Nickel Iron vs. Lead Acid - Off Grid battery debate

[nwdiver]

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.

[johnpearcey]

.... 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.

[Mike90250]

...........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.

[nwdiver]

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.

Year	NiFe	PbSO4
2019	0	$6200
2021	0	$7098
2023	0	$8126
2025	0	$9304
2027 Replace	0	10652 - 3000 = $7652
2035 Replace	0	13161 - 3000 = $10161
2043 Replace	0	17477 - 3000 = $14477
2051 Replace	0	24901 - 3000 = $21901
2059 Replace	0	37670 - 3000 = $34670

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.

[johnpearcey]

.... 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.

[johnpearcey]

.... 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.

Year	NiFe	PbSO4
2019	0	$6200
2021	0	$7098
2023	0	$8126
2025	0	$9304
2027 Replace	0	10652 - 3000 = $7652
2035 Replace	0	13161 - 3000 = $10161
2043 Replace	0	17477 - 3000 = $14477
2051 Replace	0	24901 - 3000 = $21901
2059 Replace	0	37670 - 3000 = $34670

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.

[nwdiver]

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?

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.

[johnpearcey]

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.

[Mike90250]

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.

[nwdiver]

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?

[Brian1]

Test. Looks like I am back.

Since I last posted I have made some improvements to my system.

A couple of months ago I replaced my Flexmax 80 with a Midnight Solar Classic 150 which allowed me to finally bring out the last 2 BP175 panels so I have now deployed a total of 8 panels. This occurred right after a hurricane and I lived exclusively off this system for 2.5 days.

A couple of weeks ago I installed a 500 farad capacitor across the inverter input to help with the fridge surge when it turns on and the batteries are below 2/3 charged and I am running other stuff. I found the batteries were having trouble supplying that instantaneous surge alone and thought the big capacitor would help. I have not gotten to test that yet. It is made of 6 x 3volt 3000 farad capacitors in series so you end up with an 18 volt x 500 farad capacitor. I recall there was opinions about how to charge this capacitor initially. I gave it it's own fuse so to charge it I had a couple of very large 2.2 ohm resistors in series across the fuse connections without the fuse in there and I waited until nighttime so the battery voltage was around 13.4 volts which gives a current of around 3 amps. I let that go for a couple of hours until the current was less than 1 amp then I moved my connection to a single resistor for a couple more hours until there was no current and then I disconnected that arrangement and put the fuse in. I will let you know how that goes once I get a chance to run the battery down far enough to test.

That is all the improvements to date aside from I am trying to build kind of a pergola arrangement over my back porch so I can mount all 8 of those BP175s in one place in an organized manner instead of scattered around the house in pairs.
Beyond that, the batteries are still working just great.

Unrelated to this I have also installed a 3.96kW grid tied PV system on the roof. This seems to be doing fine.

I made a quick video for the national solar tour I could share if there is interest.

Brian

[johnpearcey]

Useful article about the latest NiFe developments:

https://www.perma-batteries.com/en/product/batteries-encell/#

[peakbagger]

Looks like more of advertisement. The article is from 2018 which is ancient history as far as battery tech is concerned.

[Mike90250]

I see only a new way of making the porous plates, via sintering powder metal, much faster than the old pocket plate and apparently more exposed surface area.
Made in the USA ( in 2018 ) distributed out of France . Odd combination .

[mdagli1]

Hi guys, before I start another thread on the developments associated with NiFe, does anyone know the difference in performance between pocket vs sintered? From what I can tell from reading the datasheets and sales descriptions for sintered:

1. Increased charge/discharge rates due to increase surface area (C/4 rather than C/5)
2. Slightly increased charging voltage required (by about 0.05V for the higher rates)
3. Reduced voltage drop during high demand (power curve unknown)
4. Lower minimum charging current meaning reduced self-discharge rate? (C/50 rather than C/20)
5. Reduced physical plate size for the same AH capacity from their picture? (electrolyte volume the same?)
6. Improved charging efficiency (75% rather than 50% approximately)
7. Improved operating temperature range at the upper and lower limits (15oC ether way)
8. Immune to thermal runaway from a CC source (due to improved temperature tolerance?)
9. Increased cycle count for 100% DoD (more than doubled due to reduced need of electrolyte top ups but real cause is unknown?)
10. new patent (Edison patents however have expired?)
11. electrolyte mixture remains the same, 25% KOH and 3% LiOH (any research being conducted here?)
12. gassing rates remain high at above 80% state of charge meaning water loss remains an issue (any info on the thresholds changing on this?)
13. lower mechanical strength so more vulnerable to physical shock?

Could someone verify my comment please as I don't have access to the academic literature on the subject. (most are educated guesses)

thanks