AGM or GEL Batteries? Which is best?

[Sunking]

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.

Who told you that garbage? A DIY site?

If you need to use 100 AH of battery capacity per day would require:

Pb = 500 AH
LFP = 350 AH.

First if you discharged either 50% each day would wear both batteries out quick. Second WTF are you going to do during cloudy spells sitting in the dark? Size as per above and both have 3-day run times before you are forced to shutdown and wait a few days to fully recharge if you were dumb enough not to have a generator. Something to think about siting in the dark after spending all that money.

[Ampster]

............I do not want to be the one swinging the 2 x 4.

However if you ever get in a situation where you might need to do that, just remember that Aluminum will last a lot longer and is more "fit for purpose".

[J.P.M.]

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.

Do you have some reliable information besides what the greenwash media foists on the energy ignorant pubic that you could point us to that backs up the statement that LI batteries are making peaker plants less cost effective than other means of meeting their duty in CA and elsewhere ? Any real data that might help us understand your claim ? If peaker plants are reaching what you call economic obsolescence, are you implying that Li batteries are the only reason for that economic obsolescence ?

Even if they are - which may/may not be true if/as newer tech leapfrogs past Li, what does utility scale energy storage applications have to do with safety in a residential application ?

To say "some smart money..." sounds a little too close to the renewable energy dreamer handwaving, wishful thinking, rose colored glasses and grossly uninformed dismissal crap that glosses over what are often inconvenient but real details. What smart money would that be ?

Seems to me Li batteries may offer some promise of phasing out fossil fuel fired peaker plants, but to imply that promise makes Li batteries safe for a garage or basement makes about as much sense to me as saying because nuclear power doesn't have too many accidents that it's safe for your garage.

As a retired designer with some experience as a project manager of installation and startup of industrial power generation equipment, including a couple of storage interfaces, I'd suggest to you that utility level application and requirements for power generation and storage are completely different from what you may think you have experience with.

[Ampster]

Do you have some reliable information....... that LI batteries are making peaker plants less cost effective....? ...... If peaker plants are reaching what you call economic obsolescence, are you implying that Li batteries are the only reason for that economic obsolescence ?

https://www.utilitydive.com/news/pge...ojects/578389/
I have posted links before. Some time ago I went to the CEC site and there have been no peaker plants constructed in California in approximately the last ten years. I can google the last one if you want that detail. It seems to me like a disruption is occuring and investment capital is flowing into that technology. You are free to form your own conclusion. @Sunking still thinks there basements in high rises full of Lead Acid batteries and that may be true but not in the scale as noted in the above article. It is simply a trend that is informative.
I would be happy to answer any other questions after you have digested that article, but I don't want to further hijack this thread. You can start or I would be happy to start a new thread about trends in the utility industry..

[Mike90250]

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?

Here's my weather chart from a winter week (more text below)

solar clouds 1-2020.jpg

There is a good 4 days of solid clouds. I can go 3 days without running the generator, but I usually run it daily to keep the batteries up. Wed 22nd, there is a partial break in clouds and my solar did nothing of utility -still running the generator.
How many cloudy days do you need to survive ?

[SageOldmann]

Who told you that garbage? A DIY site?
If you need to use 100 AH of battery capacity per day would require:
Pb = 500 AH.

That sounds reasonable Sunking. Based on other posts you have made it sounds like, correct me if I'm wrong, I could do 2, 6 volt 480 Ah AGM in series, and run them to 20% DOD each day for my 100 Ah needs, without significantly shortening battery life. I could use 600 watts of solar panels and a 50a mppt SCC to mostly recharge the used 100 Ah on sunny days, (is this enough?), and use a generator to bring the batteries up to 100% when it gets too cloudy for too long. Do I understand you correctly or am I off on any of these numbers?

[J.P.M.]

https://www.utilitydive.com/news/pge...ojects/578389/
I have posted links before. Some time ago I went to the CEC site and there have been no peaker plants constructed in California in approximately the last ten years. I can google the last one if you want that detail. It seems to me like a disruption is occuring and investment capital is flowing into that technology. You are free to form your own conclusion. @Sunking still thinks there basements in high rises full of Lead Acid batteries and that may be true but I not in the scale as noted in the above article. It is simply a trend that is informative.
I would be happy to answer any other questions after you have digested that article, but I don't want to further hijack this thread. You can start or I would be happy to start a new thread about trends in the utility industry..

