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Nickel Iron vs. Lead Acid - Off Grid battery debate

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  • Originally posted by nwdiver View Post

    No; 80Ah wouldn't get me through some nights. 200Ah would. Even cycling the L16s to ~50% DOD sometimes they should last ~8 years. I've been running mostly off-grid since March using L16s to get a feel for the challenges. Maybe half of my cycles are to ~50% and ~30% are only to ~20%. With that kind of use I should get >8 years out of the batteries. Makes more sense to spend $3k every 8 years than spend $9k once due to the time value of money.
    You talk like you actually used 80Ah of NiFe. But you previously said you didn't buy them. So which is it? You can cycle the NiFe to zero which you can't do with the lead-acid types. I've had various types of deep cycle lead-acid for the previous 3 years and they all degraded by about 0.8% of each Ah used no matter how shallow they were used. The other thing with NiFe is that you can charge them in a few hours which you can't do with lead-acid. This is a big money saver when you're located in a country where you can go many weeks without sunshine and have to use a generator. NiFe will save you a fortune on diesel, way more than your 'value of money'. I do agree though that spending large capital up front is not the best way if it can be delayed obviously. But remember also that people who are off-grid do not do so to save money. Connecting to your local grid is way cheaper. So why do we do it? Because we don't trust the economics of our society and want something which will soldier on for many years, long after the grid has packed up and long after fiat currency has crashed. We've been called crazy until Coronavirus popped up and cause havoc and we don't look so stupid now. If things get worse, which is very likely, we could see things like hyper-inflation and even fiat money crash. Then you're going to wish you'd spent the 9k when it was so cheap!!

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    • Originally posted by johnpearcey View Post

      You talk like you actually used 80Ah of NiFe. But you previously said you didn't buy them. So which is it? You can cycle the NiFe to zero which you can't do with the lead-acid types. I've had various types of deep cycle lead-acid for the previous 3 years and they all degraded by about 0.8% of each Ah used no matter how shallow they were used. The other thing with NiFe is that you can charge them in a few hours which you can't do with lead-acid. This is a big money saver when you're located in a country where you can go many weeks without sunshine and have to use a generator. NiFe will save you a fortune on diesel, way more than your 'value of money'. I do agree though that spending large capital up front is not the best way if it can be delayed obviously. But remember also that people who are off-grid do not do so to save money. Connecting to your local grid is way cheaper. So why do we do it? Because we don't trust the economics of our society and want something which will soldier on for many years, long after the grid has packed up and long after fiat currency has crashed. We've been called crazy until Coronavirus popped up and cause havoc and we don't look so stupid now. If things get worse, which is very likely, we could see things like hyper-inflation and even fiat money crash. Then you're going to wish you'd spent the 9k when it was so cheap!!
      I guess you can think that way but for some (me included) I don't want to live through a time where we all have to fend for ourselves. I guess I am just getting too old for that stuff.

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      • Originally posted by SunEagle View Post

        I guess you can think that way but for some (me included) I don't want to live through a time where we all have to fend for ourselves. I guess I am just getting too old for that stuff.
        Well I don't want to either. But it's not necessarily a case of needing to fend for ourselves, more like whether we want to sign up to the 'new normal'. I don't and I won't. Personally I think that the elites will ensure that the power grids and the internet will be kept running at all costs otherwise their 'new normal' won't work. I don't want to be earning crypto-currency browny points in order to pay my electricity bill. I'll be off-grid with my chickens and vege-plots living the 'old' normal. At least until my NiFe's pack up - lol.

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        • Originally posted by johnpearcey View Post

          You talk like you actually used 80Ah of NiFe. But you previously said you didn't buy them. So which is it?
          I said I had seriously considered it until I looked at the numbers in terms of the time value of money. Spending $3k every 8-10 years makes A LOT more sense than spending even $6k once. $9k is a non-starter. If 400Ah wasn't enough I can always go with 600Ah and still come out ahead. Economics matters. This isn't on-grid vs off-grid this is off-grid vs off-grid. Why needlessly spend money to achieve the ~same result? The best solution is found in the middle. GC2s are too cheap and super-batteries are too expensive. Something like a L16 makes the most sense because math. If you don't trust banks and keep gold bars buried in the backyard NiFe may make the most sense... I make my $$$ work for me.
          Last edited by nwdiver; 07-13-2020, 06:06 PM.

