We have been importing these NiFe batteries since beginning of this year.
We have a test setup of 40 cells 1200Ah NiFe batteries (57.4kW) and have been testing the batteries for a few months now.
Yes, the bigger batteries are more economical. If the delivery time is not critical, we can save freight cost by combining orders.
Regarding the price difference with other battery chemistries, we should take into account that the DOD of NiFe is much deeper for the same life time, so you could use a smaller kWh for the same useful kWh.
Not to mention the expected lifetime that is in the order of twice of FLA.
Regarding the charging efficiencies, please bear in mind that the 50% charging efficiency is only for the last 20% of the capacity. Up to 50-60%, the charging efficiency is pretty much 90-95%, decreasing as we approach 80%
The other advantage of not tooping the batteries up till 100%, if that the electrolyte loss is then very minimal. We have been running our batteries for a few months now and had never to top up the electrolyte. We will be testing overcharging them during the hot summer months.
Regarding the self discharge, our batteries are getting less than 1% self discharge per day. For cycle use, this is completely irrelevant. We will be conducting more self discharge test in the time ahead.
A big reason to use these batteries is that they can be overcharged (you need to top up the electrolyte a bit more often) and you can completely discharge them without taking a big penalty in their life time.
But, the main reason we are importing them, is the environment, the components of NiFe batteries are harmless for the environment and even the used electrolyte (recommended to change the electrolyte every 7 years), you could dilute it and use it in your garden to bring up the soil PH if needed.
Unfortunately, the internet is full of myths from people who have never used these batteries. These batteries (like all other batteries), are not for all people in all situations, but we can use their strength for renewable energy storage in stationary applications.
I hope this helps.
Posted Wednesday 20 Aug 2014 @ 8:05:46 am from IP
#