To replace or to recharge, that is the question when it comes to battery powered devices. I have switched most of my small devices to rechargable batteries (the only exception is devices where Felix is suspected to kill/drop the battery powered toy) and in general I strongly dislike devices with built-in irreplacable batteries, where you are supposed to throw away/recycle perfectly working electronics just because the battery has discharged or can’t be recharged anymore.
One such example is a Chipolo Card (1st gen) which has an odd battery (CP113130, which can be bought from China in minimum quantities of 100 batteries…) It is a 3 V battery so I replaced it with a USB to 3 V converter (a few euros on Amazon or AliExpress). That works fine but since USB battery packs typically disconnects the load if it is regarded as “too low” (typically somewhere below 100 mA) one needs to either add extra load, get a pack without where such “intelligence” (check Voltaic) can be disabled, or put an adapter between the power source and the consumer that keeps the battery pack online with a quick “ping load”.
I went for the latter option since the Voltaic packs were hard to find with delivery to my place. For those who wants to solder themselves, this is a comprehensive guide with an option to buy the parts you need. Maybe I do that later if I need one more. There are many DIY projects at Tindie and I got one of them. After putting that “pulse generator” between the battery pack and the USB 5.5 V to 3 V converter, the Chipolo Card works as expected. After a few days the battery pack is down from 100 % to 75 %. The USB battery pack can still be charged and used as a normal battery pack since the pulse generator is not blocking the other USB ports.
Not the most beautiful installation I have done in my life but still better than throwing away a perfectly working Chipolo. 🙂