Announcement

Collapse
No announcement yet.

Nickel Iron vs. Lead Acid - Off Grid battery debate

Collapse
X
 
  • Filter
  • Time
  • Show
Clear All
new posts

  • Originally posted by johnpearcey View Post

    I'd probably need around 5x the capacity of lead-acid to stand even a chance to reach 8yrs.
    .... no.... with any quality lead-acid you'd need ~2x the capacity to get 8 years.

    And the charging is an energy issue which IS efficiency. If 10kWh only gets your to 95% with NiFe then 7kWh would get you to 100%. You'd need less energy to get to 100%.

    So if a lead acid battery was 80% cheaper per Ah you'd buy lead acid? 'Cause that's about what I faced. I paid $6/Ah for the L16s because NiFe was $46/Ah. >7x more expensive.

    Comment


    • Originally posted by nwdiver View Post

      .... no.... with any quality lead-acid you'd need ~2x the capacity to get 8 years.

      And the charging is an energy issue which IS efficiency. If 10kWh only gets your to 95% with NiFe then 7kWh would get you to 100%. You'd need less energy to get to 100%.

      So if a lead acid battery was 80% cheaper per Ah you'd buy lead acid? 'Cause that's about what I faced. I paid $6/Ah for the L16s because NiFe was $46/Ah. >7x more expensive.
      As I said, it's a charging profile issue not efficiency. You've continually missed this point. It's the extended length of time a lead-acid needs to top up. That's where the cost of running a generator is prohibitive. And 2x capacity would not protect you against this, you'd need a lot more, more like 5x.

      Comment


      • Originally posted by nwdiver View Post
        ...........Here's the point I realized. The only real benefit to NiFe is lifespan. .........

        Nope. There is absolutely no worry about damaging them (unless you boil them dry)
        Partial charge for 2 weeks (clouds/rain) No worry
        Cold no worry (as long as you planned ahead for the capacity reduction EVERY battery experiences when cold) They can't freeze where most humans live.
        Heat - affects all batteries negatively.
        over charge If you don't melt them, just add more water

        I add about 15 gallons every 3 months. The batteries have large water freeboard above the plates. The ^automatic^ watering system took a lot of effort out of pulling caps, using a funnel, cleaning caps and on to the next. I was spending 2 hours every month. Now I spend about 4 hours every 3 months.

        I too, am located in a winter gloom zone, storms come in for 6-12 days at a time, and not needing to burn fuel to complete Absorb is a godsend.


        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


        • Originally posted by Mike90250 View Post


          Nope. There is absolutely no worry about damaging them (unless you boil them dry)
          Partial charge for 2 weeks (clouds/rain) No worry
          Cold no worry (as long as you planned ahead for the capacity reduction EVERY battery experiences when cold) They can't freeze where most humans live.
          Heat - affects all batteries negatively.
          over charge If you don't melt them, just add more water

          I add about 15 gallons every 3 months. The batteries have large water freeboard above the plates. The ^automatic^ watering system took a lot of effort out of pulling caps, using a funnel, cleaning caps and on to the next. I was spending 2 hours every month. Now I spend about 4 hours every 3 months.

          I too, am located in a winter gloom zone, storms come in for 6-12 days at a time, and not needing to burn fuel to complete Absorb is a godsend.

          .... yeah.... all that adds up to a longer life. NiFe is an invincible battery that lasts forever. I'd pay ~3x more per Ah for that... not 7x more.

          I've probably gone a couple weeks without a complete absorption cycle but I don't make a habit of it and the batteries are still working. It's not like doing this once, twice or 3 times immediately destroys the battery. It just gradually reduces the life. If the reduction from 'improper' use is less than the calendar life then it really doesn't matter and the battery will still last ~8 years. I really only needs to last ~6 or so.

          Lets run a simulation; My choices where 200Ah of NiFe for $9200 or 400Ah of Lead-Acid for $3000

