A quick measured runtime test

A project log for Upgrade-Ready Virtual Reality Backpack

Stuck between the choice of mobile, low power VR and stationary, PC grade escapism, the best choice was clearly to mash the two together.

serverrorServError 10/27/2019 at 19:540 Comments

With an inexpensive power meter finally in hand, I did a quick single battery runtime test (dual battery test to follow).

The pack uses ideally 7000mah cells. I decided to do a run down test bringing the cells down to about 3 volts under load, even though I know I have the headroom to go further. This test cheats a bit by not using the VR headset, which shaves off maybe about 4 watts of added draw from the hardware and potentially a bit from increased CPU/GPU usage.

The pack is recharged, I use the watt meter's balancing feature to passively even out the cells a bit further, and then use my charger to see if the pack needs any topping off (not really). All cells are brought to 3.6 volts which is the max I'm planning on using for the life of these packs. I could go to 3.65 per cell but don't feel that it's worth the minimal gains.

Lets load up No Man's Sky, a title that has taken way too much of my VR time, and set it to coast around a planet to approximate the load of normal gameplay.

I hit exactly 5Ah at 1 hour in, as well as my 3 volt cutoff.

Shutting the PC down, my cells returned to a 3.2 volt rest and the gas gauge believes that about a third of the pack life is still there (there isn't, but I'm not planning on trusting this gas gauge anyway).

Putting the pack back on the charger, the pack takes about 4950mah to return to full charge, verifying my readings above.

Next up will be the dual battery test, which with the distributed load should hopefully net me a nice little bonus rather than just doubling my runtime. Stay tuned.