danger

Joaquinsfy

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Oct 9, 2016
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I read a lot of material about the danger of DC current, but i don't know, if the powerwall that we are building are dangerous to the people.

I mean with 48V you can touch positive and negative (in a installation with 150 Ah)??

I know that this has not easy answer but... any help will be helpful.
 

MicahT

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Oct 16, 2016
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Anytime you are dealing with lithium batteries there is a level of danger. We have to accept that, respect it, and act accordingly. Using proper tools and healthy cells mitigates much of the risk. 48V can be painful but at our levels it is rarely lethal. The bigger issue is the amount of current that flows through you than the voltage.

But even more dangerous is your house burning down because you tried soldering a bunch of 18650's you got out of a recycling bin and the heat caused them to short and catch fire after you left your workshop...

Use safety equipment like gloves and safety glasses, keep your work area clean of metal debris, double check your connections before you make them and work with quality components and you should be fine.
 
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station240

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Anything under 50V DC is safe, you are not going to get a shock of cabling or batteries.
This is voltage however, you can still get arcing from high current DC circuits.

The only safety issues related to the AC output of inverters, or anything you normally power from the mains.
 

MicahT

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station240 said:
Anything under 50V DC is safe, you are not going to get a shock of cabling or batteries.

I've gotten shocked by 48VDC a few times while handling exposed ebike batteries without gloves (dumb, I know).

I'd call it more like fairly uncomfortable than painful, but it's still no walk in the park...
 

Joaquinsfy

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Thank guys!!

Now i understand, be careful, but not deathly.

In spain, we use 220v AC and it makes unpleasant tickles.. and 380 AC (trifasic) thas is very dangerous.

Thanks again!!
 

hbpowerwall

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I defiantly get a warm tingle at 57v but wouldn't be happy to touch it dripping wet..
 

Nismo nick

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I have copped a few belts from welding while sweaty. I conceede that it wasn't a power wall but it was still D.C. Current is what does the damage. :shock:
 
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DC is more dangerous because it causes muscles to contract. If you grab a wire you shouldn't, your hand will clench hard and you cannot let go. So although lower voltage, it gets you for much longer.

Have no illusions, you can die. And apparently, you know you are dying....slowly and very very painfully. AC has the decency to knock you out fast.
 

Muzzlehatch

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DIYTESLAPOWERWALL said:
DC is more dangerous because it causes muscles to contract. If you grab a wire you shouldn't, your hand will clench hard and you cannot let go. So although lower voltage, it gets you for much longer.

Have no illusions, you can die. And apparently, you know you are dying....slowly and very very painfully. AC has the decency to knock you out fast.

I am not going to get too bogged down in this. Back in the day I worked on patient attacheched medical electronics. I.e. where the electrode is stuck in the patints body. It is a complex field. Licking the treminals of a 9 volt battery can kill you. A shock can set up an arythmia that can turn nasty a few hours later. Same as a hang fire when blasting or on a rifle range.

There was aartifical controversy setup when the first grids were being rolled out where The Saftey or DC VS AC was debated. It is the sort of thing you will see on QI if you can be botheredwatching TV.

In essence what kills you is the current across the heart muscle sending it into deibrillation. This is where a hugh cross chest current can clamp the whole lot tight to restart when the current is releaxed.

If you have a direct path across the chest and you hands are saturated in brine the game can change.

Just do sensible stuff and remove all jewelry. Saftey glasses is a good idea. Label your high voltage busses. Keep the box locked from curious little fingers.
 

LithiumSolar

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MicahT said:
station240 said:
Anything under 50V DC is safe, you are not going to get a shock of cabling or batteries.

I've gotten shocked by 48VDC a few times while handling exposed ebike batteries without gloves (dumb, I know).

I'd call it more like fairly uncomfortable than painful, but it's still no walk in the park...

I have felt small tingles from 24v (probably closer to 30v fully charged). It didn't hurt or anything but was enough to make me go "oh, those wires are live".
 

Elmo

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Feb 19, 2017
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60VDC or so seems to be the dividing line between moderately hazardous under the wrong circumstances and keep the hell away, this has been a topic on the ebike forums because a lot of high performance ebikers are running 72V or even more, I've seen at least a couple over 120V.

A bigger hazard at the voltages we are mostly dealing with is the explosive nature of shorts in high capacity lithium systems, someone mentioned not wearing jewelry, I'd second that, short a ring out at even 12V and it's going to be ugly.
 
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