House burned down

[Made in North Pole]

Oooh, I know this one: Both!

If you are trying to disconnect 50VDC on a 500A fault, a 200A contactor will weld the contacts as it tries to open. For either you need sufficient protection in fusing as well as isolation. That isn't to say a contactor isn't better than a fuse-- just that they serve different purposes. The both are great for interrupting their rated current at ]rated voltage for rated number of cycles. Unfortunately too much CYA.

FET, not fuse. By the way, my point is about which is more reliable between FET and contactor when there is a fault current.

 

[yabert]

FET, not fuse. By the way, my point is about which is more reliable between FET and contactor when there is a fault current.

Based on EV batteries from different manufacturers, FET is not an option for high current.
Contactors are always inside EV battery.

 

[_voltmeter_]

Wires are sized for the load so fuses are load based on the wires

i can have a load that is rated 100a and a wire rated for 300a. the wire has to be fused with 300a or less
fuses are not for appliance protection and of course not for battery protection

i dont care what victron wants, i write about the facts.

Contactors are always inside EV battery.

contactors can also fail, a damaged coil or welded contact because of the high current at disconnect...
you can say "but they are build for that" also mosfets bms are.

 

[upnorthandpersonal]

fuses are not for appliance protection

Semiconductor fuses are specifically for device protection.

Semiconductor Fuse | Fuses Unlimited

Semiconductor Fuse

www.fusesunlimited.com

 

[_voltmeter_]

Semiconductor fuses are specifically for device protection.

this thread is about a burned paralel connected battery. there is no device or battery protection with this method possible.
those fuses only protect the wiring.

always use a bms per bank that can disconnect it.
this is the protection, if this rule is ignored bad things happen as we can see

 

[42OhmsPA]

Same issue as my current one - it depends on an app from what I can tell. And I don't want to buy a new phone because it won't work with the old one or they stop supporting the app on the android version I am on.

My old phone is android 10 and the FLIR product app only works on 11 and up. I am trying to root the phone and force the upgrade to 12, but it isn't working verywell.

Once it works I just wouldn't upgrade or change anything on the phone, but as I see it that will be a common problem with all the phone type ones.

Reminds me of an old MP3 player I have - it just plays MP3 or media player play lists..... of course that is fine for music but I listen to audio books and they tend to DRM protect them all... I can export/import/strip that then put it on the player but it uses a non-standard connector and the cable is a distant memory. So it works, but it is useless.

Fwiw the Uni-T works fine for me on Android 10. I haven't /won't update because I've read oxygen os is crappy on 11.
I sometimes miss my days of rooting and flashing nightly builds but the solar addiction is much more rewarding.

 

[ScrotpusGobbleBottom]

Semiconductor fuses are specifically for device protection.

Oh my! You spittin fire! Not sure many here know much about surface mount fuses on pcb boards....aka no wires
Im gona get in trouble with you.

 

[billvon]

Based on EV batteries from different manufacturers, FET is not an option for high current.

90% of existing high current BMSes use FETs to disconnect power.

 

[Shimmy]

FET, not fuse. By the way, my point is about which is more reliable between FET and contactor when there is a fault current.

Neither a FET nor a contactor can reliably interrupt current beyond ~200% of their rating. Yes, a contactor is better, but the two important things to remember are that some kind of protection by the BMS, and some kind of protection for a catastrophic failure of the BMS are required when running more than 3 strings in parallel. Once you get over 5-6 strings that can be challenging.

 

[Lighthouse Beacon]

this thread is about a burned paralel connected battery. there is no device or battery protection with this method possible.
those fuses only protect the wiring.

always use a bms per bank that can disconnect it.
this is the protection, if this rule is ignored bad things happen as we can see

I think this has alot of truth

 

[NX0E]

Thank you for sharing this painful experience.
So long as no one was hurt, at least it is only money and memories.

Hope we get to hear about insurance outcome, if applicable.


Mega fuse is rated for 2000 AIC at 32V.

https://www.littelfuse.com/~/media/automotive/datasheets/fuses/passenger-car-and-commercial-vehicle/bolt-down-fuses/littelfuse_mega_datasheet.pdf

What are the specs of the battery bank?

Obviously if 48V not 24V, exceeds rating of fuse.
If 100 Ah or larger LiFePO4, my estimate (based on reports of measured internal resistance) is 20,000 but actual output could be less.
Based on those figures, I think Class-T (125VDC, 20,000AIC) is appropriate, or higher like 50K AIC for some fuses or breakers.

Good to put them in an outbuilding. We know that is advisable for the more hazardous chemistries, but most people here have felt comfortable with LiFePO4 in their house or vehicle. NEC does allow UL listed ESS in or on a dwelling, but not directly in occupied rooms. Rather a closet or garage, with fire or smoke detector.

If a LiFePO battery catches fires, is there a good way to extinguish them? I've seen videos of burning EVs and it seems that most of them are just left to burn out.

 

[Lighthouse Beacon]

90% of existing high current BMSes use FETs to disconnect power.

