Cloning a Sennheiser BA2015 battery pack
Frustrated by the exorbitant price of Sennheiser's BA2015 battery packs, which contain little more than two standard AA batteries and a cheap sensor, the author embarked on a reverse-engineering quest. This deep dive reveals corporate markups and culminates in a detailed guide to 3D printing and assembling a DIY replacement. The story celebrates the hacker ethos of understanding and building, even if the final product isn't perfectly polished.
The Lowdown
The article details a highly critical and hands-on investigation into the cost and design of Sennheiser's BA2015 battery pack, a seemingly simple component sold at an outrageous price. Frustrated by the high cost of official and even third-party replacements for his wireless microphone batteries, the author embarked on a reverse-engineering and DIY journey to create his own.
- Exorbitant Pricing: Sennheiser sells the BA2015 battery pack, containing two standard NiMH AA cells and a temperature sensor, for $80-100, despite the internal components costing only a few dollars.
- Sensor Deception: Sennheiser claims the pack has an "integrated sensor" for status, temperature, and preventing non-rechargeable battery charging. The author reveals this "sensor" is a mere $0.02 NTC thermistor, with most "smart" functions handled by the microphone's own circuitry.
- Teardown and Discovery: A destructive teardown of an original pack revealed two welded Panasonic NiMH cells (one flat-top, one button-top) and the NTC thermistor connected to a third contact, which is the actual mechanism to differentiate it from standard AA batteries.
- DIY Cloning: The author designed a 3D-printable case using OpenSCAD, optimizing it for printability and strength. He sourced new NiMH cells and the NTC, then assembled the pack, using a bent paperclip for internal connections.
- Cost Savings: The DIY approach reduces the cost per battery pack from $80-100 (Sennheiser) or $20-30 (third-party) to just a few dollars in parts.
While the DIY cloned battery pack isn't as robust as commercial versions and requires significant time and effort, the project successfully exposes Sennheiser's excessive markup on a simple product. The author concludes that it's a testament to how companies can overcharge for basic components and demonstrates that economical alternatives are easily achievable.