With the 72 volt wiring completed a computer can be connected to the controllers to do some initial programming and to monitor various functions to determine if all the wiring thus far is correct. The monitoring process led to the discovery that my regen throttle controller (see Regen Controller section) was not able to fully engage the thumb throttle and as a result the regeneration was well below full capacity. The regen controller “worked” in the sense that it did, in fact, engage the regen function, it just didn’t move the throttle far enough to reach full regen capacity. Even with various adjustments to the mechanism I was only able to achieve a little more than half the voltage needed to fully engage regeneration.
So the mechanism was dismantled and, as suggested by some helpful readers of this build journal, a simple lever system was created. Fortunately I was able to use the base plate, cable guide and thumb throttle mounting stub from the original design.
The lever is a 4″ long section of ½” wide 1/8″ flat stock. The bottom hole will be the pivot point. The next hole, 1″ up from the pivot, will be used to bolt on the cable from the brake lever. The top hole, 3″ above the pivot, will be used to bolt on the cable to the thumb throttle. (Photo 1) This layout provides a 3:1 ratio. In theory, the 5/8″ of “pull” provided by the brake lever will move the thumb throttle 1 7/8″. In reality, due to slop in the system and minor errors in measurements, the ratio turned out to be slightly less but it was more than enough to move the thumb throttle it’s full 1 ½” travel distance from 0 throttle to full throttle.
A 1/4″ nut is welded to the pivot hole of the lever. (Photo 2)
A 1/4″ bolt and “lock nut” are tightened securely to the mounting plate and the nut and lever combination is threaded onto this mounting bolt. The lever nut is threaded just far enough so that it is secure but still rotates freely without becoming tight against the lock nut. (Photo 3) This basically functions as a poor man’s heim joint. The lever easily rotates back and forth while remaining stable and secure on its pivot point.
The cable guide from my original controller is bolted to the mounting plate so that the cable will line up directly with the lower bolt. The guide was originally part of a discarded hand brake lever. The upper and lower cable bolts on the lever will have small holes drilled through them so that the cables can be inserted in the holes and tightened. Photo 4 shows the lever position when the thumb throttle would be at rest.
Photo 5 shows the lever position when the thumb throttle would be in the wide open position.
The completed mechanism with the thumb throttle, cable guide and lever installed. (Photo 6) Testing with the controller software program indicates this simple lever design is able to provide full throttle power to the controllers and will provide full regeneration capacity. It also pulls easily with the hand brake lever. So thanks to those who provided me with alternative suggestions for the regen mechanism. This design works far better than the earlier version.