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          • Is there anything paying usable dividends now ?
            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

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            • Originally posted by Mike90250 View Post
              Is there anything paying usable dividends now ?
              Figure of speech for growth in general. My investments are up ~25% y/y. Mostly thanks to TSLA. It's an outlier but $6k invested in TSLA 8 years ago would definitely be enough for a new bank of L16s..... And a house to power with them

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              • Originally posted by nwdiver View Post

                I said I had seriously considered it until I looked at the numbers in terms of the time value of money. Spending $3k every 8-10 years makes A LOT more sense than spending even $6k once. $9k is a non-starter. If 400Ah wasn't enough I can always go with 600Ah and still come out ahead. Economics matters. This isn't on-grid vs off-grid this is off-grid vs off-grid. Why needlessly spend money to achieve the ~same result? The best solution is found in the middle. GC2s are too cheap and super-batteries are too expensive. Something like a L16 makes the most sense because math. If you don't trust banks and keep gold bars buried in the backyard NiFe may make the most sense... I make my $$$ work for me.
                As I said, NiFe have saved me loads on diesel (about 20ltrs/w). Not to mention the wear and tear on the generator. And my NiFe cost me 2k, so in 2yrs time, these NiFe pay for themselves whereas lead-acids are dead. Time-value of money is irrelevant here. And I'm not sure where I'd get 3k in 8 years time anyway, I'll be too old to work. And I don't need any help with my maths thanks, I have a BSc in Mathematics and Physics and plenty of spreadsheets and data to analyse this problem. The maths only works if you get your original assumptions right. We live in different environments and you have to consider the system as a whole. Here in Ireland, 400Ah lead-acids would be dead in 2yrs or the diesel cost would be higher than the battery cost. And this set of NiFe batteries should last me 15-20 years. And yes, I do have some gold bars and just take a look at the spot price recently. It's going to go a lot higher.
                Update: We've had 2 straight weeks of dark cloud cover here where I live. How large would a bank of lead-acids need to be to get through this and stand any chance of lasting 8 years??
                Last edited by johnpearcey; 07-14-2020, 04:15 AM.

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                • Originally posted by johnpearcey View Post

                  Here in Ireland, 400Ah lead-acids would be dead in 2yrs or the diesel cost would be higher than the battery cost.
                  2 years? Did you buy used? I have GC2s that are still going after 6 years...

                  Agreed; You need to get quality lead-acids and ~2x the Ah that you usually need so DOD rarely exceeds 50%. That would last ~8-10 years (not 2) and save just as much diesel for 1/3rd the cost of NiFe. Take that savings... put it in a S&P index... then buy another lead-acid bank in 8-10 years and figure out what you're gonna spend the other ~$9k on. But this is 200Ah of NiFe for $9k vs 400Ah of lead-acid for $3k. What size battery do you have?

                  Here's the point I realized. The only real benefit to NiFe is lifespan. The faster charging doesn't benefit me because my lead-acid bank can already charge faster than my CC can charge them. If your PV array and battery bank are sized correctly this should be true. So the only benefit is the battery bank lasts forever but at ~3x the cost even after doubling the Ah of the lead-acid bank to limit DOD >50% the math doesn't even come close to working. In most situations why would someone spend $9k once instead of $3k every 8 years? What benefit would be realized?

                  I would argue that the lead acid carries the additional benefit of having a 'reserve'. Yeah... it will damage the battery a bit more to discharged it to 70% but if you're only doing that once a month it's won't be that bad so you can get ~300Ah out ~occasionally while with a 200Ah NiFe you get >200Ah ~never. So between 400Ah of PbSO4 for $3k or 200Ah of NiFe for $9k I don't see how NiFe makes sense. Maybe $6k but not $9k.

                  In my specific example it actually came out to <$3k. I bought 8 Trojan SPRE 415s for $305ea. I regularly cycle them to ~30% and occasionally to 50% (maybe once every ~45 days to 60%). They should last >8 years with the type of use (we'll see). How would NiFe have made more sense?
                  Last edited by nwdiver; 07-14-2020, 04:24 AM.

