What is the difference between "pila" and "bateria"
I see these words used quite specifically. It seems like "pila" is a flashlight type battery but "bateria" is used for electronic devices. Is that correct?
9 Answers
"Pila" usually refers to a small battery, sizes AAA, AA, C, etc.
"Batería" is for bigger batteries, such as that for a car or video camera.
These are great answers. I'd like to add my experience here as I think it might be helpful. Pila should be used for "simple" batteries, interchangeable even. These would included small watch and hearing aid batteries, AA, AAA, D, etc... car, camcorder, portable DVD player batteries (along with other similar types of batteries) are called pilas in many Spanish dialects but are technically baterías because they aren't simple with two sided positive/ negative connections and have more than one cell. People say they are also "baterías" because in some American-Spanish dialects, not just the U.S., batería can mean any type of battery. I believe this is the result of globalization of the Spanish language and the influence of English and French, which is the case in many parts of the Americas.
I will say as a side note. I was once selling a phone to someone from Mexico, alongside my coworker from D.F. and referred to a cellphone battery as a "pila" and it was like the two of them couldn't understand a word I said because of that small little mistake. I've been in the wireless business for 13 years and it's rare that someone asks for a "pila" for a cellphone battery but it does happen.
I wish I knew the number of times that I've been told that there is no difference. I've had others who, with great difficulty, would try to explain the difference and then give up, saying "they're the same". I used to bring this subject up a lot at church because we are always swapping/changing/recharging batteries for the microphones, guitars, etc.
The thing is, people may hold a different concept for "pila" and "batería" (speaking strictly about the electricity- source type of "pilas" or "baterías" now), but what you call a "pila", I may very well call "batería". I find that there's no real consistency or agreement between what many people call one thing or another.
Possibly the only exception to this are the big, block, car battery type of things, that I believe are called "baterías" just about everywhere.
So... in that sense, I'm afraid that the conclusion is that oftentimes the two terms are in fact interchangeable! 
I think nemopaice summed it up quite well. Regardless of what the "correct" term is, people say what they say.
Another example of people doing this with words in English is parking space. I know lots of people who say "We need to find a park" instead of "we need to find a parking space". Argh! It irritates the heck out of me!
I'm not looking this up, but relying on memory. The discovery of electricity lead to the development of "voltaic piles". I think I spelled that correctly. To produce more energy, several piles would be linked together in a "battery of piles" Thus "pilas" and "baterias".
No voy a investigar esto, sino confiarme en la memoria. El descubrimiento de la electricidad engendró el desarrollo de los "voltaic piles" (en inglés). Creo haberlo deletreado bien. Con fin de producir más energía, los "piles" se conglomeraban en una bateria."
I know this post is a couple years old, but after reading I wanted to mention... I work at an auto parts store where roughly 40% of our business in Mexican. While some of them say they need a batería, the vast majority say they need una pila, when referring to a car battery...
From my understanding, I have to agree with the differences already mentioned, but never the less, that's what I experience on a daily bases, so I thought I should mention it.
Though this could stem from even native speakers not using proper Spanish, much the same way many native English speakers don't use proper English.
For example: Many people say things like, "They was in the house all day". Which is poor English. it should be, "The were in the house all day".
Anyway, take it with a grain of salt.
Wow...all of these responses are interesting.
I saw a student project in Mexico that explained that "pilas" are non-rechargeable and "baterías" are rechargeable.
Is this just the case in Mexico?
pila
= battery
noun
Pila feminine noun 1. battery (generador)
funciona a o con pilas -> it works o runs off batteries
ponerse las pilas (informal figurative) -> to get moving o cracking pila alcalina -> alkaline battery
pila atómica -> atomic pile
pila recargable -> rechargeable battery
pila solar -> solar cell
- pile (montón)
tiene una pila de deudas -> he's up to his neck in debt
- sink (fregadero)
pila bautismal -> (baptismal) font
- pile (architecture)
I wish I knew the number of times that I've been told that there is no difference. I've had others who, with great difficulty, would try to explain the difference and then give up, saying "they're the same". I used to bring this subject up a lot at church because we are always swapping/changing/recharging batteries for the microphones, guitars, etc.
