Lithium Batteries - HRC Fuses, Short-Circuit Current, and Interrupt Ratings

[@benssolarandbattery]

Good to see someone going over this. I think we talked about it a while back when I was first building my Smart ForTwo pack. It's definitely very important, and something that most people won't know if they screw it up... until it's too late.

[@LithiumSolar]

Exactly. Fuses are one of those things you don't even know might be wrong until something goes wrong!

[@TheFlow2006]

18:01 theres a sign on these nh00 fuses which says "vde" if thats on it it is tested in germany by the vde wich is the same as the ul or even better, believe me there a hundreds of rules for electricians here in germany and everything is writtendown in the vde- norm

[@ikke12315]

true, just wanted to say the same thing after watching

[@yancymuu4977]

It's good to consider the resistance of the fuse in determining the max short circuit current. For example I have shorted a 10 amp glass fuse measured at .02 ohms across an 8 cell (28 volt) 200ah lion battery. The maximum calculated current is 28/.02 or 1400 amps. Using a scope across a .00075 ohm shunt resistor in series I measured a voltage that indicates approximately 900 amps. The fuse successfully broke the circuit. Thank you for the great instructional video. Note, I have purchased some name brand higher capacity fuses from Amazon that turned out to be counterfeit. This was detected by measuring the resistance of the fuse and comparing to mfg data sheet.

[@RobinRastle]

That sure is a concern - fake fuses, you didnt say whether they had higher or lower resistance than mfg spec. Of course the temptation is to put a higher (piece of thick wire inside the cartridge, how would you know until after disaster?

[@yancymuu4977]

Is have been a while but I believe it was 1 1/2 to 2x mfg spec.@@RobinRastle

[@a2cryss]

The class T fuse has so many tabs inside because it is a bunch of parallel little fuses put together in what looks like a 2S18P arrangement. It helps to be more precise than 1 big fuse and generates less heat to blow. It can also have a few elements blow without failure during instantaneous near-rating transient spikes. This is the same style fuse used on EV batteries (I have seen a blown one on a Model S and it was a much larger version). Kudos for making this video explaining them and their use cases.

[@chipmeister111]

Thank you for the education. I'm looking for a class T fuse for my solar and I now know a whole lot more than I had 20 minutes ago.

[@toochi84]

Great explaining of the fault current capabilities of lithium cells and why proper system fusing is important

[@LithiumSolar]

Thanks man, and thank you everything you bring to the community as well! 18650shrinkandcellholders.com/

[@Shadowmaster625]

Unfortunately this is not even close to a proper explanation of system fusing. What makes these battery packs so dangerous is that there is no way to predict the amount of current that can flow when there is a short. If you have a 350 amp fuse, it is possible that only 300 amps will flow, and that amount of amperage is still enough to lead to a catastrophic failure despite not blowing a fuse.

[@LithiumSolar]

@@Shadowmaster625 If your wiring can't handle 300A then why are you using a 350A fuse? You didn't select the proper size fuse for your application.

[@doglabdogtraining-gus.8873]

I just changed all my fuses in my teska battery pack because of you , thank you so much

[@fisherus]

Great timing of this video for me to reassure I fused my LTO battery bank correctly. Another great producer of KZbin videos suggested this to me after wiring each of my 15 LTO batteries individually to separate 20 amp automatic fuses inside a fuse box making a buss bar from the box. Then connected to 4/0 wire to the large fuse and then to my charger/inverter. This gives me an automatic 20amp fuse for each battery and a master fuse for my battery bank.

[@yannikubben2043]

The NH Fuses are used as Main Breakers for Houses here where i live in Germany. Which means they're they are able to interrupt short cicuit currents of 20 kA at 400V in Typical hous instalations here. The typical raiting is 63A. They were also used to deliever power to entire streets blocks, then they have 1000A or higher raitings....

[@AQUATICSLIVE]

Thanks for taking the time to explain fuses. A bit of a dry subject matter but needed to be said.