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                  • Originally posted by nwdiver View Post

                    2 years? Did you buy used? I have GC2s that are still going after 6 years...

                    Agreed; You need to get quality lead-acids and ~2x the Ah that you usually need so DOD rarely exceeds 50%. That would last ~8-10 years (not 2) and save just as much diesel for 1/3rd the cost of NiFe. Take that savings... put it in a S&P index... then buy another lead-acid bank in 8-10 years and figure out what you're gonna spend the other ~$9k on. But this is 200Ah of NiFe for $9k vs 400Ah of lead-acid for $3k. What size battery do you have?

                    Here's the point I realized. The only real benefit to NiFe is lifespan. The faster charging doesn't benefit me because my lead-acid bank can already charge faster than my CC can charge them. If your PV array and battery bank are sized correctly this should be true. So the only benefit is the battery bank lasts forever but at ~3x the cost even after doubling the Ah of the lead-acid bank to limit DOD >50% the math doesn't even come close to working. In most situations why would someone spend $9k once instead of $3k every 8 years? What benefit would be realized?

                    I would argue that the lead acid carries the additional benefit of having a 'reserve'. Yeah... it will damage the battery a bit more to discharged it to 70% but if you're only doing that once a month it's won't be that bad so you can get ~300Ah out ~occasionally while with a 200Ah NiFe you get >200Ah ~never. So between 400Ah of PbSO4 for $3k or 200Ah of NiFe for $9k I don't see how NiFe makes sense. Maybe $6k but not $9k.

                    In my specific example it actually came out to <$3k. I bought 8 Trojan SPRE 415s for $305ea. I regularly cycle them to ~30% and occasionally to 50% (maybe once every ~45 days to 60%). They should last >8 years with the type of use (we'll see). How would NiFe have made more sense?
                    And my cheap car battery is still going for 7 years which proves that lead-acids only last if you don't use them. So you have paid around 2.5k for the ability to actually use 120Ah regularly. The price for 120Ah set of NiFe is about 3.5k. That will last you 20 years which is 175pa. You will need to replace your lead-acids at least twice in that time by your own admission costing you 2.5k + 3.2k +4.2k = 10k over 24 years = 416pa. How could NiFe not make sense?

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                    • Originally posted by johnpearcey View Post

                      And my cheap car battery is still going for 7 years which proves that lead-acids only last if you don't use them. So you have paid around 2.5k for the ability to actually use 120Ah regularly. The price for 120Ah set of NiFe is about 3.5k. That will last you 20 years which is 175pa. You will need to replace your lead-acids at least twice in that time by your own admission costing you 2.5k + 3.2k +4.2k = 10k over 24 years = 416pa. How could NiFe not make sense?
                      I use my GC2s ~everyday. Lead-Acid batteries last if you cycle them gently.

                      I paid $2500 for a battery that suited my needs of <200Ah of storage ~180 days/yr and ~250Ah 15 days/yr. Where are you finding 120Ah NiFe for $3500? The only dealer in the US that sells NiFe (Iron Edison) sells 100Ah for $4200. If I wanted a NiFe battery with 200Ah of usable capacity I would need to spend ~$9200. If I wanted to cover the other few days that I wanted a bit more ~$12600. How would spending $9200 in an infinite 200Ah battery have worked out better than $3k on a 8yr and investing the difference? The $6k I didn't spend is already $7500 (been a good year). I have little doubt it will be $12k in 8 years with all the ups and downs of the market. What is an investment in NiFe getting me aside from saving a little work once a decade?
                      Last edited by nwdiver; 07-14-2020, 03:24 PM.

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                      • Originally posted by nwdiver View Post

                        I use my GC2s ~everyday. Lead-Acid batteries last if you cycle them gently.

