The 2 parallel circuits can be used simultaneously.
With the same base, just by changing the mounting plates, it can charge different kinds of batteries.
1. After being used for 2-3 times, it can reach best performance.
2. For thre rechargable batteries which has been stored more than 1 week, some electricity will be lost, it needs to be recharged before use.
3. It is better for the charger to work indoor with ambient air.