nanoKenbak-1 RTC battery dead

[Thomas R.]

My nanoKenbak-1's RTC battery seems to be dead. Just shows between 0.4 and 0.5 V.

Is it possible to replace that battery?

[Randy E (OoMOR)]

While I do not have a nanoKenbak-1, the picture of one seems to show a standard 2032 Coin Cell in a standard holder, so it should be easy to replace. These 2032 cells are very common, and can be found at almost any grocery, hardware, pharmacy, or other general purpose store.

Randy

[Vicente González]

Replace it with another 1616 Battery with Solder Tabs:
https://www.amazon.com/SKOANBE-Battery-Lithium-Batteries-Cartridge/dp/B0DJKSJDNN/ref=

On Wed, Jun 18, 2025 at 9:32 AM Thomas R. <samoht...@gmail.com> wrote:

My nanoKenbak-1's RTC battery seems to be dead. Just shows between 0.4 and 0.5 V.

Is it possible to replace that battery?

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[Thomas R.]

Thank you, this seems to make sense.

Hope I can get the old battery out without destroying the whole thing...

[Randy E (OoMOR)]

Oops, sorry! I missed the picture of the back showing the RTC battery. 

If it was me, I would use snips to remove the failed battery while leaving the tabs soldered in place. It should be much easier to remove the individual tabs by grabbing onto the snipped end with some needle nose pliers or tweezers while heating the joint with a soldering iron. Once the tabs are removed, clean off the remaining solder with some flux and desoldering braid. 

Good luck.

Randy

[Cuvtixo D (cuvtixo)]

Definitely DON'T do that!  It's LIR2032.  It will fit a CD2032 perfectly, but it will probably completely discharge a CR2032 in about 30 minutes, and if you connect to USB, you run the risk of an explosion. "Seriously, don't do it. Ever." -Adwater&Stir      Also the CR1616 battery in back has an estimated lifetime of 10 years.  Something else is going wrong, if it needs replacing at this stage.

[Vicente González]

I have an earlier model of the nanoKenbak-1 and the RTC battery was depleted, it differs from those in the current versions.
After desoldering it, I noticed that I actually liked how the nanoKenbak sat flat on the table without the battery in place. That got me thinking—it might be worth relocating the battery entirely.
Eventually, I tried an idea to eliminate the need to replace the battery. I connected the clock chip (a DS3231) to the lithium battery using a Schottky diode and  a capacitor.
I then began testing the setup by removing and reinserting the Lithium-ion Coin battery (LIR2032) to see whether the capacitor could maintain the time during those short gaps.
I found that if I replaced the battery in under 15 seconds, the clock continued to keep time without issue. If I keep the battery removed for a few minutes, the clock stops but the time is not cleared.
I recorded the lithium battery's voltage decay over 40 days of powering the RTC. The battery lost 70 mV, and the time remained accurate.
Today, after a month and a half in the box, I checked the time and it is still correct.
I'm adding a picture of my modification and another one showing what it would look like on the current nanoKenbak-1.
NOTE: This may be a way to void any warranty the product has. :)

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