Jump starting-Not to neg bat term---Why? - Page 2 - PeachParts Mercedes-Benz Forum

rrgrassi · #16 01-31-2007, 01:11 PM

Quote:

Originally Posted by dannym

I never said a discharged battery has no acid in it or it's safe for a discharged battery to blow up in your face.
All I said was a discharged battery is less acidic than charged battery. I don't know what you tried with your litmus paper but you can't argue with the laws of chemistry. When a battery discharges the hydrogen atoms fuse to the lead plates causing a less acidic solution. That is a fact whether you choose to believe it or not.

Anything else you get out of that your making up.

No one ever said you did, and nothing is being made up. It's all physics and chemical properties. The stronger the acid, the lower the ph number. That is basic chemistry. I took only two years of chemistry in college 20 years ago, so I do not remember everything about it. It is fascinating stuff though

Ever work on an acid etch line? I have. The semi conductor mfgs use the 12m stuff. We used sulfuric, acetic, nitric, hydrochloric, and hydroflouric acids. I never want to do that again. Those college jobs are not all fun and joy, but you do learn stuff.

OMEGAMAN · #17 01-31-2007, 01:28 PM

When ever I hook up jumper cables I always turn my head away from the battery when I make the last connection. This way if you have made a mistake and the battery does explode only the back of your head is damaged. Not your face.

retx · #18 01-31-2007, 01:43 PM

Quote:

Originally Posted by OMEGAMAN

When ever I hook up jumper cables I always turn my head away from the battery when I make the last connection. This way if you have made a mistake and the battery does explode only the back of your head is damaged. Not your face.

yeah, most people dont value the back of their head much.

MS Fowler · #19 01-31-2007, 01:46 PM

A place where I formerly worked had a shelf for charging batteries. The shelf acted as an enclosure. One day, as I unhooked a battery from the charger--without unplugging the charger first, I got an arc, and ignition of the gases. It was quite a shock, and quite a noise.

spark3542 · #20 01-31-2007, 02:12 PM

Quote:

Originally Posted by sailor15015

If you connect the neg cable last, and disconnect it first, it shouldn't spark, should it? I know electrons flow from neg to pos but the current flows from the pos and I've never seen the neg cable spark, say when reattaching it to the battery with the pos cable already attached.

I could rationalize it if it was the pos cable, because I've seen it spark many times, but never the neg.

I need to correct this one. Everything sparks when connected. It doesn't matter whether it pos or neg, they will spark the same. A good rule of thumb (in open air) is that an arc will jump 10,000 volts per inch. If your spark plug wire is producing 10,000 volts, it will arc when held an inch away from the block. Likewise, a jumper cable will arc as it approaches a battery post, but obviously the arc occurs when it is very close to the post, given that a battery is only 12 volts.

Electron flow IS current flow. Technically is does flow from neg to pos, but we can't witness that in any way in our daily lives. We decided arbitrarily way back when to assign pos and neg nomenclature.

Since the act of charging a battery generates hydrogen, I would speculate that it is more dangerous to remove a jumper cable after charging has occurred, and there is significant hydrogen in the area of the battery, hence the reasoning for the last connection (and first dis-connection) occuring away from the battery.

Also, your starter is grounded to the block, so a neg connection to the block will be a more solid connection for the starter when cranking, than to the battery and through the ground strap to the block.

Thanks