diff --git a/README.md b/README.md
index 6057792..7ad9be8 100644
--- a/README.md
+++ b/README.md
@@ -63,6 +63,10 @@ design choice
 changelog
 =========
 
+sometimes there is a battery connection issue.
+this is because the CR2012 hole is small, and the HASL is thinner as the silk screen.
+this has been fixed by making the pad larger, and adding the solder paste (not sure if this is a good idea for such a large pad though).
+
 v2
 --