House burned down

[Made in North Pole]

because you need one BMS per bank, it may be that a cell on one bank gets a short circuit or simply slowly discharges towards 0V due to dentriden. if so, the other banks charge the remaining cells of the defective bank above 3.65V, it doesn't have to be such high currents, it already smells like 20A per bank, with 6 banks that's 120A so approx. 6kW that have to go somewhere.... you can't solve something like this with a fuse. each bank needs a BMS that is set as low as possible with the charging/discharging power. I have fused my banks with 100A and limited the respective BMS to 50A power, which is enough for 3x Multiplus 2 3000

Are you aware Batrius is not exactly 1 BMS for multiple parallel banks?
There is a supervisor: Watchmon Core.
There are K9s: The actual BMS.
For instance, If you have six parallel banks, you need six K9s and one Watchmon Core. The six K9s talk to the supervisor over CAN, reporting battery parameters.
This BMS design uses contractors to control the system. You can have contactors between each bank so you can disconnect the faulty bank in a critical event. There is no chance any cell can be charged over 3.65V except when your contactors fail closed.
Which do you think has the higher chance of failing closed? FET or NO contactor?

 

[bobcov]

The fuse picture i posted was just an answer to the "what is a meltfuse" question.
The exact fuse was a mega 48v, 300 A.

The insurance is no problem.

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.

 

[Shimmy]

Which do you think may fail closed? FET or NO contactor?

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.

 

[D71]

Interesting think read Tesla 3 phase is Europe and OVER SEAS only. No USA.

~Specs home level II
USA Tesla split phase charging ~32a * 240V = ~ 7.68kW

~Specs home
Europe Tesla charging ~16A * 3 phase * 230V = ~ 11kW.

 

[Gold Country Russ]

@D71 Did you account for 3 phase? 16A X 230V X 1.73 (3-ph) =6,366W = 6.37KW

 

[bobcov]

Google is investigating this btw

My guess is the alarm thought it was a meter of steam. I hope this fail is reported and the Nest folks are able to correct what clearly went wrong.
"Nest Protect is the only alarm with Steam Check. It uses custom algorithms and a humidity sensor to look for steam" I think I'll take a hard pass on Nest "protection."

 

[bobcov]

Google is investigating this btw

If you are in the US, the Federal Trade Commission would also like to know about this. But for the fortunate waking of your son, this equipment failure was headed to fatalities. There needs to be a recall here.

 

[bobcov]

We may never know, but I see a lot of sloppy heat shrink on/under some of these lugs.

Ah, from the comfort of our armchairs, we are all fire investigation experts.

 

[Gold Country Russ]

I just ordered an EP Cube system w/39.2KWH battery. The plan was to mount on outside of house, but I just decided to do it even better. I was going to anchor on a new slab with steady brackets to house. Instead, I will prefabricate steel strut structure and imbed it in the cement. A gap and zero contact with the house are perfect. Having zero DC PV power on/in the house might be helpful with insurance long term, for peace of mind, priceless.

 

[bobcov]

Guys, please, yall looking at things way too far. The shelves were fine, the fire fighters have torn everything apart to drag all the cells outside. I dont even know what is being discussed here.

Don't stress too much. People love to solve a riddle whether it be a crime, a plane crash or a house fire. And every last one of us feels entitled to be an expert in the process. I see the same thing, but 10 x worse, on AVherald.com where every single person completes the aircraft crash analysis and offers a final report before the embers even cool. Your transparency and data sharing has been invaluable and has and will continue to provide many with excellent insights.

 

[moon]

@D71 Did you account for 3 phase? 16A X 230V X 1.73 (3-ph) =6,366W = 6.37KW

Here in Europe has a 3 Phase System 400V. Single Phase is 230V.

 

[D71]

@D71 Did you account for 3 phase? 16A X 230V X 1.73 (3-ph) =6,366W = 6.37KW

I threw it online calculator
i knew the 3 phase in Europe are advertised as 11kW right before posting.

Put in delta vs wye

These are wye applications

 

[D71]

Here in Europe has a 3 Phase System 400V. Single Phase is 230V.

The OP Victron inverters are 230vac units for his 3 phase configuration

 

[740GLE]

The OP Victron inverters are 230vac units for his 3 phase configuration

When connecting 3 230v (L-N) inverters in a wye configuration you get 400v when measuring L-L.

So it’s the same thing it’s just in how you are measuring between phases or phase and neutral.

 

[Gold Country Russ]

I threw it online calculator
i knew the 3 phase in Europe are advertised as 11kW right before posting.

Put in delta vs wye

These are wye applications
View attachment 215733
View attachment 215732
View attachment 215735

Same math different voltage so, 16A X 400V X 1.73 =11.072 so, math good & data bad.

 

[Q-Dog]

Ah, from the comfort of our armchairs, we are all fire investigation experts.

Show me where I am wrong. It is careless work and in a later post the OP says he had to fix that. I don't know of any inspector that would pass it.

In a thread about someone losing their house, on a DIY forum no less, I would feel somewhat negligent if I didn't comment on the sloppy work, lest someone see it and get the idea that it is somehow OK to be so careless.

 

[Brucey]

Are you aware Batrius is not exactly 1 BMS for multiple parallel banks?
There is a supervisor: Watchmon Core.
There are K9s: The actual BMS.
For instance, If you have six parallel banks, you need six K9s and one Watchmon Core. The six K9s talk to the supervisor over CAN, reporting battery parameters.
This BMS design uses contractors to control the system. You can have contactors between each bank so you can disconnect the faulty bank in a critical event. There is no chance any cell can be charged over 3.65V except when your contactors fail closed.
Which do you think may fail closed? FET or NO contactor?

Yes, Batrium would recommend a contactor per string. In the OPs case he chose to use one single contactor, beyond the seven mega fuses.

 

[Brucey]

Honestly, I had 5 of the 58V-rated ones (clear package) and I thought they were fine, until this House Burned Down thread.
The OP appeared to have them, so I upgraded to the 70v MEGA.
2.5 kA AIC at 70v (littelfuse sf51) is better than 1 kA AIC at 58v (littelfuse bf2)

I would never use MEGA for a battery, just for inverters and MPPTs.

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:

 

[42OhmsPA]

@Jejochen i hope the recovery and rebuild is going well.

 

[ricardocello]

When you compare with a Victron megafuse holder:

I’m using this one for my Positive Busbar.
I would have gotten Lynx if I had known about them.