Replacing the old battery on rechargeable bike lights

Hello! Recently I needed bike lights for my bike. And I remembered that I already had rechargeable bike lights that I bought ten years ago, that I hadn’t tried in a long time. I tried to recharge them, but after fully charging them, they only worked for maybe 5 minutes before they turned off again. I don’t know much about electronics, but I’ve been curious about whether it’s possible to fix old electronics for a long time, and this seemed like the perfect repair project because I might just need to replace the battery. So I went to the local queer makerspace where I’m a member to use the soldering iron and try to do it! I don’t know much about electronics and this post does not contain any safety advice because I don’t know much about safety. I think it’s nice to do projects in a community space where you can get help. step 1: cut it open The bike light felt like it was made of silicone, so I cut open the silicone in a haphazard way along something that vaguely looked like a seam. I…