LiFePO4 Batteries: Discussion Thread for Those Using Them as House Banks

[chala]

Originally Posted by ebaugh

I probably invalidated the AIC interrupt warranty on my ANL fuses since I took them out of the case. But could someone explain why AIC is even a factor for this fusing? I can see where a circuit breaker could fail due to internal issues, say getting welded on the inside, but how could my ANL fuses possibly fail to open at any current level? I suppose I could vaporize both a normal interconnect and a fuse simultaneously, but I just don't understand how it could possibly ever ever fail to open. Can anyone explain?

First it would be nice to know what an ANL is? I doubt that it is the following.
The Anti-Nazi League (ANL) a search gets 79 acronyms for ANL
Wives and girlfriends of high-profile footballers, (WAG) 163 for Wag #2317
Erythrocyte Sedimentation Rate (ESR). 336 for ESR
Cautions When Using the MRBF Terminal Fuse - Blue Sea Systems (MRBF) few for MRBF, too easy.
And for some, a T fuse is a High Rupture Capacity fuse for motor starting application.

Originally Posted by Lagoon4us

Ok i've watched the technical to and fro here and appreciate you guy's love the intricate side but really isn't this a bit pedantic?

Not having a go at all at anyone but the thread is for those using Lithium as house banks not the science, first principals, the fundamentals etc...

Cannot similar argumentative technical discussion be made of currently available battery chemistry?

So what fuse would you install?

Originally Posted by Saltyhog

I also agree that Mainsail's testing is very applicable as it tests the real components as would be used on our boats and is a data point as to what would be acceptable OCP methods. The models are a starting point, but testing the actual hardware is where the rubber meets the road.

Il like the idea of an electrician coming to somebody’s home to replace a fuse and test half a dozen of them just to try to prove that the one he install may work.
I remember a customer arguing that a firecracker would fail to lit and checking it in the firecracker shop. You should have seen the shop after it blew up.

Originally Posted by T1 Terry

For the banding or crush during use or to return them to normal shape after they have bulged. The pressure during use is what ever it takes to get all the cells butted up against each other, that point is quite easy to feel with just a sash clamp pressing the two end plates together, may be adding all the cell thicknesses together in that pack and squash it till you get that measurement, we aren't talking much pressure at all, as long as none of the cells have bulged.
To flatten them back out after they have bulged, sitting in the hot sun, about the same amount of pressure, with the cells at room temp, quite a bit more, you are trying to bend that ribbed plastic case, if there are a lot of cells that have bulged in that pack, two hands on the round handle of the sash clamp, does that give an idea. we aren't talking 10 ton hydraulic press type pressure, hand tight with a G clamp type pressure, 6mm threaded rod with a battery drill and the release clutch on the weakest setting and 3 lengths of rod up each side is plenty to compress a pack for service.

T1 Terry

Good luck but be careful I know someone that tried to reshape his battery and the battery caught fire.

[Lagoon4us]

Originally Posted by deckofficer

Sung to the tune "Money for Nothing" by Dire Straits.

You picked it!!!!

[Lagoon4us]

So what fuse would you install?

Probably a 80 to 100 amp ANL Fuse?

[Zil]

Chala. What battery chemistry caught fire? What exact reshaping is referred? I sure don't want any thing on fire.

[Zil]

Chala. I would use the ANL fuse. LOTS of info on my internet. It is a slow opening fuse.

[Zil]

I appreciate all who post their real life experiences on this forum. Thank you all! The collected wisdom will prevent me from repeated mistakes. But, I would like to see another fireworks factory test.

[Zil]

Thanks for the link to Blue Sea.

[CharlieJ]

The link referenced in post #2401 refers to the original style of MRBF fuse holder. The MRBF fuse holder was redesigned about three years ago and these instructions are not valid for the current design.