[@honumoorea873]

The knife fuse do not have a 25A interuptible curent... But 25000..A

[@AveRage_Joe]

EXCELLENT Video!!! Best explanation for the difference in main battery fuses Ive seen! You should do a video explaining how to size your main fuse/fuses as Ive seen just as many doing that improperly as well!!!👍👍👍💥💥💥💥💥💥💥💥💥

[@LithiumSolar]

Thanks for watching!! :)

[@frankz1125]

Your meter should have a max min button. It will show the actual max inrush. Great video

[@LithiumSolar]

It overloads that too lol. I need to see if I can find a clamp meter with higher ratings for these kinds of tests.

[@frankz1125]

@@LithiumSolar May have to make one with a shunt setup

[@LithiumSolar]

@@frankz1125 I retested the LG cell with the meter in inrush mode and got 118A. Thanks for the idea! :)

[@clarencewiles963]

10,000 at a boys = one oh shit. You only get 1 chance at a first impression. Thanks for going through this. What’s in a name!

[@hondaredrdr]

Great video! I never knew what the point of HRC fuses was until know. Thanks

[@Frooonti]

About the Siemens fuses and the missing UL certification: Since Siemens is a German brand and the fuses are not actively being sold in the US they simply didn't apply for one. They are however built and tested according to IEC specifications. And have certifications that are relevant/mandatory in Europe (e. g. by KEMA).

[@LithiumSolar]

Thanks for the explanation, makes perfect sense! I see the particular fuse I have does carry a KEMA certification. I also see a VDE certification. Would it be safe to say that both of those are similar to the UL certification in the United States thus indicating a high level of quality and safety?

[@Frooonti]

@@LithiumSolar All electronics sold in Europe have a CE marking, which indicates that it is conform to European standards (not to be confused with the "China export" logo which looks almost identical for totally not malicious reasons). It's kinda like the FCC marking. VDE is similar to UL, so an independent association which (among other things) certifies the safety and quality of electronics based on norms and standards. I don't know too much about KEMA, but it is primarily owned by electricity providers so in the case of fuses and other power grid equipment they probably are a pretty good certification to have.

[@testtester5653]

the Siemens fuses are not suitable for DC! A DC-arc inside the fuse during a short wouldn’t be extinguished in the same way than an AC-arc would. AC goes through 0V and self-extinguish an arc.

[@tscheckofify]

​@@testtester5653 You are right, not all NH-Fuses are rated for DC. But in this case the Siemens 3NA3810 is rated for 500V AC and 250V DC with an interrupt current of 120kA AC and 25kA DC. I would definitely recommend these.

[@kennethalmond8922]

Interesting topic. A larger DIY powerwall pack should have fuse wire on each cell that (in many cases) will burn thru below 35a/cell which will affect the overall max short amps of a pack. A cell may produce 35a but if the fuse wire burns thru at 5a (and you've verified this) then it seem like a 100p * 5a = 500a might be a better metric that 100p * 35a. The axial glass fuses are even more precise than fuse wire. So it seems like individual cell fusing could bring this topic to lower levels of max amp per 100p pack. What do you think?

[@kevinh7985]

Thanks for this very informative video. Once again it has shown me another great example of my not knowing what I did not know. I will now review in greater detail how I have fused my two 280 EV 4S2P batteries on my boat. I did use a 300 A t type fuse however I haven’t really every looked into or understood the issue of a fuse arcing. So I will also have a detailed review of all of my recent upgrade projects on the boat. Cheers Kevin H

[@diydan6045]

Perfect timing, I'm building 3 20p 16s packs to be in parallel. What would be a good size fuse for a 66 amp battery pack? Thanks for the video.

[@LithiumSolar]

Fuses are typically derated to 80% and would be sized based on your maximum load. If you have an inverter that you plan to pull 66A under max load, your fuse should be 66A * 1.25 = 82.5A. You won't find an 82.5A fuse on the market, so you round up to the next commonly-available size. That would probably be a 90A or 100A.

[@BobboNaught-YT]

Thanks for the test. If you want to capture the burst of amperage with your meter, manually set the range to the highest and it shouldn't overload.

[@DavidPozEnergy]

Awesome video.

[@dillonmccormick2511]

A link to the little fuses and fuse holders for them would be awesome. Thank you.

[@myevhobby7864]

Good content! For the nissan cell, or any other cell, you can calculate max shortcircuit current from the inner resistance of the cell.

