to happen, but it is theoretically possible.

In article >,
Ted Mittelstaedt > wrote:
>
>Even more importantly though is that car batteries can generate tremendous
>currents if they are shorted. If you for example drop a wrench across a
>set of car battery terminals on a charged battery you can easily weld the
>wrench
>across the terminals, and in a minute or so as the battery drains through
>the
>wrench you can generate enough heat for the battery to explode. And it
>might explode faster than that. If your hand is in the vicinity you will
>not
>be happy with the result.
>
In the episode of the original Star Trek series "Galileo 7", Scotty charges
the outer hull of the shuttlecraft to scare away the large, unfriendly
native. The flashy special effect is James Doohan wearing a heavy insulated
glove as he shorts the terminals of a car battery (it was rectangular,
vented, and had two posts), with a wrench.

Norm De Plume wrote:
> wrote:
>
> > Is it safe to take out and old battery from a car and
> > touch the contacts?
>
> Contrary to what action movies indicate, it's not possible to
> hurt a person by hooking his nipples to a car battery with jumper
> cables. Any injury is the result of the cable clamps, not the
> measily 12 volts of the battery. Just don't short the battery's
> two terminals together, such as with a wrench.

Some of the TV/movie torture scenes I've seen have several batteries
in series. For the current season of Fox's "24", a lamp cord was
used, which I'm sure would do the trick.

BTW - it might be more dangerous with certain high-voltage sources
in some cars. The ballasts for most HID lights are fairly high
voltage at steady state, and there's been some concern that they
might be dangerous for rescue personnel. There's also been a push
for higher voltage (~40V) batteries in cars, to take advantage of
more sophisticated electric motors.