Spinoff from house burning LFP vs AGM vs Lead Acid - Why not just run the older tried and true stuff?

I know LFP is the new norm and I am running 4 Chins 12v 200ah in series for my 48v offgrid system powering my log cabin where I'm living. Very happy with the performance, but pretty shook up about this latest incident. I also have 8 Renogy 12v 200ah AGMs in my shop doing basically nothing.

I live in northern Colorado mountains in a 100% offgrid community and I'm the only one running LFP. Most folks are running Lead Acid 2v batteries in a 12v system. Some are running AGM. Most of these systems are pretty sketchy to say the least (not even close to code, little to no fusing, etc).

Nobody has had any solar-related fires. Any house fires would burn the entire mountain as we are in a tinder box.

So why bother with LFP if there is a fire risk? Why not just go with AGM/Lead Acid as there is very little risk of them catching on fire? Or is there a risk and we don't hear about it?

AGM’s can vent hydrogen and oxygen when overcharged.
So they can blow up too, but certainly much less likely and not as devastating.

In the other thread the OP says the inspector determined the fire was from a failed fuse. So, did battery chemistry really have anything to do with it. The world may never know.

Round trip efficiency is why I won't run lead acid. Also, cost. Lead acid is more expensive now.

It's true though, if anything starts a fire in a lead acid system it's usually the charge controller.

But at the same time the hydrogen venting and acid usually prompt people to put lead acid outside in a shed or bin, instead of inside the garage or wherever.

Q-Dog said:

In the other thread the OP says the inspector determined the fire was from a failed fuse. So, did battery chemistry really have anything to do with it. The world may never know.

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No the fuse arcing is where the fire likely started, but why it blew we do not know. Fuses do not just randomly go blowing up. Something caused it to blow and that is the big unknown we will probably never know.

Takeaway is to use fuses with higher AIC. 5 years ago that wasn't as well known for 48V LFP.

hwy17 said:

Round trip efficiency is why I won't run lead acid. Also, cost. Lead acid is more expensive now.

It's true though, if anything starts a fire in a lead acid system it's usually the charge controller.

But at the same time the hydrogen venting and acid usually prompt people to put lead acid outside in a shed or bin, instead of inside the garage or wherever.

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Please elaborate on how a CC can cause a fire in a lead acid system? Overcharging?

Hi @Blakes

I have many vehicle “starter batteries”. Where I am considering LFP for my Harley motorcycle, there is a zero chance I install LFP in my airplanes.

There are pros & cons to all battery chemistries. I have a Van & a Remote Cabin ,,, both run AGMs ,,, mostly due to sub-freezing use sometimes - Canadian Winters.

However, I have been considering LFP for our van. The batteries are inside the van & it is quite easy to buy LFP & have the advantages in the van. Then the van’s Rolls AGMs could be added to the cabin.

British Columbia is already “On Fire” & I understand your tinder box statement. For both the Van & Cabin LFP would have some advantages, however there are also “Cons”. Every situation & use patterns are a little different.


My heart goes out to the form member who lost the family home, & glad they did not loose a family member in that fire. It was selfless & extremely helpful to other members for him to post about the fire. A wakeup call for all of us I suppose. A reminder to respect electrical in general & especially DC.

It has made me pause, and ponder if I want LFP in my van. I do not have a need, but it is the new tech & all the cool cats have it. For my van (& cabin for that matter), my focus has been conservation. In a world of mega increasing Kwh & large inverters, I went propane, passive cooling techniques, gasoline generator backups, solar, & 12vdc.

Our cabin runs almost 100% on 12vdc Rolls AGMs “250Ahr” & 600W array ( plus propane for all things heat ). April to November.

Blakes said:

Please elaborate on how a CC can cause a fire in a lead acid system? Overcharging?

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Could be bad system design and over volting, loose terminals, or internal failure. And just the fact that they are the complex component that gets continuously loaded every day.

They usually burn up inside their box without starting a fire.

Edit: Oh and the charge controller receives uncontrolled power. When PV power starts shorting, nothing can stop it except the short circuit self fusing itself.

UL 9540A is a battery certification for fire and thermal runaway
The manufacturer pays for fire related testing to get a battery system UL9540A certified
Most jurisdictions want UL9540A certifications for permitted installs

All my solar gear *is* in a separate utility building, an intentional design from the start, for various colorado reasons. Been on LFP for 3+ years now, and FLA for years before that, and there are no problems. Pre-wired Magnum 4024, 4x 12v300ah battery-bank ... this stuff is rock-solid.

Don't psych yourself out ... homes catch fire all the time, for all kinds of reasons, and the odds still favor kitchen and fireplace scenarios over most else, including solar gear. Unless you are smoking in bed and falling asleep ... or parking your EV in the garage ... or ...

If you *do* want to worry ... worry about fire department response times, and what you are going to do about it for your home & location.

