Originally Posted by Dave H

Well I'm certainly assuming the main leads are all attached, including the small pack. If so the current will mostly be on the main wires.

Are you thinking the current would be equally divided between the 4 packs, thus charging the small pack quicker? That can't happen due to the parallel connection, they will all be held to the same voltage by the parallel connection of the main wires. The current On the main wires will be divided appropriately during the charge.

Notice I mentioned the packs should be at a similar voltage before starting, as a practical matter it might be reasonable to speculate the smaller pack is used differently, and may not be at a similar state of discharge and thus voltage, if so that is a reasonable concern.

Also the packs should be in good condition and not have significant imbalance, otherwise that might cause some less than ideal results.