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LIFEPO4 Smoke and Fire Dept

What is all the wiring for that is connected to the cells? Looks like some of them have at least 4 smaller gauge wires connected to it.

It also would be a lot safer if the wiring were organized in a cleaner fashion. Some of that wiring is pulled up underneath busbar connections, across busbars, etc. You should be able to look at the battery and tell what each wire is for and where it is going. Right now it looks like spaghetti.
 
jhooligan65 said:
Im racking my brain. Was/are they bad cells?
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jhooligan65 said:
my BMS read around 3.3V on all cells. Even the cooked one ws 3.2V. After removing them all and checking with a meter the range is 3.27 to 3.31 per cell. resistance is between 2 and 4 megaohms. The cooked one is 6 megaphms and still has a voltage of 3.17v.
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Mega or milli?
 
jhooligan65 said:
The case was over 200 degrees F. the cell above it was a little melted. possibly swollen. They all check out. my BMS read around 3.3V on all cells. Even the cooked one ws 3.2V. After removing them all and checking with a meter the range is 3.27 to 3.31 per cell. resistance is between 2 and 4 megaohms. The cooked one is 6 megaphms and still has a voltage of 3.17v.
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Probably 1220F+. The cells should be between 0.15-0.25 milliohms or 2.5E-10 MΩ. If that is your 12kW Growatt, you need about 1200aH of battery or at least twice what you have. What is your max discharge amperage? I'm pushing 18000W out of two Sol-Ark 12K's with 2800aH. About 37A per battery. It will keep everything running cool and your cells will last longer. You may not even need those external balancers.
 
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Is it even possible to have an IR that is in megaohms? Will it ignite if applied continuous current? Or current will not even flow?

Edit: "The skin contact resistance will usually be between 1000 and 100,000 Ω, depending on contact area, moisture, condition of the skin, and other factors. The skin thus provides most of the body's protection from electric current."
 
chess-equality said:
Is it even possible to have an IR that is in megaohms? Will it ignite if applied continuous current? Or current will not even flow?

Edit: "The skin contact resistance will usually be between 1000 and 100,000 Ω, depending on contact area, moisture, condition of the skin, and other factors. The skin thus provides most of the body's protection from electric current."
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Skin res will vary from 1,000 Ohms to over 10 Mega Ohms. Mine presently is 8.5 Mega Ohms.
 
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Bluedog225 said:
Hope you get it worked out. I’m convinced a power house is right for me. Not willing to take a chance.
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For me on 10 batteries/2800aH...Power house 50' away from house, cooled to 70F, 40A charge/discharge max per battery, 2ga wiring rated for 115A, BMS's rated for 200A - set to 100A for 5 sec max, 100A 2p dc breaker, 125A class T between cell 8 & 9 to break battery in half, 1/4" ceramic fiber mat or "fiberfrax" between batteries and on ends, 1/4" cement board underneath batteries and covering exposed wood of battery shelf, behind inverters or any electrical components, 2 RF smoke detectors interconnected to 2 in house, 1 in work van (solar system too) and 1 in garage, 40 lb CO2 fire extinguisher, 100 lb halon extinguisher, 5 gallons of water, nomex racing gloves and balaclava.
 
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chess-equality said:
The skin thus provides most of the body's protection from electric current."
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I am still careful to not touch anything in a way that the current can flow from one hand to the other through my heart. The other thing to remember is some shocks may not kill you, but falling off a tall ladder or a roof can kill you.
 
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jhooligan65 said:
After removing them all and checking with a meter the range is 3.27 to 3.31 per cell. resistance is between 2 and 4 megaohms. The cooked one is 6 megaphms and still has a voltage of 3.17v.
Click to expand...

I was going to ask about BMS record of cell voltage balance, thinking charge to 3.375V/cell might not have triggered balancing. But 3.17V on bad cell indicates not over-discharged. I suppose over-charged and then self-discharged back within range isn't impossible.

