Holder for 14250 batteries in ICAS smoke detector

cults3d

This Norwegian ICAS smoke detector shipped with a soldered-in 10-year lithium battery consisting of 3 3.6V primary cells. It's the radioactive type, and will get less sensitive to smoke over time; but they don't seem to make that kind anymore, so now I use it as a supplementary smoke detector alongside an optical one. (Each type has advantages and disadvantages, so it's good to have both.) The battery got weak after 9 years, and I figured maybe I could replace the batteries with lithium ion cells, and recharge them periodically. (We actually do test the smoke detectors once or twice a year.) So we'll see how this goes... anyway here's a battery holder for 3 of the half-AA size cells like these https://www.aliexpress.com/item/Free-shipping-10Pcs-1-2AA-Battery-CR14250-14250-CR-3-7v-300mAh-Lithium-Battery/32817308573.html?spm=a2g0s.9042311.0.0.70524c4daMCZSs It's also possible to buy individual battery holders like these https://www.aliexpress.com/item/10pcs-Black-Plastic-Battery-Box-Container-Storage-3V-Batteries-Holder-Case-Wire-Leads-For-14250-Battery/32823590146.html?spm=a2g0s.9042311.0.0.70524c4daMCZSs but there isn't enough space inside my smoke detector to install 3 of those, so I ripped out the contact spring from one of them and reused it for this design. If I did it again I'd use the cheap spring plate contacts like these https://www.aliexpress.com/item/100pcs-Battery-Battery-shrapnel-AA-or-AAA-battery-spring-5-No-positive-and-negative-contact-pieces/32881285245.html?spm=a2g0s.9042311.0.0.70524c4daMCZSs but this design works for this purpose anyway. For the "knob" end of the battery, I just wrapped a couple of turns of solid copper wire through the little holes, bent them down and soldered them to the board. I managed to use the original solder points on both ends, it fits perfectly. The "remix" consisted of taking thing:2616101 by stylesuxx, making the ends a little thicker, and adding cutouts for the spring contact and for the wrapped-wire contact on the other end.