Jeezzz...talk about a timely thread. I just changed batts in my Lavatube, and for the last 30 minutes I've been hearing a 'squealing hum'. Thanks to this thread, I just realized my AW IMR 18650 3.7V 1600 mAh battery is the culprit. As mentioned above, I'm using a Trustfire TR-001 charger.
Taking the battery out of the charger, the sound stops; put the battery back in the charger, the squealing hum begins.
The batt was almost out of juice when I put it on the charger, but now after about 45 minutes, the squealing hum is going away.
These batteries are about a year old, but still hold a pretty good charge. Even so, I believe I'll be ordering some replacements pretty quick.
Thanks for the heads-up, guys! (All is now QUIET in the charger. Think it's because the charge on the batt was so low???)