… or drill baby drill :>
Intro
In the 90s a lot of computers used Dallas modules as an RTC solution. These modules have an internal battery cell which in 2025 is simply a dead cell. This results in a “CMOS battery failed” error thrown at us during the boot process and renders clock setting impossible.
HAX
The solution is to add an external and replaceable battery cell. I’ve found lots of info about it on the internet. Below, you can find my approach to that issue.
The module has to be desoldered first.
Marking drilling lines.
To remove the material, I am using Dremmel ball-tips.
The internal battery has only a 0.44V charge.
A bit of IPA to clean it.
A bit of flux in preparing it for soldering.
And a bit of solder.
Next, two wires are soldered in place along with a CR2025 battery tray and contacts are secured with an epoxy glue afterward.
Module reinstalled and tested.
Tadaa! The CMOS error is gone 😀
Bonus mounting examples.
Outro
That’s all in this short post. Consider subscribing if you want to get an email notification about fresh blog posts.
See you in the next post 🙂
Hax Completed. Awesome!