          I start with $9200 and replace the lead acid every 8 years. Historically I earn on average ~7% in index funds. [TABLE="border: 1, cellpadding: 1, width: 300"]
          [TR]
          [TD]Year[/TD]
          [TD]NiFe[/TD]
          [TD]PbSO4[/TD]
          [/TR]
          [TR]
          [TD]2019[/TD]
          [TD]0[/TD]
          [TD]$6200[/TD]
          [/TR]
          [TR]
          [TD]2021[/TD]
          [TD]0[/TD]
          [TD]$7098[/TD]
          [/TR]
          [TR]
          [TD]2023[/TD]
          [TD]0[/TD]
          [TD]$8126[/TD]
          [/TR]
          [TR]
          [TD]2025[/TD]
          [TD]0[/TD]
          [TD]$9304[/TD]
          [/TR]
          [TR]
          [TD]2027 Replace[/TD]
          [TD]0[/TD]
          [TD]10652 - 3000 = $7652[/TD]
          [/TR]
          [TR]
          [TD]2035 Replace[/TD]
          [TD]0[/TD]
          [TD]13161 - 3000 = $10161[/TD]
          [/TR]
          [TR]
          [TD]2043 Replace[/TD]
          [TD]0[/TD]
          [TD]17477 - 3000 = $14477[/TD]
          [/TR]
          [TR]
          [TD]2051 Replace[/TD]
          [TD]0[/TD]
          [TD]24901 - 3000 = $21901[/TD]
          [/TR]
          [TR]
          [TD]2059 Replace[/TD]
          [TD]0[/TD]
          [TD]37670 - 3000 = $34670[/TD]
          [/TR]
          [/TABLE]

          Compound interest is the 8th wonder of the world. So given this situation you'd still choose NiFe? What if 400Ah of Lead-Acid was $2k? $1k? At what price would it win in your mind? Economics matters.

          As far as fuel burn for battery maintenance... let's think about this. With NiFe you get ~0.6w for every 1w that goes in. With Lead-Acid it's ~0.8w including the energy used for absorption cycles. NiFe is invincible but even NiFe can't create energy. So whatever extra fuel you'd be using to properly charge lead-acid you'd be using anyway to keep the lights on with NiFe.
          Last edited by nwdiver; 07-15-2020, 01:04 PM.

          Comment


          • Originally posted by nwdiver View Post

            .... no.... with any quality lead-acid you'd need ~2x the capacity to get 8 years.

            And the charging is an energy issue which IS efficiency. If 10kWh only gets your to 95% with NiFe then 7kWh would get you to 100%. You'd need less energy to get to 100%.

            So if a lead acid battery was 80% cheaper per Ah you'd buy lead acid? 'Cause that's about what I faced. I paid $6/Ah for the L16s because NiFe was $46/Ah. >7x more expensive.
            Absorption charging issues are lead-acids best kept secrets! For example: I use about 30Ah over night from my NiFe bank. If there is no sunshine the next day I can put back the charged used by running the generator. With NiFe you charge at constant current usually at C/5. For me I would charge at 16Amps. The charge efficiency is 80% which means I'd run the generator for 2.34hrs. That would cost me 1.64EUR. If I were using lead-acid I'd need to charge for 10hrs and the diesel cost would be 7EUR. That's over 4x the cost to recharge. I could of course decide not to charge at all that day and wait another day - then I have to double my lead-acid bank size to ensure that the usage does not go further than say 30% DOD. Then I can charge the next day, again for 10hrs. If I go 5 days like this then I'd need 5x the lead-acid bank size. On the 5th day, running the generator for 10hrs to fully charge the lead-acid bank would be about the same as 5 daily charges for NiFe. And it is very common where I live to get 5 straight days of zero sunshine. This is why I use a 5x factor with lead-acid. I paid 2.2k EUR for 80Ah NiFe which would equate to 400Ah lead-acid at a cost of over 3kEUR. And I don't have to change my batteries in 5 years time (because they wouldn't last 8yrs with that kind of usage). In miserable cloudy parts of the world, NiFe wins hands down.

            Comment


            • Originally posted by nwdiver View Post

              .... yeah.... all that adds up to a longer life. NiFe is an invincible battery that lasts forever. I'd pay ~3x more per Ah for that... not 7x more.

              I've probably gone a couple weeks without a complete absorption cycle but I don't make a habit of it and the batteries are still working. It's not like doing this once, twice or 3 times immediately destroys the battery. It just gradually reduces the life. If the reduction from 'improper' use is less than the calendar life then it really doesn't matter and the battery will still last ~8 years. I really only needs to last ~6 or so.

              Lets run a simulation; My choices where 200Ah of NiFe for $9200 or 400Ah of Lead-Acid for $3000