Neither a FET nor a contactor can reliably interrupt current beyond ~200% of their rating. Yes, a contactor is better, but the two important things to remember are that some kind of protection by the BMS, and some kind of protection for a catastrophic failure of the BMS are required when running more than 3 strings in parallel. Once you get over 5-6 strings that can be challenging

So just out of curiosity I contacted Sungold Power to ask them what they required for fusing between each of my wall batteries and they stated:


Now I know this is Sungold… and you can’t really take what they say to the bank… but the FET and relay protection you guys are talking about.. is that what he’s referring to when he says “short circuit” protection? I have heard these batteries “click” and disconnect when the BMS reaches a FULL or OVP status. Do these batteries have the ability to disconnect from their own internal buss? Is that what the relay in a BMS does? Or is that disconnect charge leads only

 

[yabert]

90% of existing high current BMSes use FETs to disconnect power.

90% of the BMS you know from DIY world.
In EV OEM world BMS use contactor... so 14 millions BMS inside EV batteries just last year.
So, do you know if there is at least 126 millions high current BMS with FET sold last years?

 

[_voltmeter_]

Not sure many here know much about surface mount fuses on pcb boards....aka no wires

the fuses protect the pcb track
wires are not only round shaped

 

[Zwy]

Neither a FET nor a contactor can reliably interrupt current beyond ~200% of their rating. Yes, a contactor is better, but the two important things to remember are that some kind of protection by the BMS, and some kind of protection for a catastrophic failure of the BMS are required when running more than 3 strings in parallel. Once you get over 5-6 strings that can be challenging.

That is what Class T's are for, regardless of what some think. This subject has been hashed out several times over the years I've been here.

The conclusion is a Class T between each battery in a bank.

It isn't there to protect the wires, it is there to protect the house from burning down.

 

[_voltmeter_]

It isn't there to protect the wires, it is there to protect the house from burning down.

yes it protect the wire form burning your house down
it will not protect your battery.
but you can learn in the next disaster...

is your house or life not worth to spend 450usd for 4x jk bms? or you dont want it because you have already a overpriced useless bms?

 

[Zwy]

yes it protect the wire form burning your house down
it will not protect your battery.
but you can learn in the next disaster...

is your house or life not worth to spend 450usd for 4x jk bms?

I have 6 JK's but those are not for my house.

I'll go back to ignoring you.

 

[_voltmeter_]

I have 6 JK's but those are not for my house.

so i see your house or life is not much worth?

i dont care about someone ignoring me, its about the other reading this and make their own conclusions.

 

[ScrotpusGobbleBottom]

the fuses protect the pcb track

But its called a trace. not. a. wire. yes, same function

 

[robbob2112]

so i see your house or life is not much worth?

i dont care about someone ignoring me, its about the other reading this and make their own conclusions.

Perhaps if you were a bit more tactful you wouldn't rub people the wrong way,... there are ways to express your opinion politely and still get your point across.

"but you can learn in the next disaster."

 

[42OhmsPA]

yes it protect the wire form burning your house down
it will not protect your battery.
but you can learn in the next disaster...

What if someone is using 2/0 wire with 125A fast acting Class Ts and 100A BMS's for multiple (over 5) packs in parallel?
How would that protect the wire and not the battery?

is your house or life not worth to spend 450usd for 4x jk bms?

No, I'd use contactor based JBD's.

or you dont want it because you have already a overpriced useless bms?

How is any BMS overpriced and useless if it does its job?

 

[Lighthouse Beacon]

I would rather take advise from someone who can write in coherent english.
And also would use proper fuses in a proper enclosure.

Well maybe, but that’s not a very nice thing to say

 

[_voltmeter_]

How is any BMS overpriced and useless if it does its job?

look at the first post of the thread

What if someone is using 2/0 wire with 125A fast acting Class Ts and 100A BMS's for multiple (over 5) packs in parallel?
How would that protect the wire and not the battery?

the bms protect the battery not the fuse.
if the charging current of the faulty battery is lower than the trip current of the fuse your battery will burn or explode causing other banks starting fire and your fuse cant do anything about it. only a bms can per paralel bank.

it does not matter how low your fuse is, the charging current can be even lower and overcharge cells over several hours.
a batrium used in first post of this thread cant do anyting in this case. maybe it can make an alarm sound but what if youre not at home.

 

[marionw]

I would suspect that in may cases it is simply a misunderstanding of cultures. I just spent the better part of the last two weeks in communications with SunGoldPower over technical specifications with respect to "open loop" vs "closed loop" communications between batteries and their SunGoldPower 10kw inverter. In every instance they responded to each and every email I sent (yes at least 24 hours delay due to time zones). Each response to my emails reflected courtesy and politeness on their part and I hopefully responded in kind. I suspect that some of the hinderance in our communication was my lack of Chinese and their lack of my somewhat "English" vernacular. In the end they answered my questions. Patience, courtesy and respect will ultimately win the day for all concerned.

 

[Lighthouse Beacon]

I would suspect that in may cases it is simply a misunderstanding of cultures. I just spent the better part of the last two weeks in communications with SunGoldPower over technical specifications with respect to "open loop" vs "closed loop" communications between batteries and their SunGoldPower 10kw inverter. In every instance they responded to each and every email I sent (yes at least 24 hours delay due to time zones). Each response to my emails reflected courtesy and politeness on their part and I hopefully responded in kind. I suspect that some of the hinderance in our communication was my lack of Chinese and their lack of my somewhat "English" vernacular. In the end they answered my questions. Patience, courtesy and respect will ultimately win the day for all concerned.

well said