Rob Dobson had been wanting to make some electronic jewelry for quite some time, following on from some experimental BLE pendants back in 2015 or so. But a big question has always been how best to power them.

LiPo batteries are obviously an option for something of reasonable size like a pendant and coin cells are commonly found in jewelry sold on Tindie. Super-capacitors (super-caps) are a viable option for very simple designs, but physically small super-caps don’t have enough capacity for anything more complex.

While investigating other options, Rob came across Li-Ion Hybrid Super-Capacitors (from Eaton, Vishay and some other companies) and alighted on some promising devices in the Vishay 196 HVC ENYCAP range. The smallest of these claim 4 Farads of capacitance in a package which is only slightly bigger than a 0.3 F super capacitor and the potential looked interesting enough to make Rob want to investigate further.

I feel that the device is close to being useful for my purposes but unfortunately not quite close enough. I think a current budget of 5mA is at the lower end of the useful range for jewelry with flashing LEDs, a processor and maybe some comms. A working life of 25 minutes at this current draw is a bit too short for my liking.

If I could double one or both of these numbers, I’d be pretty happy but, unfortunately, unless I can find a way to achieve my jewelry goals with a lower current budget, I don’t think hybrid super-caps are going to be the ideal solution for my jewelry projects.

Read all the details in the post here.