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Appendix A - Hardware Versions

There are two different hardware versions for the Digit-TL/TLH. The primary difference is that the current version has an easily replaceable CR1632 battery, and the old version has a solder mount battery which required a soldering tool for replacement.  Hardware version 1.11 is no longer in production, as v1.20 is a fully compatible improvement.  They are both compatible with Otero(software), and should be considered interchangeable.

Hardware version 1.20 on the left, and v1.11 on the right, the table below describes the notable differences.


Hardware v1.20

Hardware v1.11

Battery style

Replaceable CR1632

Solder mount BR1632

Battery life

140mAh (3.3yr)

120mAh (3.0yr)

Operating temp (T, L)

-35 to 85°C

-35 to 85°C

Operating temp (H)

-35 to 85°C

10 to 85°C

Humidity slope stability



Default enclosure

Clear plastic*


Al Enclosure Orientation**

USB opposite to keyring

Either orientation OK

*  The clear plastic enclosure includes both a vented and watertight base option. Unlike the aluminum enclosure, the clear plastic enclosure allows the device to collect light readings. The rugged aluminum enclosure can be purchased as an add-on item.

** Both hardware versions fit inside the aluminum and clear plastic enclosure variants, but the battery holder makes HW 1.2 a bit too large to fit both directions in the aluminum case. The aluminum enclosure is watertight and airtight, so response time of the Digit temperature readings is not impacted by orientation within the case.

Some comments about old hardware (v1.11)...

The battery in HWv1.11 was a 120mAh Panasonic BR-1632A, and can be found on DigiKey, part number P022.  With a soldering tool it is possible to both replace the battery, or install a different battery.  

Note: If extreme harsh temperatures are expected to last for a long time, a custom battery can be installed to handle the conditions. Acceptable battery voltage range is 3.0V to 3.6V.  Our top pick is a Tadiran TL-5101/P, which will work continuously for more than 3 years at even the most harsh of conditions (-55C to +85C).  The Digit shown below is stored inside our office refrigerator.

On old Digit-TLH devices, the humidity accuracy below 10°C was subject to battery voltage.  Often times the battery voltage would drop at cold temperatures, and the humidity readings were low if the battery voltage was less than 2.73V. Humidity readings on new hardware (v1.2+) operate normally over the full temperature and battery voltage range.

When the Digit is connected to a powered USB port, battery usage is suspended.  Therefore, it is possible to prolong battery life by connecting the Digit to a 5V USB adapter, or USB hub when it's not being used.  Another good method to prolong battery life is to disable all log items when the Digit is not in-use.  When nothing is being logged, it stays in a low-power sleeping state.

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