Notice. New forum software under development. It's going to miss a few functions and look a bit ugly for a while, but I'm working on it full time now as the old forum was too unstable. Couple days, all good. If you notice any issues, please contact me.
Boppa Guru Joined: 08/11/2016 Location: AustraliaPosts: 814
Posted: 12:40am 24 Mar 2017
Copy link to clipboard
Print this post
Ive been looking around for the batterys for my new house, and checking out the various prices/types etc I looked at the 2vsla/gells, Winstons from Trev etc
I found a supplier in Oz that actually stocks Nickel iron 1.2v batterys
100% discharge without damage, 30 year life expectancy, almost impossible to damage
Surprised these arent more widely used? Price isnt that high IMHO, does anyone know of people using these type of cells?
NICKEL IRON 1000 AMP HOUR 1.2 VOLT SOLAR BATTERIES Price: AU $855.00
I know that seems expensive, but thats the largest one they stock, they have a range of smaller sizes also eg $425 for 400ahr
Trev has the Winstons for $1.74 per ahr, these are close to that and dont need all the fiddly balancing etc (altho you need basically twice as many to get the same volts) so it seems they work out about the same price???
What am I missing because they seem like they are ideal for an offgrid house (expensive yes, but the life expectancy compared to gels etc seems to balance that out nicely and no balancing needed like the Liions)
Tinker Guru Joined: 07/11/2007 Location: AustraliaPosts: 1904
Posted: 02:18am 24 Mar 2017
Copy link to clipboard
Print this post
You need 3 times as many cells for the same voltage when you compare them with lithium batteries. So they get expensive right away. Then when you consider their poor charge retention, poor efficiency (see Wikipedia)and possible massive size the choice does not look so great to me. Probably OK for some specific application.Klaus
rustyrod Senior Member Joined: 08/11/2014 Location: AustraliaPosts: 121
Posted: 02:22pm 24 Mar 2017
Copy link to clipboard
Print this post
12 volts system need 10 batteries @ 1.2v 12 volts system need 6 batteries @ 2v
24 volts system need 20 batteries @ 1.2v 24 volts system need 12 batteries @ 2v
48 volts system need 40 batteries @ 1.2v 48 volts system need 24 batteries @ 2v
Not twice, not triple, maybe 1.6 ?
Am I missing something ?Always Thinking
Boppa Guru Joined: 08/11/2016 Location: AustraliaPosts: 814
Posted: 02:30pm 24 Mar 2017
Copy link to clipboard
Print this post
The Li batts are over 3v so need less per 12v `stack' is what I think he was talking about so pinching your table :-) iron 12 volts system need 10 batteries @ 1.2v gel/la 12 volts system need 6 batteries @ 2v Li 12 volts system need 4 batteries @ 3v
and so on for the next 12v `stepups'
Boppa Guru Joined: 08/11/2016 Location: AustraliaPosts: 814
Posted: 02:38pm 24 Mar 2017
Copy link to clipboard
Print this post
:-( whats the life expectancy on the Li batts- depending on who you talk to- some are claiming 8-10 years only, others up in the 20-25yr range And I like the `setup and ignore' of Li, if the charging is up to scratch
(I was thinking of trying out a micromite to monitor /control the charging as an experiment if I went ahead with the Li, but not sure I really want to `experiment' and such an expensive part of my house if you know what I mean)
Luckily it isnt a rush thing, until I get the old place sold etc, its all still on paper, so plenty of time to research and learn :-)
Warpspeed Guru Joined: 09/08/2007 Location: AustraliaPosts: 4406
Posted: 03:01pm 24 Mar 2017
Copy link to clipboard
Print this post
The NiFe cells are large and have a low voltage per cell as mentioned above. They also have a high internal resistance which means they cannot support high rates of either charge or discharge.
They might be worth a look if they were dirt cheap, but they are not.
Despite the relatively high initial cost, Lithiums have all the performance advantages. Lithiums allow a fast charging and discharging rate which is important to take advantage of very few short hours of clear sun in winter, and you may have a high peak loading on your inverter.
Only down side of Lithium seems to be they can be permanently damaged by even one overcharging or overdischarging accident. So its worth spending both time and money on the best BMS and some kind of completely independant battery disconnect system. Cheers, Tony.
yahoo2 Guru Joined: 05/04/2011 Location: AustraliaPosts: 1166
Posted: 06:52am 25 Mar 2017
Copy link to clipboard
Print this post
hi Boppa, the problem we have is to do with the way consumer law is written in Australia.
the gist of it is that to imply that something will last longer than you are prepared to warranty it is in effect giving a warranty for that period. No lithium battery seller is going to say that their product will outlast their warranty and last for 20 years.
As an ex installer I am required to keep my own insurance to cover warranty claims (if the manufacturer/seller no longer exists) for the warranty period of the last job I have done. That has made me cautious about throwing numbers around mostly for the sake of sending a consistent message and not unintentionally misleading clients as to what the warranty actually is.
the reason you see expected life thrown around for solar panels is that an individual panel is a few hundred dollars, the cost of trying to claim on an old panel will be more than any return you will get. lithium's are now being sold as modules or packs with all the BMS electronics built in so they are a unit that is worth anything form $1200 to $10,000 each. that is worth the effort to try and lodge a claim if some salesman is stupid enough to put something in writing.
effectively it stops a company rep saying words like design life, it also stops them from using payback examples that are longer than the warranty
technically they should also be clear about expected degradation when they mention round trip efficiencies and temperature limits and the like.
