Put wire inside car battery cell to measure voltage?

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 ----------------------
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

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.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

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
  Click to see the full signature.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Hydrometers are cheap. Buy one if you want to test batteries.

That is a *really* dumb idea. I don't know how to emphasize enough how dangerous it is.

No. It's a waste of time too!

Don't know, and don't care!

Both... and maybe it will do the same for your body too!
If you short that cell out, things get *hot*. Real hot real quick. As in the end of that coat hanger is going to vaporize before your eyes (before it takes your eyes is what I mean). Batteries generate hydrogen (as in rocket fuel!). The heat from a short might generate more too, I'm not sure. But if it happens that the top of the cell is filled with hydrogen gas you are very likely to explode a small bomb.
This is a nasty bomb too, because it will drench you in sulfuric acid. If the explosion doesn't burn your eyes out, the acid will. It will probably make your face look like something you don't want to see anyways, so being blind will be a blessing.
--
Floyd L. Davidson <http://www.apaflo.com/floyd_davidson
Ukpeagvik (Barrow, Alaska) snipped-for-privacy@apaflo.com
  Click to see the full signature.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
from snipped-for-privacy@apaflo.com (Floyd L. Davidson) contains these words:

I do if he's doing it anywhere near me!
--
Skipweasel
Never knowingly understood. (Ivor Cutler)
  Click to see the full signature.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

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...
--
Floyd L. Davidson <http://www.apaflo.com/floyd_davidson
Ukpeagvik (Barrow, Alaska) snipped-for-privacy@apaflo.com
  Click to see the full signature.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
from snipped-for-privacy@apaflo.com (Floyd L. Davidson) contains these words:

You seen those teeshirts with "I am a bomb-disposal technician. If you see me running, try to keep up" written on the back?
--
Skipweasel
Never knowingly understood. (Ivor Cutler)
  Click to see the full signature.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

That's good! (No, I hadn't seen it.)
--
Floyd L. Davidson <http://www.apaflo.com/floyd_davidson
Ukpeagvik (Barrow, Alaska) snipped-for-privacy@apaflo.com
  Click to see the full signature.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
-- Tzortzakakis Dimitrios major in electrical engineering, freelance electrician FH von Iraklion-Kreta, freiberuflicher Elektriker dimtzort AT otenet DOT gr
That reminds me of my army duty, when we were practicing tossing grenades, and someone was doing it particularly badly (note we were using "training"grenades, also only with a noise fuse and not real TNT)and the sergeant told him, if you do that son in the fire range and see everyone running, you will understand you have done something wrong.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

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
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

its
between
battery
dead,
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.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

A lot of things that a lot of people who should know better say is silly.
--
Skipweasel
Never knowingly understood. (Ivor Cutler)
  Click to see the full signature.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
<Original post snipped for safely reasons>
"Dead man walking"
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
RT wrote:

Actually, we need a phrase for these sorts of situations:
"Dead man posting"
--
Paul Hovnanian mailto: snipped-for-privacy@Hovnanian.com
------------------------------------------------------------------
  Click to see the full signature.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

[Shudder]
On batteries where this is possible you use cadmium probes.
--
*Proofread carefully to see if you any words out or mispeld something *

Dave Plowman snipped-for-privacy@davenoise.co.uk London SW
  Click to see the full signature.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On Fri, 25 Nov 2005 20:53:19 GMT, JS wrote:

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.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
I had an old friend now sadly passed on who`s preferred method of checking the state of charge of batteries was with a bit of wire post to post.The bigger the flash the better the battery was.He was in his seventies and had done it that way all his life.I used to warn him about the dangers and would test them for him myself with a drop tester when I got the chance.Now he had a big four wheeled loading shovel,good working machine but tatty,no glass in the cab etc.Batteries under the seat.Well one day the batteries were flat so he stuck the charger on anf forgot about it.A couple of days later you could smell these batteries when you past the machine.I was working away when his daughter phoned,could I come quick her father had blinded himself.Shot down to her house and he is sitting there,face burned with acid,none in his eyes luckily and a big chunk of his top lip missing.Wouldn`t let us take him to hospital/get a doctor so we cleaned him up.Asked what happened.Oh he says I just climbed up on the wheel of the shovel(taller than him) and leaned in to test the batteries and when I stuck my wire on there was a massive explosion.He`d shut his eyes luckily but couldn`t get them open again so had climbed down of the wheel and crawled up the yard on his hands and knees to his daughters house.. I went and had a look at the batteries,the top was lifted completely out of one and the caps were blown out the other one. He was ok the next day apart from being a bit red.And what was he doing the next day -yep,testing batteries with a bit of wire. regards,Mark.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On 26 Nov 2005 14:07:26 -0800, snipped-for-privacy@ems-fife.co.uk wrote:

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.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
wrote:

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".
--
John G

Wot's Your Real Problem?
  Click to see the full signature.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On Sun, 27 Nov 2005 13:44:56 +1100, "John G"

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.

Obviously. That's why I made sure I was a kid when I did it, so that personal safety wouldn't be a priority.

Spotting tounge-in-cheek newsgroup posts isn't your strong point is it?
Cheers,
Colin.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Polytechforum.com is a website by engineers for engineers. It is not affiliated with any of manufacturers or vendors discussed here. All logos and trade names are the property of their respective owners.