Re: generic-adc-battery volatge-to-percent formula

[Pavel Machek <pavel@ucw.cz>]

Hi!

> 
> it could be something similar to (I might have made a mistake when applying scaling):
> 
> /* calculate remaining fuel level (in %) of a LiIon battery assuming
> * a standard chemistry model
> *    http://cseweb.ucsd.edu/~trosing/lectures/battery.pdf
> *
> * @mV: voltage measured outside the battery
> * @mA: current flowing out of the battery
> * @mOhm: assumed series resitance of the battery
> *
> * returns value between 0 and 100
> */
> 
> static inline int fuel_level_LiIon(int mV, int mA, int mOhm) {
> 	int u;
> 	/* internal battery voltage is higher than measured */

add " when discharging".

> 	mV += (mOhm * mA) /1000;
> 
> 	/* apply formula */
>  	u = 3870000 - (14523 * (37835 - 10 * mV));

	/* linear approximation between 3.756V */

> 	if (u < 0)
> 		return ((mV - 3300) * ((3756 - 3300) * 1966)) / 100000;
> 	return (1966 + sqrt(u))/100;
> }
>

Thanks,
									Pavel

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