LifePO4 vs sealed acid battery......LVD

Don't forget to consider environmental temperature extremes for LFP - if it freezes there you need a battery/bms that will terminate charging.
AGM doesn't have that restriction. AGM's are more or less bulletproof - can be mounted at any orientation, won't spill, don't need water, are vibration proof, and low self discharge. They're great for a racing boat or offroad crawler. For general use I don't think they're any batter than FLA or SLA. They still only offer 50% discharging, and still wear out, although tend to outlast these latter two. They're also about twice the cost. LFP ends up being three times the cost, or more, but last two to four times as long.

Browneye said:

Don't forget to consider environmental temperature extremes for LFP - if it freezes there you need a battery/bms that will terminate charging.
AGM doesn't have that restriction. AGM's are more or less bulletproof - can be mounted at any orientation, won't spill, don't need water, are vibration proof, and low self discharge. They're great for a racing boat or offroad crawler. For general use I don't think they're any batter than FLA or SLA. They still only offer 50% discharging, and still wear out, although tend to outlast these latter two. They're also about twice the cost. LFP ends up being three times the cost, or more, but last two to four times as long.

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When you say "AGM's are more or less bulletproof - can be mounted at any orientation, won't spill, don't need water, are vibration proof, and low self discharge"...you mean LFP?

Browneye said:

It depends on what you set the dip switches for - battery type, the boost/bulk voltage, 2 or 3 stage. The higher the boost the higher the float.
As mentioned, you can set infinite user settings with their programming tool, the dipswitches are like default or pre-programmed settings. Documentation and product quality is very high on this charger line. They make a LOT of different configurations. Victron is another option - they have a very nice app/user interface and infinite settings, but they do cost a bit more.

Notice with switches 2 and 3 set to off, boost is set to 14.4 then float is 13.8. I think that's kind of high for LFP, especially float - that would constantly peak your battery to at or over 100% SOC. I started out using the 14.0 'gel' setting, but use the 2-stage so no float. It gets the battery fully charged, but BMS wants to see 3.5Vpc to be full, and the cells all don't quite get there, so I bumped it to 14.2. If I try to go higher than that I'll get one or more cells that will reach full and shoot up, bms over-volt protection kicks in and terminates charging.

Every battery and system is a little different, you have to experiment with everything to get it to what works for yours.

As a backup power source - 100Ah battery, I would think you could get by with the NPB-240, the 240W/13A charger. If your battery was down 80%, or needed 80Ah to recharge, it would take about 6 hours of charging. That model is just $70. That one also just has a POT adjuster, so you would set it accordingly for your particular battery.

Using the 2-stage charging, you could just power-cycle it every month or two to just to ensure it gets fully charged. Leave boost at about 14.0V. If it's still charged from the last session, the charger would just terminate.

Have you considered putting out a 100W solar panel to maintain it instead of grid-power?

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Yes, I thought about solar....but later, as a 2nd step. Does that mean the charger you recommend (NPB-240) will become useless if I were to install a solar panel?

For a grid-down backup, you don't need lots of charging options, just something to bring it back up when/if it gets used. Hence the thought of a solar panel to keep it topped off. I have one for my starting battery bank for the motorhome - keeps them full and ready to go. And a much larger and separate array to charge the house LFP battery. Mostly I don't need additional charging sources, but do have the option for 120V connected charger, and a source when the engine is running with a DC-to-DC charger.

So yeah, for a backup battery the two would be kind of redundant. And the cheapo solar controllers aren't really adjustable for LFP, so you would have to choose an up-model, just more cost. OTOH, once installed, it would never need grid power, so depending on your draw, might provide for an extended backup power supply. Without knowing what kind of draw your sump pump needs, nor how often it needs to run, it's hard to say.

A lot of people prepping for grid-down include their refrigerator/freezer, computer and router, and a way to charge electronics. An off-grid power supply seems to be popular with a variety of users here.

French_guy said:

When you say "AGM's are more or less bulletproof - can be mounted at any orientation, won't spill, don't need water, are vibration proof, and low self discharge"...you mean LFP?

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No, AGM - absorbed glass mat.
LFP have some of those properties, but really should be oriented up, have a limit on discharge current, don't really like vibration as it can damage the cell internals. But they are virtually zero self-discharge and tend not to spill unless damaged. They also have more fussy charging parameters, and really shouldn't be stored long term at full charge - this degrades them and shortens their lifespan. And you can't charge them if temps go below freezing without ruining them.

One of the most popular AGM's are the Optima batteries. Odyssey is another. Super popular for high performance and offroad vehicles. Also very expensive - you can get a LFP for about the same cost, and generally get more capacity. LFP does not make a good starting battery - too much current draw for most. AGM's are perfect for that, and they're also deep cycle rated, unlike a lead-acid starting battery.

For a couple of hundred you can get a really nice large footprint marine/RV AGM battery, good for about 50-60 amp hours. Sam's, Costco, Walmart, Battery-Mart, etc. Easy to get, easy to take care of, good warranty. Probly last you ten years.

