Ni-Fe; The virtually indestructible battery

[nwdiver]

I've got a client that purchased a 1000Ah 48v 'Iron Edison' battery that I'm installing. Ni-Fe batteries had been on my radar for a while but I never had much of a reason to do a deep dive until now. I've found it fascinating AND frustrating how complex batteries are... Solar is easy... for the most part it's all the same. Silicon is Silicon. Some panels might be a little more efficient or last slightly longer... but it's really all the same. Not true with batteries. There's power density, energy density, cycle life, calendar life, material scarcity (looking at you cobalt!), ease of recycling, toxicity, maintenance, weight, gassing, what SOC does it like.......

Ni-Fe batteries are far from perfect. But they are seemingly much better at one thing... they're virtually indestructible. You can overcharge or undercharge. Charge when cold or hot. Discharge 100% or charge them 'till you're basically using them to make H2 as long as the plates stay covered. They don't care... they are the honey badger of batteries.

They do have some significant disadvantages...

• Round trip efficiency of ~70%
• Self-Discharge ~1% per day (yes; ~30%/mo)
• Require more watering than PbSO4
• Somewhat expensive ~$500/kWh (from China)
• Low Energy and Power density
• WIDE voltage range. Need to charge at ~1.6v/cell; nominal is ~1.2v

But... I dunno... I think having a battery that's almost impossible to kill might be worth those disadvantages; I also like the fact that there really aren't any significant resource bottlenecks with Ni-Fe.

I priced out a 500Ah 48v bank (~24kWh) shipped from China for <$10k including freight. It's such a simple battery I'm not too concerned about getting an inferior product. Still on the fence...

 

[Tdriver]

If it was competitive I would think Tesla would be all over it.

 

[israndy]

I think he means for use as a Powerwall, cars take energy to get up to speed and iron is HEAVY

-Randy

 

[nwdiver]

If it was competitive I would think Tesla would be all over it.

The maintenance requirements probably exclude it from the applications that Tesla is catering to. I think Tesla is also aiming at using their Energy division to help achieve economies of scale for their cars. Ni-Fe would most definitely NOT work in a car... a 48kWh Ni-Fe battery weighs more than a Model X...

I'm not sure if there's really one battery to rule them all; For backup applications Ni-Fe would be terrible since if you leave them alone they're dead in 6 months but for daily use that's not an issue. The watering requirement would be a pain for commercial applications but for home use it may not be a big deal. They off-gas H2 but not SO2 like PbSO4 so at least they don't stink like lead acid.

NCA Lithium batteries definitely rule the roost in terms of energy / power density, cycle life and probably cost but they're kinda 'prissy'. They don't like it too cold or too hot, they can't be over-charged or under-charged. I think there might be certain applications where a big heavy tank is the best fit...