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Put wire inside car battery cell to measure voltage?

J

JS

Jan 1, 1970
0
I recently read the following extract below which explains how to
test a car battery by putting stiff wires right into the cells and
measuring the voltage.

I'm attracted by this method because I do not have a hydrometer to
test the individual cells. Could someone answer these questions
about this method.

(1) Is the method described below a sensible approach?

(2) Is the method a good indicator of the cell's health?

(3) Is he advocating pushing the coat hanger wire right down
between the plates of a cell or only pressing down on the top of
the plates?

(4) Does the method damage the cells either physically or
chemically?



John

-------------------- QUOTE ----------------------

The Charging System. Part 1: The Battery
http://autorepair.about.com/cs/electrical/a/aa090303a_2.htm


The individual cells can also be tested with a voltmeter.

Take a coat hanger and make two lead extensions about six inches
long and attach them to the meters test leads.

Touch the positive lead to the positive terminal and stick the
negative lead inside the cell next to it.

It should read about 2.1 to 2.3 volts.

Now insert the positive lead in the first cell and the negative
lead in the second cell.

Proceed down the line until you get to the last cell. Here you
will put the positive lead in the last cell and the negative lead
on the negative terminal.

All the cells should read the same, or within 0.2 volts.

If one reads 4.0 or more, you have a shorted cell and the battery
is no good.

If you get a very low reading or a zero reading, the cell is open
and again the battery is no good.

-------------------- END QUOTE ----------------------
 
C

Conor

Jan 1, 1970
0
I recently read the following extract below which explains how to
test a car battery by putting stiff wires right into the cells and
measuring the voltage.

I'm attracted by this method because I do not have a hydrometer to
test the individual cells. Could someone answer these questions
about this method.

(1) Is the method described below a sensible approach?
Nope. Dangerous as a spark can cause the battery to explode.
(2) Is the method a good indicator of the cell's health?
Nope. You can only really get a good idea by putting a large load on
the battery.
(3) Is he advocating pushing the coat hanger wire right down
between the plates of a cell or only pressing down on the top of
the plates?
OH.MY.FUCKING.GOD

(4) Does the method damage the cells either physically or
chemically?
Why not just take it to your local motorist shop who have the equipment
and will gladly test it for free?
 
S

SQLit

Jan 1, 1970
0
JS said:
I recently read the following extract below which explains how to
test a car battery by putting stiff wires right into the cells and
measuring the voltage.

I'm attracted by this method because I do not have a hydrometer to
test the individual cells. Could someone answer these questions
about this method.

(1) Is the method described below a sensible approach?

(2) Is the method a good indicator of the cell's health?

(3) Is he advocating pushing the coat hanger wire right down
between the plates of a cell or only pressing down on the top of
the plates?

(4) Does the method damage the cells either physically or
chemically?



John

Static voltage is not a good indicator of the condition of the battery.
Voltage under a measured load is better.

As others have said. Putting wire in the cells is extremely BAD idea.
I have seen a battery grenade, fortunately we were not close and all we had
to do was hose the engine down so the acid did not eat everything.

Get a hygrometer or load tester. Or visit the local auto parts store with
one.
 
M

Malc

Jan 1, 1970
0
JS said:
I recently read the following extract below which explains how to
test a car battery by putting stiff wires right into the cells and
measuring the voltage.

I'm attracted by this method because I do not have a hydrometer to
test the individual cells. Could someone answer these questions
about this method.

(1) Is the method described below a sensible approach?

(2) Is the method a good indicator of the cell's health?

(3) Is he advocating pushing the coat hanger wire right down
between the plates of a cell or only pressing down on the top of
the plates?

(4) Does the method damage the cells either physically or
chemically?
Just don't do it. OK. If you have to do a load test, turn your headlights on
and use a DVM. As others have said, an off load test doesn't show very much
at all.

--
Malc

"The error of youth is to believe that intelligence is a substitute for
experience, and the error of age is to believe that experience is a
substitute for intelligence."
- Slyman Bryson
 
S

Stuart Gray

Jan 1, 1970
0
JS said:
I recently read the following extract below which explains how to
test a car battery by putting stiff wires right into the cells and
measuring the voltage.

Fuckin' hell, its cheaper just to buy a new battery, which means you won't
have a pock marked face from the explosion from the old one.
 
R

RT

Jan 1, 1970
0
<Original post snipped for safely reasons>

"Dead man walking"
 
H

Herman Family

Jan 1, 1970
0
JS said:
I recently read the following extract below which explains how to
test a car battery by putting stiff wires right into the cells and
measuring the voltage.

I'm attracted by this method because I do not have a hydrometer to
test the individual cells. Could someone answer these questions
about this method.

(1) Is the method described below a sensible approach?

(2) Is the method a good indicator of the cell's health?

(3) Is he advocating pushing the coat hanger wire right down
between the plates of a cell or only pressing down on the top of
the plates?

