Hi All! I am a Dutch university student and I have an assignment to make a Search & Rescue Robot. Because we have to work with a budget, we have decided to make our own batteries (using AA penlights). Now while calculating the required capacity of the battery pack, I encountered some problems. My first approach was to calculate the power the vehicle needs to fully function by using the simple formula P = U*I and doing this for every single electric motor and add all these for a total power requirement. This would be for example 2.8 W and calculated the amount of Joules I would need for the entire rescue operation (approximately 6100 Joules). Though when calculating the battery pack (1.5 V and 2700 mAh) I found that I only needed two batteries in series that would give me 8100 Joules ( 3 V * 2700 mAh = 8100 Joules/hour) Though this seems very unlikely. I think there is something very wrong in my reasoning (I never calculated it in this way before maybe that's why . Could someone tell me whether my approach is valid, and if not, help me to find a strategy to approach this problem. Thanks in advance!