[T1 Terry]

I think the fuses are also known as AML fuse but if you google ANL fuse it even shows a picture. I have no idea where the amp arc over figures came from without a reference voltage, ever tried to strike an arc welding with only 12vdc, hard to maintain it. With the ANL fuse in the centre of the pack acting as the only link, it would be at 6v nom, very hard to maintain an arc at those volts. I guess the ultimate protection would be every joiner being an ANL fuse like Ebaugh has, but I'm not sure thins isn't taking it too far. The cells I savagely over charged and cooked do have an internal short, but it takes day for that single cell to discharge from 3.4v down to 1v, it's not a dead short. Maybe a fuse in the negative cable would protect from an acidental short of any cell terminal to the earthed frame work, it's not a silly idea, but just how far do you go?

T1 Terry

[ebaugh]

Originally Posted by T1 Terry

I think the fuses are also known as AML fuse but if you google ANL fuse it even shows a picture. I have no idea where the amp arc over figures came from without a reference voltage, ever tried to strike an arc welding with only 12vdc, hard to maintain it. With the ANL fuse in the centre of the pack acting as the only link, it would be at 6v nom, very hard to maintain an arc at those volts. I guess the ultimate protection would be every joiner being an ANL fuse like Ebaugh has, but I'm not sure thins isn't taking it too far. The cells I savagely over charged and cooked do have an internal short, but it takes day for that single cell to discharge from 3.4v down to 1v, it's not a dead short. Maybe a fuse in the negative cable would protect from an acidental short of any cell terminal to the earthed frame work, it's not a silly idea, but just how far do you go?

T1 Terry

There are no solid answers yet for inside the pack/bank fusing. This is problematic. The normal rules work outside the pack, regardless of the type of battery whether it's AGM, LA or LFP. A short to the earth ground inside the pack (ie Boeing) in my eyes is a failure in the pack, not external where the usual bank fuse protects the whole enchilada.

Inside the pack, there just isn't enough real data or experience to answer. I'm thinking I will eventually have ANL's in all my internal parallel connections, at the 3V, 6V and 9V level, but not at 0V or 12V. Presently, they are only at the 3V and 9V levels. Further, I figure I will add a serial fuse or circuit breaker in the middle serial 6V connections. is this too much? Who knows? I'm pretty convinced it won't hurt anything and will isolate a serious cell failure, for whatever reason, to a single cell.

I'm not in a hurry to do this since the event possibility is very small. Will probably wait till summer when we are back in the US with easy access to parts. But it's not terribly expensive, not hard to do, so why not until we know more?

[T1 Terry]

There is no history of lithium ferrous cells suffering an internal dead short, even if a cell in the 3v, 6v, 9v or 12 parallel pack was to go dead short, with a fuse in between the 6v and 9v parallel packs would mean the highest voltage at the shorted cell would that of 2 parallel packs in series. The pack with the dead short would already be pulled to a low voltage so the total voltage would be less than 6v, but possibly at very high amps.
With my battery packs, I split up the 4 leaf connector packs and use the leaves separately, with a bit of heat shrink to protect the centre section. This creates a limited current path before the copper link fails. We know the cells can discharge a huge amount of current without bursting into flames, that You Tube test with the 2 lengths of 2/0awg cable dead shorted across the cell proved that, the wire started to burn the insulation but the cells stay intact.
Maybe the fuses would minimise potential damage to the other cells in the pack, but it adds so many failure points that would create cell capacity imbalance if a fuse failed due to fatigue, but wasn't noticed, that it may actually cause more problems than it would prevent.
There is no value in crossing over the faults in the Boeing battery pack to the battery packs we use, it's as relevant as crossing over lead acid battery faults, very different chemistry, the two batteries don't suffer the same problems so protecting against something that doesn't occur yet could cause problems of it's own, doesn't make sense.
We have had a few members put in side issues to create doubt in the safety of these cells for what ever reason they have, view them for just what they are, attempts to create doubt by mass hysteria, nothing more. If they can come up with verified instances where lithium ferrous cells have internally dead shorted and created a fire problem then it would be something to become concerned about, but that is not the case, so unless they can provide evidence of such cases, just put them down to troll posts and return to life as normal, ignore them.

T1 Terry

[Lagoon4us]

+1 Terry

My 4 x 400 amp cells are in an Antanov now from China, the battery box is finished, the end wall slides in to capture the pre-banded cells.

