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Do we know the battery life of the CR2032?

According to this CR2032 data sheet at 3 volts left continuously on, the battery would last 1200 hours. (If I'm reading this right)

Should we worry about having to change out the battery every couple of months?


5 Replies

steveastrouk (author)2017-06-11

The DATASHEET says "into a 15k load", thats a 200uA load current.

rickharris (author)2017-06-11

I think the bottom line to you question should we worry is probably yes.

However as said the load is the key.

Divide the load current into the mAh of the battery to get a rough idea of life span.

Generally these small button cells are used for low current applications like watches or very intermittent use like a car key entry - continuous use drains them quickly.


If you have a bucket of water and take a tea spoon out every day - the water will last a long time.

If you punch a hole in the bottom of the bucket the water will drain out quickely.

kelseymh (author)2017-06-10

It has a total energy capacity of 225 mAh. The discharge rate on that data sheet is "220 uA". That is the maximum current you can draw if you want to get the full energy capacity out of the battery without extra losses (heating). So if you can limit your load to <= 220 uA, the battery will last 1023 hours (225 mAh / 0.22 mA = 1022.73 h).

If the battery is connected to a larger load (500 uA, 1 mA, whatever), not only will the battery discharge faster, it will discharge _even_faster_ than you'd expect from computing capacity/load: draw half a milliamp, and you'd expect 225/.5 = 450 hours. But in fact you'll probably only get about 200 hours or so, because of heating (ohmic) losses.

steveastrouk (author)2017-06-09

Depends on the load !

seandogue (author)2017-06-09

It depends on what you're using it for. If used for it's original purpose (as a backup battery for memeory and similar very low load circuits, no. If used to power a lamp or some other power hungry device, quite possibly, or even quicker.