Energy to Matter under the Hood?

Question: I have completely discharged a lead/acid battery.  I have used the 
appropriate charger to bring it up to full capacity.  It weighs more, right?  
How much of the weight difference is energy converted to matter, if any?  How 
much weight would I have to pay for a balance to measure that difference in 
mass?
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Yes, it weighs more.  It is all energy converted from electrical 
to chemical form, manifesting itself in the binding energy of the matter.  It 
is not really correct to speak of energy being converted to matter here; it s 
just changing form from electricity to chemical.

A. Smith
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Yes, it weighs more.  Energy does not have to be converted to 
mass to be affected by gravity.  Energy has weight.  Such a balance would be 
priceless, because it is far beyond our technological capability.  However, if 
fingerprints were left on the battery, it would weigh many times more than the 
energy that was added to the battery.

Mooney
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