AGM (Absorbed Glass Mat) is a specific type of SLA or VRLA battery (Sealead Lead Acid or Valve Regulated Lead Acid )...correct?
So if I were to go SLA, this one could be an option:
Which is indeed close to half the price of a LFP battery.....WIth that being said, recent reviews are not so great !

This one seems to have better reviews (but I'm somehow skeptical about Amazon's reviews):

It seems the Deep Cycle Marine/RV batteries from Sams, Costco are more expensive and usuall less Ah......!

Both LifePO4 and sealed lead-acid batteries have their own advantages and disadvantages, so which one is better depends on specific application requirements.

LifePO4 batteries (lithium iron phosphate batteries) have higher energy density, longer lifespan, lower self-discharge rate, and better safety performance. These features make them widely used in areas such as electric vehicles, solar panel energy storage systems, and emergency power supplies.

Sealed lead-acid batteries, also known as SLA batteries, have low cost, high capacity, and good resistance to high temperatures, among other features. These characteristics make them widely used in areas such as automotive, uninterruptible power supply (UPS), communication, banking, and hospital sectors.

Therefore, when choosing which battery to use, it is necessary to consider various aspects such as the battery's application field, power requirements, operating environment, and cost.

Browneye said:

For a couple of hundred you can get a really nice large footprint marine/RV AGM battery, good for about 50-60 amp hours. Sam's, Costco, Walmart, Battery-Mart, etc. Easy to get, easy to take care of, good warranty. Probly last you ten years.

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Is this the type of batterie coming from Sams, Costco, BatteriesPlus, etc....you are refering to:
Price is similar to SLA AGM or Gel batteries on Amazon such as Renogy, Weize, Universal Power, Expert Power, Mighty Max, etc....Is there any reason to prefer Duracell?

Personally I would buy a lead battery locally from a North American factory - Canada, US, or Mexico, before any China ones...that's just me. I surely wouldn't buy anything under the brand Renogy.

The link you posted is a plain ol' flooded lead acid, although it's rated 'marine/RV'. That means they're rated for deep cycle use, but tend to not have real heavy plates like a golf cart battery. Which BTW, if you want 100A usable, and willing to spend $250, and can keep them watered, opt for a pair of 6V GC2's. They're a great option, very durable, I got 7 years out of them in the RV, wired in series to make 12 volts. They're generally about 220Ah, so 50% usable gives you about a hundred amp hours. Yes, they're heavy, and they're heavy duty.

There is also an AGM version of that Duracell battery - I just bought a regular Duracell SLA starting battery lfrom Sam's for the old Cadillac for $129. They also had the AGM version for $200. The 'RV/marine' version in a full size group 27 might run a little more.

Costco also has a good price for GC2's. Not sure what brand they're selling now. Generally they're about $125 now. Used to be able to get them for $70k-$80 each. Seems Sam's has gone to Duracell, they also used to have Interstates that I'm pretty sure came from Mexico. The Mexico factories seem to do pretty well, I think Johnson Controls had a factory there too, but the latest I heard they had sold off their battery division. And there's always good ol' walmart - they have good prices on decent batteries - used to be Johnson Controls, but not sure what they're selling now under their 'maxx' brand. I've bought quite a number of batteries from Walmart and never had any issues. I tend to replace starting batteries about every 4 years regardless - I don't try to squeeze life out of cheapo starting batteries. I'm in a very temperate climate here in so-Cal. AZ and the desert heat absolutely just kills batteries.

If you really want quality, then search out Trojan or Crown. And then there are proponents for Rolls Surrett. These are the top brands for lead batteries.

I go way back with 12V systems, campers and boats since the 70's. At one time I had a dozen starting batteries with all the cars and bikes, the boat and RV, etc. It was a chore to keep them all charged up all the time. If you let them sit and discharge they go south pretty quickly. Moving up to LFP was a real lesson in new technology!

Browneye said:

The link you posted is a plain ol' flooded lead acid, although it's rated 'marine/RV'.

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Are you sure? The 3rd bullet point (under "Product details") says this:

• Made with special fiber glass mats and heavier grids and plates extend performance life. With exclusive stainless steel terminals for strong, corrosion-free connections.

However, it says "flooded"...............so confusing !

I would say that's a selling point left in from the description from something else.
The specs say 'flooded'.
An actual AGM battery tends to start around $200. Optimas are $350, as are Odysssys.

Browneye said:

I would say that's a selling point left in from the description from something else.
The specs say 'flooded'.
An actual AGM battery tends to start around $200. Optimas are $350, as are Odysssys.

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With that being said - and assuming I'm OK maintaining flooded batteries - the golf cart GC2 batteries (2 x 6V in series) is a robust option.....correct?

Darn near bulletproof.