(4) Does the method damage the cells either physically or
chemically?



John

-------------------- QUOTE ----------------------

The Charging System. Part 1: The Battery
http://autorepair.about.com/cs/electrical/a/aa090303a_2.htm


The individual cells can also be tested with a voltmeter.

Take a coat hanger and make two lead extensions about six inches
long and attach them to the meters test leads.

Touch the positive lead to the positive terminal and stick the
negative lead inside the cell next to it.

It should read about 2.1 to 2.3 volts.

Now insert the positive lead in the first cell and the negative
lead in the second cell.

Proceed down the line until you get to the last cell. Here you
will put the positive lead in the last cell and the negative lead
on the negative terminal.

All the cells should read the same, or within 0.2 volts.

If one reads 4.0 or more, you have a shorted cell and the battery
is no good.

If you get a very low reading or a zero reading, the cell is open
and again the battery is no good.

-------------------- END QUOTE ----------------------

The general consensus is that this is a bad idea. In addition to the
problems mentioned, this is likely to damage the cell itself and shorten its
life. You would be infinitely better off just measuring the voltage between
the poles. Batteries which are less than about 12 volts are pretty much
dead or on the way out. Even better is the suggestion of going to a battery
shop and having them test it. If you think it is in need of a test or dead,
it probably is ready for replacement anyway.

Michael
 
P

Paul Hovnanian P.E.

Jan 1, 1970
0
RT said:
<Original post snipped for safely reasons>

"Dead man walking"

Actually, we need a phrase for these sorts of situations:

"Dead man posting"
 
T

TimPerry

Jan 1, 1970
0
The general consensus is that this is a bad idea. In addition to the
problems mentioned, this is likely to damage the cell itself and shorten its
life. You would be infinitely better off just measuring the voltage between
the poles. Batteries which are less than about 12 volts are pretty much
dead or on the way out. Even better is the suggestion of going to a battery
shop and having them test it. If you think it is in need of a test or dead,
it probably is ready for replacement anyway.

Michael

from the same article:

"A little bit about working with batteries. Whenever you disconnect a
battery, ALWAYS disconnect the negative cable first. This will prevent
sparks that may cause the gasses inside the battery from igniting."

i consider lifting the neg first a good idea because afterward and
accidental short from pos to almost any part of the cars body will have no
adverse affect. this MAY be what the author was aiming to say but taken
literally the statement is silly.
 
G

Guy King

Jan 1, 1970
0
The message <[email protected]>
from "TimPerry said:
i consider lifting the neg first a good idea because afterward and
accidental short from pos to almost any part of the cars body will have no
adverse affect. this MAY be what the author was aiming to say but taken
literally the statement is silly.

A lot of things that a lot of people who should know better say is silly.
 
G

Guy King

Jan 1, 1970
0
Nope, still don't know and don't care! Which way he is poking
it is of no significance to a guy doing a 1000 yard sprint...

You seen those teeshirts with "I am a bomb-disposal technician. If you
see me running, try to keep up" written on the back?
 
D

Dave Plowman (News)

Jan 1, 1970
0
(3) Is he advocating pushing the coat hanger wire right down
between the plates of a cell or only pressing down on the top of
the plates?

[Shudder]

On batteries where this is possible you use cadmium probes.
 
C

Chris Street

Jan 1, 1970
0
I recently read the following extract below which explains how to
test a car battery by putting stiff wires right into the cells and
measuring the voltage.

I'm attracted by this method because I do not have a hydrometer to
test the individual cells. Could someone answer these questions
about this method.

(1) Is the method described below a sensible approach?

(2) Is the method a good indicator of the cell's health?

(3) Is he advocating pushing the coat hanger wire right down
between the plates of a cell or only pressing down on the top of
the plates?

(4) Does the method damage the cells either physically or
chemically?



John

-------------------- QUOTE ----------------------

The Charging System. Part 1: The Battery
http://autorepair.about.com/cs/electrical/a/aa090303a_2.htm


The individual cells can also be tested with a voltmeter.

Take a coat hanger and make two lead extensions about six inches
long and attach them to the meters test leads.

Touch the positive lead to the positive terminal and stick the
negative lead inside the cell next to it.

It should read about 2.1 to 2.3 volts.

Now insert the positive lead in the first cell and the negative
lead in the second cell.

Proceed down the line until you get to the last cell. Here you
will put the positive lead in the last cell and the negative lead
on the negative terminal.

All the cells should read the same, or within 0.2 volts.

If one reads 4.0 or more, you have a shorted cell and the battery
is no good.

If you get a very low reading or a zero reading, the cell is open
and again the battery is no good.

-------------------- END QUOTE ----------------------

I've spent a lot of time playing with batteries in a chemistry lab and this
is about the best way to do yourself and the battery damage. Even with a
"safe" CD or Pb probe you can still provoke a spark unless you know exactly
what you are doing, and you are dipping into a hydrogen/oxygen gas pocket
which is about the most explosive combination going.

