I'm using a digital multimeter to check the voltage on my motorcycle battery - I'm attempting to confirm the proper installation of a new alternator in the charging system.
The voltmeter has 3 ranges that I'm using: 20V, 200V, and 500V.
With the engine off the battery reads ~12.8V on all three ranges. But with the engine on (and hence the charging system going), the battery reads different voltages using each range:
- 20V range jumps around from 0-15 volts
- 200V range holds pretty steady around 17.5-18V
- 500V range jumps around from 40-100V
The multimeter is a brand new Equus Innova 3300: http://www.walmart.com/ip/Innova-3300-Equus-3300-Hands-free-Digital-Multimeter/14644665
I'm not expecting this community to diagnose the motorcycle issue, but does anyone have any idea what electrical behavior could cause these readings in the multimeter? Why would the readings be so different at each range?
I checked all the diodes in the rectifier (3-phase rectifier, 6 diodes), so I don't think any AC current is getting through to the battery/multimeter, which was my first thought here.