Thread Rating:
  • 0 Vote(s) - 0 Average
  • 1
  • 2
  • 3
  • 4
  • 5
Safety: How hazardous can a 14s be to your life?
#1
Hey Guys

So far I have only been dealing with 36v systems (which have 42v fully charged). 
If I touch the terminals there, I was clearly able to feel current to flow. How safe is a 14s system (going to nearly 60v fully charged...)? I only have (a little bit) of experience with mains-shocks (been shocked 3 times by 220v AC and don't want to do it again! 1st: wet paperstrip on plug when I was 17 or so... 2nd: Broken cable on a hairdryer, one strand of copper sticked out and got me on my hand... 3rd: changing a ceiling lamp Idea and there was current on the neutral line for some reason...)

I am sure, you might have (accidentally or intentionally) tested what happens if you touch the terminals of a 14s configuration... I would be glad to hear some of your experiences with those packs. I am sure It can be hazardous in many ways but I rather hear your incidents and don't do the same than learn all cases myselfs...  Angel Cool

Maybe this thread can be sort of a collection of incidents or «don't try this at home» events?! Or also what your precautions are while working with 14s (or greater) packs.
I really want to be safe and get as much knowledge as I can before starting to assemble my packs.

Looking forward to your answers.  Cool

Best, elkooo
Reply
#2
60 Volts can kill You, so if You do not know what You are doing, Don´t!

60 V DC must be treated with at least the same respect as live Mains, maybe more because DC can cause severe burns.

50 Years ago some places still had DC Mains at 110 Volts and people got killed trying to handle wet laundry in a defective washing machine, or placing a pot on a defective cooker.

Therefore, be careful, use insulated tools and do not touch with moist fingers, use gloves if You are in doubt.

Live long and stay healthy Smile

ChrisD
Reply
#3
12VDC can cause some discomfort if your skin sweaty. Had this plenty of times trying to jump start a vehicle and leaned on the vehicle while connecting the Pos terminal. It has like a pinching/tingling/stinging sensation.

With that said, 60VDC can pack a punch. It's at least 5 times as powerful (maybe more, not sure if it's exponential increase or not). You can safety touch a 48VDC system (which can get up to 60VDC), BUT ONLY with dry hands. HOWEVER, I do NOT recommend touching both terminals to find out. Please wear gloves if needing to touch the live terminals of a charged system.

Continuing on, if you find yourself working on 72VDC system, always wear gloves and preferably long sleeves. As Chris states, 110VDC will definitely kill.

The higher the voltage, the harder it is to pull off of it. DC causes a 100% locking motion of the muscles in contraction of the strongest muscles, with the hands that's latching on. With AC, there is a pulsing latching, which kind of gives you some time, albeit little time, to pull yourself off. Fortunately I've only had contact with AC with the back of hand and never on my palm, so I don't know what that feel likes.

In the end, if you can get away with it, make sure all live wires are clear of each other and you cannot mistakenly touch both at the same time. Wrap tap, put a cloth/sock/something over it, wire nut it, etc if needed. At the very least, if it doesn't kill, it could leave a nasty burn mark (think of how a spot welder works)
Proceed with caution. Knowledge is Power! Literally! Cool 
Knowledge is Power; Absolute Knowledge is Absolutely Shocking!
Certified 18650 Cell Reclamation Technician

Please come join in general chit-chat and randomness at Discord Chat (channels: general, 3d-printing, linux&coding, 18650, humor, ...)
(this chat is not directly affiliated with SecondLifeStorage; VALID email req'd)
Reply
#4
From what I've read, the code requirements in my jurisdiction (Oregon USA) require 48v to be *in conduit* whereas 12/24 are not required. The reasoning (I read) is that 48v is just high enough to present some cases of physical danger due to shock / current in body leading to serious risk. I presume the code requirements are based on the science of voltage risks - so I take them seriously.
Korishan likes this post
Reply
#5
I agree OffGrid. However, I think the OP was referring right at the battery bank, so I think conduit is a bit tough to do Tongue
Buuuut, the need to keep the terminals/bare-wires covered is better understood now. I didn't realize it was code to be in conduit. I'm sure in here in Florida is the same thing. Actually, considering it's NEC, it's nationwide anyways. So yeah, same code here.
I would imagine other countries have the same or similar restrictions
OffGridInTheCity likes this post
Proceed with caution. Knowledge is Power! Literally! Cool 
Knowledge is Power; Absolute Knowledge is Absolutely Shocking!
Certified 18650 Cell Reclamation Technician

