Tim, the 3914 is a linear device, the 3915 a logarithmic. The latter is more useful for audio level monitoring.
The LM3914 chip as is goes from none to all 10 LED's lit when an input at pin 5 (18 pin DIL packake) goes from 0 to 1.2 V. You need a voltage divider to drive it from higher voltages.
In your case, you would have to adjust this divider for different input ranges, use a trim pot (or several switch selected ones) as a voltage divider.
You can use either bar or dot mode, bar mode dissipates more power of course.
I used three chips cascaded for a 30 LED tacho display, ran the chips & led's from a 5 V regulator to avoid the hassle with fluctuating battery voltages.
Klaus