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maddiecycle
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# Posted: 8 Jun 2021 04:06pm
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Hello. I am setting up a small solar setup. Going to use Renogy panels and charge controller, still settling on what inverter to use, but my main question is what AGM battery brands to look at. Renogy and Trojan are good but pricey. What about other brands like Might Max, Interstate, Duracell, Universal? Worth looking at to save some money?
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gcrank1
Member
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# Posted: 8 Jun 2021 04:36pm
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Have you bought the panels and cc yet?
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maddiecycle
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# Posted: 8 Jun 2021 04:49pm
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I came into a bunch of Renogy panels that are brand new, so yes I have those. The Renogy MPPTs look decent to me....
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gcrank1
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# Posted: 8 Jun 2021 06:18pm - Edited by: gcrank1
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Before buying anything more I heartily recommend you spend some time over at 'diysolarforum.com'.
They are a lot like us here, and some members are on both fora, but they are solar specific. Imo (and I have a small scale solar system) you NEED specialist help if you really have to watch the money (like me). Warning, some stuff sounds good but aint, not all 'solar stuff' plays well with others and the products are changing quickly. For instance, panels have come way down in price and up in efficiency but storage (the battery bank, to your inquiry) is still huge money and easy to make mistakes with. Batteries are a big study unto themselves.......
Heads up 1st question: What are your intentions? Ie, what do you need to power and what do you envision powering?
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maddiecycle
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# Posted: 8 Jun 2021 06:48pm
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Thanks Gcrank1. I will check out that forum. I have experience with solar and electrical work and a degree in engineering so I do feel good about things overall and know all of the issues and pitfalls. Mainly batteries is where I need help, hence the question I asked.
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gcrank1
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# Posted: 8 Jun 2021 07:34pm
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You are lucky then, way ahead of the curve compared to many who get interested in solar!
Diy' has a battery specific sub-forum.
Fwiw, if I were starting over/from the beginning I would be going 24v rather than 12, or even 48v if going BIG. As you know, higher voltages allow smaller gauge wiring, more important than many realize.
Id still be doing as I do now, solar into battery-bank, inverted close by to 120vac (or even 240) to a service panel. By wiring the cabin to 120vac simplified the wiring, fixtures, switches, etc Big Time (I had done 12vdc previously, then had both dc and ac for a while).
Im small scale, low demand; 4 x 102w panels as 2s/2p array (with another 2s in reserve to make 2s/3p) and an MPPT charge control. Only go MPPT on anything bigger than basic. My 10ish year old Blue Sky 50 cc is adequate for my array but a newer model with more VOC input capacity would be nice, and Im limited to 12v or 24v, some newer can do 48v too.
Which gets me juice to the bat-bank, which started as 4 BIG 130ish ah agm 'ups' type batteries in parallel.
Properly wiring 4 parallel batteries is more complicated than many realize. Another note that may be of interest is that it has been said,"the 1st set of batteries will not be just killed, they will be murdered". I feel somewhat fortunate that the system I 'inherited' with the cabin purchase was fairly well set up, though kinda hacked together. Those batteries have lasted, well, one is still in use, for 10years.
At this point, knowing that remaining bat is well reduced in capacity (likely pretty sulfated) and 'cycled out' I need to be getting a new bank. I wont be going with 4 again, at least not in parallel. Since this is a recreational cabin with light duty elec needs (heavy loads are provided by my 2kw inv/gen) Im likely going with 2 6v 'golf car' batteries in series for 12v/220ish ah gross which is 110ah net MAX usable at a 50% depth of discharge (dod). Do NOT believe agm claims of 80% dod lest you murder your battery(s).
The GC2's are old school 'wet' lead acid batteries, far cheaper than agm's, require some 'not so bad' maintenance, will off-gas a bit and are real deep cycle batteries. Agms have a place, just not required at every place doing solar. I dont have to keep my bank in cabin so the off-gasing of the GC2's isnt a problem (there are at the 'powerhouse' 90' away).
Id sooo like to go LFP but am not ready to pay the price for ready made or to build my own; you may be able to. It looks like a 10+ year life, many more cycles, more cost effective over time, lighter and waayyy more dod capable without harm.
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NorthRick
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# Posted: 9 Jun 2021 01:15am
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I didn't read all of gcrank1's reply, but if you are a beginner, I'd strongly recommend flooded lead acid batteries to start with.
For a stationary application they are the way to go. AGMs cost more and have a shorter life. In a vehicle it's a trade off that can be worth it to not have liquid acid that can spill. For batteries sitting on the floor or on shelves, not so much. So for a cabin, AGM versus flooded is a no brainer in my opinion.
Now lead acid versus lithium, LFP in particular, that is getting less clear cut. Pluses and minuses to both. The biggest minus to LFP (or other lithium chemistries) is cost. And here's the big thing, if you are new to this, there is a fair chance something could go wrong and wreck your battery bank.
