Camera batteries are Lithium Ion. Then don't leak, they burst into flames of Oxygen gets into them.
TS: Have you ever seen any warning on chargers, cables, cards and other items saying "do not exposed reduced humidity"? Secondly, the target humidity for dry boxes is 45-55%, which resembles average humidity for the moderate climate zones as you can find in US, Europe and Japan. (That's the reason why people in those areas don't need any dry boxes / dry cabinets). So why should it have any negative effect on your equipment? Last but not least: dry boxes and dry cabinets are meant for long term storage for equipment when not used.