              I start with $9200 and replace the lead acid every 8 years. Historically I earn on average ~7% in index funds. [TABLE="border: 1, cellpadding: 1, width: 300"]
              [TR]
              [TD]Year[/TD]
              [TD]NiFe[/TD]
              [TD]PbSO4[/TD]
              [/TR]
              [TR]
              [TD]2019[/TD]
              [TD]0[/TD]
              [TD]$6200[/TD]
              [/TR]
              [TR]
              [TD]2021[/TD]
              [TD]0[/TD]
              [TD]$7098[/TD]
              [/TR]
              [TR]
              [TD]2023[/TD]
              [TD]0[/TD]
              [TD]$8126[/TD]
              [/TR]
              [TR]
              [TD]2025[/TD]
              [TD]0[/TD]
              [TD]$9304[/TD]
              [/TR]
              [TR]
              [TD]2027 Replace[/TD]
              [TD]0[/TD]
              [TD]10652 - 3000 = $7652[/TD]
              [/TR]
              [TR]
              [TD]2035 Replace[/TD]
              [TD]0[/TD]
              [TD]13161 - 3000 = $10161[/TD]
              [/TR]
              [TR]
              [TD]2043 Replace[/TD]
              [TD]0[/TD]
              [TD]17477 - 3000 = $14477[/TD]
              [/TR]
              [TR]
              [TD]2051 Replace[/TD]
              [TD]0[/TD]
              [TD]24901 - 3000 = $21901[/TD]
              [/TR]
              [TR]
              [TD]2059 Replace[/TD]
              [TD]0[/TD]
              [TD]37670 - 3000 = $34670[/TD]
              [/TR]
              [/TABLE]

              Compound interest is the 8th wonder of the world. So given this situation you'd still choose NiFe? What if 400Ah of Lead-Acid was $2k? $1k? At what price would it win in your mind? Economics matters.

              As far as fuel burn for battery maintenance... let's think about this. With NiFe you get ~0.6w for every 1w that goes in. With Lead-Acid it's ~0.8w including the energy used for absorption cycles. NiFe is invincible but even NiFe can't create energy. So whatever extra fuel you'd be using to properly charge lead-acid you'd be using anyway to keep the lights on with NiFe.
              Told you. Factor of 5. See my last post. You either get it or you don't. I'll say no more on the matter.

              Comment


              • Originally posted by johnpearcey View Post

                Told you. Factor of 5. See my last post. You either get it or you don't. I'll say no more on the matter.
                And NiFe are a factor of ~7... So you'd buy lead-acid if they were 1/5th the cost but they're 1/7th the cost? So why did you buy NiFe?

                Originally posted by johnpearcey View Post

                In miserable cloudy parts of the world, NiFe wins hands down.
                Energy is energy. You can use 100kWh in the winter to make up for the worse round-trip efficiency of NiFe or ~50kWh keeping lead acid in absorption for the prescribed time.... numbers.

                It's silly to think that NiFe is going to save fuel. They don't make energy. If your panels aren't producing enough energy to keep lead-acid batteries topped up then they're not going to make enough energy to keep the lights on with NiFe. You're either going to burn fuel charging lead-acid or burn even more fuel keeping the lights on.
                Last edited by nwdiver; 07-15-2020, 02:32 PM.

                Comment


                • Originally posted by nwdiver View Post

                  And NiFe are a factor of ~7... So you'd buy lead-acid if they were 1/5th the cost but they're 1/7th the cost? So why did you buy NiFe?



                  Energy is energy. You can use 100kWh in the winter to make up for the worse round-trip efficiency of NiFe or ~50kWh keeping lead acid in absorption for the prescribed time.... numbers.

                  It's silly to think that NiFe is going to save fuel. They don't make energy. If your panels aren't producing enough energy to keep lead-acid batteries topped up then they're not going to make enough energy to keep the lights on with NiFe. You're either going to burn fuel charging lead-acid or burn even more fuel keeping the lights on.
                  I gave you an example of how NiFe saves fuel. Go back and read it.

                  Comment


                  • Let's stay civil gents. NiFe only goes 10 years, then you have to refresh the electrolyte That cost me a couple grand for lab grade chemicals (lab grade needed if you want a long life.)

                    There is also the convenience factor, of I really never worry about the batteries, I just run the genset enough in winter (90 minutes, 3 pints of diesel)) to get one more day.
                    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


                    • Originally posted by johnpearcey View Post

                      I gave you an example of how NiFe saves fuel. Go back and read it.
                      You told me how you think it saves fuel and I explained how that's not possible. If you have a battery that's 60% efficient vs one that's ~80% efficient the less efficient battery isn't going to save any fuel. I'm in a similar position now where I don't have enough panels to fully charge my batteries so I go on-grid from ~midnight to noon. Less efficient batteries would just INCREASE the amount of time I would need to be on-grid because NiFe would eat more kWh than lead-acid. Not by a small amount either... ~2x as much. I'm losing ~2kWh/day due to cycling. I'd lose ~4kWh/day if I was using NiFe.

                      I suppose if you put the batteries in storage for the winter NiFe would save you a bit of fuel since you can allow them to self-discharge to 0 while you need to top-off lead-acid once a month or so... is that what you're doing?
                      Last edited by nwdiver; 07-15-2020, 06:15 PM.

                      Comment

                      Working...
                      X