| General > General Technical Chat |
| Health and Safety - Battery Banks - Lithium et al |
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| robint:
Doubtless most EEVbloggers will be familiar with Andy (certainly in Offgridder DIY solar power circles) https://www.youtube.com/@OffGridGarageAustralia Not in any way to disrespect the tremendous work he has done on Solar batteries etc over 3-4 years. Truly a dedicated proponent of this new technology. My point of concern is that he makes it so well presented that it may attract many amateur DIY wannabe off gridders who may have only elementary grasp of electrical fundamentsl. I daresay that meany here will admit to a limited experience of ELV high dc current systems. It certainly woke my own ideas up as I never had need to venture into that specialised area of Electrical Engineering. So Andy is now encouraging all these followers into this potentially hazardous area. Fortunately the Cousins are ahead of most as they have a very large community of time served off gridders and their own NEC 2020 has now come into force to lay down codes and safe practices :-+ :-+. Same goes for the Yachties - hello Sailor - who have their own code of practice for Marine environments and also a long traditional with LAB storage batteries and ELV electrical installations ABYC codes A31 Even Andy's own garage is nowhere near code compliant - no outside firemans breaker switch and primary main fuse for example etc for his 100 + kWh stored energy rig. ABYC owners had to be compliant or they wouldnt get insurance cover for their floating assets. Off gridders put their solar gear into a shed a good way away from the main house - and the shed and kit probably isnt insurable (what do the neighbours think?) I am simply pointing out here that we are tacitly accepting the situation on YT where the "kids are being encouraged to play with matches" Andy hasnt responded about my warning sounds, and he still meddles with lives circuits, open busbars etc WITHOUT WEARING GOGGLES - :palm: Even the professionals get it wrong https://fsri.org/research-update/report-four-firefighters-injured-lithium-ion-battery-energy-storage-system OBTW all the codes and regulations are fine till you go out and try and source suitable gear to fit your splendid set of roof panels (the salesman sold you). What the industry doesnt tell, is how much extra kit you need to hook these panels properly up to a storage and inverter installation (before you even considered selling it to the Utility Company). They have a proprietary system under government grant in OZ but AFAIK it just covers panels and c/o switchgear to the house circuit - no storage batteries involved - in fact against the terms of contract- I think. Andy knows Trying to find dc rated gear for switches, contactors, fuse links, isolators, breakers - it all appears to me as rampant quackery carpetbagging |
| AVGresponding:
Not really, it's more because there's no 100/120Hz zero crossing point like there is in AC systems to help you disconnect and extinguish the arc, so DC protection gear has to be more robust for a given current/voltage. |
| robint:
--- Quote from: AVGresponding on November 13, 2023, 12:55:53 pm ---Not really, it's more because there's no 100/120Hz zero crossing point like there is in AC systems to help you disconnect and extinguish the arc, so DC protection gear has to be more robust for a given current/voltage. --- End quote --- You will find listing for switchgear (from PRC) under the solar power bandwagon rated 63A mains voltage - and higher. Are you suggesting DIY enthusiasts apply a factor of safety? What should it be, HOW MUCH MORE ROBUST? eg 2:1 (32Adc) 4:1 (16Adc) 10:1 (6Adc) or do not use. What is safe to use under a) Isolation but can carry full load A b) Breaking Full load A at max voltage c) Withstanding fault current spike - without contact welding Reputable Manufacturers give these ratings for ac often supported by independent Authorities like UL. They even sometimes give dc ratings derated by a significant amount Are there reliable products on the market to meet the Solar power needs at a price he is willing to pay (industrial product may cost more that the Panel installation)? What do they do in EVs? Given high dc volts (50kW @ 400V in a public charging station). What circuit protection devices do they use - actual practice - not speculation pls. :scared: |
| AVGresponding:
--- Quote from: robint on November 13, 2023, 02:58:08 pm --- --- Quote from: AVGresponding on November 13, 2023, 12:55:53 pm ---Not really, it's more because there's no 100/120Hz zero crossing point like there is in AC systems to help you disconnect and extinguish the arc, so DC protection gear has to be more robust for a given current/voltage. --- End quote --- You will find listing for switchgear (from PRC) under the solar power bandwagon rated 63A mains voltage - and higher. Are you suggesting DIY enthusiasts apply a factor of safety? What should it be, HOW MUCH MORE ROBUST? eg 2:1 (32Adc) 4:1 (16Adc) 10:1 (6Adc) or do not use. What is safe to use under a) Isolation but can carry full load A b) Breaking Full load A at max voltage c) Withstanding fault current spike - without contact welding Reputable Manufacturers give these ratings for ac often supported by independent Authorities like UL. They even sometimes give dc ratings derated by a significant amount Are there reliable products on the market to meet the Solar power needs at a price he is willing to pay (industrial product may cost more that the Panel installation)? What do they do in EVs? Given high dc volts (50kW @ 400V in a public charging station). What circuit protection devices do they use - actual practice - not speculation pls. :scared: --- End quote --- I'd use something locally certified, it certainly looks like a problem though. The short answer is the stuff is available, but might be more expensive than you'd like. As for EVs, idk, you'd have to employ the services of your favourite search engine for that. I'm going to speculate that it's a combination of HBC fuses in the battery pack, and isolation of the AC supply to the charger rather than trying to break the DC when the AC supply is still on. |
| robint:
OK try and suggest a UK/EU available lockable isolator, circuit breaker and separate fuse link for 63A dc @ 48Vdc working @5kAdc min fault condition :-// As for EV's the industry it is very coy about revealing safety details and (quite rightly) seeks to keep meddling DIY car owners well away from lethal 400Vdc battery systems. Is there a Fireman's switch, master isolator on an EV? We have seen many spectacular fires when these EVs go ape. Firemen can only stand and let it burnt hour for 8 hours and stop the fire spreading to other property Notice our ICE cars have large energy storage fuel tanks. Fault conditions with those are mercifully few and Firemen know how to handle that situation. |
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