Flooded Lead-Acid Batteries in an Off-Grid Solar Power System 

I'm seeing that forklift batteries usually come in 24, 36, and 48 volts, all made up of two volt cells. They are designed to survive being banged around on solid rubber tires with no suspension. Reconditioned used ones can last for decades in home solar applications. You're a helpful person, so I'm passing back to you what I've learned. Getting the two volt cells out of a steel case can be work. They weigh over 100 lbs each. The lead bars connecting them have to be cut, too.

Good coverage in a short time. I use AGM batteries in my small solar system but I'm fortunate to be in an area with a lot of businesses that use AGM batteries in their big UPS systems and for backup for their video surveillance. The last group of AGM (two 100AH and two 110AH, about 15 months old) cost me $305 (versus close to $800 new). My spreadsheet for power usage assumes a maximum of 50% Depth of Discharge and the previous group of used 80AH AGMs lasted almost 9 years (5 years in UPS service, 4 years for me [to below 80% capacity] - but they were only $35 each - not likely to find a deal like that again). Using AGMs means I don't worry about ventilation or weekly water checks and, if those checks fell to my better half, that might not get checked until we were in the dark. Plus they can be on a shelving unit in the basement with the charge controllers and inverter hung off the side of a shelf for good cooling air flow. Instead of the current 420AH of AGMs, I'd like to have triple that in LiFePO4 - currently about $2500 (Amazon, free delivery in about a week) with BMSs, but they'd likely outlive me and I'd have fridge power for almost a week. I am replacing some hard-to-find AGM UPS batteries with DIY LiFePO4 using cells from batteryhookup.com - beats the $50 the UPS manufacturer wants for the AGM with maybe a 4 year life in UPS service, especially when the parts cost (cells, BMS, holder) was under $20 and I got to learn about a new battery technology. The now 6-year-old battery that I took out of my truck a year ago when it sounded like the starter was turning a little slow, now sits in the basement for testing inverters and performing jump start duty. A battery impedance meter still shows it at about 90% of its original capacity and I have an Advance Auto battery from 2005 that's in a plastic battery case for when I need portable power - neither of those is deep cycle but they see only intermittent use and they work fine for that. My solar power spreadsheet does have a page for flooded lead acid batteries with the maximum DOD being 20% (but adjustable, depending on need). If things go sideways, there will likely be lots of abandoned vehicles - useless without fuel - but the parts are still useful (power seat motor driving a solar tracker?) and I have spare charge controllers configured for flooded batteries, just in case. One formula I found for RC to AH would make an RC of 160 = 94AH, but a new, name brand battery could be 9% higher than that or about 102AH (based on some testing I did). Using half the RC as an approximation of the AH ensures you won't exceed the battery's capacity I've been there when a spark exploded a lead acid battery. I was fortunate that the battery was in a vehicle and that it blew out a bottom corner and just ate up the cuffs of my jeans and my Keds ;-( That might be one reason I prefer AGMs and the newer lithium technologies ;-) The inverter is a 2000 watt pure sine wave unit from reliablepower on Ebay (now selling them with a WZRELB label) with an identical unit as a spare. The inverter's output is cleaner (oscilloscope check) than what the local power co-op delivers. The charge controllers are EPEver 3210A 30 amp MPPT units and all of it has been in place for 4 years. The maximum load on the inverter is about 1300 watts when fridge, freezer, furnace blower and a few LED lights are all on. The average load is much less as it's rare for everything to be on at the same time. If that became a problem, I have digital timers rated at 15 amps so the fridge and freezer could each be on for 2 hours at a time but in a staggered cycle. The inverter connects to a 4 circuit transfer switch via a 12/3 extension cord - the same cord is used when the inverter generator is in use (about two weeks of treated fuel for keeping the battery bank charged when power is off and there is no sun). Longest time on the backup syetem so far was 12 hours when the county had 7-12" of snow in an area that rarely sees more than 3". Sure is nice to walk down the stairs and flip a couple of switches to have power instead of shoveling 7" of snow in the dark at 30F to get a generator out of the shed and trying to start that gen at that temperature...

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This is the exact group 27 battery that I use in all my solar setups and in my RV. O'Reilly Auto Parts is the best place that I found to get them.

Your video has been very helpful to me as I prepare to put together batteries for my grid down preparation efforts. I will now share with you what I've since learned. Please, search RU-vid for information on using forklift batteries for your solar. I predict that you may be glad you did. 🙂

Appreciate this video ALOT... A WHOLE LOT!!!

SIR, YES SIR!

thank you dear

Pop the lids off and use a small pocket mirror to save your back from having to lift those heavy batteries. Use the mirror to look inside the battery to check the levels of course.

Great video full of useful information. Just a heads up your microphone sounds good and picks up your voice pretty well, so you probably dont need yell in order to get your point across. Anyways, Thanks again for taking the time to put this video online. There isnt enough info on Lead acid based backup power sytems.

Love the content, Thanks for the tips. I have a tip for you as well. Please get a gimble. The video shaking is hard to watch the video. 100$ will get you one that keeps everything smooth no jittering. Get one that handles the weight of your phone.