But any over/under voltage of a cell ought to cause BMS to disconnect (does it have a disconnect mechanism?)
Bad connections of course are a source of voltage drop and heat. Could be considerable heat without voltage so far out of spec that BMS responds.
Busbars look like copper, but ends are grey - what is that? Copper on aluminum would be more likely to develop problems.

Compare temperatures of connections in remaining 15s battery after long period of high current. Check voltage drop from cell terminal to busbar (or cable terminal) under high current, no need to wait time for it to heat up before voltage drop appears.
 
just prompted me to recheck my battery and 1 terminal wasnt very well tight and the busbar was clearly hotter on that 1 terminal. I bet you had a similar issue. 1 loose terminal, lots of resistances, lots of heat, boom
 
I don't want to build my own batteries, time and hassle and all that, but I'm thinking it's a good idea to only get lifepo4s that have a bluetooth bms that shows cell data. Preferably with passive or active balancing.

I'm thinking if there is a cell that's frequently lagging behind the others, it's either bad or has a cruddy connection. Not much one could do about it in a sealed battery other than fight with the manufacturer, but at least you would know death is at your door.
 
cs1234 said:
I don't want to build my own batteries, time and hassle and all that, but I'm thinking it's a good idea to only get lifepo4s that have a bluetooth bms that shows cell data. Preferably with passive or active balancing.

I'm thinking if there is a cell that's frequently lagging behind the others, it's either bad or has a cruddy connection. Not much one could do about it in a sealed battery other than fight with the manufacturer, but at least you would know death is at your door.
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active or passive balancing wouldnt save this problem. Its most likely a lose terminal. the BMS would never stop this unless it had a ton of temp sensors on every cell
 
Especially with aluminum battery terminals, CLEAN AND FLAT AND TREATED TO PREVENT OXIDATION is key.

Copper also have a mild oxidation layer, but it isn’t as bad as aluminum is.

30 seconds exposed to air, and aluminum forms an insulating layer. So all current would be flowing into the bussbar through the bolt.

Clean, and treat all terminals, and clean the copper plates as well.
 
x4dow said:
active or passive balancing wouldnt save this problem. Its most likely a lose terminal. the BMS would never stop this unless it had a ton of temp sensors on every cell
Click to expand...

Yeah, I meant I just want my BMS to have passive or active balancing, because I want it. The thing the bluetooth BMS would do in this situation is possibly allow me to see a cell that isn't charging as fast the others for whatever reason, possibly a loose/bad connection. Would have to watch it before it manages to balance it of course. If that cell then continues to do such things, you would know something is possibly up.
 
All cells in series will charge/discharge equally fast, because the only way current flows through one is to flow through the others (except for equalization.)
But voltage sensed by BMS can differ.
 
I've mistakenly left nuts loose getting in a hurry. The BMS always picks it up. It may show cell number 10 with an error but it could be cell number nine or 11. If you see a faulty reading, you better start looking over all your connections and crimps.

Also install a sticky note with your typical voltage difference at maximum pack voltage. When my Sol-Ark's are in absorption phase, pushing 370A in, I'm usually watching voltage difference. All 10 batteries are different, but if you start seeing them change you better start investigating.
 
It’s interesting that the cell that failed is the only one that interconnected all three shelves. The nuts were definitely not tight enough to hold the buss bars from movement from the swelling. But I am not sure how much force is involved.
 
What is the best practice with swelling? Must be prevented at all costs?

I have 4 x 12v serviceable batteries as backup and I'm planning to take out the cells to combine them into 48v in the near future.
 
chess-equality said:
What is the best practice with swelling? Must be prevented at all costs?