Start with a less expensive and more known system (lead - been around over 100 years) and cut your teeth before trying the new, expensive system (lithium).
I have a weekend cabin and have gotten close to 10 years out of a battery bank comprised of Costco "golf cart" flooded lead acid batteries.
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Brettny
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# Posted: 9 Jun 2021 06:04am
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For price/availability I went with a 12v system. The money I saved by buying a used xantrex 12v inverter I could put 2 more gc2 flooded batteries and another pannel. I went with flooded golf cart batteries due to price and I have delt with battery of this type quite a bit in the past. I wouldnt even consider AGM due to no increase in capacity for the price. Il go lithium maybe..when my FLA are dead.
Sam's club, walmart and golf cart sales businesses would be able to supply you with flooded batteries.
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Steve_S
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# Posted: 9 Jun 2021 07:56am - Edited by: Steve_S
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I'm here & at DIYSolar too, I'll provide a quicky snapshot of stuff for you to ponder. Some you likely won't like.
EE's are fine, some of us are there. But AC & DC are different, can be confusing and terms between batt types (FLA vs LFP) are not the same creating more confusion. I'm a retired Board Level eng.
1st: Sorry by Renogy HAS a rep and it's NOT good. They spend huge on promo not much on support & terrible with it. Tons of reviews & bad experiences prove that, nothing much else to say. Avoid Renogy if possible. Free is better than nothing but do not expect too much from any of it.
A General Rule:
Battery Based system should not exceed 250A Draw from a battery bank. (excluding surge capacity)
12V@250A=3000W, 24V@250A=6000W, 4V@250A=12,000W (uncorrected for inefficiency)
Low Frequency Inverters (Best Option) can handle up to 3X surge.
High Frequency Inverter (not great) can handle 2X Surge.
Understand the difference:
https://www.magnum-dimensions.com/knowledge/high-vs-low-frequency-inverters/inversion -methods-explained-high-frequency-vs-low
Batteries in KISS form:
AGM, like FLA is old tech.
They can only be used to 50% DOD (depth of Discharge) A 200AH battery only can provide 100AH useable.
Real Deep Discharge Deep Cycle AGM/FLA is NOT cheap. IE Rolls L16 6V = $350 EA!
Many AGM/FLA Manufacturers have been bought up by investment firms, labels left intact but product quality shot to hell. To get ANY good Quality Lead Base you are spending hard cash.
BTW: My 8 Rolls Surette S-550 428AH 6V cells cost me $3200 5 years ago. 214AH of that is useable. This is now my Backup Bank.
My Primary is now 1190AH/30.4kWh LFP of which I can tap 95%.
Current Prices: (24V/280AH/7.168kWh)
8X EVE-280AH-Matched/Batched $125ea/ $1,000
1X 8S 300A BMS $250-300
1X 300A MRBF Fuse $30
2X 3/8" Battery Terminal Lugs (Plated Brass). $30
Casing/Box or Rack: ? up to you.
$1360 USD for the above Delivered to your door (if US or Canada) THAT is 280AH useable ! No futsing with watering, acid testing, no explosions, no hydrogen generation.
Attached is a Guide I wrote on Prepping & Assembling an LFP Battery Pack. I have other guides, docs and resources but that's all on DIYSolar.
Good Luck, Hope it helps
Steve
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Brettny
Member
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# Posted: 9 Jun 2021 08:49am
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For refrence I paid $690 for 307ah of useable flooded lead acid batteries.
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paulz
Member
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# Posted: 9 Jun 2021 09:13am
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Quoting: Steve_S Low Frequency Inverters (Best Option) can handle up to 3X surge. High Frequency Inverter (not great) can handle 2X Surge.
Hey Steve, when shopping for inverters do they list hi or low frequency? Haven't noticed it.
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Steve_S
Member
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# Posted: 9 Jun 2021 09:13am
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Brand, Make & Model of that Lead ? and DATE Bought !
$$ value otherwise = useless.
Cheap Chinese Made FLA is Cheap and equally poor for the price. You get what you pay for.
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SCSJeff
Member
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# Posted: 9 Jun 2021 09:38am
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My .02...
I think it depends on your use... For a weekend cabin, cheap Costco Golf Cart Batteries can last a long time if cycled gently. I'm on year 7 on mine. Probably used about 12-15 weekends a year and never below 70-75 percent. Funny... everyone says you will kill your first set of batteries. I guess that's not true across the board. But, I did lots of research and learning before I jumped in.