I'm pretty sure I don't agree with what amounts to your inference that "Utility Dive" fits the criteria of reliable information. After watching them for some time, Utility Dive seems, to me anyway, to be more of a garden variety greenwash media type that makes it's living off hyping and cherry picking half truths or less, taking most of it out of context and recasting press release info and/or stuff from other sources who play the same game to the point where they generate some B.S., and then quote it when some other hacks with the same M.O., then call it meaningful information and reprint it as news. Basically, it looks to me like the type of place where technically ignorant folks get their feel good junk that fits the version of reality that they've formed. The more informed someone is, the quicker they see it for the biased it is.

After your post, I revisited their website and looked at their editorial board. I was not impressed or surprised, starting with their senior editor who looks like Opie on Ritalin.
The rest of the editorial board seems a collection of kids who seem to believe formal education of any sort is the most important criterion to discussing and being informed about energy matters. Besides Opie, the rest of that board with any seem to be a lot of younger folks with a mix of journalism degrees and other stuff such as french, communication, political science. There's a refugee from a non profit, a former chiropractor who once read something by Dan Yergin (another energy info whore), and some guy holed up in a tiny off grid cabin in upstate NY real close to the action who, along with having a tuition receipt for studying journalism, seems to think his diploma in culinary arts and some pictures that are liked by someone at the National Endowment for the Arts are salient and meaningful contributions to C.V. related to energy issues.

Probably all nice people, and probably a very interesting and eclectic but not, IMO anyway, a bunch with a high likelihood of being qualified to offer information about energy matters. All in all, not the sort of individuals with backgrounds or experience I'd get my energy information from, but opinions vary.

The above are some of the reasons why I think your source is not one that has reliable information. So, in the context of my prior post to this thread, I'd say the answer to my posed question is no.

I'd note, sort of analogous to the ludicrous idea of thinking reporters are qualified to write papers with meaningful content for medical journals, taking what looks like a bunch of folks technically untrained and inexperienced in the energy field and thinking they can produce articles with real, objective material with real meat on it in areas where they have not the technical trained, educated or experienced about subjects they are writing about is like dreaming in technicolor. Looks to me like Energy Dive is a bunch of cooks, chiroquacks, and folks unable to get a real job in the energy field.

As for the other stuff in your post:

Don't bothering to Google what I can find on my own.
Thank you for your permission for me to form my own conclusions, but it's not necessary.
My post you responded to was in reference to lithium batteries. I don't do other's thinking for them, and I'm mostly ignorant of the state of battery storage in high rises, but I'm pretty sure Sunking was referring to AGM batteries in basements, not lithium batteries.
As for trends, they are interesting but it seems to me they are easily mischaracterized and so need context within the bigger picture. A trend is not a stampede. Some folks with something to gain would try to make it seem so.

Take what you want of the above. Scrap the rest.

[Sunking]

That sounds reasonable Sunking. Based on other posts you have made it sounds like, correct me if I'm wrong, I could do 2, 6 volt 480 Ah AGM in series, and run them to 20% DOD each day for my 100 Ah needs, without significantly shortening battery life. I could use 600 watts of solar panels and a 50a mppt SCC to mostly recharge the used 100 Ah on sunny days, (is this enough?), and use a generator to bring the batteries up to 100% when it gets too cloudy for too long. Do I understand you correctly or am I off on any of these numbers?

You are on the right path, and have a few details that have not occurred to you yet. 20 to 25% DOD is correct and the accepted design practice sizing batteries. What has not likely occurred to you yet is solar is not capable of fully charging your batteries unless grossly over sized and under utilized. The simply is not enough sun hours in a day to complete a full saturation charge. What I am leading up to is a generator is mandatory. About once a week or so, you need to run a genny to to top off the batteries, and about once a month or two run a EQ charge. As you are now aware, the genny is also required to CYA for cloudy spells.