[@blackterminal]

How do I find out the short circuit of my Chevy volt gen 1 cells? I need to find two fuses for my 36cells X2 in Parallel. It's supposed to suit 30 to 40 percent overload rated over the max listed overload but i cant find any data.

[@TheGrimshaw]

Yes this video was very helpful, I know now that my system needs a fuse overhaul.

[@smacospasovski5123]

Y re great.Im learning half understood half not but I'll put fuses not to burn my 🏠 down.Will watch all your videos.keep them coming

[@ForwardGuidance]

I'm a little confused when at 5:32 you say "when a short circuit occurs if less than 1000AMPs flows through here, it is guaranteed to break it.... if 1001AMPs flows, it will arc and could cause a fire". Does it blow at 1, 2, 3, 4 ... etc. AMPs too, because that's less than 1000? The way I've always thought about fuses, is if it is a 50AMP fuse, it blows when more than 50AMPs flows through it. Using my 50AMP example and assuming I'm right about it blowing greater than 50AMPs, you are saying fuses have another rating, the interrupt rating as in if the interrupt rating is exceeded, an arc could form at AMPs above the interrupt rating? Is there more to a fuse than the usual 10, 15, 20, 30 label that we usually see on a fuses or circuit breaker? That red automotive fuse, how many AMPs can flow through it so that it won't blow and won't arc. Interesting video, I like when these less talked about topics are covered. Thanks.

[@ForwardGuidance]

Anyone have an answer to this? I would appreciate more understanding. Thanks.

[@dhalifax562]

EXCELLENT question! I've always wondered the same. I hope someone answers.

[@ForwardGuidance]

conFUSED. lol

[@LithiumSolar]

Yes, you need to look at the interrupt rating. That's was what this video was about lol :) If you have a 50A fuse with an interrupt rating of 5000A, it's going to either melt, blow up, or catch fire if you put 100000A through it during a short circuit fault.

[@greg23842384]

I was thinking to use anl or midi fuse without casing and some spring load mechanisms so if the fuse blow cable would be pulled away thus preventing arc from forming.

[@lnxpro]

So how do you tell when one of those ceramic fuses is blown? Other than no voltage output, checking continuity etc, but only by a quick glance there may be no visual indication if the fuse blew quickly and didn't get hot to leave any sort of visual marks.

[@LithiumSolar]

There likely wouldn't be any visual indicators. You would know there's a problem when your equipment stops working and would have to use a multimeter across the fuse and see it's open.

[@mrtechie6810]

Could you explain how to choose between the Class T fuse and the HRC fuse like NT00? For the main fuse of a lithium battery, feeding an inverter.

[@bradfordpalmer2298]

Very good info to know while manning my system.

[@ErikRave]

More videos like these please 😊 Can you show a scheme of the wiring/fuses perhaps? Do you also have experience with megafuses from victron?

[@LithiumSolar]

No, I have not used, or looked at on a technial level, any of the fuses Victron uses. Theirs have a higher voltage rating I know, not sure if there's something unique about them or they just spent the time/money having them tested under different conditions.

[@offgriddreaming5403]

Do you use a holder for the class t or just connect to terminals?

[@LithiumSolar]

Yes, they need to be in an appropriately-rated fuse holder. They will get hot during normal operation (especially the higher-rated ones).

[@offgriddreaming5403]

@@LithiumSolar Thanks 👍🏼

[@ferociouspinkbunnywarrior4979]

HOLY CRAP! You managed to completely confuse me and scare the crap out of me at the same time. I found a DIY 24 V, 12 Watt solar kit for my RV with 6 ea 12V x 200W Monocrystal panels that I planned to connect 3S2P for 24 volts DC connected to the 24 vdc 60 Amp MPPT Solar Controller. The kit contains 4 SOK 12V 206 amph LiIOPh batteries that I also planned to connect series/parallel for 24vdc system. Although billed as a complete DIY kit, it is missing some obvious pieces: pm connector box, bms,main battery cutoff, buss bars, and a 24 vacuum to 12vdc converter. Now the kit does come with various sizes and lengths of cables and wiring and 15 Amp inline fuse and fuse kit, MCA, and "fuse and fuse holders ". I had already determined that this would not be nearly enough fuses I planned for more but your video has confused me and convinced me that I don't know enough about it to even try! P.S. Although you spoke against the automotive blade type 12 vdc fuses, since all RV makers use these l must assume they are OK on the 12 vdc load side?