Where I'm at (rural), the volunteer fire department will be here in an hour or so, and the odds of saving my foundation are high. In the city, most homes are now packed with enough exotic materials & finishes that even a 5-minute or less fire response from the paid/fulltime fire department might still not be enough to save your house. In both cases, neither department would ever say it, but the main job is to protect other values (prevent spread).

Instead of worrying, invest in more monitoring (video, alarms of various kinds) and suppression tech (sprinkler, others), whatever is appropriate for your scenario.

I'd like to add that 2 different guys here on the mountain who have been up here offgrid for 30+ years recently needed new batteries. Neither of these guys are 'online' so to speak, so they are not exposed to this or other forums.

My buddy reached out to the local solar guy who grew up offgrid and has designed/built many of the systems up here. He recommend against LFP (for unknown reasons) and my buddy ended up with a bank of 2v Lead Acid batteries for his offgrid house.

Another guy reached out to Trojan (after talking to me where I recommended LFP) and apparently the guy at Trojan recommended against LFP saying something about LFP is not good for the constant charge/discharge cycles. I dunno that is what he told me.

So why are folks/companies recommending against LFP? Again, I have LFP running my cabin and now I'm worried.

I have ZERO property insurance and CANNOT get it. Believe me, I've tried.

It worries me that if my system were to catch fire and burn my cabin, not only would I be screwed but the fire would most likely spread and burn other homes up here and I would be the blame....

Blakes said:

I know LFP is the new norm and I am running 4 Chins 12v 200ah in series for my 48v offgrid system powering my log cabin where I'm living. Very happy with the performance, but pretty shook up about this latest incident. I also have 8 Renogy 12v 200ah AGMs in my shop doing basically nothing.

I live in northern Colorado mountains in a 100% offgrid community and I'm the only one running LFP. Most folks are running Lead Acid 2v batteries in a 12v system. Some are running AGM. Most of these systems are pretty sketchy to say the least (not even close to code, little to no fusing, etc).

Nobody has had any solar-related fires. Any house fires would burn the entire mountain as we are in a tinder box.

So why bother with LFP if there is a fire risk? Why not just go with AGM/Lead Acid as there is very little risk of them catching on fire? Or is there a risk and we don't hear about it?

Click to expand...

Like someone said, this was a DIY LFP battery (nothing against them). If you're using server rack or your Chins batteries, so far, I don't think we know of any houses burning down when using those types.

Blakes said:

Another guy reached out to Trojan (after talking to me where I recommended LFP) and apparently the guy at Trojan recommended against LFP saying something about LFP is not good for the constant charge/discharge cycles. I dunno that is what he told me.

So why are folks/companies recommending against LFP? Again, I have LFP running my cabin and now I'm worried.

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Ignorance, that's why. I also do not have insurance, and cannot get it and that isn't a concern. If you are as concerned as it seems like you are your safest method FLA, AGM or LFP is to make a power shed separate from the house. Being in a cold area you could have it partially set in a bank to keep warmer in the winter and/or get something like a Trophy Battery that has built-in heating or do your own thermostatically controlled heating.

Blakes said:

So why are folks/companies recommending against LFP?

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1. Stuck in their ways. Lead acid is familiar, LFP is unfamiliar. They know how to design lead acid, they don't know how to design LFP. Lead acid can be voltage controlled, LFP normally requires potentially troublesome comms unless you're an expert in running an open loop system.

2. There is something to be said for the quality of proven lead acid system design over the years. You will talk to some off gridders who don't think about their batteries, don't sit around watching them, they just water them and buy replacements every 5-10 years and otherwise live their lives. I can respect people not wanting to fix what ain't broke.

3. Lead acid are north american made and have a very good existing recycling chain. If one had isolationist ideals, those are positives. I have big doubts that LFP recycling will ever take off at scale. But then again, try designing a solar system of any kind without Chinese parts. It's unlikely.

There are many Pro's and Con's both ways, but to make a list off the top of my head:

LFP Pro's -
Energy Density: I can get 300Ah of usable capacity in the same weight and physical footprint as a 60Ah usable lead acid.
Cost per usable Watt Hour: Getting 100Ah of usable power our of a LFP battery is slightly cheaper than 100Ah of usable lead acid.
Lifespan: If you baby your high end AGM's you might get 5 usable years out of them, a bog standard LFP is expected to get drained and recharged every day for 10 years. Doing that to a lead acid would kill it in a couple years.
Offgassing: There's no hydrogen gas coming off the LFP batteries that could potentially cause fires.

LFP Con's -
Fusing: The power draw available from a LFP battery is REALLY high, you gotta drop big money on fuses and breakers that can actually handle that kind of rush.
Cold Weather: The bane of LFP for most of us. When it's cold out the risk of destroying your batteries is high and that's a LOT of money invested. Heaters can offset and insulation can help but you then have to oversize and overbuild (and overinvest) to compensate for the power to keep the batteries warm.
Availability: You can go to any WallyWorld in the country and get a 120Ah lead acid. Finding a replacement LFP battery off the shelf is damn near impossible for most folks.

