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Nickel Iron (Ni-Fe) Battery Efficiency and Capacity as a function of Temperature
Many people have been asking about Ni-Fe battery efficiency and discharge performance. I think it's important to use concrete data as part of constructive conversation. To that end, please see the attached Ni-Fe battery test results. Tests were performed at the National Renewable Energy Lab in Golden, CO.
At room temp, the batteries were charged for 7 hours at the C/5 rate. (intentional overcharge)
At freezing temps, the batteries were charged for only 5 hours at the C/5 rate. (no overcharge)
Overall, I am impressed with the battery capacity and efficiency numbers. These tests were designed to confirm battery CAPACITY, and not designed for extrapolating efficiency numbers. The fact that the freezing temperature tests were so consistent leads me to believe the data is accurate and valid. I hypothesize that we could have found a more efficient round trip at normal temps by charging for slightly less than 7 hrs.
Iron Edison NREL Ni-Fe Battery Test - Freezing Temps.jpg
Iron Edison NREL Ni-Fe Battery Test - Normal Temps.jpg
This post is intended to share data for peer review, and is not an endorsement of any company.
At room temp, the batteries were charged for 7 hours at the C/5 rate. (intentional overcharge)
At freezing temps, the batteries were charged for only 5 hours at the C/5 rate. (no overcharge)
Overall, I am impressed with the battery capacity and efficiency numbers. These tests were designed to confirm battery CAPACITY, and not designed for extrapolating efficiency numbers. The fact that the freezing temperature tests were so consistent leads me to believe the data is accurate and valid. I hypothesize that we could have found a more efficient round trip at normal temps by charging for slightly less than 7 hrs.
Iron Edison NREL Ni-Fe Battery Test - Freezing Temps.jpg
Iron Edison NREL Ni-Fe Battery Test - Normal Temps.jpg
This post is intended to share data for peer review, and is not an endorsement of any company.