Stable voltage divider circuit

Sure there is a better way. I'm not sure if you need a reference voltage or a regulator but you can use a TL431 to get 5.00V. The TL431 is cheap yet very precise and stable, I use to read 4.99V with power supplies using it as a reference.

Tom

There are better ways, but you don't need them. Regular metal film resistors have temperautre coeffiicients of 50ppm/C. Two combined give a worst case error of +/-100ppm/C which is 4,000ppm or 0.4% over 40C, almost exactly the resolution of your 8-bit A/D converter (one part in

It you wnat to do better, you can buy +/-15ppm/C metal film precision resistors off the shelf from broad-line electronic distributors like Farnell, who also stock thin film precision dividers which offer ratio temperature coeffiicients down to about +/-5ppm/C.

For the sort of divide ratio you'd need, the dividers cost about $5 apiece - about twice what you'd pay for a pair of precision resistors.

It depends on the bike voltage and the scaling factor of the attenuator to make it fit the full scale A/D range. The A/D range is fixed at 5V and measured with approximately 0.02V maximum error. If your input scaling is S then your scaled reading error will be S*20mV, making maximum allowable S=2.5 for maximum battery voltage range of