[Alinco] DJ-V5 With External battery?

[Joe]

I borrowed an Alinco DJ-V5 for use at the Pikes Peak International Hill 
Climb race this Saturday.  I'm helping to provide safety communications 
during the race.  I have two battery packs, however, I have a large gel 
cell that I'd like to use for reliability during the race.  The problem is 
that when I connect the external battery pack to the DJ-V5 with the plug, 
the HT won't turn on.

Is this typical??  Sure could use the BIG battery to ensure all day 
communications.  I'm leaving first thing in the morning (Friday) and won't 
be able to receive replies after that.

Thanks in advance for your help!


73,
Joe
WDØM