House burned down
- Thread starter Jejochen
- Start date
Ampster
Renewable Energy Hobbyist
That is my understanding of how it works and a possible explanation for the source of the fire in the OP's home
OffGridInTheCity
Solar Wizard
In my 18650 powerwall, each cell has fuse wire - which is from Tesla's design for their cars. In my case it's 30awg tinned copper wire - so if an individual cell goes bad -> shorts in a 100p pack the current from the other 99cells burn this this small fuse wire disconnecting that cell from the overall pack so things don't go crazy. As a secondary benefit, if you accidentally short a 100p pack (or overall battery), most of the fuse wires (90%+) will instantly melt pulling the teeth from the pack/battery's destructive potential.
This established a low fire risk 'fusing' strategy for my 18650 powerwall and thus I don't fuse each of the 9 x 14s batteries in parallel that make up the powerwall as it's handled at the cell level.
LifePo4 cells don't have this option as a 280ah cell (for example) is a single unit with pretty good amperage potential during a short. On the other hand, I don't think I've ever read of a LifePo4 cell 'going haywire' except if severely punctured.
However, both LifePo4 and 18650 are not safe from external fire. I presume that external fire caused a LifePo4 to add to the fire and then cascaded to the neighboring cells. The only way I can think of to slow this down would be some kind of compartmentalized battery box.
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Ampster
Renewable Energy Hobbyist
We don't know the exact sequence of events in the case of this thread.
OffGridInTheCity
Solar Wizard
What's running thru my mind these days is...... is secondary damage from flame.
Obviously one should not put at risk items (batteries for example) near something flammable. But one has to think what 'flammable' means - and I didn't do that to a deep enough extent in my propane fueled event. For example, a fuse can cause flame via arcing... and thus, should be contained so the flame cannot reach other items. Same concept as the shed fire reaching the propane bottles.
One practical takeaway for me is that while I have key breakers and bus in a metal "Control Box" I don't have my ABB SACE S3 400a main battery shunt trip in a metal box... it's just exposed. After all this, I plan to buy a metal box for it.
Zwy
Emperor Of Solar
I have mine in a box.
Ran across this thread in a boating forum. https://www.cruisersforum.com/forum...o-break-in-a-catastrophic-event-274602-4.html
On the first page of that thread, there was this post by CaptainRivet:
"Yes in a short or anything >25% above (depending o quality of your BMS, some can +25%, some +100% but that is max) your BMS current rating the mosfets in your BMS will fry closed in 95% of the time leaving your plus connected, negative is always connected.your BMS with fried mosfets will most likely still show you the cell voltages...
By the way the same applies to your inverter/charger, eg Multiplus is also only protected via mosfets on plus, the negative is always connected to be able to monitor and eg remote switch on. This a lot sailors connect directly on the terminal of your battery/bank, with an extra fuse to avoid upgrading cabling and main busbars as its the only bigger source added. So this is now your 2nd main battery and main cable fuse combined and must be therefor Class T or NH too!!!
The BMS (and Multiplus) limits the currents to protect lifespan of your battery and switch loads and charge sources off to peotect it from over- or undercharging.
But these protection capabilities cannot withstand the enormous short curcuit or other catastrophic failure currents that a lifepo4 is creating, a rule of thumb is AH capacity multiplied with 20 gives you the roughly the short curcuit current reached by this bank/battery. So a 100Ah can do 2000A, a 500AH bank already 10000A. That is the job of a fuse, see above what and how to implement.
And you just think about your mosfet based BMS. Their are plenty other out there.
Eg My electrodacus BMS has only 2 shunts on the positive busbar of the bank, nothing else that will cut or protect the installation."
OffGridInTheCity
Solar Wizard
Good observation.
Batrium doesn't have the battery load going thru it but rather let's one trigger external items via low amp relays - such as an ABB SACE shunt-trip coil. There's nothing hi current as part of the Batrium Core w/longmons. Mine is in a plastic box (physical protection) along with the IotaWatt but I think it's OK due to low voltage/current of these electronic units.
If you think about it - there's a reason that 240v/120v AC distribution boxes are metal containers. If a breaker fails or a wire get's loose, the metal box can help contain any shorting/arcing from igniting other stuff outside the box.
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Fuses fail too. Even the best. The damage - fire gets started even after fuses blow sometimes. Think ppl are saying add bms as parallel…to batrium. You are saying class t fuses.
