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Measuring Voltage with an Inverter | 9 comments (9 topical, editorial)
Re: Measuring Voltage with an Inverter (3.00 / 0) (#1)
by commanda (alwynne at unwired dot com dot au) on Thu May 15th, 2008 at 12:24:09 AM MST
(User Info)

The inverter is a switch-mode device, so it will be switching on and off really really quickly. The battery voltage will be going up and down slightly as the inverter draws current and then doesn't. Your multimeter can't get a reading because it is seeing this noise.

What I would do is; find a capacitor and connect it in parallel with the multimeter leads, at the meter. Pull the leads out of the meter, stuff one pigtail from the capacitor into each socket, then push the lead back in. Best bet somewhere from 100nF to 100uF.

Your mileage may vary.

Better multimeters (Fluke) tend not to suffer this problem.

If that doesn't work, try adding some series resistance in one lead. Assuming it's a digital meter with a 1 Megohm input impedance, anything up to 10K should help the filtering without changing the actual reading by enough to worry about.

Amanda



Re: Measuring Voltage with an Inverter (3.00 / 0) (#2)
by Flux on Thu May 15th, 2008 at 12:42:18 AM MST
(User Info)

I think you will have trouble running a 1kW inverter from a few 5Ah batteries, the battery current capability will not supply the peak current of the inverter.

Similarly a few 5W panels are not going to run the inverter for many minutes a day.

Diodes will worsen the problem by adding a volt drop in addition to that caused by the limited battery capability. The inverter when connected and not running will store some charge in its input capacitors but the effect will not happen when running.

Try Amanda's tricks to make sure the meter is reading correctly but expect very low volts from those batteries driving a big inverter.

Flux

[ Parent ]



Measuring Voltage with an Inverter | 9 comments (9 topical, 0 editorial)

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