diff --git a/README.md b/README.md
index 8897c48..c90ddbc 100644
--- a/README.md
+++ b/README.md
@@ -24,6 +24,11 @@ this will simulate a USB plug with integrated circuit.
 the BUGGED LED should switch on.
 this also ensures the battery is not empty.
 
+when the LED is on, the USB bug detector draws 3 mA.
+when the LED is off, the USB bug detector draws 64 nA.
+this results in a idle battery life of 419 years (for a typical 235 mAh CR2032 battery).
+this is more than the self life of the battery (~ 1%/year).
+
 fabrication
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