72V electrocution?

[le15otl]

Just getting into using 72V (max 75.6) and am slightly worried about getting electrocuted when touching the terminals.
I understand anything above 50v can ''potentially'' kill you but what's the deal with 75v (high discharge capable) batteries?

Any users here ever touch their high voltage battery? What happens ? Is there any chance of actually dying?

Thanks...

 

[Voltron]

I haven't actually touched mine...But one time I got a connector too close to my aluminum rack and a spark jumped the air gap, destroying the connector and gouging an inch long divot in the rack...



it reminded me of the star wars line.... "thats a lot of carbon scoring... looks like you droids have seen some action" lol

 

[wesnewell]

Have you ever heard of anyone being electrocuted on an ebike? No! There's a good reason for that. Don't worry about it, it won't happen. And yes, I've grabbed both ends of my 24s 100.8V charged lipo pack before, many times. Just don't short them out. It will blow the connectors off and likely burn the crap out of your fingers, but it won't electrocute you. I've done that too just once when I was't paying attention to what I was doing. The human body has very high resistance.

 

[Punx0r]

Depending on your personal skin resistance, it could give you a painful shock if your skin is wet. if dry, little more than a tingle or warm burning sensation. Either way, the risk of harm is very, very low.

 

[gogo]

There are a few threads that come up from a search of E-S and electrocution.

Subject: Is DC more lethal than AC.....why

 

[Alan B]

People have been electrocuted by 6 volts. The skin normally provides some electrical protection if it is dry and unbroken. DC is slightly less dangerous than AC, and the electrical safety folks are moving toward changing the regulations for DC hazards and raising the value to 100 VDC while AC will remain at 50V.

Energized conductors penetrating the skin present an entirely different hazard, and ebike voltages are certainly high enough to be lethal in that situation. Do not work on your ebike when you are sweaty or bleeding.

Wearing clean dry leather gloves will provide a lot of additional protection against both the electrical hazard and against the arc flash plasma hazard that you occasionally see when mistakes are made with wiring. Plan your work, and work de-energized whenever possible. All conductors should be insulated. Pay special attention around connectors.

 

[Dauntless]

The real point you need to get is that the 120v AC off the wall is low risk, but not risk free. DC is less risk but still not risk free. While I've felt bad after some good jolts of line current it never knocked me down, I'd expect less from your battery. But if you have a health issue that increases the risk. If you're being careful there's not so much to worry about.

I'd worry more about if your battery is lithium and the possibility of maybe a carbon fiber frame that will conduct very well creating an explosive situation rather than an electrical one. My oem 12v battery melted down in my Mustang I'd had barely 3 years. I'd sat with the radio on listening to Peyton Manning's retirement press conference and didn't start the car to charge it before I left it. Hours later to start the car I had to push start it. 30-40 minute drive in traffic, as I'm getting home there's wisps of steam coming out while the car is moving, so I took a moment to put safety glasses on before I even popped the hood and saw it seriously steaming. Maybe the car was off for a minute when I used something long to pop the caps, it was bubbling in there. Even the lead acid can pose more important risks than electrocution.

 

[Bicycle365]

...... Don't worry about it, it won't happen. And yes, I've grabbed both ends of my 24s 100.8V charged lipo pack before, many times. Just don't short them out. It will blow the connectors off and likely burn the crap out of your fingers, but it won't electrocute you. ........

I love watching Natural Selection at work !

 

[Alan B]

120VAC kills more people than all other voltages, as I recall.

Take care,

 

[le15otl]

Thank you for all the wisdom. I am a bit reassured but still there's a mixed load of views. I will play still safe when i have wet hands or there's blood around...

 

[friendly1uk]

AC causes spasms that give chance to let go. DC makes you clamp down.

I would be cautious. Adopt good practice, or one day you could grab them with wet hands

 

[liveforphysics]

I've taken 100-116vdc from hand to hand across the chest perhaps an average of 5-10 times per day for the last ~5years or so. Never experienced more than an uncomfortable tickle.

I've taken 110-120VAC perhaps 50 times in my life, it nips quite a lot harder than 116vdc, because it's AC peaks are in the 170v range.

