AGM or GEL Batteries? Which is best?

[Ampster]

The world is changing Charlie Brown. I haven't been into a basement of a high rise building in years and @Sunking is probably correct. On the otherhand Megawatts of Lithium battery storage is making Peaker Plants in California and Australia economically obsolete. Some smart money must be able to understand those risks and mitgate them so the risk is acceptable.
The military is implementing Lithium batteries because of the weight savings alone. Yes Lead Acid batteries are still being used to start cars and trucks and ironically even my EVs have one.
It is clear the Boeing engineers made a big mistake and their vendor overcharged those Lithium batteries. I am putting 28 kWh of LFP in my garage and have no concerns because LFP is the safest Lithium chemistry. I am replacing 10 kWh of old Nissan Leaf batteries that @Sunking has said are like old men in their 70s. They go over the hill quickly.

[Sunking]

Care to elaborate?

Should be obvious, lithium Ion batteries are the second most dangerous batteries ever made, second only to atomic batteries used in deep space probes. OTOH AGM batteries were made for military aircraft where spills, breakage, leakage, fires, and gassing cannot be tolerated. Go into any large high-rise building and in the basements you will find AGM battery banks as large as 18-wheel trucks lined up.

Lithium is so dangerous they are not allowed to be shipped on planes. In fact Lithium Ion batteries used in Boeing 777 caused a crash and delayed the release of the 777. You would have to live in a cave not to hear about all the lithium battery fires in ships, planes, cars, cell phones, e-cigerettes, toys, and the list goes on and on.

Unlike a lead acid battery that can catch fire, at least you can extinguish the fire with conventional technology every one has. Not so with a Lithium battery fire, put water on ot and you will just make the fire angry and teach you a lesson you will never forget if you survive. Nope sit back ad watch is what local FD are taught about lithium fires unless they have special equipment and training. Example with an EV fire, the car is required to be quarantined in a fire pit for 48 to 72 hours because it is very likely to catch fire again after being extinguished.

Lithium batteries have there place, but it no tin my home.

So I say, do the world a favor, go by Lithium batteries and fill your house with them..Do you agree with me?

[SageOldmann]

I guess I'll ask this again down below since some of you went off in a different direction and my question got lost in the conversation.

[Mike90250]

Batteries in parallel, is doable, with care
AGM are tricky, the cable resistance is higher than the very low internal battery resistance, so the care going into the cables and connections is critical

http://www.smartgauge.co.uk/batt_con.html

But AGM are fumeless, until something goes wrong. They still need to be vented, which means an enclosure and then they are hidden and you forget all about them, until the smoke happens or the power goes off.

[Ampster]

As a guy getting ready to drop the money to buy a set of 400 ah batteries, there's nothing more dangerous about lithium batteries is there?

It depends on who you ask and how they are managed. It also depends on the chemistry. Not all Lithium batteries are alike. LIP0 or LiPoly is the most dangerous. LFP or LiFePO4 is the safest.
There is a lot of good advice on this forum about the various forms of Lead Acid batteries. There are other forums where the expertise is more about Lithium batteries. I came from the EV conversion perspective where Lead Acid was too heavy and too inefficient. I am in the minority on this forum as a fan of Lithium batteries.

[chrisski]

Read his post. He has an open flame gas water heater in the garage where his batteries would be. He was worried about hydrogen fumes. I know an alternative is he could make a covered container and vent it to the outside.

As a guy getting ready to drop the money to buy a set of 400 ah batteries, there's nothing more dangerous about lithium batteries is there?

My situation is an RV install. I will put the solar system in the large luggage compartment under the RV of my fifth wheel. Also, I will somehow partition this out to keep the equipment safe from items moving around.

[Ampster]

Well if he was concerned about Safety, last thing he would want is Lithium.

Read his post. He has an open flame gas water heater in the garage where his batteries would be. He was worried about hydrogen fumes. I know an alternative is he could make a covered container and vent it to the outside.

[chrisski]

Well if he was concerned about Safety, last thing he would want is Lithium.

Care to elaborate?

[Sunking]

If you are concerned about safety have you considered Lithium?

Well if he was concerned about Safety, last thing he would want is Lithium.

[Sunking]

Can't use flooded. Batteries are in a confined space with open flame water heater. No other option. But you have answered my question Linus. In your opinion, No GEL. The Guy with the AGM is actually more on target given the big load from the compressor start up based on what you said. Anyone else care to weigh in?

