24V SuperCapacitor Charged
$2 for 10 PCBs & 24 Hour Production: https://jlcpcb.com
24V Supercapacitor (9x 2.7V capacitors in series) charged using boost and buck converter bench power supplies. Protection circuits thermally imaged and lots of talk about backfeed through the PSUs.
24V Supercapacitor Module on Banggood: https://ban.ggood.vip/8ssx