Ron Baker, Pluralitas! wrote:

Seems likely that those 4 batteries are in series.
When they are in series the voltages add but the
current rating is that of the weakest battery.
(If they are put in parallel they better all have the
same voltage and the current capacities add.)
Your 4 - 1300 mAh batteries probably look effectively
like one 6 V, 1300 mAh battery to the radio.
So 13 hours is probably right.

That seems sensible. After 10 hours of charging, the 1103 registered
max battery charge bars (though granted it might not be 100%).