[@chrispfeil6605]

Data sheet was for mini blade fuses but you had full size blade fuses as an example? Interrupt current of full size is likely much higher.

[@LithiumSolar]

That does appear to be the incorrect datasheet for the fuse I was showing. My bad, thanks for pointing that out :) This is the correct datasheet, still 32V @ 1000A IR m.littelfuse.com/~/media/automotive/datasheets/fuses/passenger-car-and-commercial-vehicle/blade-fuses/littelfuse_atof_datasheet.pdf

[@chrispfeil6605]

LithiumSolar good stuff! Cheers.

[@technologicalsingularity1788]

Great video as usual! keep it on man.

[@BobCollins42]

Question: You determined the short circuit current of a representative LiFePO4 cell by (crude) experiment. How would you determine, or estimate, the short circuit current of a 100 A-h prismatic cell? I have recently found a research paper where they showed a plot of current vs time of a short circuit event on a 160 A-h battery. The current peaked at 1080 A and the short circuit lasted 730 ms. A builder is unlikely to configure more than about four of these larger cells in parallel giving a peak short circuit current of 4320 A. There are quite a few fuses which advertise an interrupt rating (IR) that would accommodate this event. Your thoughts?

[@huskypup3489]

Divide the cell voltage by the cell's spec internal resistance. That's the approximate short circuit current. The capacitance of the cell might produce a burst of current in excess of this, but it will be of short duration.

[@brucebugbee6604]

Thanks for this video. Very good safety information. Question: do you install fuses in your balance leads and if so, what kind of fuses do you recommend for balance leads?

[@abubakreleimam897]

Many Thanks. This is a very important video. It contains many many information.

[@mixedmediaartgirl300]

why did the catastrophic fuse blow immediately? i got a new camper and it wasn't plugged in to shore power. i have 3 battleborn lithium batteries, an ic series 2000 inverter where the 300 amp littelfuse popped immediately after turning on the fireplace, then tv. the company is really giving me the run around and i'm actually in a hotel because of it. please tell me why this could have happened so i can make sure when tehy finally service it they actually fix the problem

[@edwardwitek3817]

I have a solar battery bank with four 12V / 115 Ah deep cycle flooded batteries in parallel connected to a 3,000 W pure sine wave inverter. What amp rating / I.R. rating fuse should I use for the positive feed leading to the inverter? Also, what amp rating / I.R. rating fuses should I use on the connections between batteries should one of them short out? Thanks.

[@TheRayDog]

I assume you figured this out by now. But for posterity, the installation manual of the inverter will spec cabling. Probably 4/0 for a 3kW unit. With that, 400A fusing. I'd personally do 125A MRBFs at each battery post. I prefer fusing each battery in a parallel setup rather than the final leg to the inverter.

[@ThanosSustainable]

I would expect the glass fuses to have a much greater interrupt current, since once the wire inside melts, the distance between the contacts is to big to be bridged by a 32V arc.

[@LithiumSolar]

That makes sense, but goes beyond my level of understanding. I suspect with amps in the 10,000+ range, the glass tube would probably just blow up vs the wire melting. That's just my guess though, I'm not going to test it!

[@jimmilstein7166]

@@LithiumSolar Maybe the wire vaporizes into a conductive plasma for an arc.

[@GeneGetman]

This was very helpful! thank you

[@shmuelnaarai677]

Great stuff! I have a blown fuse on a parkside PAP20 A1 battery pack for cordless drill. Could you please suggest a suitable replacement for that unit. The original fuse is on board. Thanks & Regards. Sham.

