Are NiFe cells worthwhile for a small solar PV Battery setup?

NiFe cells (Edison Cells) are very old battery technology first patented by Edison around 100+ years ago and were used for the first electric vehicles (competitive with early petrol internal combustion engined vehicles). The main advantage of NiFe cells over Lead acid are that they are less toxic (disposal issues with their much shorter useful lifetimes of lead acid), have useful lifetimes approaching 30-50 years, are extremely robust and have slightly higher energy density and can be stored completely discharged unlike Lead-acid cells. Downsides are higher self discharge rates (not really critical for solar PV) and have less efficient charge and disharge cycles. Finding suppliers appears to be extremely difficult as they appear to be only available from Russian or Chinese manufacturers/suppliers.

http://www.armyradio.co.uk/arsc/customer/product.php?productid=1481&cat=87&page=1

You might ask over here: http://www.candlepowerforums.com/vb/forumdisplay.php?f=9

-john

nickel toxicity will probably preclude their manufacure in the US until more widespread wind/solar acceptance...we need to corner the market on lithium!!!


the lithium iron phosphate (LiPO4) cells look promising though...

Last I checked the price point, return on investment, was with conventional flooded lead-acid cells for battery chemistry. Yes, gel-cells, AGM batteries, have a lot of advantages, most of which don't make a lot of difference in small PV systems type use. Flooded lead-acid batteries are old school and very rugged. The big thing to remember with a FLA battery is that for all sorts of engineering reasons the total practical output is one third the total capacity. Limit it to that, with only the occasional excursion, and you multiply the lifespan.

In these the best form factor was in what are termed 'golf cart' batteries. These get sold a lot and account for the majority of the market so there is a pretty lively competition keeping the price low while, at the same time, making them the easily batteries to find.

AGM batteries are coming up fast in use, and have been for twenty years, and they might be the way to go in some situations but for a stationary system FLA still gets you more for your money.

NiFe cells have their merits, especialy long life and freedom from damage by deep discharge or being left discharged.

The main drawback is the great variation in voltage between on charge and on load, near the end of discharge.

To fully charge a 10 cell (12 volt nominal) battery can take 18 volts or more. Very few 12 volt appliances can tolerate that.
At end of discharge the voltage would drop as low as 9 volts, which is too low for most 12 volt appliances.
The corresponding range for a 12 volt lead acid battery would be from about 11.5 volts up to 14.4 volts, a much smaller range.

One could of course use a voltage regulator, but that adds extra expense, complication, and risk of failure.
Alternatively one could use a 125 volt battery, and use this only to power loads that accept a wide range of input voltage.
Many electronic appliances and electronic lighting ballasts work from 90 volts up to 277 or higher.
They should be fine on a battery that varies from perhaps 95 volts up to about 200.
Such DC voltages are dangerous and not recomended for the novice.