1.5V is a nominal voltage. Depending on the history of the cell the actual voltage may vary. The Ahs are the nominal capacity of the battery, i. e. a nominal current can be drawn for a nominal time. With more cells in the adapter a higher current can be drawn. It can also reduce the drop in voltage under load and result in a higher actual capacity. The drawback with parallel multicell adapters is the possibility of currents flowing between the cells when the cells have different voltages.
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If it isnīt broken, it doesnīt have enough features yet.