Electronic – Are there general guidelines for LiPo discharge current

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I'm doing a hobby project where I'm designing a smart RC car around the size of a mini sim card. The BOM has been narrowed down, and I reckon it's doable with a 4-layer board.

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Image source: https://www.gsmarena.com/glossary.php3?term=sim

I'm now doing research on possible batteries to use. I'm eyeing the Panasonic CG-320 (15 mAh rated) or this 70mAh LiPo battery. Both are well within my size targets, but I'm unable to find any datasheets that specify a maximum discharge current.

For reference, my power budget is less than 5mA when sitting idly, less than 100mA when running around, and 300mA worst case (e.g. in case of motor stall).

Are there any rules of thumb regarding discharge? Based on what I've read, a maximum current of 0.75C for charging is ideal, but I'm unable to find any figures for the other way around.

Best Answer

Discharge is rated in "C" for example if your selected battery states 20C the maximum discharge is 20 * Battery capacity.

One of the reasons LiPo batteries are used in RC projects is the fact they can normally handle a high C rate (They can deliver a punch to the high-power motors).

If we look at the two options, you provided

Panasonic CG-320 - I've found a more detail breakdown of its specs here - LINK

The highest diagram they shown details a max discharge of 1C, they also mention in the handling guidelines to not let the battery voltage drop below 2.7V so you may need to do some voltage monitoring to be safe. Annoyingly thats the only mention I can find of discharging, so from that you could possibly assume the max discharge is 1C.

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The 70mA Battery you linked has basically no technical documentation I'd recommend looking for a better documented version. Without a datasheet its impossible to know whats safe.

A better documented alternative would look like this Farnell LiPo this part has a datasheet with all the info you need here - Datasheet. I would recommend looking around the high end suppliers, Digikey, Farnell, RS & Mouser they generally require suppliers to provide proper technical documentation.