                        I paid $2500 for a battery that suited by needs of <200Ah of storage ~180 days/yr and ~250Ah 15 days/yr. Where are you finding 120Ah NiFe for $3500? The only dealer in the US that sells NiFe (Iron Edison) sells 100Ah for $4200. If I wanted a NiFe battery with 200Ah of usable capacity I would need to spend ~$9200. If I wanted to cover the other few days that I wanted a bit more ~$12600. How would spending $9200 in an infinite 200Ah battery have worked out better than $3k on a 8yr and investing the difference? The $6k I didn't spend is already $7500 (been a good year). I have little doubt it will be $12k in 8 years with all the ups and downs of the market. What is an investment in NiFe getting me aside from saving a little work once a decade?
                        I imported direct from China. That price included transport costs and all import duties. I agree that reducing the spend on a depreciating asset is a good idea and especially if you can put that money to use elsewhere. But that's not really the main issue here. In your situation, a lead-acid might indeed last 8yrs but in certain use-cases, as I keep repeating, the lead-acids will die a very early death. They will absolutely not last 8yrs. During the winter here, I could never top them up to more than about 95%. And if you can't do that, then you loose that top 5%. If you keep that up regularly, the capacity will drop very quickly indeed. This is one of the downsides with lead-acid. You have to spend hours at tiny currents topping up that last 5%. Fine when the suns shines all day and not good when you go weeks without sunshine. NiFe just don't have that problem. You can run them all their life at whatever charge capacity you wish. That's a real cost saver when running generators. I could have spent the money on extra solar panels instead of NiFe but then I'd still have to replace the lead-acids every 8 years. I also don't have the room for more panels just at this moment.

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                        • Originally posted by johnpearcey View Post

                          I imported direct from China. That price included transport costs and all import duties. I agree that reducing the spend on a depreciating asset is a good idea and especially if you can put that money to use elsewhere. But that's not really the main issue here. In your situation, a lead-acid might indeed last 8yrs but in certain use-cases, as I keep repeating, the lead-acids will die a very early death. They will absolutely not last 8yrs. During the winter here, I could never top them up to more than about 95%. And if you can't do that, then you loose that top 5%. If you keep that up regularly, the capacity will drop very quickly indeed. This is one of the downsides with lead-acid. You have to spend hours at tiny currents topping up that last 5%. Fine when the suns shines all day and not good when you go weeks without sunshine. NiFe just don't have that problem. You can run them all their life at whatever charge capacity you wish. That's a real cost saver when running generators. I could have spent the money on extra solar panels instead of NiFe but then I'd still have to replace the lead-acids every 8 years. I also don't have the room for more panels just at this moment.
                          You'd get lead-acid to 100% for the same energy that it takes to get your NiFe to 90% because the coulombic efficiency of lead-acid is ~15% higher than NiFe. After cost that's the other big compromise with NiFe; I didn't want the potential head-ache of importing direct from China so I bought from an American Company. But for an apples-apples comparison the ~same lead-acid battery I bought for ~$2500 here I could import from China for <$1k so the cost difference really doesn't change.

                          Hopefully this debate will be a moot point by the time my L16s need replacing in ~8 years. We need a battery with ~90% round-trip efficiency that cost <$100/kWh, doesn't require maintenance and lasts ~20 years. Good chance something like that is coming soon, we're already getting close.

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                          • Originally posted by nwdiver View Post

                            You'd get lead-acid to 100% for the same energy that it takes to get your NiFe to 90% because the coulombic efficiency of lead-acid is ~15% higher than NiFe. After cost that's the other big compromise with NiFe; I didn't want the potential head-ache of importing direct from China so I bought from an American Company. But for an apples-apples comparison the ~same lead-acid battery I bought for ~$2500 here I could import from China for <$1k so the cost difference really doesn't change.

                            Hopefully this debate will be a moot point by the time my L16s need replacing in ~8 years. We need a battery with ~90% round-trip efficiency that cost <$100/kWh, doesn't require maintenance and lasts ~20 years. Good chance something like that is coming soon, we're already getting close.
                            Yes, the efficiency of my NiFe is currently running at 59% which is not great at all. But to be honest I really haven't noticed it because when the sun shines it's free. So if you drop 40%, you kinda don't care. It just means it takes 2 days to fully charge rather than 1. And the cost of running a generator is (oddly) roughly the same per hour no matter how hard you run it. Better efficiency would of course be welcome since it would translate into savings in fuel and solar arrays. But the other compromise which you haven't mentioned which I've noticed more with NiFe is that you can't pull as much power from them as you can lead-acid. Frankly, for raw power, lead-acid rock, no question. But in my environment, lead-acid are way too fragile whereas NiFe are far more robust. If I could get a wind turbine up then I'd probably comfortably use lead-acid but that would cost over 12k.

