Question about building an 18650 Li-ion battery bank - how many mAH is required ?

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  • johnnyhavana
    Junior Member
    • Aug 2017
    • 17

    Question about building an 18650 Li-ion battery bank - how many mAH is required ?

    Hi everyone,

    been into solar for about 6 months now with a small rig up and running.

    I've watched quite a few videos on people building better battery systems with rechargeable 18650 Li-ion battery banks, i guess something like Tesla offers.

    My question is the capacity of batteries, we would need.
    I know there are all kinds from 500 upto 4300mAH, but if i understand this the higher the mAH the quicker output like for an electric scooter, but with solar its more trickle, so we would really only need a lower mAH battery since we trickle charge it.

    I guess it also depends on your usage/discharge required?? so am a bit confused, for me, i am basically running lights in and outside of my shed for now, so thats my usage, all LED lighting.
    Can anyone shed light on this please.
    thank you
    Johnny
  • max2k
    Junior Member
    • May 2015
    • 819

    #2
    Originally posted by johnnyhavana
    Hi everyone,

    been into solar for about 6 months now with a small rig up and running.

    I've watched quite a few videos on people building better battery systems with rechargeable 18650 Li-ion battery banks, i guess something like Tesla offers.

    My question is the capacity of batteries, we would need.
    I know there are all kinds from 500 upto 4300mAH, but if i understand this the higher the mAH the quicker output like for an electric scooter, but with solar its more trickle, so we would really only need a lower mAH battery since we trickle charge it.

    I guess it also depends on your usage/discharge required?? so am a bit confused, for me, i am basically running lights in and outside of my shed for now, so thats my usage, all LED lighting.
    Can anyone shed light on this please.
    thank you
    Johnny
    have you also watched videos showing Li- ion catching up fire? They burn fast too. It is the most dangerous battery chemistry and you don't sound very comfortable yet with technology involved. Why don't you start with AGM for example? It would require little maintenance and while expensive it won't last much longer than your learning period at which point you'll switch to something else anyway. Otherwise deep cycle FLA would be the most logical choice if you don't mind dealing with their maintenance.

    Comment

    • Mike90250
      Moderator
      • May 2009
      • 16020

      #3
      I'm becoming more and more fond of advising beginners to get a automotive jump start pack, and plug into the cig lighter or USB socket and start with some factory designed gear, instead of trying to cobble together a DIY firebomb with no circuit breakers or fuses in the proper locations.
      Powerfab top of pole PV mount (2) | Listeroid 6/1 w/st5 gen head | XW6048 inverter/chgr | Iota 48V/15A charger | Morningstar 60A MPPT | 48V, 800A NiFe Battery (in series)| 15, Evergreen 205w "12V" PV array on pole | Midnight ePanel | Grundfos 10 SO5-9 with 3 wire Franklin Electric motor (1/2hp 240V 1ph ) on a timer for 3 hr noontime run - Runs off PV ||
      || Midnight Classic 200 | 10, Evergreen 200w in a 160VOC array ||
      || VEC1093 12V Charger | Maha C401 aa/aaa Charger | SureSine | Sunsaver MPPT 15A

      solar: http://tinyurl.com/LMR-Solar
      gen: http://tinyurl.com/LMR-Lister

      Comment

      • SunEagle
        Super Moderator
        • Oct 2012
        • 15126

        #4
        Originally posted by Mike90250
        I'm becoming more and more fond of advising beginners to get a automotive jump start pack, and plug into the cig lighter or USB socket and start with some factory designed gear, instead of trying to cobble together a DIY firebomb with no circuit breakers or fuses in the proper locations.
        I am close to deleting any new post concerning a DIY Li battery system to keep nu-bees from thinking it is a safe way to build their own energy storage system.

        There are just way too many stupid people out there that believe the Youtube videos showing how easy it is when it is not easy or safe.

        Comment

        • J.P.M.
          Solar Fanatic
          • Aug 2013
          • 14939

          #5
          Originally posted by SunEagle

          I am close to deleting any new post concerning a DIY Li battery system to keep nu-bees from thinking it is a safe way to build their own energy storage system.

          There are just way too many stupid people out there that believe the Youtube videos showing how easy it is when it is not easy or safe.
          If you do that, it'll only mean one less way to improve the gene pool.

          Comment

          • Gdwats
            Junior Member
            • Jul 2017
            • 207

            #6
            The fact that you are talking about mili amphours is a red flag. Please listen to these folks, you wont find better advice anywhere.
            900W, 40A MPPT, 230AH FLA,24V Samlex 1500W

            Comment

            • johnnyhavana
              Junior Member
              • Aug 2017
              • 17

              #7
              Originally posted by SunEagle

              I am close to deleting any new post concerning a DIY Li battery system to keep nu-bees from thinking it is a safe way to build their own energy storage system.

