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  • Wondering why batteries didn't last

    Hello all, newbie here and I'm hoping I can get some help. My wife and I bought an off grid camp in the Adirondacks about 3 years ago. The previous owner used a generator but I didn't want to listen to that so I installed a basic solar system. It worked well but the batteries only lasted 2 years. The system consists of a Renogy 100w monocrystalline panel, a 30 amp Wanderer PWM charge controller and (2) 125 amp hour AGM batteries. I then ran a 1000w/2000w sine wave inverter off that to power the camp. We didn't run much other then a few led lights, phone chargers, and the occasional radio. I also have a 12 volt RV water pressure pump for a shower and faucets. The camp doesn't get used a ton at this point and the inverter usually gets turned off when we are not there but the charging system stays on. It does get quite cold in the Adirondacks during the winter which is the reason I went with AGM batteries in the first place.

    I did have an overcharge alarm once or twice on the controller. Not sure why but it happened once when the inverter was left on.

    I have the controller feed to a positive and negative busbar. The busbars then feed the batteries the inverter and the 12 volt pressure pump.

    That's as much info as I can think of at the moment but is there anything obvious that would cause the batteries to go bad so quick?

    Thanks!

  • #2
    IMO, you are underpowered on panel with a single 100 watt panel for 250 AH of batteries. A single 100 watt panel puts out around 6 amps, tops, and rarely that much. Mine kind of start at nothing and slowly peak around noon time, And taper back down as the sun goes down.

    I’d feel more comfortable with around 600 watts of panels, but the only way to know for sure is to got to a program like PV watts to find out for sure. That has historical data of your area for solar production. I’m in sunny AZ which is best case, and I don’t think NY is best case. Also needed is an energy audit to see how many panels you need to get based off the worst case production plus a back up for no sun.

    I’ve not taken my RV out in any true dark rainy days, but the overcast days I’ve seen, I was at about 1/4 to 1/3 rd normal production.

    My inverter is a 2000 watt inverter, and that draws 1 amp at idle, and there’s at least 14 hours a day where that gets pulled off a battery. Yours probably draws less, but I would not be surprised if it is around 1/8 to 1/4 what that single panel puts out.

    Comment


    • #3
      You are seriously under PV's and have a very large inverter, which it's self-consumption is likely more than your loads are. Well, you got 2 years out of that, so that was pretty good
      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


      • #4
        We are at the camp sporadically and usually several days or weeks between visits. When we are there most of the usage is at night so I've been more concerned with storage then charging capability. Am I wrong on that?

        Comment


        • #5
          Holy especially need to worry about charging while you’re around.

          Plz red this sticky: https://www.solarpaneltalk.com/forum...battery-design

          With your charge controller, all you need to do is add more panels. Because its a PWM charger, these panels need to be put in parallel. Also, you need to plan for thicker wiring as more panels get added.

          Generator power is pretty easy. Know your max loads and buy a generator for that. Solar is not so easy and requires a lot of math. Solar does not produce anywhere the power that a gas powered generator does, and is exponentially more expensive, so you really need to plan.

          I also recommend a battery monitor so you can see how much your single panel is killing these batteries.

          Comment


          • #6
            [QUOTE=chrisski;n423468]Generator power is pretty easy. Know your max loads and buy a generator for that. Solar is not so easy and requires a lot of math. Solar does not produce anywhere the power that a gas powered generator does, and is exponentially more expensive, so you really need to plan.[QUOTE]

            Besides, earplugs are cheaper than PV and more portable as well. They also work in shade and in any orientation.

            Comment


            • #7
              Get all 12V appliances such as RVers use, and ditch that energy gobbler
              inverter. There are some small, very quiet generators you could start at
              night if needed, check the variable engine speed inverter models. Bruce Roe

              Comment


              • #8
                Originally posted by bcroe View Post
                Get all 12V appliances such as RVers use, and ditch that energy gobbler
                inverter. There are some small, very quiet generators you could start at
                night if needed, check the variable engine speed inverter models. Bruce Roe
                I've thought about going the 12v route but right now with the inverter I can switch over to generator power if needed. I literally only need electric to charge phones, a couple night lights and the 12 volt pressure pump to flush the toilet so it seems like overkill to run a generator all night plus I just don't want to hear it in the summer. However, I may go that route for the few times we use it in the winter.

