SmartThings button with external power issue

Hello there,
I have a SmartThings button that I press 3-4 times daily and my battery typically dies in 2-3 weeks at maximum. As this is quite annoying, I removed the 2450 battery and soldered a cable to power it externally. Now I am using 2 3000mah 18650s with a converter to step down the voltage to 3V and still it lasts 1 month before I have to charge the batteries.
Does anyone have an idea why it is consuming so much battery?
P.S. The button has temperature reading and from the forum I have read people are using a DTH to increase the period between readings to conserve extend the battery life. I have tried integrating the DTH but I am not smart enough to make this work. Nevertheless the 2 18650s should power it for much much longer even with frequent temp updates.