12v flooded battery and what may the settings be for, bulk, absorption and float... Yeah and equalization. Do you know? (Its a 12v tudor flooded battery with a victron 100/20)

I’ve been watching many different videos about batteries…..and after all is said and done, I’m thinking the Lead Acid Deep Cycle maybe my best option. I’m building a rather unusual set up, and durability is key. I’m setting up a service truck for a long term vehicle build, so it will be able to do many tasks. So it’s a 1992 GMC, I’m going to remove the bed, and build a custom utility bed with my welder/generator and a separate dedicated generator connected to an Automatic Generator Start switch a charge controller and a couple of inverters, as well as a DC to DC charger and at least one, possibly two 250 watt solar panels up top. A large dedicated metal toolbox up on top of the roof rack will hold the “house batteries” with one solar panel on it, the toolbox will be insulated and fire resistant, with cooling fans and a fire extinguishing system (just in case). I was going to get two large 250AH batteries, but it seems several car size RV batteries should work as well. The duties of the battery bank, will be to power one inverter for general 110 use in the cab, and a second inverter to power climate control system for the cab and battery box, the generator (insulated for sound) will automatically start early on cold mornings to heat up the cab, and warm the antifreeze with a block heater. Thermostats will determine when heating or cooling is needed.

Great video what inverter do you use and. What is the safe watts I can draw of it

I just bought two Group 29DC deep cycle marine batteries (flooded lead acid). I guess battery manufacturers are now putting the amp hours on the battery label instead of "reserve capacity" because both of my new batteries state 122 Amp Hours right on the top label where reserve capacity used to be.

I have been using FLA Batts and they last 6 to 7 years. Don't overcharge or run them down past 12.2 ---If they go down past 12 Volts and stay as little as I day they will sulphate and Die.

I have 14 of those from Autozone,...I'm thinking about getting two more...lol...they are running a 24 volts 2000 watts Aims inverter / charger ...I have 1000 watts of panels, and a 40 amp Epever charge controller, 4215 BN...I didn't use much power so the battery bank was at 24.4 this morning , sometimes it drops a little lower but not much...I got too many batteries and had to get more solar panels a month ago so I don't want to get too many more...maybe max out at 18 of them...lol...the first ten were 90 amp hours but the last 4 are 105, 180 and 210 reserve minutes, and if I get two more they will be the bigger ones...that would give me 765 amp hours @ 24 volts...I'm thinkin that's enough for me...I started this little solar journey about a year ago...I haven't used the grid for four months...I used to use the gasoline genereator some but now I've even stopped doing that...I used a # 2 welding lead on the battery wiring and there's four ends attached to the inverter...nothing has ever gotten warm on any of that...one thing I did on my system is, I put a #6 wire to all the 12 volts connections, like an 8 legged spider with a big brass Kearney in the middle...that's my BMS...so that when I hook up my 410 watt inverter to run small stuff, it is running off either the top set or bottom set of 7 ( for now) batteries, that way it doesn't run one battery down...This is one of the coolest things I've ever done...I guess it's a good thing I bought my inverter when I did...it has went up $116 since I got mine in December...I barely could afford it as it was...thanks for the great video...everyone said don't use those kind, but I've been around cars and batteries since I was a kid...and I know it takes a lot longer to charge a marine battery so I knew they would be okay...it just takes a lot of them to throw out a bunch of amps but they recover nicely...I'll probably get two more and stop at 16...I think I have about enough...yay...those things cost...lol Buying the last two will be like getting a get out of jail free card...

True Deep Cycle batteries will provide double or triple the Amp Hours that you're getting from the Marine Batteries you featured in the video.

I have a 48 volt 840 amp system off grid, 12 years. I just got done running a 3 1/2 day test on my essential load panels through my Sunny Island. Let me hit you up with a bit of grammar: Nothing is ever "four times (4X) less expensive." That is "getting bigger" to "get smaller." What you meant to say is that: "FLA IS 1/4TH THE COST OF LFP ... or ... 25% AS EXPENSIVE." Guess I'm a dickhead.

Dear sir, Thanks for the great video. Can I connect the new battery in series with the old one?

Hey shoe string,what charge controller & inverter do u have hooked up to your batteries for emergency power?

IFLA. Industrial flooded lead acid. Just search The Gilley Show. You may change what batteries you use. 🙂

shouldn't they also be kept in a relatively warm location? or is that only for the non deep cycle high cold cranking amp batteries (car batteries)?

Are there any issues to keeping solar panel and charge controller connected to battery continuously, 24/7?

Hello is it ok to discharge them to 10.5v ? also what percent discharge (DOD) is achieved from the 12v cutoff voltage ??

Thank you for this video. I built a lead acid set up in my RV. But the batteries are inside and aren’t ventilated ( yet) ( a huge retrofit would be needed).Is this a serious issue? Meaning, do they off gas when running or being charged only, or all the time? Is opening the door regularly going to be enough? I don’t smell anything ( gases)- is that an indication that it’s minimal, or are the gases odorless?? Thx for you answers. And I’m a new subscriber to your channel!