That being said, I am currently waiting on an order of LFPs to replace them 
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gcrank1
Member
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# Posted: 9 Jun 2021 10:05am
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I-net searches on the performance of a given brand and even specific model battery may not apply to anything made within the last year or two; no way to base expectations of lifespan/cycles/cost effectiveness unless perhaps buying the very most premium products. From my search in the past 2 years of such I dont think Trojan is up there any more, much less the other brands mentioned in the 1st post. Btw, boating/fishing forums are informative regarding so-called 'deep cycle' batteries.
To me, if Im looking at 'less than the best' I would like the best bang for the buck but it all seems a craps-shoot.....so I either go LFP or stick with what Im most comfortable with, the old Lead Acid, on the 'lower cost end' and expecting only 80% new from what they are said to have in the manufacturers rating (ie, a 100ah should have 80ah I can depend on, only 40 of which is usable). Inexpensive enough to upsize the bat-bank, kinda like panels are cheap enough now to 'over-panel' an array.
I do understand that over the time the LFP should be just happily chugging along I will likely replace the LA at least once, but I have had good life with my LA bats for many years the way I handle them.
And in 10yrs we probably wont be doing cabin life any more......
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ICC
Member
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# Posted: 9 Jun 2021 10:31am
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Quoting: paulz when shopping for inverters do they list hi or low frequency
That may be hard to find listed. Look at the weight though. Low frequency inverters are heavy brutes because they have a big transformer with lots of heavy copper windings.
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Steve_S
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# Posted: 9 Jun 2021 10:43am - Edited by: Steve_S
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SCSJeff & Gcrank1 your both right. In the sense that a Part Time weekend use is quite another thing than daily cycling & 7/24/365 use.
That is the break point too for costs. A small simple weekend build that's used 2-3 days at a time AGM/FLA are likely still the better option, especially if not a Heavy Demand system. But that window is getting short & shorter.
A point of Resale of Cabin/Home with solar systems. Anyone looking to buy a place does not want to fuss with things, They want Simple, Easy and no hassle to run with it. I have seen buyers drop a house price and after purchase chuck the solar system because it was too complex or maintenance demanding (like playing with Lead Batteries). If your thinking long term and understand that at some point the place may be sold or given as an Inheritance, the same applies too AND everyone wants it Documented ! No Docs = Lower Price argument point.
Case in point, a nice property down the road just sold for 80K over asking. People went into a bidding war for it. WHY ? 2 years ago a Pro Installed Dual Tracking system was installed, each has 12 Panels and the house is still Grid Tied but is completely independent thanks to the solar & 48V/50kWh LFP (commercial) battery bank.. AND the Documentation and setup was "perfect" and people wanted it BAD.
Many labels are no longer who/what they were.. Look at Exide as one example, after the Big Disaster they got flogged off and quality dropped in 1/2 overnight..
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Brettny
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# Posted: 9 Jun 2021 11:06am
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Quoting: Steve_S Brand, Make & Model of that Lead ? and DATE Bought ! $$ value otherwise = useless. Cheap Chinese Made FLA is Cheap and equally poor for the price. You get what you pay for.
4 duracell made by east Penn. 2 US battery, also made in USA. They make chinese flooded lead acid batteries? I'm sure alot of AGM batteries or sealed lead acid batteries are chinese made. Bought 4 duracell GC2 in early 2020 and 2 US battery in early 2021. The distribution place that had US battery also had trojan for $35 more for each battery. I didnt see a benefit as what we are really hoping for is thicker plates and the weight was nearly the same.
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Brettny
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# Posted: 9 Jun 2021 11:09am
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Quoting: Steve_S Case in point, a nice property down the road just sold for 80K over asking. People went into a bidding war for it. WHY ? 2 years ago a Pro Installed Dual Tracking system was installed, each has 12 Panels and the house is still Grid Tied but is completely independent thanks to the solar & 48V/50kWh LFP (commercial) battery bank.. AND the Documentation and setup was "perfect" and people wanted it BAD.
I'm not seeing the collation. Some spent prob what 60-100k on that solar system alone? All home sales righ now are high and I can give you examples in my area too that sont even have solar.
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Steve_S
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# Posted: 9 Jun 2021 11:19am
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hahaha, 60-100K oivey.
exiting stage left, too much... lmao
Every 3rd house & many of the farms around here have Solar on them but whatever.... solar guys here have waiting lists fr people wanting installations, many are even having supply problems slowing them up.
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gcrank1
Member
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# Posted: 9 Jun 2021 01:52pm
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Check out 'batteryuniversity.com' for lots of good info on batteries in general and specific.
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NorthRick
Member
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# Posted: 9 Jun 2021 03:59pm
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I think ya'll scared maddie off. 
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gcrank1
Member
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# Posted: 9 Jun 2021 06:10pm
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Hope not!