Please come join in general chit-chat and randomness at Discord Chat (channels: general, 3d-printing, linux&coding, 18650, humor, ...)
(this chat is not directly affiliated with SecondLifeStorage; VALID email req'd)
Reply
#6
@Korishan - Yes, thank you. I was referring to 'transmission' lines i.e. from PV combiner box to Charge Controller and possibly from Charge Controller to Battery bank if long enough. For example, my Charge Controllers are about 10 feet from battery control box (with circuit breakers / shunts) and the Electrician said conduit was required as the wires ran up on the ceiling over to the other side of the room.

Its interesting that the electrician 'waved his hands' in frustration that there was no way to 'conduit' very short distances - like 12 inches from battery control box to the Inverter. However, putting things like shunts and circuit breakers into a box as a terminus for conduit is definitely encouraged. One of the key things about control boxes and conduit is that it protects exposed wire against things 'hitting it' - so protected locations / short distances such as connecting batteries in parallel get 'a pass' as far as conduit, but should be protected.

>Buuuut, the need to keep the terminals/bare-wires covered is better understood now.
Agree 100%. As I work with my larger battery with wrenches to tighten bolts ... its so important to keep + and - covered / separate as much as you can. If you do a design where a 'slip' of the wrench can short + and -, it will be sure to happen eventually Smile
Reply
#7
(10-02-2019, 03:47 PM)OffGridInTheCity Wrote: Its interesting that the electrician 'waved his hands' in frustration that there was no way to 'conduit' very short distances - like 12 inches from battery control box to the Inverter. However, putting things like shunts and circuit breakers into a box as a terminus for conduit is definitely encouraged. One of the key things about control boxes and conduit is that it protects exposed wire against things 'hitting it' - so protected locations / short distances such as connecting batteries in parallel get 'a pass' as far as conduit, but should be protected.

The plastic conduit can easily be cut shorter. I hadn't thought of putting the shunt in a combiner box. That's a good idea. And those boxes come in various different sizes. This also gives the added protection of keeping insects/dust off the connections as well (especially if you keep your gear out of house/garage and in something like a shed (which are usually not environmentally sealed)

(10-02-2019, 03:47 PM)OffGridInTheCity Wrote: >Buuuut, the need to keep the terminals/bare-wires covered is better understood now.
Agree 100%. As I work with my larger battery with wrenches to tighten bolts ... its so important to keep + and - covered / separate as much as you can. If you do a design where a 'slip' of the wrench can short + and -, it will be sure to happen eventually Smile

Hahahha take all your metal tools and plasti-dip them Wink no more chances of sparks!

And yeah, Pete had a similar slip-up when a dangling wire got loose and hit his battery pack connection. Sparks!
Proceed with caution. Knowledge is Power! Literally! Cool 
Knowledge is Power; Absolute Knowledge is Absolutely Shocking!
Certified 18650 Cell Reclamation Technician

Please come join in general chit-chat and randomness at Discord Chat (channels: general, 3d-printing, linux&coding, 18650, humor, ...)
(this chat is not directly affiliated with SecondLifeStorage; VALID email req'd)
Reply
#8
If you just work with everything like it could kill you... you will be fine.

That said, I started having a much greater respect for electricity after it does try and kill you, something you have already experienced OP, which puts you ahead of most.  Which is probably why you are asking smart questions.
Korishan likes this post
Reply
#9
In Qld Aus licencing starts at 50V DC systems, it used to be 100V DC but was reduced in the last couple of years as 50V DC systems were considered “safe”.

That said, I’m very cautious making sure I take the same precautions as I would with a 240V AC system when working on my 48V system
Reply
#10
i grabbed once in a 12v 30a dc power supply, lucky for me it was grounded, yah, it stings...
I thought it was disconnected from the grid, always check.

In the Netherlands you don't need papers if you are working below 62v.
But this information is 25 years old, things could have changed a bit.
Reply


Forum Jump:


Users browsing this thread: 1 Guest(s)