I've insulated the sides of the powder coated box with Neoprene to 'impossobilise' any accidental arcing.

The fuse block (ANL) Is the turning point for the cables that exit the rubber lined oval hole. Likewise the Neg cable exits the box and connects to the BEP Shunt this turns the cable to run parallel with the box.

I've given up on all the 'nil stocks' and will run 2 Junsies monitoring the 4 cells, i'll use a smoke alarm on hi and lo voltage alarms, I've also ordered 2 x 100amp latching relays to play with.

There's a 6volt 20amp charger on it's way to do initial charging.

I've finished the install of our 750watts of solar and this will be the SOLE charging method through a Lithium MPPT Regulator.

My basis is the 'KISS' System...

When my confidence increases i'll look into other charging regimes but for now to have in excess of 300amps available for our house bank we will be happy sailors.

[goboatingnow]

Originally Posted by T1 Terry

There is no history of lithium ferrous cells suffering an internal dead short, even if a cell in the 3v, 6v, 9v or 12 parallel pack was to go dead short, with a fuse in between the 6v and 9v parallel packs would mean the highest voltage at the shorted cell would that of 2 parallel packs in series. The pack with the dead short would already be pulled to a low voltage so the total voltage would be less than 6v, but possibly at very high amps.
With my battery packs, I split up the 4 leaf connector packs and use the leaves separately, with a bit of heat shrink to protect the centre section. This creates a limited current path before the copper link fails. We know the cells can discharge a huge amount of current without bursting into flames, that You Tube test with the 2 lengths of 2/0awg cable dead shorted across the cell proved that, the wire started to burn the insulation but the cells stay intact.
Maybe the fuses would minimise potential damage to the other cells in the pack, but it adds so many failure points that would create cell capacity imbalance if a fuse failed due to fatigue, but wasn't noticed, that it may actually cause more problems than it would prevent.
There is no value in crossing over the faults in the Boeing battery pack to the battery packs we use, it's as relevant as crossing over lead acid battery faults, very different chemistry, the two batteries don't suffer the same problems so protecting against something that doesn't occur yet could cause problems of it's own, doesn't make sense.
We have had a few members put in side issues to create doubt in the safety of these cells for what ever reason they have, view them for just what they are, attempts to create doubt by mass hysteria, nothing more. If they can come up with verified instances where lithium ferrous cells have internally dead shorted and created a fire problem then it would be something to become concerned about, but that is not the case, so unless they can provide evidence of such cases, just put them down to troll posts and return to life as normal, ignore them.

T1 Terry

All very good points Terry. I would disagree however with one point Li Tech is Li tech no matter want the material is. Yes ferrous cells have some particular characteristics that help in certain situations, but everything that applies to Li cobalt also applies to ferrous cells , its just certain specs are different.

Dave

[T1 Terry]

Lithium ferrous doesn't make it's own oxygen in the case of a fire or overcharge, the only flammable parts are the electrolyte gassing or vaporising, the plastic case and the plastic separators between the plates. If the vapour is vented then there is no build up of flammable material, it would require an external fire to ignite the batteries, not the other way around.
Lithium cobalt does produce it’s own oxygen in the case of an overcharge so internal fire or self ignition and combustion are a real threat, they will support their own fire and ignite flammable materials around them, that to me makes a huge difference between lithium ferrous and the other types of lithium batteries.

There was a chart that shows the temp of each type of lithium battery when they burn, the lithium ferrous battery virtually stayed on the bottom of the scale because there was no oxygen added to increase the burn temp. Buggered if I can find it at the moment though

T1 Terry

[ebaugh]

Terry,

I'm not sure if this is what you are looking for? Has nothing to do with oxygen, but it does show where a "full" lithium cobalt battery heated to 200C will self generate additional heat. So with adjacent cells, should one runaway, it can easily take out the rest of the grouping. LFP does not have this characteristic.

Ive looked for good data on the electrolyte gas, but without much success. I'm not sure the electrolyte is even exactly the same from one manufacturer to another.