Over the years, I’ve purchased a lot of battery backups. Unfortunately, I now have a pile of them with dead lead-acid batteries. Lead-acid batteries have a short lifespan, even when they’re just sitting around being trickle-charged in a backup unit.

Most of the time, power outages are nothing more than a quick blink—just a few seconds. For that, I wanted a battery backup that I could leave connected to my equipment and basically forget about for years.

A while back, I picked up a few 400F Easton Supercapacitors and have done quite a few experiments with them.

By my calculations, they only have about 1/30th the energy density of a lead-acid battery. To make them usable, I built a couple of banks of six supercaps in parallel. Since each one is rated at 2.7V, the bank can handle up to about 16V.

One issue I ran into was charging them from a completely discharged state. The battery backup struggled to bring them up to voltage when they were totally drained. But once charged, the setup works!