Feeling cute today, may build a 480V battery later. .

curiouscarbon

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cool project concept.

i am too scaredy cat to even do 48V (albeit LFP, but either way.) so i am limiting myself to 12V and 24V systems for now until learn more.

Magid gloves are supposed to be the standard hand protection from what I gather. Very important with increasing voltage.
The rubber dries out over time exposed to air leading to cracks and can get tiny puncture from e.g. stray stranded conductor, which ruins the protection.
So I would always use the leather glove even though it degrades dexterity.
So definitely take the 1 year from opening as real. At time of manufacture they do a "HiPot" (High Voltage Potential) basically simulating a hand being in the glove and generate very high voltage on the outside of the glove. If a small hole is present in the rubber inner glove, the high voltage potential can jump through that small (maybe not visible to eye) hole and harm the person wearing it.

one time i unwired a gable fan from AC. i am not a trained electrician. i put on the gloves, used a multimeter to verify the circuit was live, then went and shut off the breaker to that circuit, came back and verified the plug no longer registered a voltage, and only then proceeded to unscrew the outlet cover and disconnect the hardwired fan. maybe those precautions were excessive or even not enough, but personally i prefer to be inconvenienced instead of zappy time.

wishing for a safe outcome!
 

Supervstech

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cool project concept.

i am too scaredy cat to even do 48V (albeit LFP, but either way.) so i am limiting myself to 12V and 24V systems for now until learn more.

Magid gloves are supposed to be the standard hand protection from what I gather. Very important with increasing voltage.
The rubber dries out over time exposed to air leading to cracks and can get tiny puncture from e.g. stray stranded conductor, which ruins the protection.
So I would always use the leather glove even though it degrades dexterity.
So definitely take the 1 year from opening as real. At time of manufacture they do a "HiPot" (High Voltage Potential) basically simulating a hand being in the glove and generate very high voltage on the outside of the glove. If a small hole is present in the rubber inner glove, the high voltage potential can jump through that small (maybe not visible to eye) hole and harm the person wearing it.

one time i unwired a gable fan from AC. i am not a trained electrician. i put on the gloves, used a multimeter to verify the circuit was live, then went and shut off the breaker to that circuit, came back and verified the plug no longer registered a voltage, and only then proceeded to unscrew the outlet cover and disconnect the hardwired fan. maybe those precautions were excessive or even not enough, but personally i prefer to be inconvenienced instead of zappy time.

wishing for a safe outcome!
48V makes big sparks when shorted, but you gotta be very susepable to feel a shock from it.
Sweaty skin, sure… it’ll bite hard.
But using safe practices. 48V is just as easy to use as 12V is.
 

Hedges

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one time i unwired a gable fan from AC. i am not a trained electrician. i put on the gloves, used a multimeter to verify the circuit was live, then went and shut off the breaker to that circuit, came back and verified the plug no longer registered a voltage, and only then proceeded to unscrew the outlet cover and disconnect the hardwired fan. maybe those precautions were excessive or even not enough, but personally i prefer to be inconvenienced instead of zappy time.

That's most of the process, but you left out "lock-out tag-out", make sure the significant other doesn't come turn the breaker on while you're working on system, thinking it is the reason something else in the house didn't work.

What you did include was confirming circuit went from live to not live when breaker was turned off.
That step is missing from our OSHA approved process, as I've pointed out each time an employer taught it.
They taught, Lock breaker off, confirm zero voltage. But they fail to confirm that was the correct breaker.
 

rin67630

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Oh, 120 certainly CAN kill you… but you have to be pretty unlucky.
I have been almost killed on a hot day where I was quite sweated and my metal ladder touched a heater.
I wanted to cut a blue wire that should have been neutral.
The current came into my finger grasping a plier, crossed my heart and got out along my leg.
I could not leave the contact until I fell to the floor
I woke up later, gasping for air, probably the devil did not want me that time.
I am now left with a scar from a 3rd grade burned wound on my finger.
It was 30 years ago.
 
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Shimmy

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I still have a burning question.
Is there a use case for high voltage battery packs other than economics of wiring.

If you have one or more then I am all ears. I for one am already way past the danger line. So why not go all the way
You can have a higher efficiency inverter if the DC voltage is about equal to your AC peak voltage, IIRC. Also, for lead acid UPSs it helps you ride through the coup de fouet as you initially load the battery.
 

brandnewb

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Also, for lead acid UPSs it helps you ride through the coup de fouet as you initially load the battery.
Could you please elaborate a bit more on this? And please take into account that I am dabbling with LifePO4's
I do not mean to highjack this thread though. Please ignore me if it starts to look like that.
 