I am KF5LJW and you know what that means. OK you fit the AGM profile. An AGM battery biggest advantage is the very low internal resistance, lower than most lithium types for a given capacity. What that means is they can withstand very high charge and discharge rates expressed as C-RATE. A typical FLA battery can only deliver about a C/8 maximum discharge rate without suffering significant voltage loss. A C/8 Discharge rate would be 10-Amps on a 80 AH battery. A 80 AH AGM on the other hand can easily supply 20 to 40 amps. Some AGM batteries made for Telecom. Space Craft and UPS can deliver as much as a 4C rate or 15 minute discharge rate. On a 80 AH battery is 320 amps. But it comes with a cost.

As for battery voltage and size depends on the application. More importantly how much power are we talking about. 12-Volt systems are small toy sized systems. They are not capable of doing a lot of work. Example if your panel wattage or inverter is larger than 500 watts, is time to move up to 24, 49, or 96 volt systems. Bottom line is this: Never ever parallel parallel batteries. If you need 400 AH, then buy 400 AH batteries. You will not find 400 AH 12 volt batteries. You would have to use 6, 4, or 2 volt batteries in series to make 12 volts.

Whatever you do, do not listen to ham radio operators to tell you how to use solar, battery, or anything about Grounding or Power. 90% of them have no clue.

FWIW, to have backup power, solar is the last thing you want. No commercial radio operator or any professional uses solar for back up power. All of them use a Battery Plant and Rectifiers to run all the equipment. Nor would you want to use solar on radio equipment. You will soon discover why with all that noise you will be generating will wipe out your RX. Only good reception will be after sunset. If you want battery back up for your radio toys, use your Astron PS as a battery charger, and float your batteries. Your batteries will last 4 times longer and no NOISE.

[chrisski]

Thanks. I do want to hear what you put in for batteries and read an update after they've been in for a while. For me, the batteries are the hardest choice.

[SageOldmann]

I have generators. They are for the heavy lifting like the furnace, fans, and refrigerator. Solar will be used daily with a pure sine wave inverter for tv, computer, ham shack etc and be available for them also in a power failure.

[chrisski]

Mike90250 I'm seeing dozens of posts all over the place where people use 2 banks of 2, 6 volt 225ah AGM batteries in series then both banks are wired parallel give them 12 volts with double the amps of just the one bank. One solar expert said.... "It is common practice to series then parallel connect lead acid, Lithium and other types of batteries. How you wire up larger banks of batteries is up for debate but four 6 volt batteries to make a 12 volt 450Ah battery is commonly done without problems."

Does this work or does the "parallel is a bad idea" come into play for this kind of set up as well? Will it still end up steering power to one battery bank more than the other?

I'm choosing the battery system for what I'm building now. What caught me first is the "I have limited funds but have enough to bring my current system up to either of these levels." If you're on line power now, and only plan on using this for power outages, I really think you can get a brand new pair of Craftsman Inverter Generators at 2300 watts each, parallel them together with the accessory cords to 4100 watts total which may go through a gallon of gas total an hour, and run what you need when the power goes down for a whole lot less effort and money. My big assumption is you won't lose power more than 24 hours at a time and you have vehicle access to this place.

This system I'm building may not be the most rational decision, but I've decided I'm going to get 600 watts of panels on top of my RV to power a 1000 watt inverter powered by a 400 amp (type undetermined) battery bank. I will be able to watch all the TV I want with that, and I can make myself coffee out of an electric brewer, one cup at a time. I will also be able to microwave my popcorn. My fridge and water heater will both be gas.

[SageOldmann]

My suggestion, use the expensive, short lived AGM. Also, consider building the bank out of two series wired golf cart batteries (6v, 200ah) which solves the AGM "battery in parallel" problem. (AGM is so low resistance, that the parallel interconnect wires will steer power to one battery which will end up doing 80% of the work and fail earlier than expected)

Mike90250 I'm seeing dozens of posts all over the place where people use 2 banks of 2, 6 volt 225ah AGM batteries in series then both banks are wired parallel give them 12 volts with double the amps of just the one bank. One solar expert said.... "It is common practice to series then parallel connect lead acid, Lithium and other types of batteries. How you wire up larger banks of batteries is up for debate but four 6 volt batteries to make a 12 volt 450Ah battery is commonly done without problems."

Does this work or does the "parallel is a bad idea" come into play for this kind of set up as well? Will it still end up steering power to one battery bank more than the other?

[Ampster]

I understand. I don't presume know your desire to assemble a pack but when I saw that $1000 price tag for two 370 Ahr AGMs I couldn't help but do the math. Those AGMs are $225 per kWh.
In addition, because of their efficiency and larger depth of discharge you would not need the same capacity of Lithium batteries as you would need in AGM.

I am not trying to talk you into something you are uncomfortable with, but for the benefit of other readers. who may have the desire to DIY, I thought it might be useful to explain that there are less expensive alternatives.