This innovative USB-C rechargeable battery pack brings your vintage HP calculator back to life!

Replacement for HP 82120A

I was tired of having to constantly buy new N-Size batteries and was also not satisfied by the amount of charge in the standard rechargeable pack, so I decided to design one to use in my HP-41 series calculators.

UPDATE: I have implemented an improved DC-DC circuit that lowers the unit's output voltage to ~3.3V when the LiPo battery nears the end of its charge so that the BAT-Annunciator of the calculator is triggered. When the BAT-Annunciator is triggered the battery will run another 20-30 minutes before completely shutting down.

This brand-new, professionally 3D-printed battery pack is specifically designed for HP-41C/CV/CX/CL calculators.

Features:

• USB-C Rechargeable: Ditch the disposable batteries and enjoy the convenience of modern charging. Includes a USB-C cable for easy connection to any USB power source (USB adapter not included).
• Long-lasting Power: Equipped with a high-capacity Li-Po battery, this pack provides around 50 hours of continuous use for your HP-41 calculator.
• Fast Charging: Recharge the battery in approximately 1.5 hours using a USB-C wall adapter (not included).
• Durable Design: Professionally 3D printed in Nylon for a strong and lightweight construction.
• Easy Installation: Simply replace the original battery compartment with this custom-designed pack.
• BAT - Annunciator support: Indication of near-empty battery is working

Notes:

• Charging: While the battery can be charged inside the calculator, for optimal lifespan, I recommend removing the pack for charging.
• 3D printed note: The 3D printed case may have slight cosmetic variations due to the printing process. Functionality is not affected.
• Performance: Some modules can decrease the stand-by time. Notably, the NoV-64D module consumes 15 mA even when the calculator is in standby mode. Also, the power consumption of the HP-41CL is significantly higher than that of a standard HP-41C calculator.

What's included:

• 1x USB-C Rechargeable Battery Pack (3D printed in Nylon)
• 1x USB-C Charging Cable

Give your beloved HP-41 calculator a new lease on life with this eco-friendly and convenient rechargeable battery solution!

Please note: This is an aftermarket product not affiliated with Hewlett-Packard.

Compatible models:

• HP-41C
• HP-41CV
• HP-41CX
• HP-41CL

Don't wait - upgrade your HP-41 calculator today!