If you're concerned about your battery pack running out of juice, you can use an AC/DC Air Pump to save yourself the trouble. They run off 220V AC power and automatically switch over to DC power when the AC fails. This reduces the recharging time considerably. Whether you use your air pump frequently or only occasionally, it will be useful to charge it on a daily basis.
The AC/DC Air Pump is a convenient back-up for your aquarium during a power failure. It operates on its internal battery for up to eight hours before requiring AC power again. It automatically switches over to DC mode when the AC is shut off, ensuring your aquarium has uninterrupted air flow. Powered by an internal rechargeable battery, this air pump is easy to install and maintenance-free.
The AC/DC Air Pump has a dual outlet for convenient air consumption. A fully charged pump can operate for up to 36 hours. However, it must be remembered that pump life depends on its operating mode. When it is plugged into a wall outlet, it can continue to pump air. In addition, it has an automatic deflation function.sunsun-china.com