As for panel wattage, well that is a moving target. It depends on your location and time of year. Example lets say you need 1 Kwh of electricity per day. or about 8-9-cents worth of electricity. Two locations, Tuscon and Gloomy Doomy Seattle or Portland where they stay under the cover of ganja smoke most of the time. To generate 1 Kwh of electricity in Tuscon in December only requires 200 to 300 watts of panels because that area receives roughly 4 Sun Hours in winter. . If you are stoned in Seattle will require 1000 to 1500 watts of panel to generate the same amount of power in winter months. If that is not bad enough, stoners also are forced to use much more expensive AGM batteries to handle the extremely high Charge Current required to recharge in a couple of hours.

So yes sir you are well on your way to understanding. Just some loose dots you have not connected as of yet. Now you have a couple more dots to line up to achieve your objective. Basic steps:

1. The most important step is the first step, determine your daily energy needs in Kwh. Fail to do that, then your plan is to fail and loose money. All other steps are determined by step 1.
2. Determine battery Voltage and Capacity.
3. Determine panel wattage and controller for your area.
4. Determine Inverter size.
5. Determine generator and battery charger size. You want the generator sized large enough to provide a C/6 charge rate, and supply power to the loads. This will minimize run times and fuel burn.

[SageOldmann]

1. The most important step is the first step, determine your daily energy needs in Kwh. Fail to do that, then your plan is to fail and loose money. All other steps are determined by step 1.
2. Determine battery Voltage and Capacity.
3. Determine panel wattage and controller for your area.
4. Determine Inverter size.
5. Determine generator and battery charger size. You want the generator sized large enough to provide a C/6 charge rate, and supply power to the loads. This will minimize run times and fuel burn.

This is what I’m working with as of right now. Tell me where I’m off base.

1.
Looks like 1.75 Kwh based on 15 amps or 2.53 based on 22 amps. I have two options right now based on 15 amps of equipment running a minimum of 5 hours per day, that would require either around 75Ah per day, or with options, that would run it up to 22 amps, or about 105Ah per day. I can go either way. If going with the 105 Ah requires a LOT of spending for bigger or better "whatever" I would rather go with the 75Ah.

2.
This is an unknown for me. I guess I am working from my solar panel capacity which is limited. I do know I want 2, 6 volt AGM batteries in series. My best
guesstimate is about 480Ah.

3.
Given limited mounting space and some 12 volt panels I stole for almost nothing. I am looking at 620 watts for
my 12 volt panels in parallel. I will probably go with a 40a MPPT SCC. A 30a SCC would be close, given I will
probably never actually see the 32 amps from these panels but who knows, I may get bigger panels later.

4.
Got my hands on a 1,000w pure sine wave inverter for peanuts. I’m hoping it’s big enough for my needs.

5.
I have a 1600 watt (2000w surge) generator. 13.3 amp. I can buy a second and parallel connect them for
3,200w if I absolutely need to, but prefer to use just this one if possible.
I don’t have a charger. I guess I should get one just to keep the batteries topped off every day. Any
suggestions on amps/type/brand?

[Sunking]

This is what I’m working with as of right now. Tell me where I’m off base.

1.
Looks like 1.75 Kwh based on 15 amps or 2.53 based on 22 amps. I have two options right now based on 15 amps of equipment running a minimum of 5 hours per day, that would require either around 75Ah per day, or with options, that would run it up to 22 amps, or about 105Ah per day. I can go either way. If going with the 105 Ah requires a LOT of spending for bigger or better "whatever" I would rather go with the 75Ah.

2.
This is an unknown for me. I guess I am working from my solar panel capacity which is limited. I do know I want 2, 6 volt AGM batteries in series. My best
guesstimate is about 480Ah.

3.
Given limited mounting space and some 12 volt panels I stole for almost nothing. I am looking at 620 watts for
my 12 volt panels in parallel. I will probably go with a 40a MPPT SCC. A 30a SCC would be close, given I will
probably never actually see the 32 amps from these panels but who knows, I may get bigger panels later.

4.
Got my hands on a 1,000w pure sine wave inverter for peanuts. I’m hoping it’s big enough for my needs.

5.
I have a 1600 watt (2000w surge) generator. 13.3 amp. I can buy a second and parallel connect them for
3,200w if I absolutely need to, but prefer to use just this one if possible.
I don’t have a charger. I guess I should get one just to keep the batteries topped off every day. Any
suggestions on amps/type/brand?

OK you asked for it. Have you read the STICKIES. It is detailed out for you.But here is a start.