Lead Acid Pro's -
Cold Weather: OK, so it's been freezing out for the last 2 months, the batteries don't really care.
Safety: The amount of amperage a lead acid can dump at once is limited by the physics of how lead actually works. You can use many off-the-shelf fuses and breakers and they'll do the job just fine.
Availability: Again, any WallyWorld or analog carries lead acid "Marine Deep Cycle" batteries on the shelf. Not so much with LFP.

Lead Acid Con's -
Heavy!!! : You're needing 2x as many batteries to have the same energy density, so twice as many trips to the car and back. If you've got industrial batteries you're going to be hurting by the time you've got them all moved.
Energy Density: Most lead acid flavors only like to be drained to about 50% of capacity. That hurts!
Energy Output: When you need that 6000w of surge to fire up the well pump or the AC, lead acids just have a hard time stuffing that many amps out at once where an LFP can do it MUCH easier. That means more cells in parallel.
Voltage Capacity: Most lead acids are 12v, so if you run a 48v system you can't just go buy a 48v lead acid battery, you have to get 4 of the 12v and connect them together which means more lugs and more wires and more crimps for each battery set. Copper costs add up when you're stringing together lots of banks.


Those are just a few I can think of off the top of my head.

The house burning down due to a fuse failure can happen with ANY Battery Chemistry regardless of voltage as well. Quality Breakers & Fuses rated for " the purpose" they are being used for with proper & correct mounting is essential towards building a safe system.

A great deal of people are using LFP for ESS systems, Numerous companies make LFP ESS battery systems including major battery providers such as Roll Surette who've been building Serious Lead Acid forever (including submarine batteries). Overall consensus is that LFP is far safer than other chemistries currently available. The fact remains that when dealing with any form of energy system (storage, generation, usage) it has the potential for problems.

Ask yourself, how many house fires occur where there the cause is electrical, then consider all other cases of electrical fires occurring. More often that not it is a Failure of some sort, even when everything was perfectly done according to code.

Lead Acid is NOT SAFE either, I used it for years and managed it with active venting, temp management and constantly futsing with water/acid. The hydrogen given off during Equalizing can be quite high and people do screw up and do so with slightly exposed plates & things happen. Others never have a problem because they are diligent as hell...

Blakes said:

I know LFP is the new norm and I am running 4 Chins 12v 200ah in series for my 48v offgrid system powering my log cabin where I'm living. Very happy with the performance, but pretty shook up about this latest incident. I also have 8 Renogy 12v 200ah AGMs in my shop doing basically nothing.

I live in northern Colorado mountains in a 100% offgrid community and I'm the only one running LFP. Most folks are running Lead Acid 2v batteries in a 12v system. Some are running AGM. Most of these systems are pretty sketchy to say the least (not even close to code, little to no fusing, etc).

Nobody has had any solar-related fires. Any house fires would burn the entire mountain as we are in a tinder box.

So why bother with LFP if there is a fire risk? Why not just go with AGM/Lead Acid as there is very little risk of them catching on fire? Or is there a risk and we don't hear about it?

Click to expand...

Do you run an active equalizer on your series string? If not you might want to think about it.

robbob2112 said:

Do you run an active equalizer on your series string? If not you might want to think about it.

Click to expand...

I'm not even sure exactly what that means. I have a Renogy 48v inverter with built-in mppt set for LFP.

Blakes said:

1. I know LFP is the new norm and I am running 4 Chins 12v 200ah in series for my 48v offgrid system powering my log cabin where I'm living. Very happy with the performance, but pretty shook up about this latest incident. I also have 8 Renogy 12v 200ah AGMs in my shop doing basically nothing.

I live in northern Colorado mountains in a 100% offgrid community and I'm the only one running LFP. Most folks are running Lead Acid 2v batteries in a 12v system. Some are running AGM. Most of these systems are pretty sketchy to say the least (not even close to code, little to no fusing, etc).

Nobody has had any solar-related fires. Any house fires would burn the entire mountain as we are in a tinder box.

So why bother with LFP if there is a fire risk? Why not just go with AGM/Lead Acid as there is very little risk of them catching on fire? Or is there a risk and we don't hear about it?

Click to expand...

Re-Reading your “setup” & if you are concerned the following are my cursory opinions;

1. Perform a safety audit - use the forum & post your schematics & get opinions here on your system “as built”​
2. Assuming you are running Solar/Inverter/120vac (where distance is not an issue) - consider a fireproof housing separate from your cabin & run the power 120vac into the cabin​
3. As @Steve_S wrote all energy storage & delivery systems can be dangerous ,,, not just LFP​
4. You like your current 4 Chins & 48vdc setup​
5. Per item #1 above ,,, Review your system ,,, connections ,,, design ,,, fuses ,,, etc​

I understand the fire concern. Review, Inspect, and Change what you don’t like with your current system.

If in doubt error on the side of safety.

I seen a car accident yesterday.
Should I stop driving cars?