SparkFun Forums

[roach]

I'm thinking of using a replacement (OEM) iPod nano LiPoly battery in my application. It happens to be about the right dimensions (39.5 x 23.0 x 4.3mm), with decent charge density (330 mAh). But looking at the battery (image here).

It looks like the battery has three leads, instead of two. Has anyone seen this before? Does anyone know what the third wire is for?

[OldCow]

It could be a temperature sensor signal or something like that to help the charger circuit.

[roach]

Could be, but I'm going to plug this into a MAX1555/1551/1811/whatever, and as far as I know, none of these need temperature sensors... I just want to be sure I'm not cutting off something important...

[ohararp]

Either it is for temperature sensing, resistance measurement, or possible cell balancing (doubt that though). I only offer the third suggestion if the battery was outputting 7.2V, but I doubt it is.

Otherwise you should be fine. Might what to check what type of charge and discharge rating the battery requires (1C, .5C, etc). Where (330 mAh/1000 = C). Multiply C by the value preceding it and you can determine the amperage input/output the battery can give. Microcontroller's operate well at .5C-2C. RC planes can require values much higher; 10-20C are common.

[Philba]

many of the Li chargers use temperature rise to prevent overheating the battery. Having seen several videos of Li battery melt-down, I wouldn't dismiss it so quickly.