In theory, even 2v can instantly kill you if it were 2v with the right current path (like needles stabbed into each side of your heart).

In practice human skin protects us from this happening, or much of any major shock happening until voltage goes above the breakdown voltage for the skin. This breakdown voltage depends on many factors and will vary person to person day to day. For myself it seems to be around 150-200v that shocks go from being a tickle to having pain and instant violent muscle contractions and heart palpitations etc.

 

[wesnewell]

Hopefully , this will put this to rest
[youtube]-a0Tga0F3Js[/youtube]

 

[friendly1uk]

Who hasn't put a 9v battery on their tongue?

It's 60v per cm to damage flesh, but it's hitting nerves and tweeking muscles that kills, not the much higher tissue damage level shocks.

Wes, put some wet gloves on then try it with all them low resistance parallel paths and you might not post again.

As a qualified bloke, it's manslaughter not accidental death if I give bad advice. I would like to point people towards the many regulatory bodies of qualified man throughout the world who study accident data and have all decided about 50vdc is where we need proper protection.

Go past 50v and any resulting actions will be uninsured. Death or chucking things.

It's good practice to follow the regs. They will keep you out of trouble. No employer can legally ask you to do otherwise. If you choose to operate outside the regs that is your choice, but I don't find it wise to advise others to

 

[Alan B]

Some people are poor conductors.

It really depends on the condition of the skin and the resistance it offers. The water in the blood, body fluids and internal organs are fairly good conductors, the insulation of the skin is the only thing protecting you. It doesn't take much to penetrate it.

Take care and work safe,

 

[Brake]

 

[Brake]

 

[liveforphysics]

Wes, put some wet gloves on then try it with all them low resistance parallel paths and you might not post again.

In the vehicle safety inspection for deathbike to go on track at Laguna Seca, the guy asked me if my wiring was all safe. In response I for some reason rested my gloved hands on top of the big lugs for pack +-. My gloves were stoaked with the sweat of many hundreds of sweaty rides in them. Pretty solid jolt to take while trying to proclaim your vehicle safe for the track.

 

[Brake]

Lol. Funny in all the wrong ways. Ouch


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[Eteck]

Take the same precautions you would around normal house wiring maintenance, such as replacing a switch or outlet, and you should be fine.

 

[dogman dan]

Well, here's my common sense idea.

I never uncover a positive and a negative wire at the same time. This is to prevent the KFF thing, where you weld wires or plug contacts with bare hands. But in the process, I can't ever actually grab positive and negative at the same time. I do this with all voltages. 12v can still melt a wire in your hand.

This will be harder to do of course, if you handle naked cells, naked pouches, or use cells with lugs on the top. But I've had a few tickles from 110, (learning not to grab plugs from the sides) and have survived doing stupid shit like replacing a house breaker box hot, to save a big fee to get a building permit and have the electric company pull the meter. You do shit one handed, and never work on more than one wire at a time. I stood on rubber to handle those half inch house wires, but see no real need to do that for the bike stuff. Just have clean dry hands, and not standing barefoot in a puddle.

 

[Ykick]

I'm with common sense approach of avoiding household electrocution - "one hand always in a pocket and never bare feet"

 

[speedmd]

Some people are poor conductors.

Is this what they call a "dim bulb"?

 

[docw009]

As you get old, and your fingers get leathery, calloused, and dry, so you might not get bit if you put your hands around a big battery. I remember when I was 11 years old, building a "portable" tube radio, and that little 90 volt RCA battery in its cardboard pack stung the #$%@ out of me when I touched the terminals.

I sure wouldn't let my little grand daughter get close to open 72 volt wires in my garage, especially if she had been sucking her thumbs.

Sometimes we get too casual about 110 volts. People have gotten killed reaching for hair dryers that fell into a sink. In Europe, where they have 220 volt mains, I suspect people are very careful.

 

[MadRhino]

You can survive being hit by a lighning during a thunderstorm, or be killed by a battery...

I know that when you have to die it can be by the most stupid ways, and when you have to live you can survive the most brutal experiences. Stop worrying, and try to live your best now. :wink: