I tried to trickle charge a 5 cell MaxAmps 1400 mAh pack on my Intellipeak Pulse and it makes this low pitched buzzing sound. If you try to peak charge it (even @ .5 amps), the buzz becomes a higher pitch.

On a std. 110v wall charger it does not make any noise...I've charged & used this pack before and it seems to work fine. This was the first time using in on the other charger. I charged my Ballistic 1400 hump pack on the Itellipeak charger and it made no noise at all....(this I assume to be normal)
The MaxAmps pack is a 5 cell flat pack and you can feel the buzzing at the center cell on the flat tab side (not sure if that is relevant info or not)

Any idea of what's happening here??