We werent even close to bein into the weeds yet
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maddiecycle
Member
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# Posted: 10 Jun 2021 01:51pm
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Hi all, this is super helpful. GC2 is an interesting prospect I should explore more. I'm old enough to have maintained my FLA automotive batteries back in the day with distilled water and a specific gravity tester. Doesn't scare or bother me at all. Pop the caps off, check the level and the SG, keep some distilled water handy, move on. Maybe those will be the way to go after all.
Otherwise yes to low frequency inverter, good advice regarding Renogy quality, and personally I am trying to avoid Lithium if for no other reason than the environmental impact, kids mining in Africa, etc.... Lithium and other rare metals for semiconductors and power storage will become the Big Oil of the 21st century - including a driver of wars and conflict, if you ask me.
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maddiecycle
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# Posted: 10 Jun 2021 01:56pm
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Oh and yes would love to run a 48v system but looks like most inverters take at max 24v, and even those are rare and a lot more $$. I plan to put the panels right next to the cabin and make a battery/electrical box under the cabin (it is on a post-and-beam foundation with a couple of feet clearance below), so I can run maybe 25 feet of 10ga wire from the panels to bring about 80v DC @ 10amp into the charge controller, and then put the CC, batteries, and inverter right next to eachother, 12v won't be so bad.
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Steve_S
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# Posted: 10 Jun 2021 02:05pm
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Lithium Iron Phosphate Batteries (LiFePO4/LFP) contain No Cobalt No Nickel or any "exotics" as you suggest, that is another set of Lithium Chemistries, such as NCM or NCA which is used in EV's etc... LFP also does not catch fire or explode like the other chemistries.
The ONLY LFP that uses any form of "Rare earths" are those which are doped with Yttrium for Cold Duty work making them capable of operating up to -30C temps.
FYI: Rare Earth Elements are called that NOT because they are Rare or in limited quantities. It is the Mineral Classification.
Everything to make LFP is available domestically and none of it is toxic or excessively harmful. Lithium is also a extremely common mineral which is everywhere, even under your feet right now.
BTW: Using Non Deep Cycle in a deep cycle application, they will die fast and ungracefully.
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maddiecycle
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# Posted: 10 Jun 2021 02:12pm
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Steve_S good point about the rare earths not being in LiFePO4, still there is a major Li supply chain and infrastructure issue in the US. Regardless, I don't need the cost and lightweight of Li for a fixed weekend cabin installation. No one said anything about using non-deep cycle batteries here.
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scott100
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# Posted: 10 Jun 2021 03:03pm
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Concerning battery banks. I do lust for Steve's LiFePO4 bank, but share Brett's desire to keep it as cheap as possible.
In my case, I put in a bank of GC2 Duracell's from Sam's club. Made by East Penn (makers of Deka). They have a pretty good track record in the marine world (my other hobby). Current pricing is about $90 each, so my bank of 8 were about $720. Wired series parallel for 24v, I have a 430 ah bank at 24v (so 215 ah usable). I have to top off with distilled water a couple times per year, so no big deal.
The inverter I put in is this one from Aims. Not really sure how well respected Aims stuff is, but the price point seemed right for a mid quality inverter. They do mention their surge current specs are for a half second rather than 40 ms found on some other units. So far, I've been happy with it.
https://www.aimscorp.net/3000-Watt-Pure-Sine-Wave-24-Volt-Inverter.html
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gcrank1
Member
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# Posted: 10 Jun 2021 06:00pm
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Be aware that Solar Charge Controllers (scc) have input specs to follow with care; ie, Max voc from array, which can spike in cold so you want a 'buffer', dont edge the Max! Then there is the more apparent max amps from the array which may really ever be seen outside of the lab. That is to say, whatever the peak advertised amps output is those panels wont make it there but there is no downside to going a bit bigger there too in case you decide later to add more panels.
MPPT scc may not give as big a boost over PWM as the ad-copy/hype but does start the array charging sooner so you maximize the light of the day; ie, every little bit counts.
Many scc's now do an automatic read of bat-bank voltage when you hook up, bat-bank to scc 1st, then array, so if you get a 12/24v capable you can at least have that option in the future. On the higher-priced end they will also accommodate the 48v.
If I didnt already have a 12v inverter (so Im stuck at 12v system) and had to buy new Id get a 24 and likely 4 x gc2, 6v bats wired as 2 series/2 parallel (2s/2p) for a 24v bat-bank providing about 440ah's/ 220 net usable. Inverted to 120vac would make for a pretty effective system, both in cost and functionally now and future.
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jawarren77
Member
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# Posted: 11 Jun 2021 12:24pm
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I have 4 of these 2s/2p for 12v 680ah. Runs all our lights, microwave and random tools.
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maddiecycle
Member
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# Posted: 11 Jun 2021 03:20pm
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Helpful. Gcrank how do you get 24v out of a 2s/2p config with 6v batteries? Seems like 12v. 24v from four 6v batteries would need all 4 in series.
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