Battery juice is life of any robot. If you do not know the basics of choosing your battery your robot may not work or survive long. All of us know V =IR and P= VI but mostly we ignore these golden rules while designing our bots. Batteries provide power to your robot and lack or excess power may kill it. So help your robot live by these basics.
Know, that you need to balance cost, weight and performance when it comes to battery. There is no way to can fit a Lead acid battery on a multirotor GPS ariel robot nor you will fix a LIPO in a wearable project. So weight out what your power needs, weight needs and budget allocations.
Generally, nothing beats the 1.5v x Alkaline batteries which we use at homes but these needs to be replaced and not eco-friendly. The rechargeable ones get you a 1.2v instead of 1.5 generally but it can be a decent trade off considering most sensors and microcontrollers work in a range of 5v plus.
So if you are not sure - start with Alkaline battery provided your power i.e voltage x current works out well.
The other option is to use NiMH battery, these are heavier than alkaline but the cost and recharge tradeoff makes it a hot favourite among entry-level robots. The final option is the lead acid battery which is the cheapest but a heavy option so it can be used only on metal based mid-scale robots but can be a killer combination where you can bear the weight vs cost ratio.
As you have seen that there is no perfect rule but stick to alkaline if this is your first bot and scale up in your journey. If you would like us to blog more on batteries do comment, like and share.
Image Attribution: By en:User:Brianiac (en:Image:Batteries.jpg) [Public domain], via Wikimedia Commons