Hi, cool system. I have 2 big 200 ah deep cycle wet batteries in Parallel. So i‘m thinking about adding some 80 ah marine batteries parallel to the big ones. That shouldnt be a problem? Thanks a lot.

UPDATE : I have 18 batteries now...I may get two more. I have two more 100 watts solar panels coming Friday, so I thought I would get a couple more for them to charge. 1200 watts of solar charging 1000 amp hours of battery. These ones I use have 210 RC , they are a 29 DP-DL. It is 11 PM, 25.6 volts left. I think 20 will be enough. I'm trying to find some #2 welding lead wire locally tomorrow. I'm going to call it " The Twenty Mule Team " and hope it lasts twenty years. That's my plan for this year for my stuff. I have off grid power already but it won't hurt to improve it. I want to get my system in A number one shape this summer. At least no one should say I made a half way attempt at it. My power will be dependable and enough when I am done tinkering. Suppose I took two years' electric bill to build the whole thing ? And then I have 10 years of free power after that...that sounds okay to me. Well, it's like being in the lake above your knees, might as well jump on in there. LOL ...I feel for those who don't get something put together, whatever it is, big or small, as long as it is dependable. I want my stuff to be rock solid good to go. I'm hoping that by having a big bank the batteries will last a long time. Not much danger of boiling 20 of them all at once...they charge kind of slow when they all get together. Yeah since I will be done buying batteries this month, I will save for the pricey inverter. This is my first solar system. It is going to be nice when I get it all done, I think. Seems like everyone builds theirs a little differently. My 105 amp hour batteries cost me around $100 apiece, but they seem good enough to me for that price. The plates are just a little taller and wider in the ones I get. And they hold more acid , so less frequent checks. I've tried to cover my bases, that way. Oh, if your battery level is hard to see, a dental mirror from dollartree can be very useful...you might want to wrap it with tape before use though, except the end.

I have truck batteries will they work

IVE USED 2 CAR BATTERIES ON MY SMALL SYSTEM TO RUN LIGHT AND SYSTEM, FOR 2 YEARS NOW, I JUST MADE SURE CONTROLLER WAS SET TO 11 JUST OVER 59% OF BATTERY CAPACITY I FOUND I COULD GET 6 HOURS OF TV POWER AT LEAST OFF THE 2 BATTERIES,

well at my location the cheapest lead acid deep cycle batteries , when i calculate the usable A in each type lead acid is 3-3,5 times more expensive the cheapest is the eve 280 ah lipo4 cells not the asembled ones they are however still cheaper then lead acid ,, i have been running a 8s 280ah 24v as my energy storage for about a year now its enough for 3- 4 days of power i am however gonna make a identical 24v more , for more storage i have been looking for used forklift batteries as i figured some of the smaller handtrucks were going to litium however no luck

I'd prefer to use Lithium phosphate, they're safe, higher capacity, they can be safely discharged to near empty, they have longer cycle life, and nowadays you can get them for the same price as AGM. They also produce no gasses and are very low maininence.

If you're going to go with lead acid, get some golf cart batteries with a high amount of amp hours. Those are better for off grid and those useless marine batteries.

Can't you get a tiny mirror and a flashlight to check your fluid level without having to pull them off the shelf?

SLA batteries are a huge pain in the neck. Their only redeeming quality is lower INITIAL cost. The truth of the matter is that Total Cost of Ownership (TCO) is not significantly better than building your own LiFePO4 battery system. Add in the lower weight and size of lithium, the relatively constant voltage, and the dramatically reduced maintenance requirements, and you quickly realize why most of the systems being built today, at least in the US, are ditching the SLA batteries and going with either lithium or at least AGM. There are several DIY lithium batteries on the market today that make it easy and relatively affordable, over the long term, to get all of the benefits of a far superior battery chemistry. No need to stick with 20th century solutions, if you don't want to.

Is it true that flooded lead acíd batteries can survive a huge CME as opposed to lithium ion batteries in a freak solar flare attack

Shoestring are you still using your LiFePO4 Flypower batteries. Are they any good?

You said to not let the voltage go below 12.1vdc, but wired in parallel how to you know each batteries voltage to keep them above 12.1? Also having 4 batteries wired in parallel would you wire the charge source (solar) in the middle of at an end? Thanks

what voltage would a 35ah battery after drawing 35 amps for one hour?

use a scrap piece of a mirror and a light to check inside the lower batteries, no need to pull it out

I like the fact that the materials for my agm batteries were not mined out of the ground by 10 year old child labourers in Africa and slave labour.

Which is worse, shouting your entire RU-vid or promoting batteries in parallel. Follow this episode and you will have hearing loss and a system that ages like an ice cream cone on a picnic bench.

do you use an inverter or an ups?? , i used for years an ups, now i use a decent inverter no load 0,6A with a nice screen,

car batteries compared to marine deep cycle, cost three times less, with 30 amp deep cycle you get a 90 amps regular, amazon prices or other reseller, i charge mine to 13.1, and discharge 11.7 early morning.

Your annoying

Do used golf cart batteries (8v batteries) suffice for solar set up?