              There are just way too many stupid people out there that believe the Youtube videos showing how easy it is when it is not easy or safe.
              OK ok ok, sheesh, i have watched many videos and i know its very dangerous, there was one in particular that really did control and test everything properly, made some mistakes but was able to monitor the volts and keep them in check. Was just asking but i'll stick with my good old golf cart batteries . NO BOOOM

              Comment

              • Gdwats
                Junior Member
                • Jul 2017
                • 207

                #8
                Excellent plan!
                900W, 40A MPPT, 230AH FLA,24V Samlex 1500W

                Comment

                • Gerard Fivewin
                  Junior Member
                  • Oct 2014
                  • 24

                  #9
                  Originally posted by Mike90250
                  I'm becoming more and more fond of advising beginners to get a automotive jump start pack, and plug into the cig lighter or USB socket and start with some factory designed gear, instead of trying to cobble together a DIY firebomb with no circuit breakers or fuses in the proper locations.
                  How about if someone ask about the tesla wall, made of li-ion(s) ??

                  Comment

                  • SunEagle
                    Super Moderator
                    • Oct 2012
                    • 15126

                    #10
                    Originally posted by Gerard Fivewin

                    How about if someone ask about the tesla wall, made of li-ion(s) ??
                    There are a few members that have pursued the installation of a Tesla PowerWall unit. I am sure they can provide answers to your questions.

                    Comment

                    • Gerard Fivewin
                      Junior Member
                      • Oct 2014
                      • 24

                      #11
                      I mean, you guys are worried about using li-ion batteries whether its factory made or DIY.
                      Is this also a bomb, wow look how they make powerbanks in a factory. Picture, screenprint from this vid https://www.youtube.com/watch?v=XzhtFwmJVDo
                      Attached Files

                      Comment

                      • NEOH
                        Solar Fanatic
                        • Nov 2010
                        • 478

                        #12
                        Originally posted by Gerard Fivewin
                        I mean, you guys are worried about using li-ion batteries whether its factory made or DIY.
                        Is this also a bomb, wow look how they make powerbanks in a factory. Picture, screenprint from this vid https://www.youtube.com/watch?v=XzhtFwmJVDo
                        I do not think the device in your photo is a "Power Wall".
                        It appears to be either a "testing" station and/or "top-charging" station.
                        The device in your photo is not a Retail product.
                        No, it is not a bomb.
                        Last edited by NEOH; 10-12-2017, 03:29 PM.

                        Comment

                        • J.P.M.
                          Solar Fanatic
                          • Aug 2013
                          • 14939

                          #13
                          Originally posted by Gerard Fivewin
                          I mean, you guys are worried about using li-ion batteries whether its factory made or DIY.
                          Is this also a bomb, wow look how they make powerbanks in a factory. Picture, screenprint from this vid https://www.youtube.com/watch?v=XzhtFwmJVDo
                          Truly awe inspiring ! Although it seems they've got a ways to go before the get the process automation/robotics nailed down. A real confidence builder ain't it ? More lame brain junk from the idiot's bible.

                          Comment

                          • SunEagle
                            Super Moderator
                            • Oct 2012
                            • 15126

                            #14
                            Originally posted by Gerard Fivewin
                            I mean, you guys are worried about using li-ion batteries whether its factory made or DIY.
                            Is this also a bomb, wow look how they make powerbanks in a factory. Picture, screenprint from this vid https://www.youtube.com/watch?v=XzhtFwmJVDo
                            That video is from a manufacturer that makes small portable storage units using Lithion chemistry batteries. The picture you posted is nothing more than a test station. It is not a home sized energy storage bank and will never be one.

                            Gerard, if you want to build your own battery bank using Li technology I can't stop you. What I can do is point out to others that a DIY lithium battery bank that is more than one of those portable units can cause fires if not built properly.

                            For that matter there are a number of "factory made" lithium battery powered devices that do go up in flames like the E cigarette units and those hover boards that have lit up some people. So get off your high horse and listen when I say DON"T PLAY WITH FIRE or build a DIY Lithium battery system.

                            Comment

                            • jflorey2
                              Solar Fanatic
                              • Aug 2015
                              • 2331

                              #15
                              Originally posted by johnnyhavana
                              My question is the capacity of batteries, we would need. I know there are all kinds from 500 upto 4300mAH, but if i understand this the higher the mAH the quicker output like for an electric scooter, but with solar its more trickle, so we would really only need a lower mAH battery since we trickle charge it.
                              No; you are confusing a lot of things here.

                              First is ENERGY. Energy is amp-hours times volts. That's how long you can run loads.
                              Second is POWER. Power is amps times volts. That's how large a load you can power. (In EV's it's how fast you can accelerate and how fast you can go.)

                              Those are two separate ratings. mAH is how batteries are often rated; you have to look at the datasheet to get max discharge.
                              so am a bit confused, for me, i am basically running lights in and outside of my shed for now, so thats my usage, all LED lighting.
                              I'd get a lead-acid battery or a well designed lithium ion battery with a protection circuit.
                              I mean, you guys are worried about using li-ion batteries whether its factory made or DIY.
                              Is this also a bomb, wow look how they make powerbanks in a factory.
                              That's a testing facility. Testers like that have VERY good fire suppression systems, because that's where they catch bad cells.

                              Comment

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