|
I just can't help myself, guy.
You're right, I think, if you're saying it wouldn't hurt to run the wires out to the battery for an accurate measurement. Or at least, a repeatable measurement; accuracy is not a strong point with these OEM gauges.
The current drawn by the voltage gauge (50mA) is about 1000 times greater than the residual drain used by the radio and ecu memory not counting the 5mA once-a-second spike used by the clock. What might surprise you, is it is half that used by the 1.2W lamp that illuminates it. I was lazy about wiring the lamp, so that would have been 150mA for me.
Auto batteries are built mainly for cranking, so amp-hour ratings are difficult to nail down for long-term small loads, a performance they are significantly derated for. So a typical 50 amp hour rating that will run your left-on 10 amp lighting for 5 hours won't necessarily keep your 1 amp dome light pair on for 50 hours. To run the Volvo voltmeter for 10,000 years you'd need 10000 * 24 * 365 *.05 = 4,380,000 amp hours in that battery, er atomic pile.
So, I figure if you connect it to a good battery, you'll need to jump it if you leave it parked for about four weeks. 'Course if you wire it through the switch, you could probably get away with parking it for a month. (smile)
--
Art Benstein near Baltimore
|
