AGM or GEL Batteries? Which is best?

[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.

[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.

[chrisski]

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

Care to elaborate?

[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]

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]

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.

[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.

[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.

[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?

[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]

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..

They don;t put utility scale batteries in a house, they are outside in steel building with lots of clearance in the event of an explosion. They have highly trained personnel with factory training and PPE. I have read your advice, and you are an extremely dangerous DIY who knows just enough to get yourself and others hurt. If they do will come to you and this website with a lawyer.

Yep military uses them to kill people. Soldiers are expendable and cannot sue the government or battery manufacture. In fact just talked to a Captain of an active submarine a week ago. Found it very military. He and his crew just learned there was a virus pandemic going round and they cannot go home for another week. You are not military, you are a civilian and an active member of the Green Mafia.

Bet you were glad I came back huh?

[Ampster]

They don;t put utility scale batteries in a house, they are outside in steel building with lots of clearance in the event of an explosion. They have highly trained personnel with factory training and PPE. I have read your advice, and you are an extremely dangerous DIY who knows just enough to get yourself and others hurt. If they do will come to you and this website with a lawyer.

Exactly that is the kind of risk management strategy I am talking about. For my garage my AHJ just wants to see a NEMA cabinet. Since I am using LFP batteries and several fail safe devices like a automotive grade BMS and a UL approved inverter I think I can manage the risk of over charging those cells. I know enough about risk management to know there is little risk that the advice I give will result in a lawsuit. I am careful to use qualifiers so that the NEC should always govern. I know enough about tort law in California to not worry about advice offered on a public forum. Besides, I have an umbrella policy.

Yep military uses them to kill people. Soldiers are expendable and cannot sue the government or battery manufacture. In fact just talked to a Captain of an active submarine a week ago. Found it very military. He and his crew just learned there was a virus pandemic going round and they cannot go home for another week. You are not military, you are a civilian and an active member of the Green Mafia.

Bet you were glad I came back huh?

I think the site owners are glad to have you come back for the traffic that you will generate for them. I think most newbies go to other sites unless they want good advice on Lead Acid or living off grid. There is still some good advice about solar system diagnostics as well. That is what I hang out for. Most of the grid tie TOU knowledge I get elsewhere.
I belong to enough other forums that I can get my intellectual stimulation satisfied. There is not much happening here that interests me, especially in the off grid Lead Acid realm.

I don't care one way or the other if you are back although one thing I do enjoy about having a conversation with you is that it is good practice for dealing with my 86 year old sister.

[bcroe]

Bet you were glad I came back huh?

That is good, we needed more action and history here. Anyway I do not want to be
the one swinging the 2 x 4. Bruce Roe

[SageOldmann]

Based on everything I have heard, if someone needed 100Ah of battery usage everyday he would need a 200Ah amp AGM battery bank because he can’t go lower than 50% DOD. To fully recharge every day he would need about 500 watts of solar panels and a 40 amp charge controller to recharge the 100 Ah he used.
One guy has a different approach. He thinks you should use the 500 watts of solar panels and a 40 amp charge controller to recharge the 100 amps used every day, but double the size of the battery bank to 400Ah so your DOD would only be 25%. Would this be good or bad for the batteries? Would it give them a longer life? He says it also gives you a cushion of 100 Ah for a cloudy day when you can’t fully recharge after using 100Ah the previous day and need to use another 100Ah today. This would then be 50%DOD for the 400 Ah battery bank. Any down side to doing this if it takes an extra day or two to get back to full charge?

[Ampster]

That is good, we needed more action and history here.

Get out the popcorn.