Not sure if this has been said before but
when you put energy storage item (i.e. battery, energy cristal, etc) in a storage block (batbox, MFE, MFSU) while the block emits energy to other machines
the charge in the block might be larger than the maximum.
EX: MFE stores 600000 EU but if it has 599999 and a non-empty energy cristal, it will charge to more than 600000 EU