Shimmy

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Could you please elaborate a bit more on this? And please take into account that I am dabbling with LifePO4's
I do not mean to highjack this thread though. Please ignore me if it starts to look like that.
Technical or ELI5?
When lead acid batteries take a sudden discharge, they experience a significant voltage drop as the capacitance is drained and the chemical reaction begins. This voltage drop is short term in duration; the healthier the battery the shorter the duration and magnitude of the voltage dip (the French translates roughly to "crack of the whip" for the voltage-time curve characteristic). Traditionally, a UPS has a low voltage cut-off setting that is not time-dependent to protect the batteries. (Specific to UPSs, the voltage cut-off is typically lower than for a system that sees more deep discharges over its life.) The higher the voltage of a battery bank (and lower current) the more you are going to have functional leeway for the inverter to continue operating even if you do hit the cut-off voltage per cell... as long as the UPS doesn't trip the battery.

If in contrast you just had a 48VDC battery system for a ~2MW UPS, the inrush current would lead to such a significat voltage drop that it would be quite difficult (no matter how much copper you used) to manage operation.

ELI5:
When you go from 0 to heavy load on a battery you get an initial voltage drop. A higher voltage battery string can help you ride through that voltage drop.
 

Jim H

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cool project concept.

i am too scaredy cat to even do 48V (albeit LFP, but either way.) so i am limiting myself to 12V and 24V systems for now until learn more.

Magid gloves are supposed to be the standard hand protection from what I gather. Very important with increasing voltage.
The rubber dries out over time exposed to air leading to cracks and can get tiny puncture from e.g. stray stranded conductor, which ruins the protection.
So I would always use the leather glove even though it degrades dexterity.
So definitely take the 1 year from opening as real. At time of manufacture they do a "HiPot" (High Voltage Potential) basically simulating a hand being in the glove and generate very high voltage on the outside of the glove. If a small hole is present in the rubber inner glove, the high voltage potential can jump through that small (maybe not visible to eye) hole and harm the person wearing it.

one time i unwired a gable fan from AC. i am not a trained electrician. i put on the gloves, used a multimeter to verify the circuit was live, then went and shut off the breaker to that circuit, came back and verified the plug no longer registered a voltage, and only then proceeded to unscrew the outlet cover and disconnect the hardwired fan. maybe those precautions were excessive or even not enough, but personally i prefer to be inconvenienced instead of zappy time.

wishing for a safe outcome!
I too have a healthy dose of chicken with certain activities… electricity is one of those .I have a probably silly question ,considering some of these story’s I reading here, but my trailer mounted array I’m trying to finish is 86 ish volts voc , runs 60 ft to the SCC ,then is reduced for the rest of the 24V system. I bought a pair a magid gloves rated 0 and the leather cover gloves .. I have no intention of working on hot wires at all But accidents do happen and it’s hard to kill the entire array ever time I need to touch somthing… it’s sorta creepy…
I know the Inverter can get me with the 120v .. i doubt the 24 v will be as much of a threat , but what about the 80 + volt on all the array and chassis ground wires,bonding wires ,shutoff disconnects, fuses, metal frames and etc….… am I wrong to want to wear the gloves working on that stuff (standing on dirt Tilting the panels manually) Or washing them.? it seemed like the smart thing to do , but seems pretty fearful compared to all the stories I have read about macho activities by so many.
it just seems there a lot of potential for a mistake with a large , complicated, Mobil wired array On damp earth with 80+ volts… What say you….???
jim.
 

Shimmy

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I too have a healthy dose of chicken with certain activities… electricity is one of those .I have a probably silly question ,considering some of these story’s I reading here, but my trailer mounted array I’m trying to finish is 86 ish volts voc , runs 60 ft to the SCC ,then is reduced for the rest of the 24V system. I bought a pair a magid gloves rated 0 and the leather cover gloves .. I have no intention of working on hot wires at all But accidents do happen and it’s hard to kill the entire array ever time I need to touch somthing… it’s sorta creepy…
I know the Inverter can get me with the 120v .. i doubt the 24 v will be as much of a threat , but what about the 80 + volt on all the array and chassis ground wires,bonding wires ,shutoff disconnects, fuses, metal frames and etc….… am I wrong to want to wear the gloves working on that stuff (standing on dirt Tilting the panels manually) Or washing them.? it seemed like the smart thing to do , but seems pretty fearful compared to all the stories I have read about macho activities by so many.
it just seems there a lot of potential for a mistake with a large , complicated, Mobil wired array On damp earth with 80+ volts… What say you….???
jim.
If you are standing on the ground (especially barefoot) and touching things then you have a valid concern. That turns your ungrounded island into a grounded island and can shift current and voltage flow. Likewise if you are on a metal step ladder doing the same, you have an incidental ground.