                Comment


                • #9
                  Originally posted by chrisski View Post
                  Holy especially need to worry about charging while you’re around.

                  Plz red this sticky: https://www.solarpaneltalk.com/forum...battery-design

                  With your charge controller, all you need to do is add more panels. Because its a PWM charger, these panels need to be put in parallel. Also, you need to plan for thicker wiring as more panels get added.

                  Generator power is pretty easy. Know your max loads and buy a generator for that. Solar is not so easy and requires a lot of math. Solar does not produce anywhere the power that a gas powered generator does, and is exponentially more expensive, so you really need to plan.

                  I also recommend a battery monitor so you can see how much your single panel is killing these batteries.
                  I don't mind adding panels. I believe I can go up to 400w with my current charge controller and I thought of upgrading to an mppt if needed and I was wrong about the batteries, they're 100amp hour each not 125. Not a big difference but worth noting. We have a generator for backup but I refuse to listen to that while we're up there. I literally only need the electric to charge phones, run a couple night lights and a 12 volt pressure pump for water pressure (mostly for the toilet) so running a generator all night seems like overkill.

                  Somebody else mentioned going 12v and getting rid of the inverter. If I kept the 200 amp hour battery size, got rid of the inverter and upgraded to 400w on the panels does that sound more reasonable? I know I don't have much usage info but a 12 volt water pump is around 8 amps and might get an hours worth of use over a couple days and 12 volt lights vary but we only leave a couple on so people can find their way to the bathroom at night. We use propane lights otherwise.

                  Comment


                  • #10
                    For lights and such, just get a cheap mod sine inverter in the 300w range. many have usb ports on them, and they consume much less than the big inverter

                    Motors (pumps) don't like mod sine, but perhaps your existing inverter has a "sleep" or standby mode, and that can be used with your water pressure pump.
                    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


                    • #11
                      You only run the generator for an hour to charge the batteries, often in the AM when boiling coffee. Either use a simple automotive charger in the 30A range or you can get a fancy solar battery charger for 4x the same $
                      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


                      • #12
                        Originally posted by Mike90250 View Post
                        You only run the generator for an hour to charge the batteries, often in the AM when boiling coffee. Either use a simple automotive charger in the 30A range or you can get a fancy solar battery charger for 4x the same $
                        This might be about the best option. I don't mind running the generator a bit to charge the batteries. My pressure pump is 12 volt and runs directly off the battery so the inverter doesn't run that anyway.

                        Comment


                        • #13
                          I do like my battery monitor. We’re it to be a cloudy day where I had not recharged from the night before, it lets me gauge if I can make it through the night without turning the genny on. I’ll set a goal like 75%, at night and I’ll turn it on for an hour or so. Likewise in the day, if I’m down low without much chance for sun, on it will go for the morning coffee and an hour to recharge the battery.

                          Other than that, I turn it on twice a day for about five to ten minutes so my family can run the microwave to warm their food. These RV trips need to be enjoyable for them. It’s not survival school.

                          Comment


                          • #14
                            Originally posted by chrisski View Post
                            I do like my battery monitor. We’re it to be a cloudy day where I had not recharged from the night before, it lets me gauge if I can make it through the night without turning the genny on. I’ll set a goal like 75%, at night and I’ll turn it on for an hour or so. Likewise in the day, if I’m down low without much chance for sun, on it will go for the morning coffee and an hour to recharge the battery.

                            Other than that, I turn it on twice a day for about five to ten minutes so my family can run the microwave to warm their food. These RV trips need to be enjoyable for them. It’s not survival school.
                            Yeah I'll probably invest in a battery moniter, definitely sounds like its worth it. Thanks

                            Comment

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