Redundancy is in aviation for safety. Nothing wrong with that. The sub builder that died going to see the Titanic thought he had good enough was good enough figured and built too. He had paying passengers That is the mind set and we must flow to change it when needed. Flexible…Adaptive. The fuses in the OP system appear to been Victron approved. Again Victron approved. He followed Victron manufacturer recommendations. That needs to be stressed. The OP followed advice of manufacturer. Victron won’t change unless sued and forced. That is unfortunate. If they change from law suit then might go out of business with follow up civil law suitS. Plural. Might make it so only authorized dealers can purchase. No DIY Sales could result.
These builders wanted save money. Profit. Csst is cheaper and thin. Deemed safe even though reports and fire inspectors see other wise. It is the world we live in.
PPL are cheap shhhhsss I know better and have an ANL fuse in my system however a “T” class fuse is on the way. This post reaffirmed my change in decision. I had a conversation with a poster on chit chat about fuses and victron 58v fuse in particular around same time as this post. He is building a 48v golf cart. Coincidence. I’ve got my factory packed batteries in a metal cabinet with wheels….for a reason. Might roll it down the hill. . I kept it small. Emergency back up.only…..btw gas inverter generators fail all the time too.
As did inverter welders.
GE evo ac locomotive have 36 HUGE igbt monsters - fiber optic controlled with back up comm and square fuses …..these were for main traction motors and they still fail. Make glorious melted mess. Nightmare for electricians change out melted buss bars on them. Risk of back injures due to heavy igbt weight…out of position work. Sometimes result of software glitch. Fiber optics cable kinked. Lot of field R&D. Everything is not nailed down and exact. No matter what we tell ourselves.
Likewise We are in effect R&D field techs testing this home power generation storage - equipment long term. We assume the risk. We allowed it into our homes as risk but supposed control safe with practices. We also drop our guard vs vigilant to be on look out smug in ourselves - comfortable. About that time is when we get a bite…. Or feel the burn.
There is a fresh post on this forum of a bms fire most likely from lightning hitting inverter. Fused breaker. Got bms too but bms is getting fault due to name - DALY by some reading and responding. So…. They fail too but lightning hitting inverter most likely started all of it. My factory pack batteries have bms on each 12 volt battery with blue tooth and NOW would not have batteries without blue tooth to monitor. My system is small on purpose. There are also limits to batteries.
Batrium seems like excellent idea for alerts. I am not saying do away with it. Just in addition might be advisable. Of course cheap bms could be the source of problems too. So what now? The real and only safe solution is dump the home system. Then when grid goes down live 19th century style. Must of been a reason we don’t go back to living like that?
I am amazed someone did ask if the Tesla was plugged up and blame it for the OP.
Ppl get mad at me for my opinion - they are fragile ego monsters …my opinion is just that opinion… sometimes ppl are very ignorant as are we all at one time… me initially using anl fuse in my when know better is on me ..stupid……extreme sports. We have to be a critic of things and ourself is a good place to start … we can become the enemy of better if we don’t. NOW Those bean counters wanting those GE fuses done away with were greedy self serving pricks
why I stay on chit chat.Molten copper cut through this like hot knife through butter but …it will give very limited fire break ….these are sealed batteries placed in a metal cabinet. Notice it says “maximum 4 x 100ah batteries in parallel for 400Ah.” ‘’Maximum 4 in series for 48 volt 100Ah.”
Someone might think they could have 4s4p. Not addressed. But why are they limited to ~20k? Hmmm… OP had 100kWh of cells. Maybe need actual arc chute contactors as design with arrestor - arc chutes that can handle all that voltage and amps dropping out under load.
We built special heavy metal containers to house contactors…for locomtoives. Keep it away from ppl. Pplcostalot of money when hurt or killed….law suits. I tend think it is best to let the manufacturers argue for their products. We can endorse but why argue? I know we are tribal….
No one got hurt or killed in this post was good over all thing. One of problems for toroidal transformer inverters are their ability to go above and beyond 3x surge ability. Harder to fuse. Bigger wires. Notice my Transformer pic next to name.
You can’t do this with high freq. transformer
These idiots have a ~$4000.00 fuse playing with it. Spoiler they are just using it for visual. The transformer they are using is show of capable power. ~9.6million views. Victron is low freq.