At that point you could either ground the Rv chassis to earth, or treat all exposed metal as potentially live.

Personally, I would use electrical gloves on anything I could not verify as de-energized or grounded out.

That said... how do you get into your RV... do you use electrical gloves on the door handle? You have to draw the line somewhere.
 

Hedges

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Might not be a bad idea:

 

Jim H

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If you are standing on the ground (especially barefoot) and touching things then you have a valid concern. That turns your ungrounded island into a grounded island and can shift current and voltage flow. Likewise if you are on a metal step ladder doing the same, you have an incidental ground.

At that point you could either ground the Rv chassis to earth, or treat all exposed metal as potentially live.

Personally, I would use electrical gloves on anything I could not verify as de-energized or grounded out.

That said... how do you get into your RV... do you use electrical gloves on the door handle? You have to draw the line somewhere.
Funny you mention a worst case scenario of being barefoot and touching the ground ,as the panels are all mounted about 2 ft off the ground on the trailer. I am constantly sitting down, kneeling or touching the earth with my hands scooting around while doing things on various parts of the panel trailer. At this point its not totally up and running , but soon it will be., but I still disconnect the series wires between panels to reduce it to single 20 voc level When doing certain type work on the array. I also cover the whole thing with a piece of Astro turf or cardboard stuff Sometimes .
There are two trailers , one trailer is full of panels and the enclosed trailer one is full of the equipment..

as far as getting in the rv , I have for 6/years used mostly shore power at different places and never had a concern or problem . I have used a couple of different type inverter gen sets ( floating neutral) with no problems for weeks at a time ... I have tested it for hot skin a few times … no issues… the new system on the two trailers will be bonded and grounded and tied together but will be totally separated from the rv except for the shore connection to the equipment trailer.
I guess I will find out if I need gloves to get in the rv … then I will have to figure what’s wrong…

I do not like sharks.. and I really don’t like electricity either… as they are both silent and sneaky…I solved the shark problem by moving off the boat to the mountains , but the electrical issue remains

Jim.
 

73powerstroke

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Yes, but it means also another league in regulations.
Above 48V, you shouldn't fiddle yourself, if you expect your Insurance to take over fire damages.
And you may be badly injured as well. DC is much more harmful than AC.
I work on old tube radios. I've felt the shock of 900v dc plate voltage. Nasty white marks on finger. Chest muscle pain. Dc sucks
 

dianea

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I had a few retired Exide 12KVA and 8KVA UPS supplies, both 240 volt lead acid banks, expired, but still functional. Over the months at high load, a single battery would open from depleted electrolytes and fuse itself under load. The smell.

I would like to see high voltage battery banks, but my close up experience with arc flash from 480 volt 300 horsepower drives that had no massive quantities of electrolyte in one area... the thought of high voltage venting batteries flashing on fire is terrifyingly pyrotechnic on a grand scale and nightmare fuel...
 

JBertok

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These types of UPS/Alarm SLA batteries only have a life of about 5 years, and the clock starts ticking as soon as they're born. Regardless of sitting on a shelf, or being actively maintained at a full charge, they just do not last. In the 20+ years of maintaining all types of APC/etc. Uninterruptible Power Supplies for computers, I always opt for the lower Ah cells (~6Ah) of the same form factor when I replace these since they hold up a little better. The higher capacity SLA (~9Ah) batteries seem to have thinner grids and less longevity and durability in favor of that higher capacity, so the higher Ah ones live even less. When one of these in a string gets degraded beyond serviceability, its internal resistance increases, it gets hot, distorts its housing, and can even outgas the familiar aroma of sulfur. You don't have to worry about them shorting or exploding though, so there is that! Temperature is the easiest degradation telltale to detect. Whatever your plans are, I would not make much of an investment in utilizing them long-term.
 

MrThisIsME

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Soooo jealous, I too have a UPS fetish. Seriously I am considering changing careers to be a sales manager for a UPS distributor in the Houston area. Will give me access to older equipment removed from customer sites.
Dear UPS fetish boy. You will love this story then:

I work in large data centers. Years ago one data center I was affiliated with had older APC UPS' rated at ~85% efficiency in an N+1 configuration. They were slated to be replaced with more efficient, I think 92% UPS'. Three months before the install day, one UPS had a bad controller and overcharged all 256 110Ah AGM batteries. Those bad batteries came out and new batteries went in to keep redundancy for the 3 months remaining.

Three months later the new UPS's went in. Where do you think a good majority of those 256 - 3 month old batteries went to. :)
 
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