One of the problems with converting 1:32 scale farm and plant machinery to radio control is the lack of space to house batteries. You are usually limited to 100 or 200 mAh depending on the model and what you have added. An easy way to get around this drawback is to add extra batteries in your accessories. The Class Butterfly Mower battery pack was one of my first conversion and used AAA batteries which I originally used with my Massey 8680 and Fendt 936 before I converted them to 3.7 V. I have since converted it to house two 3.7 V 650 mAh LiPo batteries so it is ideal for my newer designs.
One advantage to the Class Butterfly Mower as a battery pack is that the weight hanging over the front of the model improves the steering greatly by increasing the traction of the front tires.