Good luck.
You don't need a separate BMS, but you do need a controlled means of disconnection of an individual string. The fuse only senses current; it cannot address other failure or risk modes.
As I understand it, using a watchmon with an external contactor or shunt-trip breaker on each string does the job.
The purpose of the class-T fuse is essentially a fail-safe for an unreliable disconnecting means. The only substitute for one is a properly rated DC circuit breaker able to interrupt full bank amps fault current.
It all comes down to fault impedance. If you have a low enough impedance and the fuse exceeds its interrupting rating then it will arc. With DC it is significantly harder to break that arc, so it will continue until something else manages to break it-- like a significant length of wire melting.
Plum Crazy Rob
Solar Enthusiast
What caused this if you dont mind me asking (LEARNING...)?? Wasn't what I expected when you said "butt joint burn-thru". Damage to conductors from stripping cable?? Would this show on a FLIR beforehand??I had a butt-joint burn thru (2 years ago) but it was in a metal connection box and might have saved my house....
Zwy
Emperor Of Solar
Don't want to derail too much here, it is in my Battery Box Build thread in my signature. Rear bracket came with the ebay sourced breaker, I had to shim it with a couple of nuts to get tight to backside of cover.
Zwy
Emperor Of Solar
This is where the shunt trip ABB breaker comes in.
High or low voltage cell limit (or any other critical fault you program such as battery temp) is hit, the Batrium shuts down the whole system using the shunt trip ABB breaker. Some might complain, "Well, it shuts down the whole system".
That is what I want, it forces me to go and find the problem. It has happened when I played with charging voltage limits and had a runner. It works exactly as designed.
I am adding a Luyuan box for more capacity and that will have a JK so the whole system won't shut down but there can't be any charge/discharge occur with the Batrium controlled bank. The JK box will have a Class T fuse installed. I'd worry more about the JK failing and not disconnecting in a cell high voltage limit situation than the Batrium. No current goes thru the Batrium.
No need, one shunt trip breaker on the whole battery bank with a Class T fuse on each 16S (or whatever series you are using) battery. Each 16S battery in my case has a K9 that monitors and balances each battery and relays cell, balancing and temp data to the CORE.
The purpose of the Class T on my system is overcurrent protection for current either way.
On your house electrical panel, do you have a second electrical panel so the current runs thru 2 breakers? Back in the old days of fuses, were there stacked electrical boxes so there were 2 fuses per circuit?
Let's get realistic here. Attempting to find fault with using only a Class T fuse for overcurrent protection is pointless, just like having redundant overcurrent protection in your house electrical panel would be.
Brucey
Solar Wizard
You may want to consider a Predator unit for much less unless you really want/need the efi complexity.
OffGridInTheCity
Solar Wizard
The original electrician wired these butt-joints and wrapped them in black electrical tape. I happened to have a pic prior to the burn...
The consensus has been that he forgot to tighten the screws or they came loose.
Here are the daily max temps in C in that box leading up to the burn-thru.
Used my #2 Midnite Classic 150 temp probe in the box to monitor the incoming PV wire which never get's above 55C at max PV on a hot day. The probe was about 6-8 inches away from the butt-joint. Between 10am and 1:30pm Oct 11th the probe reported up to 81C = 178F. Butt-joint really hot - maybe over 200F as the PV amps increased thru the day.
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OffGridInTheCity
Solar Wizard
Maybe - I see this 9500 has 62db at 23feet - https://www.chainsawjournal.com/predator-9500w-inverter-generator-57080/
Still a bit noisier but also a bit more powerful.
Brucey
Solar Wizard
Yes, significantly more powerful, also the Honda is 52dB in Eco mode and is 58dB during normal non eco operation.
I have a Honda eu2200 and there is a fair bit of difference between eco and non eco, but still not objectionable at a distance at full power.
Either one will be massively quieter than the open frame generator you were trying to quiet with the shed.
SilverbackMP
Solar Addict
- Joined
- Apr 4, 2022
- Messages
- 988
Those things are giant pieces of shit. I went through two, both under 75 hours with multiple flushing oil changes. There won’t be a third.
The valves are bent or compression release broken in the second unit (which I didn’t buy a warranty for unlike the first). I haven’t torn it apart as of yet.
Next “small” generator will be a 5 or 10kw military unit with a quiet pack.
