As long as you are connecting batteries of the same voltage rating in parallel(+ to+, - to-), amp hour differences(from size,age,mca)does not matter. Hooking them together will provide greater current capacity. So Kirby can troll longer...
If the batteries were hooked in series (+ to-), to increase voltage, than equally rated batteries should be used. Current flow in a series circuit is equal at all points, so a smaller battery would discharge faster.
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