Electronic – How to protect Li-Ion battery from a defibrillator pulse

batterieslithium ion

I'm working on a design where the rechargeable Li-Ion battery is placed closely (attached with a magnetic connector) to a body-worn contact. The concern is that in an event of a defibrillation, the voltage could arc to the battery contacts on the connector and cause an issue. One of the ways to ensure this doesn't happen is with an air gap of 4mm or more (for 4000V). However, since this device is intended to be small, a 4mm gap is a huge hit so I am looking for an alternative solutions. The device doesn't have to survive the pulse, just has to prevent the battery from getting damaged / exploding. I've thought about using PTC fuse to limit the current to the battery along with some ESD diodes but am not entirely happy with that solution. If you've dealt with something similar or have a better approach, I would love to hear it. Thanks!

Best Answer

Seems defibrillator currents are relatively modest (a few tens of A) so maybe you could limit the voltage with a gas discharge arrestor or TVS, and having the voltage limited could then limit the current with something like a pair of MOSFETs.