[@joaoncr]

Thanl you for your video. I am planning on drawing a nominal amperage of 400 amps out of the batteries. Would it be ok to connect fuses in parallel? I cant find 500 amps fuses! Thank u

[@LithiumSolar]

Fuses shouldn't be wired in parallel that way. You can get the Class T fuses larger, but they do get expensive. Mouser has the JLLN I showed in the video for $106 special order www.mouser.com/ProductDetail/Littelfuse/JLLN500X?qs=sGAEpiMZZMuvhwH9hxnX5qjBbeTzrq%2FCphyG3HnGyuA%3D you can also get them on eBay ebay.to/2x3HbGN but Mouser looks like a better deal.

[@mrtechie6810]

That's huge! What are you building? Sounds dangerous. You might want to have an EE inspect your design and implementation.

[@dillonmccormick2511]

Question: I have a 12v 20Ah lithium ion battery pack that I built out of 2200mah LG 18650s from battery hookup. I am not using an inverter as this power bank ONLY power small landscape LEDs. However, I would like to protect my LEDs in the event my battery pack encounters a short circuit. On average the LEDs pull about 12 amps, but I round to 15 to be safe. What fuse/fuse holder should I install between my battery and the load? Thank you so much for all the information you provide.

[@mrtechie6810]

For high current lithium batteries, I suggest a high breaking capacity battery fuse in addition to the breaker. A high current arc is very dangerous...boom!

[@LithiumSolar]

Yes. That was the entire purpose of this video.

[@eksine]

Amg/ mega fuses and Ani fuses are also popular. I bought a 200 amp Ani fuse but the end terminals are so tiny I don't see how they can handle 200 amps

[@omaha42000]

Love the videos. Just wanted to comment that AliExpress and Amazon and eBay are filled with counterfeit products. Just because a fuse has a brand name does not guarantee that you are getting the real thing.

[@tablet4170]

great thanks. plz make one for the various breakers also :)

[@LithiumSolar]

DC breakers are much more complicated since most on the market today are polarized, meaning current can only flow in one direction. On a battery bank, current can flow in both directions, making most of the breakers available inadequate. Many countries are starting to require non-polorized breakers for DC, such as in PV systems, but those available tend to be rather expensive making fuses the better choice :)

[@MarcusMussawar]

you should have a secod fuse ins series for protecting your batteries etc at the max expected system current draw

[@mrtechie6810]

Circuit breaker for that.

[@eksine]

I've seen ANL listed as 6,000 amps on amazon so that spec sheet seems off

[@turbotim9009]

Very helpful video!

[@valchalas]

in case of short in a pack, the max amps are limited by the type and size of cables and connecting nickel strips. usually they are near the nom. amperage of cells

[@huskypup3489]

This is just plain wrong. A 3Ah 18650 cell will deliver at least 25A of short circuit current and the tab stock connecting parallel cells will easily handle that much amperage.

[@ForPropertyInvestors]

Ive got 4s3p, 12V lithium prismatic batteries for RV. 300amp hr total. 3C discharge or 6C surge. I think this is 1800amps total? Im not sure just learning about this! What size fuse should i put in the positive line at the battery 2500watt inverter 5000watts surge line. 4ft wire run at 4AWG inverter line. 1ft, 0 AWG at the battery. BMS is 200amps. Can i use Bussman 300amp Mega fuse or should i use a Class T??

[@harip9159]

HOW TO SELECT THE HRC FUSES FOR DIFFERENT TYPES OF STARTING & DIFFERENT HP MOTORS PLEASE EXPLAIN THE THUMB RULES TO SELECT IN TERMS FLC(FULL LOAD CURRENT)

[@RevoPowerUSA]

Great explanation for the difference in main battery fuses! I consider this is one of the common mistakes that people do when they are going to use a fuse. What happen if someone use a wrong fuse? Can the battery pack catch fire or just it overheat?

[@LithiumSolar]

If the wrong fuse is used, it could melt or arc under a short circuit condition and catch fire. It could also just open and nothing bad happen... You wouldn't notice until a fault actually occurred and it's too late, which is why it's important to use the correct fuse from the start.

[@RevoPowerUSA]

@@LithiumSolar Thanks for your answer! You're right nobody is going to notice.

[@reginaldjones9924]

Hey...I just learned a lot from this video, thanks. But where do you get the fuses and holders? Did not see it at bottom.

