I just picked up a H9 ESV myself. It's odd that you would get a lower reading with a multimeter as the ESV *does* load the battery, which should make it's reading lower than the multimeter's reading.

Just to test the accuracy, I plugged my freshly charged receiver pack into the ESV and got a reading of 5.4V. While still plugged into the ESV, I put the probes of my Fluke meter across the ESV probes and got 5.4V as well. At least mine is accurate then.

Cary