I thought this would be a quick calculation, but there were some snags. A good exercise though!

The V3 manual uses a draw of

**0.75 amps** in their battery life calculation (assuming A/D is on and phantom is on).

https://www.gracedesign.com/support/manuals/v3_manual_RevE_online.pdfThe DR-680 manual says that phantom draws 3 mA per channel, which is just wrong. But they give run times for Eneloop NiMH batteries (2 Ah capacity), and from there, we can get to the current draw. They say 4 hours with 6 phantom channels, which would be 2 Ah / 4 = 0.5 amps. Without phantom power they say 5.5 hours which would be 0.364 amps. [So the difference of 0.136 amps across 6 phantom channels would be about 23 mA of extra current per phantom channel.]

https://tascam.com/downloads/products/tascam/dr-680mkii/e_dr-680mk2_om_vb.pdfSince we’ll be using a TalentCell battery to feed both 9V to the V3 and 12V to the DR-680, the calculations are smoother if we convert the amps to watts:

V3 draws 0.75 amps at 9 volts = 6.75 watts

DR-680 draws 0.5 -or- 0.364 amps at 12 volts = 6 watts -or- 4.36 watts

Combined, the V3 and DR-680 use

**12.75 watts -or- 11.11 watts**The smaller TalentCell battery has a 100 Wh capacity. The manual says that you’ve got 25% left when it goes to one light. Using that, the run time should be

**6.75 -or- 5.88 hours** depending on whether you’ve got phantom power turned off or are using it on all 6 channels on the DR-680. I’m guessing that you could push it another hour or so without a problem.

The larger 132 Wh TalentCell battery will give you about

**8.9 -or- 7.8 hours**.

I run the larger TalentCell with 2 channels of phantom power on the DR-680 at festivals and in theory I should get 20 hours down to one light. That sounds about right, since I rarely get to two lights when running all day.