Yeah, I got mine out after a few years. It lost sensitivity as magnets do, and I didn't want to pinch a nerve. They have new ones that are much slimmer now, but also much more difficult to remove...I passed.
We actually do have promising 'batteries' for this sort of application as of 2017, though; lithium hybrid supercapacitors. They're roughly an order of magnitude worse than Li-Po batteries today, in energy density and cost. But the advantages over LiPos are a higher ~10C charge/discharge rate, no thermal runaway "Galaxy S7" issues, and a maximum charge retention rate on the order of 80-95% after 10,000 cycles should let them last decades at least. A very compact 100F/24mAh module is available today at 1.8-2.7V from Murata, and I think Taiyo-Yuden has offerings too.
I think we're still making progress. Anyone buying one of those magnets knew they were buying into an alpha version of a product; it's not like we asked the FDA to approve things first.
Not a good choice for implanted batteries, but possibly the replacement for the power storage unit for EMALS. The electromagnetic catapult on the Ford-series carriers apparently works fine; it's the flywheel energy storage system which powers it that's giving trouble. They need something they can charge up in a minute or so and then discharge in a few seconds. Ultracapacitors are starting to look good compared to the flywheel thing.
We actually do have promising 'batteries' for this sort of application as of 2017, though; lithium hybrid supercapacitors. They're roughly an order of magnitude worse than Li-Po batteries today, in energy density and cost. But the advantages over LiPos are a higher ~10C charge/discharge rate, no thermal runaway "Galaxy S7" issues, and a maximum charge retention rate on the order of 80-95% after 10,000 cycles should let them last decades at least. A very compact 100F/24mAh module is available today at 1.8-2.7V from Murata, and I think Taiyo-Yuden has offerings too.
I think we're still making progress. Anyone buying one of those magnets knew they were buying into an alpha version of a product; it's not like we asked the FDA to approve things first.