[@bradley200711]

i am designing a battery bank with eight 330ah/6volt lead acid deep cycle batteries into a 24 volt system (660ah@24volt). Can someone suggest the HRC fuse I should consider for mid point fusing of each bank? I reviewed DIY Off Grid Solar's video where he used a 300 amp HRC mid point fuse for his battery bank but as demonstrated in this video, the short circuit amps is a critical issue. How is the mid point fusing of the battery bank determined? Thanks, Brad.

[@CarlvanGoens]

are the ABB DC breakers any good for leaf gen 2 modules?

[@LithiumSolar]

I'm not sure what the short-circuit current is of the leaf cells, but here are the datasheets fro the ABB breakers library.e.abb.com/public/475ef3d72a0a249dc1256cbf003cad2f/ITSCE-604050012.pdf some of the ratings go pretty high, even for DC, depending how you have the poles wired.

[@CarlvanGoens]

@@LithiumSolar thank you for the quick reply, I meant Midnite Solar breakers, not ABB in either case, do the same characteristics of fuses count for breakers? or is one better suited than the other is it worth combining them? IE breaker on the positive side & fuse on the negative

[@LithiumSolar]

The Midnite MNEPV breakers are polarized, meaning current can only flow in one direction. They are good for PV combiner boxes but not good for battery banks since current flows both directions at the battery bank (charge one way, discharge the other).

[@mrtechie6810]

I suggest you use a high breaking capacity battery fuse in addition to the breaker. Better safe than sorry!

[@ketas]

about noname fuses, seems like 10*38mm is so cheap for like 30a seen in better multimeters and higher voltage sla upses but then, i would hate myself if it arcs starts fire, and i cheaped out on fuse

[@LithiumSolar]

I would not buy a no-name fuse. There are too many reports of them not blowing and melting instead (potentially starting a fire). If in the US, it's best to stick to something with a UL marking.

[@ThanosSustainable]

That’s why you should always cell-level fuse your packs. Claiming that the cell-level fuses shouldn’t be your first line of Defence, doesn’t cut it; why not only use these, together with the BMS protection, of course?

[@LithiumSolar]

While the cell fuses do work for a dead short of a battery pack, it still should not be the reason a proper fuse is not used. Yes, of course they will work though :)

[@doglabdogtraining-gus.8873]

Any chance you can show a diagram of your system with all fuses circuit breakers? Thank you

[@halfpastnews4999]

If a Lead acid battery circuit develops a SHORT CIRCUIT and the fuse is blown, the fireworks usually stop. Does a lithium battery act the same or---Can they SHORT CIRCUIT internally and keep on burning?

[@LithiumSolar]

Lithium batteries have a significantly lower internal resistance when compared to lead acid. This leads to significantly higher short-circuit current potential. Depending on the size of the battery, the fuse could catch fire or even explode if a dead short were to occur with an improperly-rated fuse.

[@daniellund9854]

Great video 👍 One side note: the Siemens fuses have a short max value of 25kA(25.000) not 25A Keep up the good work 💪

[@LithiumSolar]

I was waiting for someone to catch that. 860 views so far and you were the first :D

[@fmarpt]

Where did you get the siemens 3p holder? Provide link please. Thanks

[@LithiumSolar]

These are the fuse disconnects I'm using ebay.to/2XkyBhL

[@fmarpt]

Can't seem to find information if it is important the direction to connect it, should the handle side go to the battery or the load? Also how did you parallel connected them, separate cables and latter joint, or some kind of copper connection on the fuse holder? Thanks.

[@fortheregm1249]

When you use 2 packs in series the short circuit current is not doubled . thats only the case if the current is so low ( ie a 28AWG wire) that its limited be the resistance of the wire. The max is what you measured at the battery. 2. Why dont you use the "Max" function on your clamp meter to read the max inrush ? because thats the actual current that will create the plasma in short circuits. 3. when a fuse between the batteries "blows" under short circuit, it will still have the FULL voltage of the system across it and can form plasma/arc. so if you have 100 X 1.2volt batteries , if a fuse between the batteries blows it will have 120 volts across it. ( insert BMS/balancer brown alert here ). 4. so the fuse between your batteries can actually arc and current limit and actually render your one good little fuse ineffective. 5. i personally only use one good fuse exactly in the middle of the battery pack and no external fuses. ( yes i know thats not the standard protocol ) ( you also need to protect balancer and bms at this point ). 6. i wouldnt really worry about arcing under 150v dc unless you drive inductive loads.

