NiFe battery pro's and con's

Cpfarr

Hi all, hope I'm not repeating a thread already here...

A little background; I've got a bank of FLA's and I've just had to remove one of my three strings due to five batteries going bad. I'm anticipating the need to replace the remainder of the batteries next year and I'm researching my options for battery types.

There seems to be a lot of half truths and salesmanship on the web pertaining to these batteries so... I'm trying to get some real world background from those of you who have experience with NiFe batteries. What are the pro's and con's of these batteries?

Thanks, Chad

Cariboocoot

Re: NiFe battery pro's and con's

Quite a few discussion on the forum about NiFe (and also LiFePo).

http://www.google.ca/search?hl=en-CA&source=hp&q=site%3Asolar-electric.com+NiFe&btnG=Google+Search&gbv=1

mike95490

Re: NiFe battery pro's and con's

Pro, is that they don't care if they sit for weeks on end, running between 30% and 80% of charge, which would destroy lead/acid cells.

Cons: high resistance, lower efficiency 70% vs Pb/H2So4 $85%, awkward electrolyte changeout every 4-7 years (it gets "poisoned" from atmospheric Co2) Much less energy dense, figure 3-4x the bank size for the same useful amp hours (you have to add ~30% more ah for the NiFe because of the higher internal resistance) so your 600ah Pb bank become a 900ah NiFe bank. Very wide voltage range from 10% to 100%, it will require inverters that will work over the large range, and chargers that can be programmed to fit the NiFe Charge Profile. 46V - 68V in my system. thirsty batteries,

706jim

Re: NiFe battery pro's and con's

Pros:

1. Batteries were "free"; salvaged from railroad "wig wags". ("Still perfectly fine!")

Cons:

1. Tremendous voltage variation between charged and discharged.

2. Minimal real capacity compared to what was expected.

3. Slimy electrolyte compared to acid. Oozes out of the top of cells. (Yuk!)

3. A zillion interconnects required to make up a decent bank.

4. An environmental DISASTER to try and dispose of. (What exactly do you do with 100 useless cells on an island?)

I was able to dispose of them properly thanks to the Coast Guard, but otherwise would have been stuck with a horrible mess to clean up.

I guess I'm saying I'd avoid them.........

westbranch

Re: NiFe battery pro's and con's

with the addition of a weak acid the KOH electrolyte can be turned into a Potassium salt with appropriate cautions taken to keep it off your skin. http://www.newton.dep.anl.gov/askasci/chem03/chem03011.htm

mike95490

Re: NiFe battery pro's and con's

Or the electrolyte (KOH) can be diluted and used as fertilizer and soil acidity reducer. That's my plan.