I’m finishing my latest Gem project and need to decide which motor to run . The big 3 motors are the G.E 7hp , Advanced 7hp (8 brush) and the 7.5hp Rife 4 fun . I have ran all 3 motors but never in the same Gem or with the same battery pack . So i decided to do a comparison of all 3 in my new Gem . Into the parts closet I go .
The Gem is a 2014 e4 with 1,000 miles on it . It has a 10.35 trans , 24.2" tall tires and a 27s Lifepo4 battery bank (about 92v) . With a 5hp GE motor it would easily go over 40mph . I let others drive it so it is limited to 37mph .
With the smaller motor , the controller was set to drop field current at higher rpm to increase power in the upper rpm range . With these larger motors I slightly increased minimum field current at high rpm . This drops the armature current which will increase torque and consume less power . My number one goal is fast acceleration . With the large diameter tires and low gear ratio to over come , this thing needs lots of torque to get the acceleration i’m looking for .
The R4F motor weighs 46lbs , The GE 7hp weighs 57 and the Advanced 8 brush weighs a hefty 65lbs . One thing for sure my back is going to hate me when this is over