I agree, it would be nice if all DVM readings were the same. The problem with inexpensive voltmeters is not only their room-ambient accuracy, but also that changes in temperature and large voltage excursions result in varying readings.
Most voltmeters have a potentiometer that can be tweaked, maybe even two pots for gain and offset. In my case, I have a good calibrated standard DVM that I use to 'calibrate' the cheap DVMs at their nominal operating voltage at the temperature they're used in most of the time. 'Good enough' for the job at hand with lead-acid, although Lithiums DO demand precision if pushing their operating limits.
Merry Christmas to all!
JoeS.
On Dec 15, 2014, at 10:46 , king_of_neworleans wrote:
> LED panel voltmeters and also the cheap DVMs I have used are all over the place in accuracy. Or I should say, inaccuracy. I mounted one unit right on my control box, along with a tachometer. I ended up assuming a fully charged bank is 50.9v open circuit after resting for 6 hours, and comparing that to the meter reading, for an approximate correction to the meter. This doesn't sit well with me. I would much rather have a digital panel voltmeter that is accurate and reads to the hundredth of a volt, or at least one that reads to the tenth and is adjustable, so I don't have to do so much arithmetic figuring my state of charge. Sure, I could pay several hundred bucks for a Fluke, but my budget is just too tight. I don't want to use an analog meter on my control box because moving the box disturbs the meter movement. Even the motion of the boat disturbs an analog meter.
>
> So what does everyone else use for a voltmeter?
>
Posted by: Joe Siudzinski <siudzinski@telis.org>
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