amertahir

I had similar issue, but I was using Synergy Digital version of the BA2015. The issue I faced was that the +ve terminal of the BA2015 wasn't touching the +ve metal tab on the SKM's battery compartment. So I broke off the plastic case of BA2015 and removed only the +ve side plastic to remove the spacing. After that, I inserted it into the SKM and works fine. It turns out the Sennheiser BA2015 is basically a NTC 10K 3950 thermistor connected with the -ve terminal of a standard Panasonic rechargeable NIMH and to the middle metal contacts in the SK/SKM battery compartment. I just tested Panasonic Eneloops connected to the thermistor I extracted from the generic BA2015 battery pack and put it in my SK100 G3 bodypack. It charges just fine on Sennheiser L 2015 charging station. I hope that helps.

Reviving this super-old thread hoping someone would get some benefit from my experiences. I was able to open up a replacement BA2015 battery pack and understand what is the extra chip/sensor they've used to make NIMH battery chargeable with the Sennheiser L 2015 charger. It turns out it's a pretty standard NTC 10K B 3950 1% Thermistor (like this one: https://www.ebay.com/itm/402635385350?hash=item5dbef06a06:g:E5kAAOSwqLlf9SNK) connected to battery's -ve terminal and the middle pin (metal contacts that lie between the two -ve spring tabs in the battery compartment) inside battery compartment. You can solder this thermistor between the -ve terminal (bottom one if the battery pack's +ve side is facing right from your view) and the middle pin (it's location described previously). The thermistor doesn't have any -ve or +ve terminals so it can be connected in any way. Then, you can put in any NIMH rechargeable batteries inside and be able to charge the microphone/bodypack with the Sennheiser L 2015 charging station.