Ask HN: What is the most undervalued startup you know?
Bill Gray&#x27;s Velkess project was a superior idea to Tesla&#x27;s Powerwall (IMO!).<p>It is now unfortunately defunct or at least the website says they&#x27;re on hold indefinitely.<p>Here is a youtube video explaining:<p><a href="https:&#x2F;&#x2F;www.youtube.com&#x2F;watch?v=u6I2lKtfpLQ" rel="nofollow">https:&#x2F;&#x2F;www.youtube.com&#x2F;watch?v=u6I2lKtfpLQ</a><p>It was a flywheel battery. A physical battery. It turns electrical energy into kinetic energy (and back on demand) at a very high efficiency rate. If I remember the specs correctly it could supply 15 kwh. I think the cost for first adopters would have been $6500 a unit. Actually here are the full specs from a sheet I got from the website before it went down:<p><pre><code>    Technical Specifcations
    Continuous Power               3kW
    Peak Power (60 seconds)        9kW
    Nameplate Energy               15kWh
    Depth of Discharge             100%
    Interface                      48VDC Virtual Lead Acid Bus
    24h Roundtrip Efciency         &gt;80%
    Expected Service Life          10 years
    Physical Package meter(inch)   1 x 1 x 1 (40 x 40 x 40)
    Weight kg(lbs)                 340 (750)
    Standard Connectivity          Wi-Fi, Ethernet
    Optional Connectivity          CAN Bus, RS-485, Xbee, Powerline, LoRa

    Energy storage systems of any size can be built by linking 2 or more (n) Velkess L systems togetherin parallel. 
    Multiple parallel Velkess L modules will self balance and behave as a single energy storage system with performance equal to (1 module) * n.
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The clever part was that the flywheel (flywheels are dangerous due to the large amount of kinetic energy) would employ a lasso effect to crumple and use its own energy to destroy itself if there was a technical problem.<p>The killer app quality it had was that a flywheel of this sort could theoretically run for many decades without failure. The first iteration had &#x27;10 years&#x27; expected service life but I believe that was being very conservative and it had the capability to last much, much longer.