1. Right idea, wrong units of measure that leads to errors and does not account for system losses. You work with Watt Hours, not Amp Hours. 12 volts x 15 AH x 5 hours = 900 Watt Hours.

2. Battery Capacity = 5 days x Daily Watt Hours / Battery Voltage. 4500 WH / 12 volts = 375 AH battery

3 You might have troubles that may or may not work out for you. Depends on your location. 600 watts of panels should work unless you are in the Pacific NW. With 6 panels you will wire them 3S2P and you must use a MPPT Controller. Your calculations are incorrect to to size controller. I will give you the formula and let you figure out what is wrong. MPPT Controller Current = Panel Wattage / Battery Nominal Voltage. 620 watts / 12 Volts = ?? Amps. Do you have an issue?

4. Common mistake, hope it works. A 1000 watt Inverter @ 12 volts will take 80 to 90 AMPS at full power. A 12 volt 150 AH battery can only deliver 15 to 20 amps, enough for a 200 to 250 watt inverter.

5. Again right idea but way off on numbers. This is because you do not understand units of power and basic ohms law. A 1600 watt generator @ 13.3 amps only tells you the generator voltage = 1600 watts / 13.3 amps = 120 volts AC. 1600 watts @ 12 volts DC = 133 amps, enough to blow up a 150 AH battery in 1 minute. The Generator will work, all it needs is a 50 amp 12 volts DC charger. 12 volts x 50 amps = 600 watts just like your panels, or about 30% of your generator capacity.

Keep digging, you are on the right path. I will help you, but you must do the work yourself and find the answers. When done you will know how and why. Right now I can tell you a 75 or 150 AH is grossly undersized, and with 620 watts of panels will cook them with 50 amps of charge current. With 600 Watts of panels you are looking at a minimum 300 AH battery with 375 being a great fit based on your numbers. You may not like the results, but at least you will know why and the consequences if you try.

[SageOldmann]

Great information and education. I'm no electrical engineer but this is very helpful and I hope I can figure this all out. I'll do my homework over the weekend and see where I end up. I'm sure I will have additional questions afterwards. Thanks.

Two things right now though to clarify. You said “The most important step is the first step, determine your daily energy needs in Kwh"
So I used this calculator I found on-line www.rapidtables.com/calc/electric/Amp_to_kW_Calculator.html to convert my amps for each device to kilowatt hours with these parameters.
AC single Phase / 15 amps / 115 voltage / power factor of “1”. It gave me 1.75 Kwh. Is this not what I was supposed to do? Isn't this my watt hour needs?

Also I am calculating based on 5,12 volt panels, not 6. 3 are 100w rated a 5.39 amps each, and 2 are 160w rated at 7.89 amps each, if that makes any difference. That looks like 32 amps to me, not 51 which the formula suggests. Maybe I just don't understand how this exactly works.

[chrisski]

I hope someone will chime in and say if this is correct or not on the first part. Also don't want to derail to OP's thread, and I think these are on track.

I decided not to use 12 volts into the charge converter, in part because a lot of the charge converters I looked at would not start to charge the batteries until panel voltage exceeded battery voltage by 4 to 5 volts, and then this could drop so panel voltage exceeded battery voltage by one or two volts. I think I could loses a lot of charging hours on a cloudy day because that original Battery + 4 volts was never enough to turn the charge controller on simply because the panel produced 12 volts on an overcast say when the battery was at 12.5 volts.

This is about #4: Also, as far as max discharge rates for batteries, I have not seen much, if any of that on any of the downloads from the manufacturers' sites. Where exactly do I get this discharge rate? Is this some term I'm not familiar with? Perhaps this is a fixed rate based off battery type like SLA or LIFePsO? All I can find is anecdotal evidence that Lithium seems to power a 2000watt inverter better than what his 2000 watt inverter did when he used the AGM batteries. I like tech data.

I've got up to 5 months before I start wrenching this system togethe, and honestly the battery portion seems to be the hardest for me to figure out. I've seen suggestions to look a 2V or 4V cells for a 12V 400 AH system in series, but there is far less data about these lower voltage batteries than the 6volt or 12 volt. I could be looking in the wrong place.

[Sunking]

Sage now I get different units of measure. is it 12 volt battery with 15 amps for 5 hours, or 15 amps at 120 volts. That is a factor of 10.

