The description of the Transfer Charge spell states that transferring more charges than the item can hold causes damage to the item.
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Transfer Charge
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You must declare how many charges you are transferring before casting this spell. If you transfer more charges from the source than the receiving item can hold, the receiving item must succeed at a Fortitude saving throw or take 1d6 electricity damage. This spell provides no knowledge of how many charges a receiving item can safely hold, but you can choose to transfer fewer charges than the maximum allowed to reduce the risk.
In Breaking Objects, under Hardness it states:
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Hardness:
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On average, a sturdy piece of equipment (such as a weapon or a suit of armor) has a hardness equal to 5 + 2 × its item level. Any other piece of equipment has a hardness equal to 5 + its item level.
Which means that a level 1 weapon has hardness 7 and a typical level 1 item (say, a battery) has hardness 6. This means that the damage from Transfer Charge will always be resisted by every item. If it doesn't bypass hardness it never causes any damage and as such, there's no downside to transferring the wrong amount. That said, by RAW there's no downside to a battery that has the broken condition; it would only be a problem if you did this enough times to fry the battery completely.