[@mrtechie6810]

You wouldn't worry about arcing? So what happens if there is a short across the main battery cables? The MCB may vaporize, and arcs form and maintain. Boom!

[@fortheregm1249]

@@mrtechie6810 been a while since i seen this Vid and i forgot what its about, but Arcing is just plasma. in low voltages metals just melt instantly. you need High voltage to ionize and jump across the first gaps in order to maintain plasma/arc. Thats why HID lamps have igniters. thats why your car fuse isnt sand filled but the house fuse is. Even tho the currents are MUCh higher in automotive applications.

[@mrtechie6810]

@@fortheregm1249 Shorting a large lithium battery produces short-circuit currents of *many* thousands of amperes (unlike typical lead-acid car batteries). Such high currents will vaporize/burn the breaker/fuse/assembly. Carbon conducts. Fire (superheated air) IS a plasma. All of which will continue to conduct the fault current. The arc interrupting capacity of the fuse shall be greater than the potential short circuit current of the battery. Short circuiting a large lithium battery could lead to a VERY bad day! That is why large lithium batteries require a class T fuse, in addition to the low breaking capacity circuit breaker that protects the downstream circuit. (BTW In my application, the nominal system voltage is 48V, not a mere 12V.) Even if the circuit breaker has a large AIC, what if it fails? You don't want to risk shorting out a high current source. Hence redundant safety devices. Even if they didn't operate fast enough to prevent your device from being damaged, they are likely to save your life, your batteries from exploding, and your home from burning down!

[@fortheregm1249]

@@mrtechie6810 "many thousands of amperes" My guess is the traces or the mosfets in BMS will just go poof. the BMS itself usually has short circuit protection. I've worked on high energy systems that pull 300Amps. People forget how consistent and expensive connections have to be to actually channel that kind of current . In that 300A system the cost of copper and terminals was higher than everything else. anyways 48v is still no joke, you dont need to worry about plasma, whats gona get you is the wire insulation igniting. I'd defo use a traditional fuse in that setup ( as oppose to resettable ). BTW a car battery has like 700amp CCA. that means 700amp for 30 seconds at -20C while voltage NOT dropping below 7.2v. If you short a car battery it will EASILY give you 5000 Amps ! and no it will not make plasma.

[@fortheregm1249]

@@mrtechie6810 Also when say 5000 amps i mean with proper connection, not two long 18AWG wires accidentally touching, in that case you just get a good smoke show from the wires. 220V in that very same wire will give you plasma for days !

[@fc436]

the short current is determined also by cables. never will reach 2800A a short on 3m 6mmq cable due to voltage drop. for 2800A you need a very big short cable. is more critical the voltage interruption that people ignore. 32v in 48v system

[@yjxu66]

Why circuit breaker (vs fuse) is not preferred?

[@mrtechie6810]

They can't break a very high current arc.

[@dommendoza]

That's good teaching. the breaker trip capacity is 100%? load be for trip or 75%? be for trip. dc battery Blue Sea breaker or Noark brand. I don't know about the dc battery breaker. but ac breaker 75% to 80% load be for trip

[@BATTERY73]

Excellent work sir

[@merlin6404]

hi there grate video i must say thou i was wondering if any one could help me out here i have a 20s (72v nomanel) lipo pack and 300a thou i have spent days trying to find a fuse that would suit this task if any one has any info pleas share

[@ajaychebbi]

Very educative!

[@dannyhunn6025]

The knife style fuses are only used in industrial applications

[@LithiumSolar]

Interesting. That would also explain why they don't seem to be readily-available...

[@tiredofeverythingnew]

Good info thanks for sharing

[@zaeces]

Why not to use dc breaker?

[@merlpriester]

He noted earlier that breakers are usually polarized for for power flowing one way. You would need a non polarized breaker and they are more expensive.

[@RobinRastle]

for higher Amps use more of those cheap ceramic fuses in parallel ie nx30. Thats what the big $$$$ class T super hyped fuse does.