I have 4 x 12v serviceable batteries as backup and I'm planning to take out the cells to combine them into 48v in the near future.
Click to expand...
Keeping the voltage of every cell between spec and limiting to 0.5C or less charge/discharge.
 
rhino said:
Keeping the voltage of every cell between spec and limiting to 0.5C or less charge/discharge.
Click to expand...
Rigid endplates and two 1" cargo straps, installed before charging above 3.28 or 30% cap that cells are shipped with. It works great for me.
 
x4dow said:
just prompted me to recheck my battery and 1 terminal wasnt very well tight and the busbar was clearly hotter on that 1 terminal. I bet you had a similar issue. 1 loose terminal, lots of resistances, lots of heat, boom
Click to expand...
Aside from using a torque wrench when installing ..would lock washers on each terminal help to keep them from loosing over time? Since the washer puts presser against the screw in theory it should work like it does in auto and other mechanics applications.
 
And that's why they still use lead acid on submarines. And no lithium on my boat.

www.aspistrategist.org.au

The Attack-class submarine battery debate: science fiction or engineering? | The Strategist

In view of Derek Woolner’s warning last month that the Royal Australian Navy’s new Attack-class submarines will be obsolescent by the time they’re delivered, it’s time to revisit the main storage battery question—including what we’re ...
www.aspistrategist.org.au www.aspistrategist.org.au

Long odds but a cabin full of smoke and no place to run no thanks.

I was thinking of building one https://diysolarforum.com/threads/i...epo₄-battery-for-boat-very-new-at-this.45598/

Maybe on the deck in a metal box someday but lead works fine.
 
32 volt boater said:
And that's why they still use lead acid on submarines. And no lithium on my boat.

www.aspistrategist.org.au

The Attack-class submarine battery debate: science fiction or engineering? | The Strategist

In view of Derek Woolner’s warning last month that the Royal Australian Navy’s new Attack-class submarines will be obsolescent by the time they’re delivered, it’s time to revisit the main storage battery question—including what we’re ...
www.aspistrategist.org.au www.aspistrategist.org.au

Long odds but a cabin full of smoke and no place to run no thanks.

I was thinking of building one https://diysolarforum.com/threads/i-want-to-build-a-32v-lifepo₄-battery-for-boat-very-new-at-this.45598/

Maybe on the deck in a metal box someday but lead works fine.
Click to expand...

The article is old ... and a joke.
It only considers Li-ion (NMC/NCA) batteries.
Like never heard of LiFePO4, LTO.

An LFP battery can at most let out smoke. It is easy to put them in an air tight cabin (problem? solved !).
But a lead-acid battery can EXPLODE.
Now that is something I definitely do not want to happen in a closed metal can under the water ....
 
32 volt boater said:
And that's why they still use lead acid on submarines. And no lithium on my boat.

www.aspistrategist.org.au

The Attack-class submarine battery debate: science fiction or engineering? | The Strategist

In view of Derek Woolner’s warning last month that the Royal Australian Navy’s new Attack-class submarines will be obsolescent by the time they’re delivered, it’s time to revisit the main storage battery question—including what we’re ...
www.aspistrategist.org.au www.aspistrategist.org.au

Long odds but a cabin full of smoke and no place to run no thanks.

I was thinking of building one https://diysolarforum.com/threads/i-want-to-build-a-32v-lifepo₄-battery-for-boat-very-new-at-this.45598/

Maybe on the deck in a metal box someday but lead works fine.
Click to expand...
"Power cables in Bonefish’s forward battery well were sparking and glowing cherry red, small flames and electrical arcs licking across the battery bus. A petty officer rang the alarm “Fire on third street!”



The crew frantically blasted CO2 fire extinguishers to cool the overheating battery but the flames continued to grow and light smoke began wafting across the submarine began surfacing to periscope depth. Nine minutes later Bonefish’s skipper ordered the hatches to the battery compartment sealed, hoping to starve the flames.


But even as damage control crews struggled to comply, there was an explosion and a fireball coursed across the compartment, blasting sailors against the wall. In moments, jet black smoke poured across the ship, blinding the crew and making breathing poison."
nationalinterest.org

A Fireball: This U.S. Navy Submarine Was On Fire Underwater

Fortunately, most of Bonefish’s crew miraculously escaped the calamity with their lives—but that doesn’t lessen the tragedy of the three crew members who were not so fortunate.
nationalinterest.org nationalinterest.org
 
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