I don't know when this was written, but sums it up pretty well:

OTOH there are a lot of advantages with LifePo4 batteries as well, and their purchase cost keeps coming down.
But we still really haven't dug into your particular requirements - what is the amp-hour or watts draw of your pump? How long does it typically run and how many times in a given time span that you expect a battery to provide backup power?

What are the extremes of the environment it will live in - highs and low temps?
What are your intentions for charging it and keeping it charged?
You mentioned a sump pump - for your home? How often does grid power go offline? And for how long?

All of these considerations help formulate a proper response to the needs identified.

We can talk about pros and cons of various battery types all day long, which may or may not address your actual needs or requirements.

When we purchased our house 10 years ago, the basement was equipped with the usual sump pit and AC primary sump pump (a Zoeller I think) - Very common in Michigan. But I didn't like to rely on 1 pump only, especially knowing we could have power outages once in a while (ice storm, high winds, thunderstorms, etc....Our provider in Michigan is being very criticized right now on how they manage the grid) So after 1 year, I purchased a battery operated backup sump pump (Wayne ESP25 - 12VDC pump). A friend gave me 2 brand new VRLA AGM Yuasa batteries (12V 38Ah each) that I installed in parallel.
To be honest, I don't think the backup sump-pump ever kicked-in other than me doing some tests (or I didn't know)
But the batteries are now close to 10 years old and most likely need to be replaced. I still want to have peace of mind with a backup sump-pump, when we are out of town on vacation, or when I'm in a business trip (my wife would not know how to start the generator)
So I was considering LiFePO4, then all my questions about SLA AGM (why not after all). But I was in a Sam's Club tonight and saw some 230Ah GC2 batteries, and gosh they are HEAVY.....So even though they are bulletproof and probably all I need, the idea to carry them and bring them downstairs in the basement is.....compelling me to consider LiFePO4. I was looking on Amazon, and I'm considering Power Queen or Redodo (12V 100Ah)
The 12VDC pump draws 10A continuous and 18A peak. The controller of the ESP25 kit activates the pump for ~12 sec I believe. When we have heavy rain or snow is melting, the primary pump can run every 10 min, and the backup pump would have to do the same in case of an outage
Maybe later I will consider another battery + inverter + transfer switch to power the primary pump before the backup pump in case of power outage, but for now I want to take care of my current batteries and replace them.....at least my backup will be fully operational again and not rely on old batteries

Yuasa are very good agm batteries - and you've proven that now. They're super popular for power-sports, likely their primary application.

As far as weight, GC2's are not hard to carry in one time - 68lbs each. Or borrow a young buck for few minutes to do it for you.

You've gotten by with 76Ah, 50% usable, for ten years - my inclination would be to drop a 100Ah AGM in there and call it a day. It's highly likely your charger isn't ideal for LFP, but we wouldn't know that without some specs.

If the pump is only running 12 seconds six times an hour - that's not much draw, maybe one amp an hour. A 100Ah battery would run it for at least a couple of days during a grid-down scenario.

Browneye said:

Yuasa are very good agm batteries - and you've proven that now. They're super popular for power-sports, likely their primary application.

As far as weight, GC2's are not hard to carry in one time - 68lbs each. Or borrow a young buck for few minutes to do it for you.

You've gotten by with 76Ah, 50% usable, for ten years - my inclination would be to drop a 100Ah AGM in there and call it a day. It's highly likely your charger isn't ideal for LFP, but we wouldn't know that without some specs.

If the pump is only running 12 seconds six times an hour - that's not much draw, maybe one amp an hour. A 100Ah battery would run it for at least a couple of days during a grid-down scenario.

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My current charger is a cheap Black+Decker BM3B permanently attached to the batteries...but regardless of the new battery I pick (SLA AGM or LFP) I was planning on buying a new one (Mean Well or Victron)
Out of the 100Ah AGM batteries on Amazon, is there one better than the others? Or should I go Duracell?

Sorry, I'm really not familiar with what they're selling on Amazon for agm batteries.

If I was going to buy one it would be a group 27 like this - and there's even a review from a user with a wayne sump pump!

With my 38Ah Yuasa batteries, should I read 38Ah/2 = 19Ah per battery if I were to do a capacity test (discharge at 0.1C = 3.8A and cut-off at 12V)?

Back to the OP on disconnect.... Consider a voltage controlled relay to cut the inverter load instead of battery power.
If the minimal idle draw continues to pull the battery voltage down over a few days the BMS can easily handle that.

If the LVD is activated often consider more battery and more solar.

time2roll said:

Back to the OP on disconnect.... Consider a voltage controlled relay to cut the inverter load instead of battery power.
If the minimal idle draw continues to pull the battery voltage down over a few days the BMS can easily handle that.

If the LVD is activated often consider more battery and more solar.

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I'm not using an inverter. The battery wires goes into the Wayne "controller" that feeds the pump which is a 12VDC - I guess this controller has a charger (that I'm not using), a relay and some kind of logic to activate the relay for a specific time (~12sec) when the sensor is triggered by high water level