[@huskypup3489]

Why put a fuse on the negative lead too?

[@LithiumSolar]

Because negative is not bonded to ground in a standard DC power system.

[@huskypup3489]

@@LithiumSolar I'm an electrical engineer, and I don't understand your answer. What is the fault scenario that is protected by a fuse in the negative lead?

[@bluedeckelectronics]

Thank you !

[@rvrss7192]

Still not enough. In many applications usual 2C cells aren't sufficiently effective (they'll simply overheat in a large battery under such load) so more powerful cells are being used, with respectively higher short circuit current requirements. I can hardly imagine say ~10kWh battery rated for 2C (as a whole, not just individual cells) in 50-100V range could deal with 20kA interrupting fuse.

[@gonefilming2020]

O.K., watched the video 3 times, read through the comments and still don't get it. I use three 100Ah LiFePO4s in parallel for 300Ah in total to feed a 3KW inverter. All juice cubes have their very own BMS and the battery manufacturer claims, that the BMS will protect the battery from a dead short across the terminals. Trustworthy or not, there is no way that I see, to protect the individual cells within the batteries from a short circuit by any fuse. So a Class T fuse at some rating considering a 20kA current flow can not be applied. Where would I put it? I can just select properly dimensioned cabling between the batteries and inverter based on a 300A current flow and fuse the line right after the battery array with the appropriate 300A fuse. What am I missing here?

[@frankz1125]

I prefer breakers over fuses.

[@LithiumSolar]

Breakers are nice and convenient, but much more expensive. Most of the breakers on the market that carry UL listings/other certifications are polarized, meaning current can only flow in one direction. They are good for PV where current only flows one way, but in a battery bank, it flows both ways. There are non-polarized options available for a price. I believe the new NEC code revisions require non-polarized, but don't quote me on that ;)

[@mrtechie6810]

I suggest a high breaking capacity battery fuse in addition to the breaker. A high current arc is very dangerous...boom!

[@DIYwithBatteries]

18650 Red cells always make an issue and it smells like candy and i got lot of them in scrapped laptops

[@LithiumSolar]

I don't have that problem with mine ;) There are some, but a very low percentage.

[@DIYwithBatteries]

@DIY Projects yeah that's true buddy, some of those r good but the others r so bad and they have very thin heat shrink. Anyway that's good reply.

[@DIYwithBatteries]

@@LithiumSolar yeah sum of those are good 🙂sir.

[@dtvking]

You make some very vailed points but PLEASE, Health and Safety 1st. Holding any battery with bare hands and shorting it out!!! Gloves and full-face mask at a minimum and on a fireproof surface. Secondly, Hacksawing towards your hand which almost fell fail to the blade 2-3 times as the blade snagged. Sorry to poo poo what is a very interesting and worthwhile video but not a good example to others. Thanks

[@LithiumSolar]

Thank you for pointing out the valid safety concerns. It's always good to keep those in mind. I'll take better precautions next time.

[@frankz1125]

I have a bunch of 250A 700 vdc fuses if anyone is interested

[@huskypup3489]

I'm not sure I'd be confident buying these parts from Amazon--I think there's a fair amount of counterfeit product sold there.

[@LithiumSolar]

Best way to reduce the chance of that is to check the seller you're buying from. If the seller is the actual company itself or "Amazon.com" it's probably fine. If unsure, other sites like Mouser will have genuine components.

[@jeoffer]

Are you cracking your knuckles during this video? 8:00

[@LithiumSolar]

It's the cap of the highlighter going on and off lol. Sorry.

[@jeoffer]

@@LithiumSolar All good I was trying to be funny. ;-)

[@jussikankinen9409]

Why print paper and not use ipad its good wiping paper

[@RobinRastle]

Damn Boy - you fell over at 5:08 - glass fuses 32V THATS THE AC RATING NOT DC

[@lnxpro]

BOOM, First!. wait. wrong channel. No boom here. lol.

[@LithiumSolar]

No booms here, must be thinking of AverageJoe? Lol

[@lnxpro]

@@LithiumSolar yeah. lol.

[@Woodyjims-shack]

Sub 👍