                            I'm not sure I share your optimism though in battery development. Corporates don't like products that last 20yrs, they like a faster buck and quicker turn-around. But if it happens, I'll be trying some out for sure. Keep me posted!

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                            • Originally posted by johnpearcey View Post

                              Yes, the efficiency of my NiFe is currently running at 59% which is not great at all. But to be honest I really haven't noticed it because when the sun shines it's free ...... But if it happens, I'll be trying some out for sure. Keep me posted!
                              ...... point being that the 'problem' you mentioned previously of only getting to 95% and being unable to fully charge as lead-acid batteries require would not occur with lead-acid batteries in your case....

                              The 60% round-trip efficiency alone is almost a deal killer BEFORE the cost is considered. That's terrible, I thought NiFe was closer to 70%. Looking at my monitor I've put 1754kWh into my batteries and gotten 1463kWh out for an efficiency of 83% but that includes a lot of unnecessary absorption time.

                              It's already happening... the battery in my Tesla is 8 years old, I've cycled ~60MWh through it and it still retains >90% of its original capacity. I had considered lithium but reducing the burden on the supply chain, cost and recyclability put lead-acid over the top.

                              Here's a question I pose to nuclear advocates. How much cheaper would a 8 year battery have to be compared to NiFe for it to be the winner over NiFe for you? If I could get a NiFe for <3x the cost per Ah (total not 'usable') vs lead-acid I would choose NiFe. So if a 200Ah NiFe battery was available for <$4500 I agree that might be a better deal... but not >$9k. So how cheap would a lead-acid with a 8yr life have to be for you to chose lead acid over NiFe?

                              This is the trap people fall into... they choose one quality they think is critical and ignore all the others. A generator that emits no carbon and can operate 24/7 for 18 months without re-fueling is awesome.... how much does it cost? A battery that's invincible and lasts ~forever is great... how much does it cost? Economics matters.
                              Last edited by nwdiver; 07-14-2020, 07:12 PM.

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                              • Originally posted by nwdiver View Post

                                ...... point being that the 'problem' you mentioned previously of only getting to 95% and being unable to fully charge as lead-acid batteries require would not occur with lead-acid batteries in your case....

                                The 60% round-trip efficiency alone is almost a deal killer BEFORE the cost is considered. That's terrible, I thought NiFe was closer to 70%. Looking at my monitor I've put 1754kWh into my batteries and gotten 1463kWh out for an efficiency of 83% but that includes a lot of unnecessary absorption time.

                                It's already happening... the battery in my Tesla is 8 years old, I've cycled ~60MWh through it and it still retains >90% of its original capacity. I had considered lithium but reducing the burden on the supply chain, cost and recyclability put lead-acid over the top.

                                Here's a question I pose to nuclear advocates. How much cheaper would a 8 year battery have to be compared to NiFe for it to be the winner over NiFe for you? If I could get a NiFe for <3x the cost per Ah (total not 'usable') vs lead-acid I would choose NiFe. So if a 200Ah NiFe battery was available for <$4500 I agree that might be a better deal... but not >$9k. So how cheap would a lead-acid with a 8yr life have to be for you to chose lead acid over NiFe?

                                This is the trap people fall into... they choose one quality they think is critical and ignore all the others. A generator that emits no carbon and can operate 24/7 for 18 months without re-fueling is awesome.... how much does it cost? A battery that's invincible and lasts ~forever is great... how much does it cost? Economics matters.
                                The charging problem is a charging profile issue, not an efficiency issue. With the last 5% for a lead acid, the generator has to run on and on and on until the current finally drops to an amp or so. With NiFe, you just stop it when you like, no harm done and plenty of diesel saved. I'd probably need around 5x the capacity of lead-acid to stand even a chance to reach 8yrs. My 3rd experiment was last year - I bought 4 cheap (Banner) 100Ah for about 500EUR. They lasted 12 months at 20% DOD. I've attached a graph of the charge capacity (green) for the year so you can see what the usage was. Voltage is black and amps is blue. You can see it dropping 5Ah every month. (The dip in Feb is not to be believed, an effect of the initial forming charge I think). You can see a S.G. adjustment in Oct and Dec. By Feb, completely unusable. Screenshot from 2020-07-14 22-02-03.png
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