Try this

1. Charge the battery fully and let it stand for at least 8 hours with no
load (disconenct it)

2. Get an accurate digital voltmeter and measure the off load
(disconnected) battery voltage. If it's not over 12.4V at 68F (adjust down
by 7mV for each degF) scrap it.

3. Disconnect or isolate the sparks and crank the engine for 30 secs none
stop.

4. Measure voltage again - if it fails to bounce back up to 12.2V within a
minute, scrap it. (it's either screwed or too small for the car)

Or just take it to the shop and get them to use the heavey discharge
tester.
 
R

R. Murphy

Jan 1, 1970
0
If you want to measure the voltage, use a voltmeter on the regular
terminals. If not up to par, then it needs charging. If it won't charge up,
then it doesn't matter which cell is faulty, since you can't replace all of
them.

If you do want to check the electrolyte level/strength, buy a hydrometer.

Or alternatively, stop winding us up! :)
 
G

Grimly Curmudgeon

Jan 1, 1970
0
We were somewhere around Barstow, on the edge of the desert, when the
I recently read the following extract below which explains how to
test a car battery by putting stiff wires right into the cells and
measuring the voltage.

I'm attracted by this method because I do not have a hydrometer to
test the individual cells. Could someone answer these questions
about this method.

(1) Is the method described below a sensible approach?

(2) Is the method a good indicator of the cell's health?

(3) Is he advocating pushing the coat hanger wire right down
between the plates of a cell or only pressing down on the top of
the plates?

(4) Does the method damage the cells either physically or
chemically?
<snip bollocks>

The bit you quote is misleading and dangerous advice. I get the
impression that guy's website is probably a collection of bad practices
he's been doing for years and got away with.

Regarding his battery testing advice...

1. Car batteries are pretty much all in one case, so there's no point in
identifying a dead cell. If the battery is a whole isn't up to snuff,
whether it's caused by a dead cell or not, the battery's fit for
renewal.

2. The only type of battery where you'd need to do individual cell
testing, is likely to have individual cells (fork truck or other
heavies), or at the very least have cell interconnectors on top, where
you can safely test cell voltages without risking your good looks by
dipping probes into the electrolyte.

Honestly, I've read some shit on the 'net, but that takes the individual
baked sugary cake-like thing.
 
J

John G

Jan 1, 1970
0
Colin Stamp said:
Ouch!

Thin insulated wire works quite well on car batteries. You have to
experiment with different types until you find the right balance of
conductor area and insulation thickness but with the right stuff, the
conversion of the insulation to smoke takes just enough energy out of
the conductor to prevent it burning through until virtually all the
insulation is gone.

As a kid, I used to pride myself on my ability to completely fill a
double garage with smoke in under seconds.

Cheers,

Colin.

Whatever you might have done it does NOT WORK ALLRIGHT.

The spark you make ignites the hydrogen and could easily kill you.

As they say on TV "Do NOT try this at home".
 
C

Colin Stamp

Jan 1, 1970
0
Whatever you might have done it does NOT WORK ALLRIGHT.

I beg to differ. If generating a large volume of, probably toxic,
smoke in a very short time is what you're after, then it works a
treat.
The spark you make ignites the hydrogen and could easily kill you.

Obviously. That's why I made sure I was a kid when I did it, so that
personal safety wouldn't be a priority.
As they say on TV "Do NOT try this at home".

Spotting tounge-in-cheek newsgroup posts isn't your strong point is
it?

Cheers,

Colin.
 
¤

¤¤¤ Abo ¤¤¤

Jan 1, 1970
0
Colin said:
As a kid, I used to pride myself on my ability to completely fill a
double garage with smoke in under seconds.

As a young kid at school I decided that a bit of wire in the live and
neutral points in a socket would be a good idea because the current would
just flow along it. I even managed to convice a couple of mates, and tried
it to prove the point.

The resulting flash and bang scared the shit out of me, along with the rest
of the *German* language class lol...
 
P

PC Paul

Jan 1, 1970
0
¤¤¤ Abo ¤¤¤ said:
As a young kid at school I decided that a bit of wire in the live and
neutral points in a socket would be a good idea because the current
would just flow along it. I even managed to convice a couple of
mates, and tried it to prove the point.

The resulting flash and bang scared the shit out of me, along with
the rest of the *German* language class lol...

As apprentices we pratted about and wrapped solder around the live and
neutral pins of a plug then plugged it back into a switched off socket.

*Huge* flash when it was switched on. The solder vaporised almost instantly
but the shock value was amazing.

Would never do that sort of thing now though.

A good way to demonstrate the high instantaneous current capacity of Nicads
is to get an AA or even AAA Nicad and short it out with solder - again it
vaporises immediately, but a bit less spectacularly.
 
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