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Help Please! Electrical Shock From Battery!

irlandes, have you personally been bit by 12 volts? Do you personally know someone who was bitten by 12 volts?

I seriously doubt that you ever got single digit ohm readings through skin, under a ring or anywhere else. The only time I have heard of anyone hurt by low voltage and a wedding ring was a guy who got the ring between ground and the + terminal of a 28 volt aircraft generator. It wasn’t the voltage that got him. It also wasn’t the current going through his body either. It was the heat from the ring turning white hot from the current going through it, not him.

I do believe irlandes, keith, about the possibility of the body having rather low resistance due to wearing jewelry. Reason being, is that I have gotten bit by a standard automotive battery. I told my story at the top of the thread. At that time, I wore a watch with a metal band all the time. The skin on my wrist under the watch band was different, softer, paler, and tended to be perpetually wet on a hot day. That probably didn’t help my situation. I have proven time and again that 12 volt batteries are fairly safe to work around and will not normally give you a jolt, but I do know that on that one occasion I did indeed get a jolt from one. I think that I ended up giving the current a very nice, low resistance path to travel through me. Between the metal watch band, sweat, and nearly the entire front of my body leaning against the vehicle allowed me to get a little jolt. It was a rare situation, but it certainly can happen.

Then you are the first I have ever heard of that actually got bit.

Which means you didn’t read the original post that started the thread, which raises the question “What’s the point?”

Yes I did read the original post, but there is some question as to whether the shock came from battery or something else.

"DC burns. I was working on a power supply once when I accidently sent 500 VDC through my body. I never felt a shock, but when my hand started to burn where it was grounded, I felt that. "

I have been shocked by DC a couple of times and it felt much like being shocked by AC. Once I grabbed a hold of a large capacitor charged to 500 volts DC and I felt a big jolt, another time I hit the 25,000 volt DC anode voltage of a color TV picture tube and people from the front office ran to the back of the shop to see what happened. I would not describe it as a burning sensation.
Fortunately the 25KV crt anode voltage power supply is limited to about 3 milliamps and as soon as I made contact with it, the current brought the voltage down to whatever volts was needed to push the 3 milliamps through my body so I wasn’t really experiencing 25 kv.

When you hit high voltage that is not current limited, like 12,480 line to line/7,200 line to ground powerline distribution voltage, it usually results in the need for a closed casket funeral. I met someone who survived being shocked by this voltage, he had both arms amputated from being cooked by the current and his shirt was set on fire by the current. Doctors credited his sweat soaked shirt for shunting the current around his body and saving his life.

I also tend not to believe that a person can be shocked by a 12 volt car battery. The problem for me is that it’s happened to me a few times. I once got shocked when pulling off a spark plug wire while the engine was running, which I found wasn’t a good idea. I haven’t done that again, but I have felt a shock while working on a battery. The battery in my car often gives me very minor acid burns. I don’t know why there so frequently seems to be acid on the outside of it. But I suppose that might be making it easier for the battery to shock me.

If the conditions are right, 12-14 VDC can indeed "

Good point there. I have not tried it, but what you say could well be true and I have not considered that.

"Yes I did read the original post, but there is some question as to whether the shock came from battery or something else. "

For any who missed the thread-starter:

“Today I was shocked from a deep cycle marine battery (12volt I think?) full on and it really jolted me.”

OK just to let you all know, I do know a little bit about electricity. I started fixing radios and TV’s at 14 and I recently retired from a major distribution transformer manufacturer as the supervisor of their QA and testing department at the three phase plant. Along the way I graduated from the Navy’s top electronics school, before it was discontinued because it taught too much. I also taught at the Navy’s top electronics school, the one that replaced the one I graduated from. I’ve worked on the most powerful airborne radar ever made.

I’ve been bit by a lot of different voltages, both AC and DC. The worse was from a coil that discharged through my body at an estimated 150kV. I don’t know if it was that high for sure, but it did knock me out, in fact, I came to laying on the floor behind the chair I was sitting in, and the chair was not knocked over, that one hurt for days afterward.

I’ve done the safety lectures, I’ve done the skin resistance measurements, wet and dry. I will say that those who felt something from a 12 volt battery did indeed feel something, I just don’t know what. I have handled a lot of 12, 18 24 and some 28 volt batteries and never felt anything, including when working on the flight deck in the tropics where the humidity is 100% and salty at that.

I bow to your experience. Is it possible that people feeling something from a 12 volt battery are feeling electricity?

I really can’t tell someone that that are not feeling what they are feeling. I have handled a lot of batteries, 12 -28 volts under a lot of conditions and have never gotten a shock from the battery directly. It also does not fit what I know about electricity and the human body. What I’m saying is that I find it very hard to believe and what they are feeling could be from something else.

The shock you feel depends more on the current than on the voltage. Normally a 12 volt battery doesn’t cause much of a shock, because dry skin has fairly high electrical resistance. In a wet environment though, where you have good electrical conduction from the battery to the skin, it could happen. You’d notice a good sized shock. Like if you were standing barefoot it a metal boat full of water, and you grabbed the battery with wet hands, or worse would be if you touched the battery to your metal watch-band which was wet. Under the right situation you can get a pretty good sized shock (possibly even lethal) from a 12 volt battery.

Standing in a “boat” full of water would make a difference how?

Here’s an experiment that I will not plan on trying, but anyone who thinks 12 v batteries can’t shock you can consult a doctor, lawyer, and electrical engineer while considering trying it (a longwinded way of saying I just don’t know what would happen):

Swirl each of your thumbs around in your mouth and then touch one to each terminal of a fully charged 12 v car battery. Hmm, wonder if it would be different if the engine were running.

“I have handled a lot of batteries, 12 -28 volts under a lot of conditions and have never gotten a shock from the battery directly.” <-- maybe because of all those courses and schools you went to you were careful. Possible?

I’ve handled the capacitors from countless (over 100, <1000) disposable cameras and never been shocked. That doesn’t mean they’re not dangerous. You can make a (primitive) taser with a disposable camera.

Just because you weren’t shocked when you presumably followed appropriate procedures has no bearing on whether or not someone else was when maybe they didn’t.

looks like we are going in circles here.

Have you tried the experiment?

I have licked my fingers and touched them to both terminals of a car battery to make a point to a friend that thought you could get a shock from one. I received no shock. Perhaps if I had thoroughly coated my fingers with saliva and bore down on the terminals with 50 or more pounds of pressure I would have overcome my skin resistance enough to have felt something. The car was running at the time and the terminals were clean.

During 15+ years designing patient data monitoring equipment, including 12 lead ecg, I learned how variable skin conditions are across populations (age, health, etc). Some people have very thin epidermis and so lower resistance/impedance.

It only takes 10-20 MICRO-amps to cause fibrillation. Equipment is designed to limit leakage to <10 uA for this reason. Back when i started in that field we thought <20 mA was safe.

If someone has thin epidermis, even a small pin sized protrusion of metal that can’t be felt could compromise the insulating properties of the skin.

The vast majority of people will never get any shock from a 12 volt battery no matter if they’re soaking wet with sweat. I routinely grab the terminals on batteries i have with no handles but i would never say it can’t happen based on my prior experience.

10 Micro amps? 10 Millionths of an amp? Does this mean it’s not safe to put your tongue on a 9 volt radio battery’s terminals?

If you put your tongue on a 9-volt, the current would only be going through your tongue, not your heart, so it might hurt a lot, but it’s not likely to kill you.

This is why electricians practice the “one hand in pocket rule”, when working on equipment that may still be live. You might get a good zap with one hand, but it won’t go through your heart like if it goes up one arm and out the other.