I guess your problem is that your model requires scale animations for that charging style.
Not sure, but I guess Blender also supports scale animation.
I just did a quick test in my blender. I made one small object, scaled it and then added the 3d cursor at the back of that object and turned on "Manipulate Center Points".
Then went in Animation Tab, inserted a keyframe called LocScale, then set the animation slider forward by 10-15 steps and then I scaled the object, where the pivots are also with the 3d cursor, then again went in Animation Tab and same inserted the key frame - LocScale.
1. This is the original object.
2. The object is now scaling and animating (watch the animation slider)
But I guess my idea is not brain storming. :/