Iron Edison get around this by the fact that you are effectively dismantling and refurbishing the battery on a regular basis. every part of the cell is replaceable and they will make it clear that you are responsible for the quality of the electrolyte and that in-turn dictates the life of the components submersed in it. they are also warrantying individual cells.
I'm confused, no wait... maybe I'm not...
Warpspeed Guru Joined: 09/08/2007 Location: AustraliaPosts: 4406
Posted: 07:46am 25 Mar 2017
Copy link to clipboard
Print this post
What you may be missing is that NiFe cells cannot be either fast charged, or stand very high rates of discharge. They are essentially a very low performance battery for very light duty use.
What that means is you are going to need a very large battery that will only be able to power a relatively small inverter. Any really heavy loads pull the battery voltage right down. NiFe batteries simply cannot supply the high peak currents that more modern battery technologies can easily support.
They also charge very slowly. You cannot pour current into them over a short period the way modern battery technologies allow. If you try, the battery voltage rises right up, and they start to gas and lose water at an alarming rate. Battery recovery will always be very slow, and adding more solar panels would not be a solution for that.
NiFe batteries have been around for over a century, and they were never popular for anything except very large stationary standby batteries for very light and infrequent use. Their long life and reliability are their only strong point. And very poor electrical performance and energy efficiency their weakest point.Cheers, Tony.
Boppa Guru Joined: 08/11/2016 Location: AustraliaPosts: 814
Posted: 04:04pm 25 Mar 2017
Copy link to clipboard
Print this post
I wouldnt have minded size, but the low charge and discharge wouldnt be a good thing
Oh well
Edited by Boppa 2017-03-27
Warpspeed Guru Joined: 09/08/2007 Location: AustraliaPosts: 4406
Posted: 07:33pm 25 Mar 2017
Copy link to clipboard
Print this post
Generally if some type of technology has been around for a very long time, and has never been popular commercially, there is usually at least one very good reason why.Edited by Warpspeed 2017-03-27Cheers, Tony.
yahoo2 Guru Joined: 05/04/2011 Location: AustraliaPosts: 1166
Posted: 09:32pm 25 Mar 2017
Copy link to clipboard
Print this post
I had a look at LG chem's 9.8 kw low voltage pack
they are rated at 8.8kw available so I am guessing that is 90% discharge
and the warranty is for 10 years provided it is operated between -10C and 45C temp and there has been less than 30 Mwh nominal energy use from the battery.
so effectively they are saying they will warranty 4200 cycles to 90% discharge over 10 years. I have calculated it on a smaller capacity to account for degradation.
If the pack is only cycled once a day and drained to 75-85% instead and we assume that the degradation is not purely a factor of time but based on hard cycling and temperature.
Then the potential cycles that may be possible gets a bit ridiculous, I have seen one supplier quoting 10,000 cycles @ 80% discharge. I am sure they will be asked to remove that but you get the picture. You will have to bequeath it to the grandkids in your will.
that's not a battery, its a family heirloom!
One of the problems that I see with people installing large battery banks is the assumption that it will make or save money, it wont, the bigger it is the more our electricity costs.
the only way it works now is to increase the energy used directly from the panels, average houses are using around 25% direct solar use. With not much effort it can be lifted to 50% and with a lot of cunning tricks it can get to 70+%.
if we go on an energy efficiency drive at the same time and reduce our energy usage as well then the costs really come down. The battery is just there to get us through the night.
As for on-grid systems I have yet to see any credible numbers that show a net DIRECT FINANCIAL benefit from adding storage to a solar install.
There are other reasons, but they all cost more than grid + solar. It needs to impact our business or health or something like that.Edited by yahoo2 2017-03-27 I'm confused, no wait... maybe I'm not...
Boppa: For what it is worth I have been importing form China & Vietnam for over 20yrs from various businesses, I can import 40x 1'200Ah NiFe Battery's from a military manufacturer are $750 each into Sydney, they weigh some 70kg each with Electrolyte composed of Potassium hydroxide and Lithium hydroxide ...Not Acid.
HOWEVER: I am currently at setting up a business that offers the above battery's with a Diesel generator for Off Grid and Grid tied system as required.
I understand I will need to use a Multi power-input Inverter, that can handle a 6~10kW Generator power & also Solar, Wind & Aqua power etc. to charge the NiFe Battery bank, as the customer requires it!
I am needing advice on Automatic Mains Failure (AMF) switching gear and Automatic Transfer Switch (ATS), provides automatic switching of your premises from Solar, Battery, generator &/or to state grid supply and back again ?Small minds discuss people, Average minds discuss events, Great minds discuss ideas, Be GREAT !
See this Great engine with No Crankshaft: http://www.revetec.com
Georgen Guru Joined: 13/09/2011 Location: AustraliaPosts: 462
Posted: 12:06am 09 Apr 2017
Copy link to clipboard
Print this post
Not sure if this thread is good place to write about ideas on what to do to increase percentage of direct solar use.
But I would love to read about them. Would you be able to write something on this topic?George
Notice. New forum software under development. It's going to miss a few functions and look a bit ugly for a while, but I'm working on it full time now as the old forum was too unstable. Couple days, all good. If you notice any issues, please contact me.
Print this post
