How does the grip share two battery packs? Is the battery life doubled?
The grip allows use of two batterys as well as an external power source. All three sources are connected together using diodes. Think of a diode as a one-way valve. The power source with the highest voltage will be connected to the camera contacts, and the other two will be essentiall disconnected. As one power source drops in voltage, the mix may change, so that the highest voltage is always applied. So, if you have two charged battery packs installed, as the charge drops on one pack, the current will start to be drawn from the other, until it’s voltage drops down below the first. Both battery packs will effectively discharge at the same rate, effectively half as fast as they would have normally. If you use an external AC adapter with the grip, assuming the input voltage is higher than that of the battery packs, the battery packs will not be drained at all… all power will come from the external source. Some real world details… the diodes used to connect the power sources to the ca
