If make a 5V battery pack as a series of four 1.2V NiMH batteries, there is some risk of polarity reversal when the pack is discharged too much. I doubt this risk is reduced by plugging such packs in series.
What if I wire up the eight batteries from two such packs as a single pack with connecters between the cells that lie at the same potential within the pack? A priori, I'd expect this provides some protection against polarity reversal by averaging the characteristics of the two cells that stay at each potential. Is this true?
Are there any issues with charging such a "wide" pack arrangement? Are there any advantages to building in the connectors to access the intermediate potentials, like LiPo batteries require?
As an aside, are high draw 10 amp-hour NiMH D cells at more or less risk of polarity reversal? Obviously, the financial risk in destroying a cell is higher.