[Mike90250]

I hope someone will chime in and say if this is correct or not on the first part. Also don't want to derail to OP's thread, and I think these are on track.

I decided not to use 12 volts into the charge converter, in part because a lot of the charge converters I looked at would not start to charge the batteries until panel voltage exceeded battery voltage by 4 to 5 volts, and then this could drop so panel voltage exceeded battery voltage by one or two volts. I think I could loses a lot of charging hours on a cloudy day because that original Battery + 4 volts was never enough to turn the charge controller on simply because the panel produced 12 volts on an overcast say when the battery was at 12.5 volts.

All charge controllers require "overhead" to charge batteries. generally, a PV panel with a 20V Vmp is used to charge a 12V battery with a PWM charger
( anyone need a glossary at this point) Vmp = Voltage max power. PWM = Pulse Width Modulation

PV panels produce full voltage with just a small amount of light. Amps are produced from More Light. If you overload a PV panel, it's voltage will sag, so at 6:30 am, there is usually too little light to extract any power from a PV panel. Battery voltage or array voltage has nothing to do with it, it's how may photons are hitting the panel to kick electrons loose.
Panel Temperature is what regulates the voltage, cold weather, slighter higher voltage, hot weather = a little less voltage.

This is about #4: Also, as far as max discharge rates for batteries, I have not seen much, if any of that on any of the downloads from the manufacturers' sites. Where exactly do I get this discharge rate? Is this some term I'm not familiar with? Perhaps this is a fixed rate based off battery type like SLA or LIFePsO? All I can find is anecdotal evidence that Lithium seems to power a 2000watt inverter better than what his 2000 watt inverter did when he used the AGM batteries. I like tech data.

I've got up to 5 months before I start wrenching this system togethe, and honestly the battery portion seems to be the hardest for me to figure out. I've seen suggestions to look a 2V or 4V cells for a 12V 400 AH system in series, but there is far less data about these lower voltage batteries than the 6volt or 12 volt. I could be looking in the wrong place.

Not all battery mfgs are proud of their product discharge curve ( voltage sag under load ) and lead acid batteries are only good for a couple minutes of high surge. Lithium batteries are better at heave surges & loads for longer time, before they run out of juice. But both can hold the same watt hours of power, lead acid is not as good at delivering it quickly.

[Ampster]

I hope someone will chime in and say if this is correct or not on the first part. Also don't want to derail to OP's thread, and I think these are on track.
......

This is about #4: Also, as far as max discharge rates for batteries, I have not seen much, if any of that on any of the downloads from the manufacturers' sites. Where exactly do I get this discharge rate? Is this some term I'm not familiar with? Perhaps this is a fixed rate based off battery type like SLA or LIFePsO? All I can find is anecdotal evidence that Lithium seems to power a 2000watt inverter better than what his 2000 watt inverter did when he used the AGM batteries. I like tech data.

I've got up to 5 months before I start wrenching this system togethe, and honestly the battery portion seems to be the hardest for me to figure out. I've seen suggestions to look a 2V or 4V cells for a 12V 400 AH system in series, but there is far less data about these lower voltage batteries than the 6volt or 12 volt. I could be looking in the wrong place.

The discharge rate and the charge rate should be in the manufacturers specs. They are often couched in terms of C rate. I think there are stickies that explain in more detail. Just make sure you interstate the distinction between 1C and 1/C. They are entirely different.

I think what you may be seeing or hearing is that Lithium is more efficient. It can charge faster at 1C versus 0.3C for Pb. Lithium does not waste as much energy in heat during the constant voltage phase (Absorb) as Pb. Secondly you can use 80% of the Litihum battery capacity compared to 50% for Pb. That means you can get by with a smaller pack which can offset the higher cost of Lithium.
I realize some of the above is anecdotal. The literature from the Lithium battery suppliers, once you get past the specs is full of sales info. Pb is a tried and proven chemistry. However there are reasons that all the grid storage and EVs are powered by Lithium. Not to mention the smartphones that have become ubiquitous. Those reasons are efficiency and long term cost of energy storage.

There are risks with Lithium. If you understand the risks, know how to mitigate those risks then the overall risk can be reduced and compared with the long term cost per kilowatt-hour of stored energy.

All I am trying to do is give you the framework so you can make the best decision for youself. I have no skin in th game but I have been using Lithium batteries for 25 years without incident.