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diy solar

House burned down

That is great to hear that the insurance company actually does what they are supposed to do. What brand? Your experience is a good endorsement and counter to the usual horror stories.


He is in Belgium so they may have greater protect for consumers than in the US.

Here they would pay for the fire, add a surcharge if it was negligence then cancel your policy once you were done rebuilding.

I'm more concerned about his fuse holder setup. What is the backer they are attached to? I've also seen mention that "Victron recommends this fuse". Well, yes, but you also have to look at how they are installed.

When you compare with a Victron megafuse holder:

View attachment 215746

View attachment 215747

His fuse holders were red, flame resistant and had covers to seal them up. Not much different than the Victron version. There is one picture with part of them with covers on.

Not sure if they had the interlock or not, but were mounted side by side.

The backer appears to be OSB or equivalent - so not ideal, but many people are using similar - so common practice even though it could be a factor.

We will never know for sure -

I choose to believe a shorted cell vented and blew the fuse then caused an arc and set off the vent gasses.
contributor was the single contactor verse 7 IMO and Mega verse class T or other arc supressing fuse.

From the math a couple of us did the temperature of the wire connecting the fuses may have been high enough to melt the sheath off, temp rise in under a second to over 200c.
 
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Check out Uni-T.
I've been happy with this one I ordered back in November, no issues on my Oneplus 6T. App isn't invasive like many others I looked at. They also have some nice standalone.
View attachment 215660
Resolution isn't as good as the FLIR pro, it's much nicer than the regular FLIR I use at work with an iPhone.

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.
 
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.
 
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.
 
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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
 
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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.
 
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.
 
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
 
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.




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.
 
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:
D52D9FEF-C73F-4B69-B17C-A7716BE898C7.jpeg

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



CA41455A-0788-4310-A61D-65A40E3A3C57.jpeg
 
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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?
 
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.
 
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?
 
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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. :)
 
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