And don't pack them all together in a single box on an aeroplane ....After market batteries are good for single project, not for lifetime.
Like going to mission where known to be for weeks most time without power.
So buying a 10-15 units of official batteries (olympus E-M1) costs 75€ each...
Tested aftermarket costs 19,90€ each.
Do you drop 750-1125€ or 199-298€
Hmmm... let me guess...