We continue to explore the workings of the Edison nickel-iron battery, following the advice in the 1914 instruction manual we link to below. This booklet explains how the charging and recharging cycles involved ‘transfer of oxygen from one electrode to the other’. And how the NiFe battery was hence in effect an ‘oxygen lift cell’.
To put things differently, the active material in the positive plates was ‘super oxidized’ in a charged cell. While the negative plates were in a ‘spongy, or deoxidized state’ at that point. Edison’s NiFe batteries shipped in a discharged state. Hence, the first thing a new owner of an Edison nickel-iron battery had to do was rectify this.
Charging an Edison Nickel-Iron Battery
Edison NiFe batteries required a pattern of charging and discharging, ‘to ensure proper capacity and a long life’ the manual explains.
- The first full charge, at the stipulated rate for the battery size took twelve hours.
- Three more overcharges followed after complete discharges, to set the battery.
- Interim, shorter charges at higher rates were in order without ‘injuring the cell’.
- Although ‘the discharge voltage would be lower’ compared to using ‘normal’ rates.
A full charge at the normal rate took seven hours to complete. The Edison nickel-iron battery ‘vented freely’ towards the end of recharging, requiring opening of ‘compartment doors and lids’.
Discharging Edison’s Nickel-Iron Batteries
A ‘normal discharge’ within standard battery capacity took a nominal five hours. However, Edison regarded short periods of high discharges possible, ‘up to six times the normal rate’. But it recommended avoiding ‘abnormal voltage drops on very steep grades’ based on user experience.
The Effect of Extreme Cold Weather
The potassium hydroxide electrolyte remained stable in terms of specific gravity, during charging and discharging. It was, however sensitive to severely cold weather. Thus the manual recommends ‘closing compartment openings fully’ on those occasions. Our final post discusses aspects of maintenance
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